Mitigation Assessment Team Report

Hurricane Harvey 

in Texas

Building Performance Observations, 

Recommendations, and Technical Guidance

FEMA P-2022 / February 2019
MITIGATION ASSESSMENT TEAM REPORT

Hurricane Harvey in Texas

Building Performance Observations,

Recommendations, and Technical Guidance

FEMA P-2022 / February 2019
Houston, TX

ISTOCK
Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of 

FEMA. Additionally, neither FEMA nor any of its employees makes any warranty, expressed or implied, or assumes any legal 

liability or responsibility for the accuracy, completeness, or usefulness of any information, product, or process included in this 

publication. Users or information from this publication assume all liability arising from such use.

All photographs and figures used in this report were taken by the MAT or developed for this report unless stated otherwise. Aerial 

imagery noted as “courtesy of the Texas Civil Air Patrol” was obtained by the Texas Civil Air Patrol as directed by FEMA.

All documents were prepared with accessibility and compliance with Section 508 of the Rehabilitation Act of 1973 in mind. For 

further information or clarification regarding items such as technical drawings or maps, please contact the FEMA Building Science 

Helpline at FEMA-BuildingScienceHelp@fema.dhs.gov or 866-927-2104.

Map imagery sources (unless otherwise noted in the report):

Aerial imagery: Google Earth Pro, https://www.google.com/earth/ (used with license, accessed September 2017 through 

December 2018). 

FIRMs (Flood Insurance Rate Maps): FEMA Map Service Center, msc.fema.gov

Copyright information:

Figure R301.2(4)B is excerpted from the 2012 International Residential Code (2011); Washington, D.C.: International Code 

Council. It is reproduced with permission. All rights reserved. www.ICCSAFE.org
Members of the Mitigation Assessment Team

Team Leader

Daniel Bass, RA, CFM

FEMA

Team Manager

Manuel Perotin, PE, CFM

CDM Smith

Report Manager

Samantha N. Krautwurst, PE

AECOM

Team Members

Gavin Allwright

CDM Smith

Jovannie Cartajena-Cabrera

FEMA

Edward Curtis, III, PE, CFM

FEMA

Kate De Gennaro

NOAA Texas Sea Grant

David Drnevich, PE

FM Global

Andrew Foote 

FM Global

Jerry Frye

FEMA

Nathan Gould, PE, SE

ABS Consulting

Dennis Hwang

NOAA Hawaii Sea Grant 

Javier Janer, RA

American Institute of Architects

Thomas Kane

FEMA 

Dr. Thomas Kirsch, MD, MPH, 

FACEP

National Center for Disaster 

Medicine and Public Health

Phil Line, PE

American Wood Council

David Low, PE

DK Low & Associates

Joseph Main, PhD

National Institute of Standards 

and Technology

Robert Nystrom, PE

CDM Smith

Brian O’Connor, PE, CFM

CDM Smith

Walter Peacock

NOAA Texas Sea Grant

Michael Pfeiffer, PE

International Code Council

Rebecca Quinn, CFM

RCQuinn Consulting, Inc.

Paul Saphos, RA

FKP/Cannon Design

Kelsey Schill

CDM Smith

Pataya Scott, EIT

FEMA 

Thomas Smith, AIA, RRC, F.SEI

TLSmith Consulting Inc. 

Henry Snow

FEMA 

James Snow, PE, SE

ABS Consulting

Eric Stafford, PE

AECOM

Larry Tanner, PE, RA

Tanner Consulting

Heather Wade

NOAA Texas Sea Grant

Donnie Walsh 

FEMA

Gregory Wilson

FEMA

Internal Support

Drone Support:

Scott Aldridge, CDM Smith

GIS Specialist:

Caitlin Olson, CDM Smith

Graphic Artists:

Lee-Ann Lyons, AECOM

Billy Ruppert, AECOM

Technical Editors and Formatting:

Young Cho, AECOM

Susan Ide Patton, PG, AECOM

Ivy Porpotage, AECOM

Amy Siegel, AECOM

508 Compliance:

Carol Cook, AECOM
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT i

Executive Summary 

Hurricane Harvey was the wettest rainfall event in U.S. history, 

dropping up to 70 inches of rain in portions of southeastern 

Texas. 

Hurricane Harvey made landfall over San Jose Island, 

just north of Port Aransas, TX, on August 25, 2017, 

at 10 p.m. CDT. At landfall, Hurricane Harvey was a 

Category 4 hurricane with estimated sustained winds 

of 130 mph. It was the eighth named storm during 

the 2017 hurricane season and the first of the three 

major 2017 hurricanes to impact the U.S. mainland 

or territories. 

Mitigation Assessment Team 

Deployment and Observations

In response to a request for technical support from 

the Federal Emergency Management Agency’s 

(FEMA’s) Joint Field Office in Austin, TX, FEMA 

deployed a Mitigation Assessment Team (MAT) to 

Texas in November and December of 2017 to evaluate 

building performance during Hurricane Harvey. The 

MAT was deployed to Harris County to assess flood 

performance issues, and to Aransas, Nueces, Refugio, 

and San Patricio Counties to assess wind performance issues. MAT members evaluated building 

systems to determine the effectiveness of various design and construction practices and ascertain 

the effect of code adoption and enforcement on reducing flood and wind damage. To improve 

resiliency in future events, the lessons learned from MAT deployments and reports can either be 

incorporated into best practices for future retrofits or new hazard-resistant building design. 

NOTEWORTHY STORM METRICS 

• First Category 4 hurricane to make

landfall on the Continental United

States since 2005 (NOAA NWS,

2017)

• Sustained winds of 130 mph winds

(NHC, 2017)

• Dropped an estimated 70 inches of

rainfall over parts of Texas during a

7-day period (NOAA NWS, 2017)

• One of the most destructive storms

in U.S. history, with an estimated 

$125 billion (2017 dollars) in 

damages (NOAA NCEI, 2018), which 

is the second highest in U.S. history 

behind Hurricane Katrina
ii MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

EXECUTIVE SUMMARY

In Harris County, the MAT evaluated the relationship between residential building damage and the 

age of the building and assessed the performance of dry floodproofing measures in non-residential 

buildings. The MAT visited a mixture of new and old construction in the same general vicinity 

to help assess the performance of residential buildings constructed to both minimum floodplain 

management standards and higher standards under the same flood conditions. For non-residential 

buildings, the MAT visited dry floodproofed buildings that were mitigated with FEMA funding 

following Tropical Storm Allison (2001), as well as buildings that were dry floodproofed with private 

funding. 

In Aransas, Nueces, Refugio, and San Patricio Counties, the MAT primarily examined the wind 

pressure performance of main wind force resisting systems (MWFRSs) and building envelopes, the 

effects of wind-borne debris on building envelopes, rain infiltration at building envelope breaches, 

and the performance of ground-mounted solar panel arrays. To assess building performance, the 

MAT reviewed the code requirements related to construction of buildings in high-wind areas. 

Although Texas has not adopted a building code at the State level, many communities visited by the 

MAT had adopted the 2009, 2012, or 2015 International Building Code® (IBC®) and International 

Residential Code® (IRC®). In addition, the Texas Department of Insurance (TDI), which is the 

administrator of coastal windstorm insurance, adopted the 2006 IRC in July 2007. To qualify for 

an insurance policy under the Texas Windstorm Insurance Association, buildings in all 14 coastal 

counties and parts of Harris County must meet the 2006 IRC with Texas Revisions, which references 

the 2005 edition of the American Society of Civil Engineers (ASCE) standard ASCE 7, Minimum 

Design Loads and Associated Criteria for Buildings and Other Structures. 

Hurricane Harvey’s wind speeds produced pressures that approximated design pressures derived 

from various editions of ASCE 7, depending on a building’s proximity to the track of the storm and 

building and site characteristics, which provided an opportunity for the MAT to evaluate building 

performance at near design conditions. 

Summary of Damage Observed by the MAT

Hurricane Harvey caused widespread damage to buildings, power distribution systems, and water 

utility services in both the region impacted by its landfall and the area affected by the historic 

rainfall. Hurricane Harvey caused extensive sheet flow and riverine flooding in southeastern Texas; 

houses constructed before the communities had joined the National Flood Insurance Program 

(NFIP) and adopted floodplain management regulations and Flood Insurance Rate Maps (FIRMs) 

were hit the hardest. Although most of the damage from Hurricane Harvey was caused by flooding, 

at and near design-level wind pressures in accordance with ASCE 7-05, as referenced by the 2006 

IBC and IRC, caused significant damage to older buildings in Aransas, Nueces, Refugio, and San 

Patricio Counties. 

Flood. Flood damage from Hurricane Harvey was extensive and significant, impacting residential 

and non-residential buildings located in the 1.0-percent-annual-chance probability (100-year event) 

floodplain, 0.2-percent-annual-chance probability (500-year event) floodplain, and areas outside the 

0.2-percent-annual-chance floodplain. In Harris County and municipalities in the county, including 

the City of Houston, 22 percent of buildings experienced flood damage. The majority of flooddamaged residential buildings were older, slab-on-grade buildings built before the communities 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT iii

EXECUTIVE SUMMARY

joined the NFIP or were built outside the 0.2-percent-annual-chance probability floodplain. Houses 

built in the 1980s, to a lower base flood elevation than what is required by current FIRMs, also 

sustained inundation damage. Recently constructed NFIP-compliant houses suffered minor damage 

because of non-flood damage-resistant materials, mainly insulation and drywall, used below the 

elevation specified by regulation. 

Figure ES-1 summarizes closed flood insurance claim data for a representative residential area in 

Texas. As shown in the figure, averaged claims were approximately $88,000 lower per building when 

local floodplain management regulations had been adopted before, rather than after, buildings 

were constructed.

Observed failures at dry floodproofed buildings resulted from overtopping of flood walls or 

barriers, structural failure of flood barriers, seepage through flood barriers, seepage through utility 

penetrations, and insufficient planning. As a result of these failures, critical building systems located 

in basements and first floors were damaged and rendered inoperable.

Figure ES-1: Effect of floodplain management on housing claims
iv MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

EXECUTIVE SUMMARY

Wind. Within the greater Rockport, TX, area, winds from Hurricane Harvey caused extensive 

damage to roof coverings and rooftop equipment, which resulted in rain damage of interior 

finishes, furnishings, and equipment. Wind-related building damage is primarily attributable 

to using improper materials in hurricane-prone regions; design deficiencies; poor installation or 

failure to follow installation guidelines for wall coverings, windows, and doors in high-wind zones; 

and inadequate attachment of roof coverings and roof-mounted equipment. MWFRS damage was 

observed mainly at older buildings; the observed building envelope damage for more recently 

constructed residential and non-residential buildings was less severe than that for older buildings. 

MAT Recommendations

The recommendations developed by the MAT are based on its field observations. The 

recommendations are directed toward design professionals, contractors, building officials, 

floodplain administrators, and building owners along with some that are directed to FEMA. The 

higher priority recommendations for each general topic are summarized in the text that follows.

General recommendations. TDI should provide training to Windstorm Inspection Program 

inspectors and building code enforcement staff, placing emphasis on changes reflected in the latest 

adopted edition of the building code. The Texas Water Development Board and other stakeholders 

should develop/modify training on the flood provisions in model building codes and/or floodplain 

management ordinances. Facility and building owners should perform vulnerability assessment of 

their facility to help identify wind and flood hazards prior to a disaster. 

Building codes and floodplain management ordinances. TDI should adopt the 2018 IBC and the 

IRC as the model codes for its Windstorm Inspection Program and consider developing a more 

stringent high-wind retrofit program. Communities should review and update portions of local 

floodplain management or flood damage prevention ordinances and guidance, particularly where 

they conflict with requirements in model ordnances and building codes. 

Flood-related building performance. Communities and building owners should consider elevating 

new and Substantially Damaged/Substantially Improved buildings above the NFIP elevation 

requirements to protect them from flooding. Local floodplain administrators, design professionals, 

and building owners in Texas Recovery Advisory 1, Dry Floodproofing: Planning and Design Considerations

(2018g) and Florida Recovery Advisory 1, Dry Floodproofing: Operational Considerations (2018f). Flood 

damage-resistant materials should be used below the design flood elevation inside dry floodproofed 

buildings when possible. Also, facility managers should develop an emergency operations plan for 

severe weather. 

Wind-related building performance. Building owners and/or facility managers should ensure 

adequately roof-mounted equipment is adequately anchored and consider protecting the glazed 

openings on their existing buildings. Windstorm inspectors and local building officials should 

enforce the use of approved materials in high-wind regions and ensure they are installed in 

accordance with the manufacturers’ requirements. Design professionals should specify, and 

contractors should use, face nails on fiber cement siding. Design professionals, contractors, and 

inspectors should place more emphasis on proper soffit installation in high-wind regions to limit 

wind-driven rain from entering building envelopes and damaging building interiors. FEMA should 

ensure that securing roof-mounted equipment is incorporated into eligible Public Assistance Hazard 

Mitigation Proposals. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT v

EXECUTIVE SUMMARY

FEMA technical publications and guidance. FEMA should complete Guidelines for Wind Vulnerability 

Assessments for Critical Facilities. FEMA should include lessons learned from the 2017 hurricane 

season in finishing this publication. FEMA should update the Risk Management Series guidance 

publications to include lessons learned from the 2017 hurricane season and to reflect updates to 

current building codes since the publications’ release. FEMA should make the requirements for 

projects developed under the FEMA Public Assistance and the Hazard Mitigation Assistance 

programs consistent between the programs. Hazard Mitigation Proposals for dry floodproofing 

under the Public Assistance program should be required to reference ASCE 24, Flood Resistant 

Design and Construction. In addition, FEMA should update dry floodproofing guidance, in 

particular Technical Bulletin 3, Non-Residential Floodproofing – Requirements and Certification 

(1993). Furthermore, FEMA should evaluate existing dry floodproofing guidance and post-flood 

investigations to develop a recommendation for inclusion in ASCE 24. FEMA should update FEMA 

P-758, Substantial Improvement/Substantial Damage Desk Reference (2010) to incorporate new lessons 

learned and recommended guidance and clarifications since it was published in 2010; at the same 

time FEMA 213, Answers to Questions about Substantially Damaged Buildings (2018b), should be updated 

to be consistent with the updated FEMA P-758. Finally, FEMA should consider expanding existing 

training materials related to Substantial Improvement/Substantial Damage.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT vii

Contents

Executive Summary .................................................................................................................................... i

Mitigation Assessment Team Deployment and Observations.................................................................i

Summary of Damage Observed by the MAT..........................................................................................ii

MAT Recommendations.......................................................................................................................... iv

Acronyms and Abbreviations..............................................................................................................xxix

Chapter 1. Introduction.............................................................................................................................1-1

1.1 Organization of Report ............................................................................................................ 1-3

1.2 Hurricane Harvey: The Event ..................................................................................................1-4

1.3 Hurricane Harvey: The Impact................................................................................................1-6

1.3.1 Flood.............................................................................................................................. 1-6

1.3.1.1 Storm Surge................................................................................................... 1-6

1.3.1.2 Rainfall .......................................................................................................... 1-6

1.3.1.3 Inland Flooding ...........................................................................................1-11

1.3.1.4 Subsidence....................................................................................................1-15

1.3.2 Wind .............................................................................................................................1-16

1.4 Historic Storm Events in Texas............................................................................................... 1-18
viii MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

TABLE OF CONTENTS

1.5 The FEMA Mitigation Assessment Team............................................................................... 1-21

1.5.1 Team Composition ..................................................................................................... 1-22

1.5.1.1 Involvement of State and Local Agencies.................................................. 1-22

1.5.1.2 Pre-MAT Deployment and Site Selection...................................................1-23

1.5.2 Hurricane Harvey MAT ..............................................................................................1-23

Chapter 2. Building Codes, Standards, and Regulations..........................................................................2-1

2.1 Floodplain Management Requirements.................................................................................. 2-2

2.1.1 National Flood Insurance Program ............................................................................ 2-3

2.1.1.1 General Performance Requirements for Buildings.................................... 2-4

2.1.1.2 Minimum Requirements for Buildings in Zone A...................................... 2-5

2.1.1.3 Minimum Requirements for Buildings in Zone V...................................... 2-8

2.1.1.4 NFIP Community Rating System................................................................. 2-9

2.1.2 Floodplain Management in the State of Texas........................................................... 2-9

2.1.3 Floodplain Management in Selected Communities Impacted by 

Hurricane Harvey......................................................................................................... 2-9

2.1.3.1 Harris County ..............................................................................................2-11

2.1.3.2 City of Houston............................................................................................2-12

2.1.3.3 City of Bellaire..............................................................................................2-13

2.1.3.4 City of Port Aransas.....................................................................................2-14

2.2 Building Code Wind Requirements....................................................................................... 2-14

2.2.1 International Building Code and ASCE 7 .................................................................2-15

2.2.2 International Residential Code ..................................................................................2-18

2.2.3 Texas Windstorm Program .........................................................................................2-18

2.2.3.1 Texas Department of Insurance .................................................................2-19

2.2.3.2 Basic Tenets of the Texas Windstorm Code...............................................2-19

Chapter 3. Flood-Related Observations................................................................................................... 3-1

3.1 Residential Buildings................................................................................................................3-3

3.1.1 General Observations...................................................................................................3-5

3.1.2 Enclosures Below Elevated Buildings........................................................................ 3-11

3.1.3 Perimeter Wall Foundations (Crawlspace) ............................................................... 3-15

3.1.4 Ongoing Slab-on-Grade Elevation Project ............................................................... 3-16

3.1.5 Floodplain Management Requirements versus Damage ......................................... 3-19

3.1.5.1 Proof of Benefit of Building Elevation ...................................................... 3-19
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT ix

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3.1.5.2 Proof of Benefit of NFIP Construction .................................................... 3-20

3.1.5.3 Proof of Benefit of NFIP Participation...................................................... 3-20

3.2 Non-Residential Buildings with Dry Floodproofing.............................................................3-23

3.2.1 Planning and Implementation of Dry Floodproofing Systems................................ 3-26

3.2.2 Judicial and Correctional Facilities – Downtown Houston...................................... 3-28

3.2.2.1 Harris County Jail – 701 N. San Jacinto Street, Houston, TX ................. 3-30

3.2.2.2 Harris County Criminal Justice Center – 1201 Franklin Street, 

Houston, TX................................................................................................ 3-36

3.2.2.3 Jury Assembly Building – 1201 Congress Street, Houston, TX................3-44

3.2.2.4 Harris County Civil Courthouse – 201 Caroline Street, Houston, TX ..3-48

3.2.3 City of Houston Public Works Building - 611 Walker Street, Houston, TX............ 3-53

3.2.4 Theater District and Underground Parking and Tunnel Complex ........................3-56

3.2.4.1 Dry Floodproofing Mitigation Measures ..................................................3-58

3.2.4.2 Performance during Harvey ...................................................................... 3-59

3.2.4.3 Summary of MAT Observations ................................................................ 3-70

3.2.5 Energy Corridor Office Building #1 ........................................................................ 3-71

3.2.6 Energy Corridor Office Building #2 ........................................................................ 3-75

3.2.7 Houston Galleria Office Tower..................................................................................3-80

3.2.8 Four Leaf Towers ........................................................................................................3-86

3.2.9 Starbucks at 4660 N. Braeswood ...............................................................................3-90

3.2.10 Texas Medical Center ................................................................................................ 3-94

3.2.10.1 Texas Children’s Hospital (TCH)..............................................................3-98

3.2.10.2 The University of Texas MD Anderson Cancer Center .......................... 3-103

3.2.10.3 Harris Health System Ben Taub Hospital ................................................3-111

3.2.10.4 Baylor College of Medicine (COM)..........................................................3-115

3.2.10.5 CenterPoint Energy Grant Substation......................................................3-119

3.2.10.6 Thermal Energy Corporation (TECO) Paul G. Bell, Jr. 

Energy Plant.............................................................................................. 3-123

Chapter 4. Wind-Related Observations ................................................................................................... 4-1

4.1 Residential Buildings................................................................................................................4-2

4.1.1 Structural Systems / Main Wind Force Resisting Systems......................................... 4-3

4.1.2 Exterior Wall Coverings...............................................................................................4-8

4.1.2.1 Vinyl Siding ...................................................................................................4-8

4.1.2.2 Fiber-Cement Siding................................................................................... 4-10

4.1.2.3 Brick Veneer ................................................................................................ 4-13
x MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

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4.1.2.4 Other Cladding Types ................................................................................ 4-20

4.1.3 Roof Coverings............................................................................................................ 4-21

4.1.3.1 Asphalt Shingles.......................................................................................... 4-22

4.1.3.2 Architectural Standing Seam Metal Roofing............................................ 4-26

4.1.3.3 Tile Roofing Systems................................................................................... 4-28

4.1.4 Soffits, Fascia, and Roof Ventilation.......................................................................... 4-28

4.1.4.1 Soffits and Fascia......................................................................................... 4-29

4.1.4.2 Roof Ventilation.......................................................................................... 4-32

4.1.5 Doors........................................................................................................................... 4-33

4.1.6 Windows and Shutters................................................................................................4-34

4.1.7 Garage Doors..............................................................................................................4-42

4.1.8 Debris Impacts............................................................................................................4-45

4.2 Non-Residential Buildings......................................................................................................4-48

4.2.1 Main Wind Force Resisting System............................................................................4-49

4.2.1.1 Nursing Home in Rockport........................................................................4-49

4.2.1.2 Texas Department of Transportation Maintenance Facility 

in Rockport.................................................................................................. 4-51

4.2.2 Roof Systems and Rooftop Equipment......................................................................4-56

4.2.2.1 Regional Medical Center in Aransas Pass.................................................4-56

4.2.2.2 Fisheries Laboratory in Port Aransas .......................................................4-63

4.2.2.3 Older Building with Aggregate Surfaced BUR ........................................4-64

4.2.2.4 Rockport-Fulton Middle School.................................................................4-66

4.2.2.5 Live Oak Learning Center ........................................................................ 4-70

4.2.2.6 Fulton Learning Center ............................................................................. 4-76

4.2.2.7 Port Aransas Schools ................................................................................. 4-78

4.2.2.8 Pharmacy.....................................................................................................4-82

4.2.2.9 Port Aransas Hotel......................................................................................4-82

4.2.2.10 Rockport Hotels .........................................................................................4-84

4.2.2.11 Older Rockport Retail Building ................................................................4-86

4.2.2.12 Metal Building System in Aransas Pass.....................................................4-89

4.2.3 Non-Load-Bearing Walls, Wall Coverings, and Soffits.............................................4-90

4.2.3.1 Refugio Church...........................................................................................4-90

4.2.3.2 Rockport Hotel............................................................................................ 4-91

4.2.3.3 Metal Building System at Rockport High School .....................................4-95

4.2.3.4 Civic Center in Aransas Pass ..................................................................... 4-97
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT xi

TABLE OF CONTENTS

4.2.4 Doors, Windows, and Shutters...................................................................................4-98

4.2.5 Building Operations................................................................................................. 4-100

4.3 Wind Performance of Solar Panel Systems.......................................................................... 4-101

Chapter 5. Conclusions and Recommendations...................................................................................... 5-1

5.1 Summary of Conclusions and Recommendations..................................................................5-2

5.2 General Conclusions and Recommendations.........................................................................5-3

5.3 Building Codes, Standards, and Regulations..........................................................................5-4

5.4 Flood-Related Building Performance......................................................................................5-6

5.5 Wind-Related Building Performance ....................................................................................5-12

5.6 FEMA Technical Publications and Guidance ....................................................................... 5-16

5.7 Summary of Conclusions and Recommendations................................................................5-20

Appendices

Appendix A: Acknowledgments............................................................................................................A-1

Appendix B: References....................................................................................................................... B-1

Appendix C: Recovery Advisories........................................................................................................ C-1

List of Figures

Figure ES-1: Effect of floodplain management on housing claims....................................................iii

Figure 1-1: MAT area of focus.......................................................................................................... 1-2

Figure 1-2: Hurricane Harvey storm track ...................................................................................... 1-5

Figure 1-3: Hurricane Harvey storm surge levels recorded by NOAA............................................1-7

Figure 1-4: Hurricane Harvey annual exceedance probabilities for the worst-case, 4-day 

rainfall according to NOAA .......................................................................................... 1-8

Figure 1-5: Rainfall totals of southeastern Texas and the Houston metropolitan area ............... 1-9

Figure 1-6: Tropical Storm Allison (2001) rainfall totals (top) versus Hurricane Harvey 

rainfall totals (bottom). Rainfall totals scale uses the same color coding for 

both maps. .....................................................................................................................1-10
xii MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

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Figure 1-7: Overview of riverine flooding in Harris County (map does not show sheet 

flow flooding effects in the county) .............................................................................1-11

Figure 1-8: Example of rainwater flowing across the ground, flooding buildings in its 

path when stormwater drainage networks are overwhelmed.....................................1-12

Figure 1-9: Map showing exceedance probabilities, based on HWM, for Harris County 

watersheds......................................................................................................................1-13

Figure 1-10: Comparison of 1-percent-annual-chance flood hazard width for Brays 

Bayou in the southwest portion of Houston (top image), which has a very 

broad SFHA, and the SFHAs for White Oak Bayou and Buffalo Bayou near 

Downtown Houston (bottom image), which are much narrower..............................1-14

Figure 1-11: Land subsidence in the Houston-Galveston Subsidence District, 1906-2000, 

retrieved May 2018.........................................................................................................1-15

Figure 1-12: Wind swath plot of estimated 3-second gust wind speed in mph at a height of 

33 feet above ground, Exposure C (solid lines). The top figure shows the wind 

field for Hurricane Harvey, whereas the bottom figure shows the area around 

its initial two landfalls. .................................................................................................1-17

Figure 1-13: Track of Hurricane Harvey (red line) relative to landfall locations of 

significant historic hurricanes in Texas between 1950 and 2017 ...............................1-19

Figure 1-14: Areas of operations for the MAT Flood, Dry Floodproofing subunit in Harris 

County........................................................................................................................... 1-25

Figure 1-15: Locations of facilities observed by the MAT TMC Flood Unit.................................. 1-25

Figure 1-16: Primary areas of operations for the MAT Residential and Non-Residential 

Wind units were Aransas Pass, Bayside, Corpus Christi, Holiday Beach, Port 

Aransas, and Rockport (including Estes and Fulton)................................................ 1-26

Figure 2-1: Floodplain management regulations and building design in communities 

with adopted building codes ......................................................................................... 2-3

Figure 2-2: Comparison of ASCE 7-05 (red contours) and ASCE 7-10 basic wind speeds 

for Risk Category II buildings converted to ASD (blue contours) ............................2-17

Figure 2-3: 2012 IRC Wind Design Required map ........................................................................2-19

Figure 2-4: Texas Windstorm Designated Catastrophe Areas...................................................... 2-20

Figure 3-1: Representative residential neighborhood visited by the MAT [Zone AE] .................3-4
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT xiii

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Figure 3-2: An approximately 5-foot-high HWM (shown as the dotted red line) observed 

by the MAT while assessing residential buildings on September 9 in Harris 

County [Zone AE]..........................................................................................................3-5

Figure 3-3: Residential building located within the Limit of Moderate Wave Action 

(LiMWA) based on the February 2016 effective FIRM [Zone AE].............................3-6

Figure 3-4: A 54-inch-high HWM on residential buildings in Nueces County [Zone A] ............. 3-7

Figure 3-5: A 42-inch-high HWM on a house in Harris County built in 1955 [Zone AE] ...........3-8

Figure 3-6: Flood damage to Nueces County apartments [Zone AE] ........................................... 3-9

Figure 3-7: This elevated house built in 2002 (HWM, shown as the dotted red line) had 

much less damage than surrounding older slab-on-grade houses (example 

shown in Figure 3-8) [Zone AE] ................................................................................. 3-10

Figure 3-8: Slab-on-grade house (located across the street from the elevated residence 

shown in Figure 3-7) has large debris pile [Zone AE]............................................... 3-10

Figure 3-9: Elevated residence built in 2016 with flood damage (approximately $12,000) 

[Zone X] ....................................................................................................................... 3-11

Figure 3-10: Relatively new house built in 2016 had limited exterior flood damage, yet 

interior repairs were required due to flood inundation and penetration of 

wind-driven rain [Zone AE] ........................................................................................ 3-11

Figure 3-11: Elevated residence built in 2016 in Aransas County [Zone AE] ............................... 3-12

Figure 3-12: Elevated residential building non-compliant flood opening [Zone AE] ................. 3-13

Figure 3-13: Extensive damage to the enclosure of an older (1982) elevated residence in 

Port Aransas; the enclosure did not have flood openings [Zone AE].......................3-14

Figure 3-14: The enclosure of a newer elevated residence in Port Aransas with compliant 

flood openings on each side of the house (see insets) suffered only limited 

damage to its contents [Zone AE]................................................................................3-14

Figure 3-15: Elevated residence built in Nueces County in 2016 to Zone AE floodplain 

management requirements [Zone VE, per updated preliminary FIRM] ................ 3-15

Figure 3-16: Residential crawlspace observed by the MAT in a Harris County house built 

in 2002 where the insulation along the elevated floor had to be removed 

[Zone AE] ..................................................................................................................... 3-15

Figure 3-17: Non-flood damage-resistant materials removed from the crawlspace of the 

adjacent elevated Harris County building built in 2014 [Zone AE}.......................... 3-16
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Figure 3-18: Recently elevated slab-on-grade foundation where steel beams were used to 

support the elevated slab and limit pier spacing [Zone AE]......................................3-17

Figure 3-19: Exterior of new masonry perimeter foundation wall adjacent to piers 

supporting the elevated slab [Zone AE]..................................................................... 3-18

Figure 3-20: Closed-cell foam was applied to all exterior walls when this slab-on-grade 

house was elevated........................................................................................................ 3-18

Figure 3-21: Example of neighborhood in Harris County where newer elevated residences 

(house on left was built in 2013) are situated next to older residences (nonelevated older residence on right was built in 1948) [Zone AE] .............................. 3-19

Figure 3-22: Example of an elevated residence (left side) next to a non-elevated residence 

(right side); the elevated house sustained much less damage during 

Hurricane Harvey......................................................................................................... 3-19

Figure 3-23: Distribution of residences analyzed in the representative residential area, as 

of June 2018 .................................................................................................................. 3-21

Figure 3-24: Map of Downtown Houston showing the confluence of White Oak Bayou 

with Buffalo Bayou, and the four Harris County facilities visited by the MAT 

discussed in this subsection......................................................................................... 3-29

Figure 3-25: Harris County Jail as viewed from the Main Street Bridge ....................................... 3-31

Figure 3-26: FIRM for Harris County Jail in the City of Houston.................................................. 3-31

Figure 3-27: View of east wall of jail along N. San Jacinto Street where water levels reached 

the top of the concrete wainscot (red line) ................................................................ 3-32

Figure 3-28: View of west side of the jail along White Oak Bayou ................................................. 3-33

Figure 3-29: Location of below-grade communication vault (red circle) on N. San Jacinto 

Street ............................................................................................................................. 3-33

Figure 3-30: Concentrated floodwater entry points........................................................................ 3-34

Figure 3-31: Maximum water depth at the electrical service equipment ...................................... 3-34

Figure 3-32: At-grade ventilation grill on north side of the building that was not inundated .... 3-35

Figure 3-33: Inmate transfer tunnel door........................................................................................ 3-35

Figure 3-34: FIRM for Harris County buildings on south of Buffalo Bayou in the City of 

Houston......................................................................................................................... 3-37

Figure 3-35: Harris County Criminal Justice Center viewed from the southwest......................... 3-37
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Figure 3-36: Flood shield that automatically deploys as waters rise at ramp to underground 

parking garage.............................................................................................................. 3-38

Figure 3-37: Check-valve in sanitary sewer lateral........................................................................... 3-39

Figure 3-38: View of the Criminal Justice Center from the southeast with approximate 

depth of flooding indicated by dotted red line..........................................................3-40

Figure 3-39: Floodwater seepage at submarine door ......................................................................3-41

Figure 3-40: Floodwater did not reach critical equipment that was elevated after Tropical 

Storm Allison................................................................................................................3-42

Figure 3-41: Wall finishes were removed from the first floor as a result of sewage leakage.........3-43

Figure 3-42: Jury Assembly Building viewed from the south..........................................................3-45

Figure 3-43: Door to the electrical utility vault, which is not designed to prevent floodwater 

entry ..............................................................................................................................3-45

Figure 3-44: Submarine door separating the Jury Assembly Building from the 

underground pedestrian tunnel .................................................................................3-46

Figure 3-45: Harris County Civil Courthouse viewed from the southwest....................................3-48

Figure 3-46: Submarine door that separates the Civil Courthouse basement from the 

underground pedestrian tunnel .................................................................................3-49

Figure 3-47: Automatic floodgate at ramp to basement parking garage.......................................3-50

Figure 3-48: Flood level at the Civil Courthouse during Hurricane Harvey (red dotted line) ...3-50

Figure 3-49: Civil Courthouse corridor ........................................................................................... 3-51

Figure 3-50: Floodwater entry through unsealed penetrations .................................................... 3-52

Figure 3-51: City of Houston Public Works Building; red outline denotes an open-air 

courtyard on the south side of the building............................................................... 3-53

Figure 3-52: FIRM for the City of Houston Public Works Building...............................................3-54

Figure 3-53: Tranquility Park Parking Garage and tunnel network (left); partial-height 

flood door installed in the tunnel network (right).................................................... 3-55

Figure 3-54: FIRM for the Theater District; approximate locations of flood breaches are 

shown (uniquely numbered from 1 to 9).................................................................... 3-57
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Figure 3-55: Examples of the floodgates installed to protect the Theater District and 

underground tunnels and parking garages................................................................3-58

Figure 3-56: Underground components of the Theater District, parking garage network, 

and tunnels are shown in relationship to the approximate locations of the 

nine significant flood breaches that occurred ...........................................................3-60

Figure 3-57: A disconnected pipe allowed stormwater to enter the cavity under the Green 

Parking Garage floor slab, resulting in the complete inundation of the garage..... 3-61

Figure 3-58: Submarine doors on the road that connects the Green Parking Garage to 

the Little Tranquility Park Parking Garage being deployed in preparation for 

Hurricane Harvey ........................................................................................................3-62

Figure 3-59: Submarine door shown in Figure 3-58 after its failure..............................................3-63

Figure 3-60: Glass block wall that failed when exposed to floodwater pressures (left); 

floodwater entering through Breach No. 3 (right) ....................................................3-64

Figure 3-61: Floodwater entry point at a gap in a retaining wall ..................................................3-65

Figure 3-62: Floodwater entry point at demolished retaining wall section...................................3-66

Figure 3-63: Unsealed joint between the concrete foundation wall and reinforced masonry 

wall with granite façade where significant seepage into the Wortham Theater 

occurred........................................................................................................................3-67

Figure 3-64: Floodgate protecting emergency exit along Buffalo Bayou ...................................... 3-67

Figure 3-65: Submarine door that isolates the Wortham Theater from the Green Parking 

Garage...........................................................................................................................3-68

Figure 3-66: Floodwater entry point though glass door entryway..................................................3-69

Figure 3-67: Emergency exit door along the east side of the Wortham Theater; the red line 

indicates the approximate HWM during Hurricane Harvey.................................... 3-70

Figure 3-68: Aerial image of Energy Corridor Office Building #1 (taken on August 30, 

2017) showing floodwater around the office complex............................................... 3-71

Figure 3-69: FIRM for the Energy Corridor Office Building #1 .................................................... 3-72

Figure 3-70: Civil Air Patrol photo showing the east side of the parking garage ......................... 3-73

Figure 3-71: Deployed passive floodgate at the top of the loading dock ramp (red outline)...... 3-74

Figure 3-72: Energy Corridor Office Building #2 (left image) and loading dock and ramp 

(right image)................................................................................................................. 3-75
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Figure 3-73: FIRM for Energy Corridor Office #2.......................................................................... 3-76

Figure 3-74: Flooding of the loading dock during a severe thunderstorm in 2009...................... 3-77

Figure 3-75: Flooding around Energy Corridor Office Building #2 August 29 to August 30 ..... 3-78

Figure 3-76: Floodwater entering protected area flowing within utility switchgear conduit ....... 3-79

Figure 3-77: Houston Galleria Office Tower.................................................................................... 3-81

Figure 3-78: Loading dock flood during the 2015 Memorial Day Flood....................................... 3-81

Figure 3-79: Passive floodgate located at the top of the loading dock ramp ................................3-82

Figure 3-80: Loading dock flood doors (the red line is a reflective strip and not an 

indicator of HWM); inset shows one of the flood doors installed to protect MEP.....3-83

Figure 3-81: Loading dock sump pump screen protection (left) and high water level 

alarm (right).................................................................................................................3-83

Figure 3-82: Wet alarm (left) and sealed pipe penetration (right)................................................3-84

Figure 3-83: Parking garage for the Houston Galleria Office Tower.............................................3-85

Figure 3-84: Four Leaf Towers Condominium Complex, where red arrows indicate streetlevel access locations to the complex and blue arrows indicate access to 

parking garage..............................................................................................................3-86

Figure 3-85: FIRM for Four Leaf Towers Condominium Complex................................................3-87

Figure 3-86: Examples of active and passive flood barriers at Four Leaf Towers..........................3-88

Figure 3-87: HWM near the swimming pool at the Four Leaf Towers condominium complex ..3-89

Figure 3-88: FIRM for the Starbucks building at 4660 N. Braeswood Boulevard.........................3-90

Figure 3-89: Shows the Starbucks building elevated on fill with dry floodproofing..................... 3-91

Figure 3-90: Membrane installed on the fully grouted and reinforced CMU wall....................... 3-91

Figure 3-91: Pedestrian flood doors installed to access restrooms, storage room, and 

employee entrance ....................................................................................................... 3-92

Figure 3-92: Starbucks during Hurricane Harvey flooding ........................................................... 3-92

Figure 3-93: Floor drains (red arrows) where floodwater entered................................................. 3-93
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Figure 3-94: Approximate flood levels during Hurricane Harvey on the outside of the 

building (left) and inside (right) ................................................................................ 3-93

Figure 3-95: FIRM for TMC..............................................................................................................3-96

Figure 3-96: Locations of facilities observed by the Harvey MAT at TMC.................................... 3-97

Figure 3-97: Texas Children’s Hospital aerial view looking north.................................................3-99

Figure 3-98: FIRM for Texas Children’s Hospital.......................................................................... 3-100

Figure 3-99: Flood doors in basement tunnel (left) and below-grade parking 

garage (right) ..............................................................................................................3-101

Figure 3-100: Flood log gate (left) and swing floodgate (right) at parking garage entrances .... 3-102

Figure 3-101: Aerial view of the MD Anderson Cancer Center north campus looking north..... 3-104

Figure 3-102: Map of the MD Anderson Cancer Center north campus ....................................... 3-105

Figure 3-103: FIRM for MD Anderson Cancer Center north campus and mid-campus 

buildings along Brays Bayou...................................................................................... 3-106

Figure 3-104: Marble-faced floodwall (left) and aquarium glass windows in floodwall (right) 

at the Main Building .................................................................................................. 3-107

Figure 3-105: Passive floodgates (red arrows) at entrances through floodwall at the Main 

Building ...................................................................................................................... 3-107

Figure 3-106: Flood doors in basement that subdivide basement areas within the Main 

Building ...................................................................................................................... 3-108

Figure 3-107: Central operations 24-hour facility that provides continuous 

flood monitoring ........................................................................................................ 3-108

Figure 3-108: Water level on Bates Street outside of MD Anderson Cancer Center north 

campus at the Main Building during Hurricane Harvey .........................................3-110

Figure 3-109: Harris Health System Ben Taub Hospital aerial view looking north.......................3-112

Figure 3-110: FIRM for Ben Taub Hospital and Baylor College of Medicine ................................3-113

Figure 3-111: Basement tunnel submarine door between Ben Taub Hospital and the Baylor 

College of Medicine (viewed from Ben Taub) ..........................................................3-114

Figure 3-112: Basement auditorium used as water retention area (left) and reported water 

level in subbasement indicated by staff member (right) ..........................................3-115
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Figure 3-113: Baylor COM aerial view looking north ......................................................................3-116

Figure 3-114: Swing flood door (left) and guillotine floodgate (right) .........................................3-117

Figure 3-115: Typical sump pit in basement (left) and ejection pipes over floodwall (right).......3-117

Figure 3-116: Elevated central plant structure (in red outline)......................................................3-118

Figure 3-117: CenterPoint Energy Grant Substation and TECO Paul G. Bell, Jr. Energy 

Plant; aerial view looking northeast...........................................................................3-119

Figure 3-118: FIRM for CenterPoint Energy Grant Substation TECO Paul G. Bell, Jr. 

Energy Plant................................................................................................................ 3-120

Figure 3-119: Exterior substation floodwall with water height shown (left) and interior wall 

surface (right)..............................................................................................................3-121

Figure 3-120: Substation floodgate ...................................................................................................3-121

Figure 3-121: Substation sump pit and pumps................................................................................ 3-122

Figure 3-122: TECO floodwall adjacent to Brays Bayou (left image) and along Pressler 

Street (behind ivy in right image)............................................................................. 3-123

Figure 3-123: Floodgates in floodwall at TECO Energy Plant ........................................................3-124

Figure 3-124: Sump pits and pumps inside TECO floodwall ..........................................................3-124

Figure 3-125: Vault flood cover restraining device (left) and barrels used as manhole cover 

restraining devices (right) ......................................................................................... 3-125

Figure 3-126: Brays Bayou adjacent to TECO Energy Plant floodwall during 

Hurricane Harvey....................................................................................................... 3-125

Figure 4-1: Apartment building under construction (Rockport) ..................................................4-4

Figure 4-2: Clips connecting stud to bottom plate and anchor-bolted bottom plate to slab 

(red arrow) (Rockport)..................................................................................................4-4

Figure 4-3: An example of all-threaded MWFRS connection system (Rockport) ........................4-5

Figure 4-4: Sheathing nails that missed the bottom plate (shiners) are shown with red 

arrows (Rockport) ..........................................................................................................4-5

Figure 4-5: Older home with roof failure due to poor connection of the rafters to the 

joists (120 mph, Exposure B) (Rockport) ....................................................................4-6

Figure 4-6: Another view of the older home with roof failure in Figure 4-5 (Rockport).............4-6
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Figure 4-7: Intracoastal Waterway home that experienced a design-level wind event 

(130 mph, Exposure C) (Rockport).............................................................................. 4-7

Figure 4-8: Wind-resistant connections (red arrows) (same building as Figure 4-7) 

(Rockport) ...................................................................................................................... 4-7

Figure 4-9: Second floor wind-resistant connections (red arrows) (same building as 

Figure 4-7) (Rockport) ..................................................................................................4-8

Figure 4-10: Older home with vinyl siding (Rockport)..................................................................... 4-9

Figure 4-11: Home that lost vinyl siding (red arrows) and soffits (blue dashed arrow) 

(120 mph, Exposure C) (Holiday Beach)..................................................................... 4-9

Figure 4-12: Installation guidance for fiber-cement siding ........................................................... 4-10

Figure 4-13: Fiber-cement siding damage to a residence (130 mph, Exposure C) 

(Copano Village).......................................................................................................... 4-11

Figure 4-14: Fiber-cement siding ripped from walls (red arrows) (130 mph, Exposure C) 

(Port Aransas) .............................................................................................................. 4-11

Figure 4-15: Fastener installed in fiber-cement siding 1⁄2 inch from edge, which led to 

failure of the plank attachment (Port Aransas)......................................................... 4-12

Figure 4-16: Failed fiber-cement siding without caulking (red arrows) (130 mph, 

Exposure C) (Rockport).............................................................................................. 4-12

Figure 4-17: Failed caulking (red arrows) (Port Aransas).............................................................. 4-12

Figure 4-19: Example of proper brick installation.......................................................................... 4-13

Figure 4-18: Common problem with brick veneer installation: sloped installation of 

corrugated brick ties offer no resistance to horizontal wall movement 

produced by wind pressures ........................................................................................ 4-13

Figure 4-20: Brick veneer tie spacing ................................................................................................4-14

Figure 4-21: Residence brick veneer failure (120 mph, Exposure B) (Rockport) ........................ 4-15

Figure 4-22: Residence with failed brick veneer installation (see also Figure 4-23) 

(Rockport) ................................................................................................................... 4-15

Figure 4-23: Double-wythe brick wing-wall that lost its brick stacked course (130 mph, 

Exposure B) (Port Aransas) ........................................................................................ 4-16

Figure 4-24: Sea Gull Condominiums (140 mph, Exposure D) (Port Aransas) ............................4-17
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Figure 4-25: Wall detail of Sea Gull Condominiums (Port Aransas) ............................................ 4-18

Figure 4-26: Sea Gull Condominiums (140 mph, Exposure D) (Port Aransas) ........................... 4-19

Figure 4-27: Aransas Princess Condominiums (140 mph, Exposure D) (Port Aransas) ............. 4-19

Figure 4-29: Older residence with original hardboard lap siding (red arrow) that had been 

re-sided with blue foam insulation vinyl siding (130 mph, Exposure C) 

(Key Allegro) ................................................................................................................ 4-20

Figure 4-28: Aransas Princess Condominiums (140 mph, Exposure D) (Port Aransas) ............. 4-20

Figure 4-30: Older residence previously sided with hardboard vertical siding (red arrows) 

that had been re-sided with foam board and vinyl siding (yellow double 

arrows) (120 mph wind, Exposure B) (Rockport)..................................................... 4-21

Figure 4-31: Neighborhood showing varying examples of gable roof (yellow dotted circles) 

and hip roof (red circles) performance (120 mph, Exposure B) (Rockport) ......... 4-22

Figure 4-32: TDI-designated Catastrophe Areas, 2006................................................................... 4-23

Figure 4-33: Home being reroofed with Class F shingles (see red arrows) (Port Aransas) ......... 4-24

Figure 4-34: Home that lost shingles due to poor adhesion of the leading edges of the 

shingles (red arrows) (Port Aransas).......................................................................... 4-24

Figure 4-35: Asphalt shingle roofing for high-wind regions........................................................... 4-25

Figure 4-36: Home with damaged ridge, hip-ridges, and eave shingles (red arrows) due to 

poor adhesion of the shingle tabs (Fulton)................................................................ 4-26

Figure 4-37: Residence with failed rake edge with loss of metal roofing edge trim (red 

arrows) (130 mph, Exposure B) (Copano Village).................................................... 4-27

Figure 4-38: Residence with failed substrate (green dotted arrows) and no membrane 

underlayment (red arrows) (Copano Village) ........................................................... 4-27

Figure 4-39: Home damaged by wind pressure (130 mph, Exposure C) (Cape Valero).............. 4-28

Figure 4-40: Home with clay tile roof failure (green arrows)(120 mph, Exposure C) 

(Key Allegro) ................................................................................................................ 4-29

Figure 4-41: Home with concrete tile roof failure (red arrows) (120 mph, Exposure B)

(Copano Village).......................................................................................................... 4-29

Figure 4-42: Home in which soffit and roof pressurization caused roof failure (red arrows) 

(120 mph, Exposure C) (Copano Village) .................................................................4-30
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Figure 4-43: Roof overhang that snapped off (red arrows); image is a different view of 

home shown in Figure 4-42 (120 mph, Exposure C) (Copano Village) .................. 4-31

Figure 4-44: Vinyl soffit product (green dotted arrow) removed by the storm, exposing the 

vent opening (red arrows) (120 mph, Exposure B) (Cape Valero) .......................... 4-31

Figure 4-45: Ventilating fiber-cement board removed by the storm, exposing the attic (red 

arrows) (120 mph, Exposure B) (Holiday Beach) ..................................................... 4-32

Figure 4-46: Home with a portion of ridge vent removed by Hurricane Harvey winds (red 

arrows) (120 mph, Exposure B) (Rockport) .............................................................. 4-32

Figure 4-47: Home with off-ridge attic ventilators (120 mph, Exposure B) (Rockport) .............. 4-33

Figure 4-48: The inactive leaf of the door to this residence failed when wind and debris 

tore the door from its hinges (red arrows) (120 mph, Exposure C) (Rockport) ....4-34

Figure 4-49: Outside layer of glazing sacrificed by the impact of wind-blown debris 

(Key Allegro) ................................................................................................................ 4-35

Figure 4-50: Newly installed impact-rated window in new construction to replace a window 

where all the panes were broken by debris impact (120 mph, Exposure B) 

(Estes) ........................................................................................................................... 4-35

Figure 4-51: Impact-resistant glazing in new construction (red circle) (Cape Valero) ................4-36

Figure 4-52: Methods of plywood shutter attachment .................................................................... 4-37

Figure 4-53: Typical plywood shutter installation on house (Rockport) .......................................4-38

Figure 4-54: Barn door sliding shutters on house shown by red arrow (Key Allegro) .................4-38

Figure 4-55: Classic roll-down shutter with missile impact (red arrow) (Copano Village).......... 4-39

Figure 4-56: Operable Bahama shutters (red arrow) (Key Allegro)..............................................4-39

Figure 4-57: Bi-folding shutters (red arrows) on house (Rockport) ..............................................4-40

Figure 4-58: Sliding slatted shutter system (red arrow) (Key Allegro) ..........................................4-40

Figure 4-60: Corrugated metal shutter system and storage system (Cape Valero) .......................4-41

Figure 4-59: Sliding plywood shutter frame system (red arrows) on house (Port Aransas) ........4-41

Figure 4-61: Home with wind failure of an unreinforced garage door (red arrow) 

(Cape Valero) ...............................................................................................................4-42
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Figure 4-62: Home with insulated unreinforced garage door with loss of the lower exterior 

panel (red arrows) (Estes) ...........................................................................................4-43

Figure 4-63: Hurricane-rated garage door that was damaged (red arrow); cause of failure 

unknown (Cape Valero) ..............................................................................................4-43

Figure 4-64: 20 feet x 9 feet hurricane-rated garage door that was not tested by debris 

impacts; red arrows show hurricane door stiffeners (Cape Valero) .........................4-44

Figure 4-65: Hurricane-rated (red arrow) garage door subjected to debris impact resulting 

in two bent rollers (green dotted arrows) (130 mph, Exposure B) (Fulton)...........4-44

Figure 4-66: Post-2009 home that was well anchored and clipped and even had a garage 

door rated for high-wind zones (140 mph, Exposure C) (Key Allegro)...................4-45

Figure 4-67: Impact from 2x4 on fiber cement siding (red arrow) (120 mph, Exposure C) 

(Key Allegro) ................................................................................................................4-46

Figure 4-68: Plywood debris impact on hardboard siding (red arrow) (120 mph, 

Exposure C) (Port Aransas)........................................................................................4-46

Figure 4-69: Small debris impacts on stucco walls (red arrows) (120 mph, Exposure C) 

(Key Allegro) ................................................................................................................ 4-47

Figure 4-70: Multiple debris impacts on hardboard siding (red arrows) (120 mph, 

Exposure C) (Holiday Beach)..................................................................................... 4-47

Figure 4-71: Large impact on fiber cement wall on the backside of the same residence as 

shown in Figure 4-66 (red arrows) (140 mph, Exposure C) (Key Allegro) .............4-48

Figure 4-72: Collapsed porte cochere at a nursing home...............................................................4-49

Figure 4-73: Blown-off HVAC units at a nursing home (see Figure 4-74 for the unit 

indicated by the yellow double arrow) ........................................................................4-50

Figure 4-74: View of one of the HVAC units indicated by a yellow double arrow in 

Figure 4-73 ....................................................................................................................4-50

Figure 4-75: General view of the leeward side of the Texas Department of Transportation 

maintenance facility ..................................................................................................... 4-51

Figure 4-76: Aerial view of the Texas Department of Transportation maintenance facility 

showing damage to buildings (Exposure B, with a large open patch adjacent 

to and north of the building) ..................................................................................... 4-51

Figure 4-77: Wind-borne roof assembly debris (roof assembly is upside down) ........................... 4-52

Figure 4-78: Windward side of the building.................................................................................... 4-53
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Figure 4-79: Joist bearing plate that is still attached to a bond beam that blew off...................... 4-53

Figure 4-80: Bearing plate studs that were not grouted into the bearing wall and provided 

no uplift resistance. This condition was observed at many of the joists...................4-54

Figure 4-81: Although the exterior windows were protected with shutters (red arrows), the 

roof structure failure nullified their effectiveness.....................................................4-54

Figure 4-82: Deck arc spot welds ......................................................................................................4-55

Figure 4-83: Portable communications tower..................................................................................4-55

Figure 4-84: General view of the regional medical center (Aransas Pass) .................................... 4-57

Figure 4-85: Aerial view of the vicinity of the hospital (Exposure B, with open patches to 

the northwest) (Aransas Pass)..................................................................................... 4-57

Figure 4-86: View of emergency repairs to the roof above the emergency room area .................4-58

Figure 4-87: Emergency room roof membrane ...............................................................................4-58

Figure 4-88: Unprotected vent opening...........................................................................................4-59

Figure 4-89: Inadequate attachment of rooftop condenser............................................................4-59

Figure 4-90: Inadequate attachment of rooftop condensers..........................................................4-60

Figure 4-91: Displaced satellite dish (yellow box) and masonry ballast (red dashed box)........... 4-61

Figure 4-92: View down one of the main hospital corridors ..........................................................4-62

Figure 4-93: Cabinets and other debris from within the hospital..................................................4-62

Figure 4-94: Aerial view of the vicinity of the fisheries laboratory (135 mph, Exposure D)

(Port Aransas) ..............................................................................................................4-63

Figure 4-95: Damaged ductwork at the fisheries laboratory ..........................................................4-64

Figure 4-96: Building with aggregate surfaced BUR (Exposure D) ..............................................4-65

Figure 4-97: Roof of the building shown in Figure 4-96 showing extensive aggregate 

blow-off..........................................................................................................................4-65

Figure 4-98: The red arrow indicates metal storm shutters. The yellow double arrow 

indicates aggregate blown from the roof shown in Figures 4-96 and 4-97 ..............4-66
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Figure 4-99: Rockport-Fulton Middle School. The HVAC units from the roof that were 

damaged had been moved to the ground after the storm and are shown in 

the foreground (Rockport) .........................................................................................4-66

Figure 4-100: Aerial view of the Rockport-Fulton Middle School (Exposure B, with open 

patches adjacent to and west and south of the school)..............................................4-67

Figure 4-101: Collapsed, older metal building system shown in the lower right of Figure 4-100..4-68

Figure 4-102: Damage to northwest roof of middle school ..............................................................4-68

Figure 4-103: HVAC unit (red arrow) that blew off the roof and a collapsed light fixture 

next to the school (yellow double arrow; see Figure 4-104) ......................................4-69

Figure 4-104: Collapsed light fixture. There was significant corrosion of the tube near the 

base plate ......................................................................................................................4-69

Figure 4-105: Interior view of the cafeteria ....................................................................................... 4-70

Figure 4-107: Cooling tower damage ................................................................................................. 4-71

Figure 4-106: Aerial view of the Live Oak Learning Center showing damage (Exposure B, 

with a large open patch adjacent to and northwest of the school) (Rockport) ....... 4-71

Figure 4-108: Blown-off coping at a curb. Depending on the curb design, interior water 

leakage may occur where copings are blown off........................................................ 4-72

Figure 4-110: Main roof damage........................................................................................................ 4-73

Figure 4-109: Cleat where a coping blew off...................................................................................... 4-73

Figure 4-111: Exhaust fan struck by wind-borne debris .................................................................. 4-74

Figure 4-112: Exhaust fan attached with only two screws (red circle shows one of the screws) .... 4-75

Figure 4-113: Blown off exhaust fan .................................................................................................. 4-76

Figure 4-114: Fulton Learning Center (Fulton)................................................................................ 4-77

Figure 4-115: Area where a section of newer coping blew off ......................................................... 4-77

Figure 4-116: Displaced condensers................................................................................................... 4-78

Figure 4-117: Aerial view of the Port Aransas schools showing roof damage (135 mph)............... 4-79

Figure 4-118: Aerial view of the Port Aransas elementary (blue outline) and middle school

(yellow dotted outline) ................................................................................................ 4-79
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Figure 4-119: Aerial view of the Port Aransas high school ..............................................................4-80

Figure 4-120: Brick veneer failure at a stair tower............................................................................. 4-81

Figure 4-121: Signage, brick veneer, and soffit (yellow oval) failure................................................ 4-81

Figure 4-122: Aerial view of a pharmacy with roof damage (135 mph) (Port Aransas).................4-82

Figure 4-123: Aerial view of a four-story hotel with roof damage (Port Aransas) .........................4-83

Figure 4-124: The red arrows indicate where PTAC wall louvers were blown away. The lower 

level windows were protected with metal shutters (yellow double arrow) ................4-83

Figure 4-125: Aerial view of roof covering damage at two hotels. The northern building is 

three stories and the southern building is two stories. (Exposure D) (Rockport)..4-84

Figure 4-126: Displaced condenser at hotel (Rockport)...................................................................4-85

Figure 4-127: First floor corridor of a hotel (Rockport)...................................................................4-86

Figure 4-128: Aerial view of an older retail building (Exposure D) (Rockport) ............................4-87

Figure 4-129: Damaged parapet; Exterior Insulation and Finish System (EIFS) over metal 

framing..........................................................................................................................4-87

Figure 4-130: Underside of the base sheet (yellow oval)...................................................................4-88

Figure 4-131: Disintegrated HVAC unit.............................................................................................4-88

Figure 4-132: Inside the building under the area shown at Figure 4-130 .......................................4-89

Figure 4-133: Metal building system fire station (Aransas Pass)......................................................4-90

Figure 4-134: Brick veneer failure (Refugio) .................................................................................... 4-91

Figure 4-135: Aerial view of a newer hotel (Rockport) ..................................................................... 4-92

Figure 4-136: End wall failure at hotel (Rockport)........................................................................... 4-93

Figure 4-137: Soffit failure at the porte cochere ...............................................................................4-94

Figure 4-138: Debris from the interior of the hotel ..........................................................................4-94

Figure 4-139: High school gymnasium damage (Rockport) ............................................................4-95

Figure 4-140: Precast panel connection to the steel frame ..............................................................4-96

Figure 4-141: End wall failure ............................................................................................................4-96
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT xxvii

TABLE OF CONTENTS

Figure 4-142: Collapsed light fixture pole (high school buildings are in the background) .......... 4-97

Figure 4-143: Soffit damage of the porte cochere at the civic center (Aransas Pass) ....................4-98

Figure 4-144: Permanently mounted screens at a hospital 

(Corpus Christi) ...........................................................................................................4-99

Figure 4-145: Sections of coping blew off at various locations along the parapet..........................4-99

Figure 4-146: Although located far inland, this nursing home was shut down as a result of 

building envelope damage and subsequent water infiltration (Refugio) .............. 4-100

Figure 4-147: Ground-mounted array...............................................................................................4-101

Figure 4-148: Aerial view of the vicinity of a rooftop solar array (Exposure D) ........................... 4-102

Figure 4-149: The yellow arrow indicates the row of missing solar panels.................................... 4-102

Figure 4-150: Damage to a rooftop-mounted solar array ............................................................... 4-103

Figure 4-151: Aerial view of a damaged rooftop solar array........................................................... 4-104

List of Tables

Table 1-1: Saffir-Simpson Hurricane Wind Scale Wind Speeds and Barometric Pressures....... 1-4

Table 1-2: Harvey Rainfall Rate Compared to Other Major Flood Events...................................1-7

Table 1-3: Details of MAT Units Deployed for Hurricane Harvey ..............................................1-24

Table 2-1: NFIP and CRS Data for Selected Communities..........................................................2-10

Table 2-2: Building Elevation Requirements in Effect Prior to Hurricane Harvey ...................2-10

Table 2-3: Building Codes in Effect at the Time of Hurricane Harvey for Selected Cities 

in Texas Impacted by High Winds ...............................................................................2-15

Table 2-4: Design Wind Pressures from ASCE 7-05 and ASCE 7-10, Risk Category II 

Buildings........................................................................................................................2-17

Table 2-5: Texas Revisions to 2006 IRC and IBC for Protection of Glazed Openings from 

Wind-Borne Debris ......................................................................................................2-21
xxviii MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

TABLE OF CONTENTS

Table 3-1: Summary of Closed Flood Insurance Claim Data for Neighborhoods 

Analyzed by MAT ........................................................................................................ 3-20

Table 3-2: Summary of Closed Flood Insurance Claim Data for the Representative 

Residential Area ........................................................................................................... 3-22

Table 3-3: Closed Flood Insurance Claim Data for Post-1982 Construction in the 

Representative Residential Area.................................................................................. 3-22

Table 3-4: Closed Flood Insurance Claim Data for Slab-on-Grade versus Crawlspace 

Construction in the Representative Residential Area................................................ 3-23

Table 3-5: Facilities and Buildings Assessed by MAT in Harris County..................................... 3-24

Table 3-6: Dry Floodproofing Key Observations Crosswalk with Report Section..................... 3-27

Table 3-7: Flood Levels, Probabilities, and Associated Recurrence Intervals at the Milam 

Street Bridge.................................................................................................................3-30

Table 3-8: Summary of Data Based on Milam Street Bridge Gage ............................................ 3-30

Table 3-9: General Flood Information Measured at Harris Gully Box Culvert ........................ 3-97

Table 3-10: Past Flood Events and Their Approximate Mean Recurrence Intervals ..................3-98

Table 5-1: Summary of Conclusions and Recommendations .................................................... 5-21
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT xxix

ACRONYMS AND ABBREVIATIONS

Acronyms and Abbreviations

AAMA American Architectural Manufacturers Association

ANSI American National Standards Institute 

ASCE American Society of Civil Engineers 

ASD allowable stress design

BFE base flood elevation

BIA Brick Industry Association

BUR built-up roofs 

C&C components and cladding 

CDT central daylight time

CFR Code of Federal Regulations

CHI Catholic Health Initiative

CMU concrete masonry units

COM College of Medicine (Baylor) 

CRS Community Rating System

DASMA Door & Access Systems Manufacturers Association, International

DFE design flood elevation 

DoD Department of Defense 

EIFS Exterior Insulation and Finish System 

FEMA Federal Emergency Management Agency 

FIMA Federal Insurance and Mitigation Administration 

FIRM Flood Insurance Rate Map

FIS Flood Insurance Study

FM FM Approvals

HCFCD Harris County Flood Control District 

HGSD Harris-Galveston Subsidence District

HVAC heating, ventilation, and air conditioning 

HWM high water mark

IBC International Building Code

I-Codes International Codes

IEBC International Existing Building Code

IRC International Residential Code

JFO Joint Field Office
xxx MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

ACRONYMS AND ABBREVIATIONS

LiMWA Limit of Moderate Wave Action

LPS lightning protection systems 

MAT Mitigation Assessment Team

mb millibars 

MEP mechanical, electrical, and plumbing

MH manufactured housing

mph miles per hour

MRI mean recurrence interval

MWFRS main wind force resisting system

NAMI National Accreditation and Management Institute, Inc.

NAVD North American Vertical Datum of 1988

NCEI National Centers for Environmental Information

NFIP National Flood Insurance Program

NIST National Institute of Standards and Technology

NOAA National Oceanic and Atmospheric Administration

NWS National Weather Service

PTAC packaged terminal air conditioners

psf pounds per square foot

PV photovoltaic

SCADA supervisory control and data acquisition

SFHA Special Flood Hazard Area

SME subject matter expert

SPRI Single Ply Roofing Industry

TCH Texas Children’s Hospital

TCPIA Texas Catastrophe Property Insurance Association

TDI Texas Department of Insurance

TECO Thermal Energy Corporation

TMC Texas Medical Center

TWIA Texas Windstorm Insurance Association

USACE U.S. Army Corps of Engineers

USVI U.S. Virgin Island 

UT University of Texas

U.S.C. U.S. Code
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-1

1Introduction

Hurricane Harvey made landfall in Texas on the night of 

August 25, 2017, as a Category 4 hurricane that dropped a 

historic amount of rainwater before it left the area 7 days later. 

When Hurricane Harvey made landfall in Texas on the night of August 25, 2017, between Port 

Aransas and Port O’Connor, it was the first Category 4 hurricane to make landfall on the continental 

United States since Hurricane Charley in 2004 and the first Category 4 hurricane to make landfall 

in Texas since Hurricane Carla in 1961.

Hurricane Harvey struck the Texas coast with 130 miles per hour (mph) sustained winds and was the 

wettest rainfall event in the country’s history, dropping an estimated 34 trillion gallons of rainwater, 

with local rainfall totals of 70 inches in some places over 7 days (NOAA NHC, 2018a). Hurricane 

Harvey was one of the most destructive storms in U.S. history. It caused extensive wind damage 

where it made landfalls and significant flood damage in the Houston metropolitan and Beaumont 

areas. The National Oceanic and Atmospheric Administration (NOAA) estimates damages at 

approximately $125 billion (NOAA NHC, 2018a). 

As part of its response to the disaster, the Building Science Branch of the Federal Emergency 

Management Agency’s (FEMA’s) Federal Insurance and Mitigation Administration (FIMA) deployed 

a Mitigation Assessment Team (MAT). MATs are composed of national and regional experts in 
1-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

building science and other relevant disciplines who assess building performance to improve resilience 

by incorporating lessons learned into new construction and the retrofit of existing buildings. The 

MAT was deployed on November 7, 2017, and deployed again on December 12, 2017 to complete 

its field assessment work. The MAT focused on buildings located in the area of Hurricane Harvey’s 

landfall in Aransas, Nueces, Refugio, and San Patricio Counties and the flooded areas of Harris 

County and the City of Houston (see Figure 1-1). 

This report describes the MAT’s observations during its field assessments and the conclusions 

and recommendations developed based on those observations. The purpose of this MAT report 

Figure 1-1:

MAT area of focus

is to evaluate the key causes of building failures and successes, describe lessons learned to help 

property owners and stakeholders mitigate damage from future natural hazard events, and provide 

recommendations to improve the resilience of buildings and communities. The report provides 

information that will help communities, businesses, design professionals, contractors, residential 

and non-residential building owners and operators, code officials, various planners, individuals, 

and other stakeholders to recover more quickly. The information can also be used to design and 

construct more robust buildings so that loss of life, injuries, and property damage resulting from 

future natural hazard events are minimized. 

Flood-related topics investigated by the MAT include floodplain management regulations and 

codes, the performance of residential buildings damaged in locations mapped on FEMA’s Flood 

Insurance Rate Maps (FIRMs), the performance of dry floodproofing systems in Harris County, the 

performance of FEMA-funded dry floodproofing mitigation projects, and the role and effectiveness 

of select emergency management and planning efforts. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-3

INTRODUCTION

Wind-related topics studied by the MAT include 

building code design requirements, the wind 

pressure performance of main wind force 

resisting systems (MWFRSs) and building 

envelopes (including rooftop equipment and 

solar panels), the effects of wind-borne debris on 

building envelopes, rain infiltration at building 

envelope breaches, and the performance of 

ground-mounted solar panel arrays on residences 

and commercial and critical facilities.

1.1 Organization of Report

This MAT report is divided into five chapters 

and three appendices. 

+ This chapter describes Hurricane Harvey, 

historic hurricanes in Texas, and the MAT 

background and process. 

+ Chapter 2 discusses building codes, standards, and regulations as they relate to wind design 

and floodplain management and their effect on design and construction in Texas. 

+ Chapter 3 describes MAT observations related to the performance of residential and nonresidential buildings under flood conditions and provides emergency management and 

planning considerations for non-residential buildings and critical facilities. 

+ Chapter 4 describes MAT observations related to the performance of buildings exposed to 

high winds and evaluates the effect building codes have had on wind performance. 

+ Chapter 5 presents the MAT’s conclusions and recommendations and is intended to help 

guide recovery efforts for communities prone to hurricanes and floods and to provide 

strategic recommendations to help improve codes and standards, design and construction 

guidance, code enforcement, and planning on a regional and national scale.

In addition, the following appendices are included:

+ Appendix A: Acknowledgments

+ Appendix B: References

+ Appendix C: Recovery Advisories

– Texas Recovery Advisory 1, Dry Floodproofing: Planning and Design Considerations

– Texas Recovery Advisory 2, Asphalt Shingle Roofing for High-Wind Regions 

MAIN WIND FORCE RESISTING SYSTEM 

(MWFRS)

An assemblage of structural elements 

assigned to provide support and stability 

for the overall structure. The system 

generally receives wind loading from more 

than one surface.

BUILDING ENVELOPE / COMPONENTS 

AND CLADDING (C&C)

Elements of the building envelope that do 

not qualify as a part of the MWFRS are 

identified as C&C in American Society of 

Civil Engineers (ASCE) standards. 

SOURCE: ASCE, 2010
1-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

1.2 Hurricane Harvey: The Event

Hurricane Harvey was the first major1 hurricane 

to make landfall on the United States since 

Hurricane Wilma in 2005. Hurricane Harvey 

formed from a tropical wave off the west coast 

of Africa on August 12, 2017 (NOAA NHC, 

2018a). On August 17, Harvey developed into a 

tropical storm that impacted the Lesser Antilles, 

later degenerating back into a tropical wave 

as it moved west across the Caribbean Sea. It 

rapidly strengthened in the Bay of Campeche on 

August 23, 2017, reforming into a tropical storm 

and becoming a Hurricane on August 24, 2017. 

Hurricane Harvey made its first landfall in the 

United States over San Jose Island, just north of Port Aransas, TX, on August 25, 2017, at 10 p.m. 

as a Category 4 hurricane with estimated sustained winds of 130 mph and a minimum pressure 

of 937 millibars (mb). Hurricane Harvey’s second landfall occurred 3 hours later on the Texas 

mainland southeast of Refugio with estimated sustained winds of 121 mph and a minimum pressure 

of 948 mb. Hurricane categories are rated on the Saffir-Simpson Hurricane Wind Scale (Table 1-1).

Table 1-1: Saffir-Simpson Hurricane Wind Scale Wind Speeds and Barometric Pressures

1 A major hurricane is a Category 3, 4, or 5 storm on the Saffir-Simpson Hurricane Wind Scale.

HARVEY’S TRACK

Hurricane Harvey was unique in its formation 

but not its track. Hurricane Harvey rapidly 

developed from a tropical depression to a 

Category 4 hurricane in 56 hours.

Although the magnitude of the event was 

unprecedented, the stalling of Hurricane 

Harvey over southeastern Texas was not; 

other tropical cyclone flood events, most 

notably Tropical Storm Allison in 2001, have 

followed similar tracks.

Strength Sustained Wind Speed (mph) Gust Wind Speed (mph) Pressure (mb)

Category 1 74–95 89–116 >980

Category 2 96–110 117–134 965–979

Category 3 111–129 135–158 945–964

Category 4 130–156 159–190 920–944

Category 5 157 or higher >190 <920

Sustained Wind Speed = 1-minute sustained over open water

Gust Wind Speed = 3-second gust over open water

mb = millibars

SOURCE: NOAA NHC, 2018B

After Hurricane Harvey made landfall, it continued northwest until the center of the storm 

stopped northwest of Victoria, TX. For the next 24 hours, the center of the storm remained almost 

stationary, making a slow loop that caused bands of heavy rain to continually fall over the Houston 

metropolitan area and southeastern Texas. On August 27, 2017, now downgraded to Tropical Storm 

Harvey, the storm proceeded in an easterly direction, re-entering the Gulf of Mexico on August 28 

and slightly strengthening. Tropical Storm Harvey made its third and final landfall on August 30 

near Cameron, LA, with sustained winds of 45 mph. Figure 1-2 shows Hurricane Harvey’s track 

from August 17, 2017 through September 1, 2017.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-5

INTRODUCTION

Figure 1-2: Hurricane Harvey storm track

SOURCE: NOAA NHC, 2018a

THE SIGNIFICANCE OF HURRICANE HARVEY

•	 Hurricane Harvey was the highest categorized hurricane to strike the U.S. coastline since 

Hurricane Charley hit Florida in 2004.

•	 At landfall, Hurricane Harvey was approximately 250 miles in diameter, with a wind speed of 74 

mph (sustained) across a width of 80 miles.

•	 Harvey made landfall in the U.S. three times: twice in Texas and once in Louisiana as a tropical 

storm, causing widespread damage in Texas and southwestern Louisiana. 

•	 Local rainfall totals in southeast Texas ranged from 20 inches to 70 inches over 7 days, making 

it the wettest hurricane in U.S. history; rainfall totals exceeded the 0.1-percent-annual-chance 

probability (1,000-year) event in some areas.

•	 Within Harris County, 300,000 vehicles were flooded. 

•	 Advance warning 2 days before the hurricane’s landfall resulted in mandatory evacuations of 

multiple counties; an estimated 560,000 people evacuated in advance of the hurricane.
1-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

1.3 Hurricane Harvey: The Impact

The path of Hurricane Harvey, with two landfalls on the Texas Gulf Coast and a third landfall in 

Louisiana, resulted in a widespread storm impact, with coastal storm surge in the areas around its 

three U.S. landfalls and historic inland flooding caused by 7 days of rain throughout southeastern 

Texas. Additionally, the greater Rockport, TX, area incurred significant wind damage during 

Hurricane Harvey’s first two U.S. landfalls.

1.3.1 Flood

Flooding impacts from Hurricane Harvey were caused by the storm surge and historic rainfall, which 

resulted in significant inland flooding; the history of subsidence in Harris County also contributed 

to the damage observed. Aerial imagery revealed that approximately one-third of Harris County was 

under water at one point, and approximately half of the inundated area was outside of the FEMAmapped 500-year floodplain. Within Harris County, 204,267 buildings flooded. Among the flooded 

buildings were 154,170 houses. Of the houses that were flooded, 48,850 were located in the Special 

Flood Hazard Area (SFHA)/1-percent-annual-chance probability (100-year event) floodplain, 34,970 

were located inside the 0.2-percent-annual-chance probability (500-year event) floodplain, and 

70,370 were located outside the 1-percent- and 0.2-percent-annual-chance probability floodplain.

1.3.1.1 Storm Surge

Although most of the damage in the area where the storm made landfall was a result of high winds, 

the coastal counties of Aransas, Nueces, Refugio, and San Patricio were inundated with storm surge 

that damaged at-grade buildings, enclosed areas below elevated residences, docks, and piers. The 

combined effects of surge and tide produced maximum inundation levels of 6 to 10 feet above 

ground level. This occurred to the north and east of Hurricane Harvey’s center at Texas landfall 

areas in the back bays between Port Aransas and Matagorda, including Copano Bay, Aransas Bay, 

San Antonio Bay, and Matagorda Bay. Higher inundation levels were recorded near the Aransas 

National Wildlife Refuge, where high water marks (HWMs) suggested water levels up to 12 feet. 

However, these water levels likely include the effects of wave runup. The tide gages in the Houston 

area recorded readings of 7.27 feet and 10.35 feet. These water levels were mostly caused by excessive 

rainfall runoff and not storm surge. Figure 1-3 shows high storm surge readings (in feet above 

ground level) measured during Hurricane Harvey.

1.3.1.2 Rainfall

Hurricane Harvey was the largest rainfall event in U.S. recorded history. The rainfall totals for 

Hurricane Harvey exceeded the 0.1-percent-annual-chance probability (1,000-year event) for many 

areas in southeast Texas, causing record flood levels for many creeks, rivers, and bayous. Figure 1-4 

shows the annual exceedance probabilities for the most severe 4-day rainfall totals that occurred 

during the 7-day rainfall event; NOAA records rainfall rates and determines corresponding 

recurrence intervals for 1-hour, 2-hour, 3-hour, 6-hour, 12-hour, 24-hour, 2-day, and 4-day rainfall 

events. Within Harris County, Hurricane Harvey established rainfall event records for 1-hour, 

2-hour, 3-hour, 2-day, and 4-day rainfall events. See Table 1-2.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-7

INTRODUCTION

Figure 1-3: Hurricane Harvey storm surge levels recorded by NOAA

SOURCE: NOAA NHC, 2018a

Table 1-2: Harvey Rainfall Rate Compared to Other Major Flood Events

Duration (cumulative)

Hurricane Harvey 

(August 2017)

Tropical Storm Allison

(June 2001)

Tax Day Flood

(April 2016)

(inches)

1 hour 6.8(a) 5.7 4.7

2 hours 11.9(a) 9.9 7.3

3 hours 14.8(a) 13.5 8.3

6 hours 18.9 21.2(a) 13.9

12 hours 20.9 28.3(a) 16.7

24 hours 25.6 28.4(a) 17.4

2 days 35.2(a) 28.5 17.5

4 days 47.7(a) 38.5 NA 

NA = Not Applicable

(a) Indicates a record level of rainfall

SOURCE: HCFCD, 2018a
1-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

Figure 1-4: Hurricane Harvey annual exceedance probabilities for the worst-case, 4-day rainfall according to NOAA

SOURCE: NOAA NHC, 2018a
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-9

INTRODUCTION

The rainfall totals resulted from Hurricane Harvey remaining nearly stationary northwest of 

Victoria, TX, which allowed inflow bands originating over the warm waters of the Gulf of Mexico to 

continually pass over the same regions. The heavy bands of rain, some exceeding 6 inches of rainfall 

per hour, were concentrated in the northern regions of the storm. The heavy bands entered the 

Houston area on August 25, with the heaviest rainfall on August 27. The rain did not stop falling in 

Houston until August 30, when Hurricane Harvey moved toward Louisiana. 

The highest total rainfall for the storm was recorded at a gage in Nederland, TX, with a reading 

of 60.58 inches. Weather radar indicates that rainfall totals in southeastern Texas were as high as 

65 to 70 inches. The majority of Harris County received a minimum of 25 inches of rainfall, with 

a maximum rainfall reading of 54 inches recorded in the southwestern corner of the county. One 

trillion gallons of rainwater fell in Harris County over a 4-day period. Figure 1-5 shows rainfall 

totals for southeastern Texas and the Houston metropolitan area. 

Figure 1-5: Rainfall totals of southeastern Texas and the Houston metropolitan area

SOURCE: MODIFIED FROM NOAA NHC, 2018a

Prior to Hurricane Harvey, Tropical Storm Allison in 2001 was considered the benchmark rainfall 

and flooding event for Houston. Dry floodproofing systems installed in Houston were designed to 

protect against an event similar to Tropical Storm Allison. During Hurricane Harvey, all of Harris 

County experienced more than 25 inches of rain, with large areas exceeding 36 inches of rain and 

a maximum recorded rainfall of 54 inches. Tropical Storm Allison, by comparison, had isolated 

areas where rainfall exceeded 36 inches, with a maximum of 40 inches in Harris County. Figure 1-6 

compares total rainfall between Tropical Storm Allison and Hurricane Harvey. 
1-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

Figure 1-6: Tropical Storm Allison (2001) rainfall totals (top) versus Hurricane Harvey rainfall totals (bottom). Rainfall 

totals scale uses the same color coding for both maps.

SOURCE: MODIFIED FROM NOAA NHC, 2018a
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-11

INTRODUCTION

1.3.1.3 Inland Flooding

The historic rainfall amounts produced by Hurricane Harvey resulted in extensive riverine flooding 

in southeastern Texas. This rainfall caused all of the major creeks, rivers, and bayous to exceed 

flood stage (Figure 1-7).

Figure 1-7: Overview of riverine flooding in Harris County (map does not show sheet flow flooding effects in the county)

SOURCE: MODIFIED FROM HCFCD, 2017

In addition to the flooding from riverine sources, sheet flow flooding damaged thousands of 

buildings located outside of both the 1-percent- and 0.2-percent-annual-chance probability 

floodplain. The historic rainfall overwhelmed stormwater drainage networks, causing sheet flow 

flooding, which resulted in backups. These backups caused rainwater to flow across the ground to 

the nearest natural drainage, flooding buildings in its path (Figure 1-8).

Analysis of aerial imagery revealed that approximately one-third of Harris County, which contains 

the City of Houston, was under water from riverine and/or sheet flow floodwater. Approximately 

half of the inundated area was outside of the mapped 0.2-percent-annual-chance probability (500-

year event) floodplain.
1-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

Figure 1-8: Example of rainwater flowing across the ground, flooding buildings in its path when stormwater drainage 

networks are overwhelmed

During Hurricane Harvey, 14 of the 22 watersheds in Harris County experienced flood depths 

at or exceeding the 0.2-percent-annual-chance probability level; whether any of the watersheds 

experienced flood depths at or exceeding the 0.1-percent-annual-chance probability (1,000-year 

event) level is unknown. An additional seven watersheds experienced flood depths at or above the 

1.0-percent-annual-chance probability (100-year event) level (Figure 1-9). 

The severity and extent of the flooding varied significantly between and among the watersheds 

within the Harris County Flood Control District (HCFCD), as did the width of the flooded areas 

between waterways. In some watersheds, flood-damaged buildings were located close to the primary 

channel, whereas in other watersheds, damaged buildings were miles from a channel. The width 

of the mapped 1.0-percent-annual-chance probability (100-year) floodplain for Brays Bayou in 

Meyerland and Bellaire exceeds 3 miles in some places, whereas the 1.0-percent-annual-chance 

probability floodplains for the White Oak and Buffalo Bayous are typically less than a half mile wide, 

excluding portions of the shipping channel, as they flow through Downtown Houston. Figure 1-10 

shows a comparison of these floodplain widths.

Within individual waterways, record-setting water surface elevations were recorded (some exceeded 

the 0.2-percent-annual-chance water surface elevations); while farther downstream, the water 

surface elevations were below the 1-percent-annual-chance water surface elevations. The lower water 

surface elevations in the downstream sections were the result of the channel naturally having a wider 

cross section at its entrance into Galveston Bay. Additionally, HCFCD has implemented numerous 

stormwater projects that have increased the depth or width of many channels. Most of these projects 

start at the entrance to Galveston Bay or at a confluence with a larger river or bayou and continue 

upstream. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-13

INTRODUCTION

For example, during Hurricane Harvey, an HCFCD gage at the Dairy Ashford Road bridge crossing 

Buffalo Bayou recorded a peak water surface elevation of 76.90 feet, exceeding the 0.2-percentannual-chance probability flood elevation of 74.70 feet. However, at the HCFCD gage located at 

Turning Basin, approximately 20 miles downstream where Buffalo Bayou enters the shipping 

channel, a flood elevation of 12.10 feet was recorded, which is slightly below the 1.0-percent-annualchance probability elevation of 12.20 feet, and did not exceed the record HWM elevation of 15.00 

feet that occurred during Hurricane Ike in 2008. 

Figure 1-9: Map showing exceedance probabilities, based on HWM, for Harris County watersheds

SOURCE: MODIFIED FROM HCFCD, 2018a
1-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

Figure 1-10: Comparison of 1-percent-annual-chance flood hazard width for Brays Bayou in the southwest portion 

of Houston (top image), which has a very broad SFHA, and the SFHAs for White Oak Bayou and Buffalo Bayou near 

Downtown Houston (bottom image), which are much narrower

FEMA Flood Insurance Rate Map

FEMA Flood Insurance Rate Map
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-15

INTRODUCTION

1.3.1.4 Subsidence

One factor that increases the vulnerability of flooding in southeastern Texas is land subsidence, the 

lowering of the ground surface with respect to a fixed elevation. Subsidence can lead to increased 

inland flooding along streams and waterways due to changes in stream gradient and due to ponding 

caused by localized subsidence in the vicinity of major groundwater extraction areas used for 

industrial and drinking water treatment. Subsidence in southeastern Texas is primarily caused by 

the withdrawal of groundwater (HGSD, 2014). Subsidence has been measured in the area since 

1906; from 1906 to 2000, areas of Harris County have experienced subsidence of up to 10 feet (see 

Figure 1-11).

In response to the subsidence that has occurred in the region, the Harris-Galveston Subsidence 

District (HGSD) was formed in 1976. The HGSD implemented restrictions on groundwater pumping 

with the goal of reducing 2003 groundwater usage rates by 80 percent by 2030. Since its formation, 

subsidence rates across the district have decreased. Current subsidence rates range from 0.3 foot/

decade to no measurable change across the 90 extensometers (subsidence measuring stations) 

located in the district. 

1

2

3

4

5

6

7

2

3

3

6

1

2

4

5

7

7

6

4

5

8

8

9

10

9

6

Figure 1-11: Land subsidence in the Houston-Galveston Subsidence District, 1906-2000, retrieved May 2018

SOURCE: MODIFIED FROM HGSD, 2013
1-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

In the past, the presence of subsidence in this region complicated flood hazard mapping and 

rendered some flood hazard maps obsolete before they would otherwise need to be updated. As 

a result, some older construction may have been built to an elevation that subsequently subsided, 

causing the building to be susceptible to flooding. However, all FIRMs within the HGSD have been 

updated, with the oldest effective maps dated June 18, 2007; the current maps include the high 

levels of subsidence that occurred in the past so the impact of subsidence-influenced flooding can 

be accounted for in new construction. 

1.3.2 Wind

Hurricane Harvey was a Category 4 hurricane with estimated sustained winds of 130 mph. At landfall, 

Hurricane Harvey was approximately 250 miles in diameter, with an eye that was approximately 20 

miles in diameter. Its hurricane force winds extended 45 miles from the right side of the track and 

35 miles from the left side of the track. 

The wind damage caused by Hurricane Harvey was concentrated in the area where the first two 

landfalls occurred; Harris County did not experience high winds. In the greater Rockport area (i.e., 

the area shown in the bottom image in Figure 1-12), Hurricane Harvey’s wind speeds produced 

pressures that approximated design pressures derived from various editions of American Society 

of Civil Engineers (ASCE) publication ASCE 7,2 depending on a building’s proximity to the track 

of the storm and building and site characteristics. In Aransas, Nueces, Refugio, and San Patricio 

Counties, wind forces damaged 40,929 buildings, resulting in $4.58 billion in damage (NOAA NWS 

Corpus Christi, 2018). 

Figure 1-12 compares Hurricane Harvey’s estimated 3-second gust wind speeds to the basic (design) 

speed from ASCE 7-10 for Risk Category II buildings.

The MAT observed MWFRS damage at older residential and non-residential buildings. However, the 

most common wind damage observed was to roof coverings and rooftop equipment. Blown-off, lowslope roof membranes were observed on older and newer buildings. However, newer roof membranes 

were observed that did not experience wind uplift problems. Many older and newer roof membranes 

were punctured or torn by wind-borne debris. Rooftop equipment was often displaced due to lack 

of anchoring or insufficient anchoring. Wind-borne equipment often punctured roof membranes. 

Roof covering and rooftop equipment breaches resulted in rain infiltration and subsequent interior 

water damage. Residences also sustained fiber cement siding damage and broken glazing. 

Building siding and veneers were another common source of failure and water infiltration. The 

MAT observed significant brick veneer failures due to missing ties, improper spacing of ties, or 

corroded ties. MATs have previously identified brick tie spacing, missing ties, and tie corrosion as 

reasons for brick veneer failure.

2 The 1998, 2005, and 2010 versions of ASCE 7 are all titled Minimum Design Loads for Buildings and Other Structures. For the 2016 version, 

the title was revised to Minimum Design Loads and Associated Criteria for Buildings and Other Structures.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-17

INTRODUCTION

Figure 1-12: 

Wind swath plot 

of estimated 

3-second gust 

wind speed in 

mph at a height 

of 33 feet above 

ground, Exposure 

C (solid lines). 

The top figure 

shows the wind 

field for Hurricane 

Harvey, whereas 

the bottom figure 

shows the area 

around its initial 

two landfalls

SOURCE: THE WIND 

SPEED ESTIMATE 

IS BASED ON 

HURRICANE HARVEY 

(2017) WIND GUST, 

SEPTEMBER 2017, 

DATA PREPARED BY 

APPLIED RESEARCH 

ASSOCIATES
1-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

1.4 Historic Storm Events in Texas

The State of Texas has suffered numerous hurricane, tropical storm, and severe inland flooding 

events in recent history, causing tremendous damage across the Texas coastal region. The Texas 

coast averages a hurricane every 3 years and has experienced 63 hurricanes since 1851; 22 of those 

hurricanes can be classified as major hurricanes. Before Hurricane Harvey, the Houston area alone 

experienced four significant flooding events within a 16-year timeframe (Tropical Storm Tax Day 

2016, Tropical Storm Memorial Day 2015, Hurricane Ike 2008, and Tropical Storm Allison 2001). 

The frequency of significant natural disasters should shape how local governments, communities, 

businesses, and critical facilities prepare for them; it is not a question of if, but when the next natural 

hazard event will occur.

GALVESTON HURRICANE OF 1900

The deadliest hurricane in U.S. history was the Great Galveston Hurricane that occurred on 

September 7 to 8, 1900. This hurricane claimed approximately 8,000 lives. The population of 

Galveston in 1900 was approximately 37,000. This hurricane traveled the Caribbean as a tropical 

storm before making landfall across the southern United States where it hit Florida, Mississippi, 

Louisiana, and Texas. The storm then traveled through the central United States and up through 

the Great Lakes, making its way through Canada. The Great Galveston Hurricane was classified as 

Category 4 at landfall, with sustained winds of 100 mph and gusts over 125 mph (NOAA NHC, n.d.). 

The minimum central pressure was 931 mb or 27.49 inches of mercury. 

The storm surge and high water level from the Great Galveston Hurricane washed out the four bridges 

linking Galveston to the mainland and downed telephone lines, cutting off the island from the mainland. 

The highest land elevation on Galveston Island in 1900 was 8 feet; the storm surge reached 15 feet. 

Over 3,600 properties were destroyed, resulting in an estimated $30 million in property damage 

at the time of the event (NOAA NOS, 2017). The horrific devastation of the hurricane motivated the 

people of Galveston to find a way to protect themselves against another disaster of this magnitude. 

Construction of a 17-foot-high seawall began in 1902 to protect 3 miles of oceanfront. Sand was 

dredged from Galveston Bay to elevate the city portion of the island by 8 feet.

This section describes some of the historical hurricane, tropical storm, and flooding events that 

severely impacted the Texas coastline. The timeline in Figure 1-13 highlights significant hurricanes 

that have impacted the Texas coast. In addition to hurricanes, Tropical Storm Allison caused 

significant damage to the Texas coast, as did significant flood events known as the Memorial Day 

Flood (2015) and the Tax Day Flood (2016).

The data for the total estimated damages for each storm event discussed were obtained from 

the NOAA National Centers for Environmental Information (NCEI) (2018). Information about 

each storm event comes from data provided by the HCFCD (HCFCD, 2016) and various National 

Hurricane Center reports on tropical systems (NOAA NHC, 2014; NOAA NHC, 2001; and NOAA 

NHC, 1998) unless noted otherwise.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-19

INTRODUCTION

Figure 1-13: 

Track of Hurricane Harvey 

(red line) relative to landfall 

locations of significant 

historic hurricanes in Texas 

between 1950 and 2017

Tax Day Flood, 2016

On April 17 and 18, 2016, storms congregated over Harris County, producing severe rainfall and 

catastrophic flooding. Harris County received 8 inches of rain, with isolated pockets of up to 17 

inches, within a 24-hour timeframe. This event claimed the lives of seven people, and over 1,800 

people were rescued from the high waters. The storms resulted in an estimated $2.8 billion in 

property damage.

Memorial Day Flood, 2015

From May 23 to 26, 2015, severe storms developed in Texas and Oklahoma, producing heavy rainfall 

and flooding. Harris County received up to 11 inches of rain within a 10-hour timeframe, and 

downtown Houston received up to 6 inches of rainfall during the storm. The short timeframe of 

the storm resulted in hundreds of rescues within Houston alone. Thirty-one people lost their lives 

during this event. The storm produced an estimated $2.7 billion in property damage, $1.1 billion of 

which was in Texas. 

Spring Flood, 2009

Beginning on April 17, 2009, a 12-day storm event caused extensive flooding throughout Harris 

County. More than 2,300 structures were flooded and five people lost their lives as a direct result of 

this storm.

Hurricane Ike, 2008

Hurricane Ike, which became a Category 4 hurricane before weakening prior to landfall, 

transformed from a tropical storm into a hurricane over the tropical Atlantic Ocean. Ike migrated 

west-northwestward, directly impacting Turks and Caicos, the southeastern Bahamas, and Cuba. The 

hurricane was downgraded to a Category 2 event prior to landfall on the northern side of Galveston 

Island on September 13, 2008. Ike traveled northward across eastern Texas with 3-second gust wind 

speeds of 109 mph. Southeastern Texas and southwestern Louisiana received 3 inches or more 
1-20 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

of rainfall, while just north of Houston received 18.90 inches of rainfall during this event. Heavy 

rainfall led to severe flooding in Missouri, Illinois, and Indiana. Hurricane Ike directly claimed the 

lives of 112 people, and the estimated U.S. property damage was nearly $35.4 billion. 

Summer Flood, 2006

On June 19, 2006, a storm event produced 8 to 10 inches of rainfall within a 3-hour time period. 

Over 4,000 structures were flooded in Harris County (HCFCD, 2016).

Tropical Storm Allison, 2001

On June 5, 2001, a tropical wave in the Gulf of Mexico developed into Tropical Storm Allison due 

south of Galveston, TX. Tropical Storm Allison formed rapidly and traveled inland toward the upper 

Texas coastline, where it stalled and looped around southeastern Texas, causing severe rainfall and 

flooding throughout the Houston area. The storm drifted back into the Gulf of Mexico, changed 

direction, and migrated toward Louisiana for a second landfall. Tropical Storm Allison continued 

northeastward across the entire east coast of the United States, causing heavy rainfall and flooding 

for 13 days. 

Houston received approximately 38 inches of rain over a 6-day period. Most of the city’s bayous 

overran their banks, flooding 73,000 homes and leaving many residents without power for days 

(NOAA NHC, 2001). The storm directly claimed the lives of 43 people, 22 of whom were in the 

Houston area. Tropical Storm Allison caused an estimated $12.1 billion in property damage, with 

approximately 20 percent of the Houston property damage incurred by the TMC.

Tropical Storm Frances, 1998

On September 8, 1998, Tropical Storm Frances developed in the Gulf of Mexico and traveled 

northward toward the coastline of central Texas. Frances produced three tornadoes with wind gusts 

up to 66 mph across Texas. Severe flooding was recorded across Harris County, with 21 inches of 

rain reported in the Houston metropolitan area (NOAA NHC, 1998). This event claimed the lives 

of two people. The storm resulted in the flooding of an estimated 1,400 structures and caused $1.1 

billion in property damage.

Texas Flooding, Severe Storm (FEMA DR-937), 1994

Beginning on October 15, 1994, a 5-day storm event in southeast Texas caused extensive flooding 

in 29 counties. The event resulted in the flooding of an estimated 26,000 structures and caused an 

estimated $1.7 billion in property damages. This storm event claimed the lives of 19 people.

Hurricane Alicia, 1983

Hurricane Alicia, a Category 3 hurricane, struck southwest Galveston Island on August 17, 1983. 

Alicia had maximum sustained winds of over 96 mph, with 3-second gusts of up to 125 mph along 

the coast. William P. Hobby Airport in Houston reported sustained winds of 94 mph, with 3-second 

gusts of 107 mph (NOAA NHC, n.d.). Hurricane Alicia was notable because it resulted in extensive 

glazing damage in high-rise buildings in downtown Houston. Storm surges of 12 feet were recorded 

at Morgan Point along Galveston Bay (FEMA, 2009a). It was reported that 21 people lost their lives 

in this storm and estimated property damage was $7.7 billion.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-21

INTRODUCTION

Hurricane Allen, 1980

Hurricane Allen was one of the top five most intense storms in history. The storm transformed 

into a hurricane on August 3, 1980, about 120 miles east of Barbados as it traveled westward across 

the Atlantic Ocean. On August 7, 1980, the storm became the strongest hurricane recorded at that 

time, with sustained winds of 185 mph (NOAA NWS, 2010) and a central pressure of 899 mb (26.55 

inches of mercury). Hurricane Allen made landfall as a Category 3 hurricane near Port Mansfield, 

TX, on August 10. The highest wind gust reported was from Port Mansfield, registering at 138 mph 

(NOAA NWS, 1983). Storm surges reached 12 feet at Port Mansfield (NOAA NCEI, 2018). Twelve 

tornadoes from this hurricane touched down across south Texas (NOAA, 1983).3 About 300,000 

people were evacuated (FEMA, 2009a). This event directly claimed the lives of 13 people, and the 

estimated damages in Texas and Louisiana were $1.9 billion. 

Hurricane Celia, 1970

On August 3, 1970, Hurricane Celia made landfall in Texas midway between Corpus Christi and 

Aransas Pass. Hurricane Celia had strong wind gusts estimated as high as 180 mph that far exceeded 

the reported hurricane sustained winds of 130 mph. However, the hurricane did not produce 

torrential rains and massive flooding over a large area as storms of this magnitude typically do. The 

heaviest rainfall was in Robstown, a suburb of Corpus Christi, where 7.26 inches fell. Rains of 3 to 

4 inches or less accompanied the hurricane along its path across south Texas. The major cause of 

damage from this storm was the extreme winds. The estimated damage was approximately $2.97 

billion. Fifteen deaths and 466 injuries were a direct result of the storm. Information on Hurricane 

Celia is summarized from the National Weather Service (NWS) website (NOAA NWS, n.d.).

1.5 The FEMA Mitigation Assessment Team

FEMA conducts building performance studies after unique or nationally significant disasters to 

better understand how natural and manmade events affect the built environment. A MAT is generally 

deployed when FEMA believes the findings and recommendations derived from field observations 

will result in design and construction guidance that will help improve the disaster resistance of 

the built environment in the affected State or Region and will be of national significance to other 

disaster-prone regions. FEMA bases its decision to deploy a MAT on information such as:

+ Magnitude of hazard

+ Potential type and severity of damage in the affected areas

+ Pre-storm site conditions, such as the presence of older housing stock and aging 

infrastructure

+ Potential value of study results to the recovery effort

+ Strategic lessons that can be learned and applied, potentially on a national level, related to 

improving building codes, standards, and industry guidance 

3 The reported number of tornadoes produced varies across information sources. The Ike MAT (FEMA, 2009a) reports 34 tornadoes, but the 

NOAA Technical Report NWS 35 (1983) reports 12.
1-22 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

+ Possibility that the field assessment would reveal pertinent information regarding the 

effectiveness of certain FEMA grants and key engineering principles and practices that FEMA 

promotes in published guidance and best practice documents

+ Gaps in knowledge or information for improving performance of buildings or their utility 

systems to help in planning, design, construction, code enforcement, strengthening 

community resilience, enhancing capabilities or training for various skillsets or organizations, 

providing or developing guidance, advancing building codes and standards, or documenting 

research needs

The MAT studies the adequacy of current building codes and floodplain management regulations, 

local construction requirements, building practices, and building materials in light of the 

building performance observed after a disaster. Lessons learned from the MAT’s observations 

are communicated through recovery advisories, fact sheets, and a comprehensive MAT report, all 

of which are made available to communities and the public at large to aid recovery efforts and 

enhance disaster resilience of buildings and utility systems, whether for existing buildings or new 

construction. Conclusions and recommendations from MAT reports are often the basis for FEMA’s 

building code proposals at code hearings to help improve design and construction standards and 

mitigate damage.

1.5.1 Team Composition

The Harvey MAT was composed of 27 subject matter experts (SMEs), split into four units. MAT 

members included:

+ FEMA Headquarters and Regional Office architects, engineers, and specialists

+ Staff from other Federal agencies, including:

– Department of Defense (DoD)

– National Institute of Standards and Technology (NIST)

– NOAA Sea Grant

+ Construction and building code industry specialists

+ Design professionals

+ Insurance company hazard mitigation specialists

MAT members included architects; structural, civil, coastal, and electrical engineers; experts 

in floodplain management, building codes, construction materials, critical facilities, urban 

floodproofing, and housing; mechanical, electrical, and plumbing (MEP) specialists; and healthcare 

specialists. The members of the MAT are listed in the front of this report. 

1.5.1.1 Involvement of State and Local Agencies

FEMA encouraged the participation of county and local government officials and locally based 

specialists in the assessment process. FEMA’s involvement was critical and helped improve the MAT’s 

understanding of local construction practices; facilitated communications among Federal, State, 

and local governments and the private sector; and improved the State and local understanding of 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-23

INTRODUCTION

the MAT’s observations, conclusions, and recommendations, enabling them to bring about changes 

in their communities.

The MAT met with local emergency management and government officials in many of the areas 

visited during the field assessment. These officials gave an overview of the damage in their area and 

helped identify key sites where the MAT should deploy. The MAT also coordinated with the FEMA 

Joint Field Office (JFO) that had been established shortly after Hurricane Harvey made landfall. 

Individuals who assisted the MAT with its field operations and report development are listed in the 

front of this report. 

1.5.1.2 Pre-MAT Deployment and Site Selection

To be able to develop the focus areas for the MAT, FEMA deployed three pre-MAT units to the 

regions impacted by Hurricane Harvey on September 8 through September 12, 2017. The pre-MAT 

units were each composed of three people, consisting of FEMA Headquarters personnel and SMEs 

with a range of expertise. Prior to deploying the pre-MAT, FEMA and pre-MAT members relied on 

a desktop analysis, news reports of storm damage, social media, NOAA and Civil Air Patrol photos, 

and locations of FEMA-funded mitigation projects to identify regions and specific locations for the 

three pre-MATs to visit. 

The pre-MATs visited Harris and Galveston Counties to observe flood damage and Aransas, 

Calhoun, Nueces, Refugio, and San Patricio Counties to observe storm surge and wind damage. The 

pre-MAT observations on types and magnitude of damage were used to identify unique conditions 

and areas to guide the MAT’s focus. The conclusion was that the MAT should focus on the following 

locations and topic areas for flood- and wind-related damage:

+ Flood-related: Dry floodproofing mitigation in Harris County

+ Flood-related: Residential flooding in Aransas, Harris, and Nueces Counties 

+ Flood-related: Texas Medical Center (TMC) in Harris County 

+ Wind-related: Residential and non-residential wind damage in Aransas, Nueces, Refugio, and 

San Patricio Counties

1.5.2 Hurricane Harvey MAT

Using the information collected by the pre-MAT, the MAT was divided into four specialty units, 

two for flood-related damage and two for wind-related damage. Each unit was deployed to several 

locations to assess the performance of specific building and facility types. The Harvey MAT was 

initially deployed November 7 to 15, 2017, and redeployed December 12 to 15, 2017, to complete field 

assessment work. The mission of the MAT was to assess the performance of residential and nonresidential buildings affected by Hurricane Harvey in Texas. 

To assess the effectiveness of flood and wind mitigation efforts 

previously undertaken, the MAT evaluated select buildings of 

interest that had previously undergone mitigation to improve 

their resilience to hurricane conditions (either flood or wind), 

as well as residential and non-residential buildings that had not 

been mitigated. The MAT focused on buildings located in the 

MITIGATION

Any action taken to reduce 

or eliminate vulnerabilities 

to life and property from a 

hazard event.
1-24 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

area of Hurricane Harvey’s landfall in Aransas, Nueces, Refugio, and San Patricio Counties and the 

flooded areas of Aransas, Harris, and Nueces Counties. 

Field Deployment of MAT Units

Four MAT units were deployed, each with a distinct focus area (see Table 1-3). Figure 1-14 through 

Figure 1-16 depict the approximate locations where the MAT units assessed building performance. 

Table 1-3: Details of MAT Units Deployed for Hurricane Harvey

MAT Units Deployment Date Focus Area

Flood Unit

November 9, 2017 – 

November 15, 2017

Dry Floodproofing Subunit

Assessed the performance of dry floodproofing at 

commercial facilities, underground parking and tunnel 

complexes, government facilities, courthouses, prisons, and 

residential high-rise facilities in Harris County.

Residential Flooding Subunit

Identified neighborhoods with a mixture of new and old 

construction along Brays, Buffalo, and White Oak Bayous for 

use in a desktop analysis. The desktop analysis assessed the 

effect of floodplain regulations on flood insurance claims in 

those neighborhoods.

Texas Medical Center 

(TMC) Flood Unit December 12, 2017 – 

December 15, 2017

Assessed performance of dry floodproofing mitigation 

measures and reviewed emergency operations planning and 

dry floodproofing implementation plans at the TMC in Harris 

County.

Residential Wind Unit (a)

November 7, 2017 – 

November 10, 2017

Assessed performance of coastal single-family residential 

buildings in Aransas, Nueces, Refugio, and San Patricio 

Counties that were exposed to high wind pressures.

Non-Residential Wind 

Unit

Assessed performance of non-residential buildings, such as 

schools, hospitals, and hotels, in Aransas, Nueces, Refugio, 

and San Patricio Counties that were exposed to high wind 

pressures.

(a) Members of the Residential Wind Unit took note of the performance of residential buildings that were exposed to storm surge.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-25

INTRODUCTION

Downtown Houston

Houston Galleria

Brays Bayou

0 2 4

Miles

Approximate Scale

Energy Corridor

Figure 1-14: Areas of operations for the MAT Flood, Dry Floodproofing subunit in Harris County

Figure 1-15: Locations of facilities observed by the MAT TMC Flood Unit
1-26 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

INTRODUCTION

When possible, the MAT interviewed building and facility owners to gain insight into how their 

buildings and facilities performed during Hurricane Harvey. The interviews focused on how 

buildings and facilities performed during other recent events and how recovery efforts were 

progressing. In addition, the MAT used an aerial drone for part of the deployment to supplement 

observations of wind damage (refer to the text box titled “Aerial Drone” for details). Each MAT unit 

took considerable time assessing successes and failures for its focus area to determine why certain 

buildings performed better than others and what lessons could be learned from the event. To help 

ensure that consistent information was obtained from each site and keep track of which buildings 

were visited, the MAT used a cloud-based data collection application (refer to text box titled “MAT 

Data Sharing” for more information).

Figure 1-16: Primary areas of operations for the MAT Residential and Non-Residential Wind units were Aransas Pass, 

Bayside, Corpus Christi, Holiday Beach, Port Aransas, and Rockport (including Estes and Fulton)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 1-27

INTRODUCTION

AERIAL DRONE

A drone and drone pilot accompanied a portion of the MAT’s deployment. This was the first time that 

a MAT used a drone. The drone provided high-resolution photos to augment the MAT’s observations 

of wind damage. Using a drone allowed large areas to be surveyed, identifying locations for more 

detailed evaluation, and provided access to inaccessible areas to study wind damage. The drone 

took photos of the surrounding area, which helped the MAT analyze the site exposure (including the 

influence of “open patches” [as defined in ASCE 7]). The MAT used the photos of the surrounding area 

for qualitative comparison of the performance of other buildings in the vicinity. In instances where the 

MAT could not access a roof, the drone photo was used to determine the presence of damage to the 

roof system or rooftop equipment (Photo 1). Drone photos were also used to analyze wall covering 

damage at upper levels of mid-rise buildings (Photo 2).

Photo 1: Drone image of a nursing home. The red 

arrows indicate rooftop heating, ventilation, and air 

conditioning (HVAC) units that blew off the roof. The 

roof deck blew off the area within the red circle. See 

Section 4.2 for further discussion of this facility.

Photo 2: Drone image of brick veneer failure at a midrise building.
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INTRODUCTION

MAT DATA SHARING

The MAT Wind Units used a cloud-based data collection application to collect and store residential and 

non-residential wind damage assessments in the field. The cloud-based data collection application 

facilitated rapid post-disaster research reconnaissance to document perishable data that could be 

used by members of academia and design professionals to understand the effects the natural hazard 

had on the built environment. 

The mobile application contains mapping capabilities, data collection functions, field report generation 

capability, and secure import and export options. Standardized inspection forms were provided on 

the platform to ensure consistent information was collected at each location by the various members 

performing wind damage assessments. 

The data collected by the Wind Units were uploaded to a database that contained wind damage 

assessments collected from the other members of the MAT. The image below is an example of the 

cloud-based data collection application data and interface. Inspected buildings are shown on a map 

and identified by a color-coded pin, where the color indicates the severity of damage based upon the 

inspection. Inspection photos and information are stored for each building inspected.

Example of cloud-based data collection application interface

SOURCE: FULCRUM COMMUNITY, 2018
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-1

2Building Codes, Standards, 

and Regulations

Texas cities and counties look to the Texas constitution and statutes 

to determine what they may or may not do. In Texas, regulatory 

authority is generally determined through home rule law. 

Texas has a long history of home rule whereby cities with a population of 5,000 or more may elect 

a home rule charter. Home rule cities have the authority to enforce building codes and other 

regulations that affect hazard mitigation. Small cities (those with populations of less than 5,000) 

that do not adopt a home rule charter are limited as general law municipalities. Counties and small 

cities are restricted to doing only what the State directs or permits them to do. 

State statute explicitly authorizes counties to regulate housing and other structures and allows 

counties to adopt resolutions or orders requiring permits. Texas counties and municipalities 

generally have the authority to adopt a building code, but those that elect to adopt codes must, 

at a minimum, adopt certain editions of the International Building Code® (IBC®)/International 

Residential Code® (IRC®). Texas Statutes Chapters 214 and 233 apply to the adoption of the 

minimum building codes in municipalities and counties, respectively. For municipalities, Section 
2-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

214.212 specifies the 2000 IRC and Section 214.216 specifies the 2003 IBC. Municipalities may adopt 

more recent editions of these codes.

Section 233.153 specifies the 2006 IRC as the minimum residential code for unincorporated areas 

of a county. Counties may elect to adopt the version of the IRC that is applicable in the county seat. 

However, Section 233.154 places the burden of inspection of new single-family dwellings on builders. 

Section 233.155, modified in 2017, authorizes counties to take action when notices provided by 

builders do not indicate compliance with the applicable building code.

State statute gives the governing bodies of each city and county the authority to adopt ordinances 

or orders and “to take all necessary and reasonable actions that are not less stringent than the 

requirements and criteria” of the National Flood Insurance Program (NFIP). 

Incorporated cities in Texas have limited authority for various purposes in areas beyond their city 

limits. Extraterritorial jurisdiction extends for different distances depending on the number of 

inhabitants in a city. An extraterritorial jurisdiction area enables a city to extend regulations related 

to certain aspects of development to outside its city limits. 

The remainder of this chapter presents requirements related to floodplain management and 

construction of buildings in high-wind areas. Section 2.1 includes a summary of the NFIP and the 

minimum requirements for buildings that communities must adopt and enforce to participate in the 

NFIP. The MAT reviewed the floodplain management regulations and building codes of selected 

cities impacted by Hurricane Harvey flooding; observations based on that review are included.

Section 2.2 summarizes the wind requirements in the International Codes® (I-Codes®) and the 

referenced standard that specifies wind loads for the design of buildings and structures. The section 

also briefly describes the Texas Windstorm Program administered by the Texas Department of 

Insurance (TDI) because the program has significant influence on construction and building codes 

in the coastal communities.

2.1 Floodplain Management Requirements

NFIP regulations, described in Section 2.1.1, form the basis of local government programs to guide 

and regulate development in flood hazard areas. The NFIP requirements for buildings have been 

integrated into national consensus standards (ASCE 7 and ASCE 24, Flood Resistant Design and 

Construction) and model building codes. FEMA deems the flood provisions in the 2009 and later 

editions of the I-Codes to meet or exceed the minimum requirements of the NFIP for buildings and 

structures. When IBC Appendix G, Flood-Resistant Construction, is also adopted, the minimum 

requirements for non-building development are satisfied. Figure 2-1 illustrates how floodplain 

management regulations and building codes can be coordinated to fulfill the requirements for 

participation in the NFIP.

As previously discussed, Texas communities are authorized to adopt and enforce building codes. The 

I-Codes include provisions for buildings and structures in SFHAs. To address the coordination issues 

between locally adopted floodplain management regulations and the building codes and referenced 

standards, communities may wish to refer to Reducing Flood Losses Through the International Codes: 

Coordinating Building Codes and Floodplain Management Regulations, 4th Edition (ICC/ FEMA, 2014). 

This publication, written by the International Code Council in cooperation with FEMA, also describes 

differences between the flood provisions in the I-Codes and the NFIP minimum requirements. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-3

BUILDING CODES, STANDARDS, AND REGULATIONS

Figure 2-1: Floodplain management regulations and building 

design in communities with adopted building codes

BUILDING CODES AND LOCAL 

FLOODPLAIN REGULATIONS

Communities that enforce locally 

adopted floodplain management regulations and also enforce building 

codes with flood provisions should examine the differences and determine 

in advance how best to resolve those 

differences. Resolving them on a caseby-case basis may result in varying 

interpretations or failure to enforce the 

more restrictive of the requirements.

2.1.1 National Flood Insurance Program

The authorizing legislation for the NFIP is the National Flood Insurance Act of 1968, as amended 

(Title 42 of the U.S. Code [U.S.C.] §§ 4001 et seq.). In the act, the U.S. Congress found that “a 

program of flood insurance can promote the public interest by encouraging sound land use by 

minimizing exposure of property to flood losses.” Since 1968, the act has been modified several times. 

The NFIP is based on the premise that the Federal Government will make flood insurance available 

to communities that adopt and enforce floodplain management requirements that meet or exceed 

the minimum NFIP requirements. 

The regulations of the NFIP are the basis for local floodplain management ordinances adopted to 

satisfy the requirements for participation in the NFIP. In addition, the NFIP minimum requirements 

are the basis for the flood-resistant design and construction requirements in model building codes 

and standards. When decisions result in development in SFHAs, application of NFIP criteria is 

intended to minimize exposure to floods and flood-related damage. 

The most convincing evidence of the 

effectiveness of the NFIP minimum 

requirements is found in flood insurance 

claim payment statistics. Buildings that predate the NFIP requirements were generally 

not constructed to resist flood damage, 

while buildings that post-date the NFIP are 

designed to resist flood damage. The NFIP 

aggregate loss data show that buildings that 

meet the minimum requirements experience 

80 percent less flood damage than buildings 

that pre-date the NFIP. Additionally, ample 

MORE PROTECTIVE STANDARDS FOR 

FLOODPLAIN MANAGEMENT

FEMA encourages States and communities to 

adopt standards that are more protective than 

the NFIP minimum requirements. The most 

common higher standard that affects buildings 

is “freeboard,” a requirement to elevate buildings 

above the base flood elevation (BFE). Table 2-2 

(Section 2.1.3) shows requirements for selected 

communities impacted by Hurricane Harvey.
2-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

evidence suggests that buildings designed to standards that exceed the minimum requirements are 

even less likely to sustain damage. 

At the Federal level, the NFIP is managed by FEMA and has three main elements: 

+ Hazard identification and mapping, in which engineering studies are conducted and flood 

maps and studies are prepared to delineate areas expected to be subject to flooding under 

certain conditions 

+ Floodplain management criteria, which establish the minimum requirements for 

communities to adopt and apply to development in mapped flood hazard areas; the 

expectation is that communities will recognize hazards throughout their entire land 

development process 

+ Flood insurance, which provides some financial protection for property owners to cover 

flood-related damage to buildings and contents 

At the State level, each Governor or State legislature designates an agency or office to function as 

the NFIP State Coordinating Agency. The duties and responsibilities of these agencies, typically 

called the “NFIP State Coordinator,” are found in Title 44 of the Code of Federal Regulations (CFR) 

§ 60.25. Common functions performed by NFIP State Coordinators include: 

+ Enact, whenever necessary, legislation to enable communities to regulate development in 

flood hazard areas 

+ Establish minimum State standards consistent with NFIP requirements 

+ Ensure coordination with other State, area-wide, and local agencies 

+ Encourage and assist communities in qualifying for participation in the NFIP 

+ Guide communities and help develop, implement, and maintain floodplain management 

regulations 

+ Provide technical assistance to communities and the general public 

+ Assist with disseminating information 

on flood hazards and regulatory 

requirements 

+ Participate in training opportunities 

+ Assist in delineating floodprone areas 

+ Notify FEMA of problems with 

community programs if such problems 

cannot be resolved through technical 

assistance 

DEVELOPMENT

Any manmade change to improved or 

unimproved real estate, including, but not 

limited to, buildings or other structures, mining, 

dredging, grading, paving, excavation or drilling 

operations, or storage of equipment or materials 

(44 CFR § 59.1).

2.1.1.1 General Performance Requirements for Buildings

NFIP performance requirements for development in SFHAs are set forth in Federal regulations 

at 44 CFR Parts 59 and 60. The requirements apply to all types of development proposed in 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-5

BUILDING CODES, STANDARDS, AND REGULATIONS

SFHAs. The NFIP broadly defines the term 

“development,” and the requirements apply 

to new development, new buildings and 

structures, Substantial Improvement of 

existing buildings and structures, and repair 

of existing buildings and structures that 

sustain Substantial Damage (refer to the text 

boxes on “Development” and “Substantial 

Damage / Substantial Improvement”). 

The NFIP provisions guide development to 

lower-risk areas by requiring compliance 

with performance measures to minimize 

exposure of new buildings and buildings 

that undergo major renovation or expansion 

(called “Substantial Improvement” or 

“repair of Substantial Damage”). Taken 

together, administration of NFIP-consistent 

requirements helps achieve the longterm objective of building flood-resistant 

communities.

The NFIP’s broad performance requirements for new buildings and the Substantial Improvement 

or repair of Substantial Damage of existing buildings in SFHAs specify that: 

+ Buildings must be designed and adequately anchored to prevent flotation, collapse, or lateral 

movement resulting from hydrodynamic and hydrostatic loads, including the effects of 

buoyancy. 

+ Building materials must be resistant to flood damage. 

+ Buildings must be constructed by methods and practices that minimize flood damage. 

+ Buildings must be constructed with electrical, heating, ventilation, plumbing, and airconditioning equipment, and other service facilities that are designed and/or located to 

prevent water from entering or accumulating within the components. 

Beyond the general requirements, specific NFIP requirements for buildings are functions of the 

flood zone and flood characteristics that affect specific locations. Requirements for SFHAs that are 

designated Zone A (including AE, A, A1–30, AO, and AH) are summarized in Section 2.1.1.2, and 

requirements for Coastal High Hazard Areas that are designated Zone V (including VE and V1–30) 

are summarized in Section 2.1.1.3. 

SUBSTANTIAL DAMAGE

Damage of any origin for which the cost to 

restore a damaged building to its pre-damage 

condition equals or exceeds 50 percent of the 

building’s market value before the damage 

occurred.

SUBSTANTIAL IMPROVEMENT

Any reconstruction, rehabilitation, addition, 

or other improvement of a building, the cost 

of which equals or exceeds 50 percent of the 

building’s pre-improvement market value. 

When repairs and improvements are made 

simultaneously, all costs are totaled and used in 

the determination.

2.1.1.2 Minimum Requirements for Buildings in Zone A

In addition to the general requirements summarized in Section 2.1.1.1, the NFIP minimum 

requirements for buildings and structures located in Zone A specify the level of protection (elevation) 

and limitations on enclosures below elevated buildings, including crawlspace foundations. 
2-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

Building Elevation and Foundations (Zone A) 

In Zone A, where FEMA designates base flood elevations (BFEs), the NFIP requirements specify that 

the lowest floors, including basements, of new buildings and Substantially Improved buildings, must 

be elevated to or above the BFE. There are no 

limitations on the type of foundation used to 

elevate buildings. Buildings may be elevated 

on perimeter walls (crawlspace), filled stem 

walls, columns, piers, pilings, or slabs on 

earthen fill (for NFIP insurance purposes, 

wood-framed walls are not recognized as 

foundation walls). Non-residential buildings 

may be elevated or protected by dry 

floodproofing that protects to or above the 

BFE.

Some SFHAs, referred to as “unnumbered 

A zones,” are shown without BFEs. In these 

areas, BFE data from other sources must be 

used if available. If data are not available, the 

BFE may be estimated using established methods, and communities are required to ensure that 

buildings are constructed using methods and practices that minimize flood damage. Once the 

elevation or height of the lowest floor above grade is established, the remaining requirements for 

Zone A apply. 

The Zone AO designation is used where flooding is characterized by shallow depths (averaging 1 

to 3 feet) and/or unpredictable flow paths. In these areas, lowest floors, including basements, are 

required to be at or above the highest grade adjacent to the building plus the depth number (in 

feet) shown on the FIRM. For example, if the depth number is 3 feet, the top of the lowest floor 

must be at least 3 feet above the highest grade adjacent to the building. If no depth is shown, the 

minimum required height above the highest adjacent grade is 2 feet. Once the elevation or height of 

the lowest floor above grade is established, the remaining requirements for Zone A apply. 

Enclosures Below Elevated Buildings (Zone A)

The NFIP requirements specify that areas below the lowest floors may be enclosed; however, the use 

of enclosures is restricted to parking of vehicles, building access, and storage. 

The walls of enclosures below elevated buildings are required to have flood openings designed to 

allow the automatic entry and exit of floodwater so that interior and exterior hydrostatic pressures 

can equalize during flooding. Designs for openings must either meet a prescriptive requirement (1 

square inch of net open area for every square foot of enclosed area) or be “engineered openings” 

that are certified by a registered design professional as meeting a specific performance expectation. 

The following installation specifications apply to all flood openings: (1) there must be a minimum 

of two openings for each enclosure, (2) the bottom of openings must be no higher than 1 foot above 

grade (exterior grade or interior floor/grade), and (3) screens, louvers, valves, or other coverings 

or devices, if any, must permit the automatic entry and exit of floodwater. Refer to NFIP Technical 

Bulletin 1, Openings in Foundation Walls and Walls of Enclosures (2008d).

LOWEST FLOOR

The lowest floor of the lowest enclosed area 

(including basement). An unfinished or floodresistant enclosure, usable solely for parking 

of vehicles, building access, or storage in 

an area other than a basement area is not 

considered a building’s lowest floor, provided 

that such enclosure is not built so as to render 

the structure in violation of the applicable nonelevation design requirements of Section 60.3 

(44 CFR § 59.1).
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-7

BUILDING CODES, STANDARDS, AND REGULATIONS

FEMA NFIP TECHNICAL BULLETINS

FEMA publishes a series of technical bulletins that provide specific guidance for complying with the 

minimum requirements of NFIP regulations. The technical bulletins and information on updates are 

provided at www.fema.gov/nfip-technical-bulletins.The following NFIP technical bulletins are cited in 

this MAT report:

•	 Technical Bulletin 1, Openings in Foundation Walls and Walls of Enclosures (2008d)

•	 Technical Bulletin 2, Flood Damage-Resistant Materials Requirements (2008b)

•	 Technical Bulletin 3, Non-Residential Floodproofing—Requirements and Certification (1993)

•	 Technical Bulletin 5, Free-of-Obstruction Requirements (2008c)

•	 Technical Bulletin 9, Design and Construction Guidance for Breakaway Walls Below Elevated 

Coastal Buildings (2008a)

Dry Floodproofing Non-Residential Buildings (Zone A)

The NFIP requirements establish performance expectations for dry floodproofing non-residential 

buildings as an alternative to elevation. Non-residential buildings may be designed so that below the 

BFE the buildings are “watertight with walls substantially impermeable to the passage of water and 

with structural components having the capability of resisting hydrostatic and hydrodynamic loads 

and effects of buoyancy.” Designs must be certified by a registered professional engineer or architect, 

stating the “methods of construction are in accordance with accepted standards of practice.” The 

dry floodproofing provisions of ASCE 24 are accepted standards of practice. The current edition 

of FEMA Form 086-0-34, Floodproofing Certificate for Non-Residential Structures (2015), may be used to 

certify designs. 

Before a dry floodproofed building is designed, numerous planning considerations should be 

addressed to determine that dry floodproofing is a viable option. Property owners and design 

professionals should examine uses of the building, mode of entry and exit and the site in general, 

floodwater velocities, flood depths, debris impact potential, and flood frequency. A critical 

consideration is whether locations where dry floodproofing may be specified have sufficient flood 

warning, which has significant bearing on whether designs that rely on human intervention are 

viable. For guidance on design and planning, refer to FEMA P-936, Floodproofing Non-Residential 

Buildings (2013) and NFIP Technical Bulletin 3, Non-Residential Floodproofing—Requirements and 

Certification (1993).

For floodplain management purposes, the NFIP requirements specify that non-residential buildings 

must be dry floodproofed or elevated to or above the BFE. However, for NFIP flood insurance rating 

purposes, non-residential buildings must be dry floodproofed to at least 1 foot above the BFE to be 

rated as dry floodproofed. If dry floodproofing measures do not extend to the BFE plus 1 foot, the 

floor of the building is the lowest floor for rating purposes, and will result in higher premiums. The 

FEMA Floodproofing Certificate for Non-Residential Structures must be submitted with applications for 

NFIP flood insurance coverage.
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BUILDING CODES, STANDARDS, AND REGULATIONS

2.1.1.3 Minimum Requirements for Buildings in Zone V

In addition to the general requirements summarized in Section 2.1.1.1, the NFIP minimum 

requirements for buildings and structures in Zone V specify the level of protection (elevation), type 

of foundation, and limitations on obstructions and enclosures below elevated buildings. Because 

of the greater hazard posed by breaking waves, structural designs and methods of construction are 

required to be developed, reviewed, and certified by a registered design professional as capable of 

resisting the effects of wind and flood loads acting simultaneously. 

Building Elevation and Foundations (Zone V) 

In Zone V, the NFIP requirements specify that the bottom of the lowest horizontal structural member 

(excluding vertical foundation members) of the lowest floor of new buildings and Substantially 

Improved buildings (including buildings that have sustained Substantial Damage) are required to 

be at or above the BFE. Open foundations such as pilings and columns are required. The use of fill 

for structural support is not permitted. Concrete slabs, including patios, walkways, pool decks, and 

slabs used as the floor of enclosures, are required to be structurally independent or, if attached, 

building foundations are required to be designed to account for the added loads and effects of wave 

action. If structurally attached to a foundation, the presence of a concrete slab may be considered 

the building’s lowest floor for flood insurance rating purposes.

Obstructions and Enclosures Below Elevated Buildings (Zone V)

The NFIP requirements specify that the space below the lowest floor of elevated buildings must be 

free of obstructions. The intent is to minimize obstructions that could interfere with the free passage 

of floodwater and debris underneath the buildings. Areas below lowest floors may be enclosed; 

however, the use of enclosures is restricted to vehicle parking, building access, and storage. 

Obstructions to be avoided—or minimized and constructed to meet the performance requirement— 

include stairs and ramps, decks and patios, equipment attached to foundation elements, foundation 

bracing, grade beams, shear walls, and slabs. Other site development that may create obstructions 

includes accessory structures, erosion control structures, fences and privacy walls, fill used for 

landscaping, septic systems, and swimming pools and spas. Refer to NFIP Technical Bulletin 5, Freeof-Obstruction Requirements (2008c).

Walls of enclosures, if any, are required to be non-supporting breakaway walls, open wood latticework, or insect screening intended to collapse under wind and base flood or lesser conditions 

without causing structural collapse, displacement, or damage to the elevated building or supporting 

foundation. When walls collapse under specific lateral loads, floodwater can flow through column 

or pile foundations without obstruction. Refer to NFIP Technical Bulletin 9, Design and Construction 

Guidance for Breakaway Walls Below Elevated Coastal Buildings (2008a). 

The NFIP regulations specify a prescriptive design approach for breakaway walls having a safe loading 

resistance of not less than 10 pounds per square foot and not more than 20 pounds per square foot 

(in almost all cases, water loads will significantly exceed the upper limit, as will most wind loads 

and seismic loads). Breakaway walls that do not meet those loading requirements may be used if a 

registered professional engineer or architect certifies that the walls will collapse under a water load 

less than that which would occur during the base flood and that the elevated portion of the building 

and supporting foundation system will not be subject to collapse, displacement, or other structural 

damage due to the effects of wind and water loads acting simultaneously on all building components.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-9

BUILDING CODES, STANDARDS, AND REGULATIONS

2.1.1.4 NFIP Community Rating System

The NFIP Community Rating System (CRS) is a voluntary incentive program that recognizes 

community floodplain management activities that exceed NFIP requirements. The CRS gives 

discounts on flood insurance premiums in communities that elect to undertake activities that support 

three goals: reduce flood damage to insurable property, strengthen and support the insurance 

aspects of the NFIP, and encourage a comprehensive approach to floodplain management. 

Communities apply to the CRS and are assigned 

a class based on the activities they undertake. 

Classes range from 1 to 10, with 1 representing 

the most active communities with the most flood 

hazard-resistant practices. NFIP flood insurance 

premium rates are discounted in increments of 

5 percent. For example, a Class 1 community 

receives a 45 percent premium discount, a Class 

9 community receives a 5 percent discount, and a Class 10 community receives no discount. The CRS 

classes are based on 18 creditable activities organized under four categories: (1) public information, 

(2) mapping and regulations, (3) flood damage reduction, and (4) flood preparedness. 

COMMUNITY RATING SYSTEM 

For more information on the CRS, visit: www.

fema.gov/national-flood-insurance-programcommunity-rating-system.

2.1.2 Floodplain Management 

in the State of Texas

In 2007, the Texas Water Development Board 

was designated as the NFIP State Coordinating 

Agency by the State Legislature (Section 16.316, 

Water Code). The NFIP State Coordinator is 

the liaison between the Federal component of 

the program and the communities, with the 

primary duty to provide assistance, guidance, 

and education for community officials. The 

State Coordinator also supports communities 

in the CRS.

Sections 16.3145 and 16.315 of the Texas Water 

Code give the governing bodies of each city and 

county the authority to adopt ordinances or orders and “to take all necessary and reasonable actions 

that are not less stringent than the requirements and criteria” of the NFIP. The State of Texas has 

no floodplain management requirements established at the State level. 

FLOODPLAIN MANAGEMENT 

IN TEXAS

As of July 2018, 1,251 Texas communities 

participate in the NFIP, and 141 Texas 

communities are identified as floodprone by 

FEMA, but have elected not to participate. 

As of April 2018, 64 Texas communities 

were in the CRS. The highest class achieved 

in Texas, by four communities, is Class 5, 

providing NFIP policyholders in the SFHA 

discounts of 25 percent and those outside of 

the SFHA discounts of 10 percent. 

2.1.3 Floodplain Management in Selected Communities Impacted by Hurricane Harvey

The MAT reviewed the floodplain management regulations and building codes adopted by Harris 

County and the Cities of Houston, Bellaire, and Port Aransas. Each community adopts and enforces 

floodplain management regulations that contain provisions required for participation in the 

NFIP. Table 2-1 summarizes NFIP and CRS data for those communities, and Table 2-2 summarizes 

elevation requirements for buildings in SFHAs in effect before September 2017. Table 2-2 also 

identifies the building codes in effect before September 2017. The following sections summarize the 

MAT observations on local regulations for each community. 
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BUILDING CODES, STANDARDS, AND REGULATIONS

Table 2-1: NFIP and CRS Data for Selected Communities

Community

NFIP Entry 

Date

Current Effective 

FIS/FIRM

CRS Entry 

Date

Effective Date of 

Current CRS Class

Current 

CRS Class

Harris County 5/26/1970 1/6/2017 5/1/2004 10/1/2014 7

City of Houston 12/11/1979 1/6/2017 5/1/2002 10/1/2009 5

City of Bellaire 

(Harris County) 9/30/1981 6/18/2007 10/1/1993 5/1/2014 7

City of Port Aransas 

(Aransas/Nueces Counties) 6/25/1971 2/17/2016 Not in CRS Not in CRS Not in CRS

CRS = Community Rating System; FIRM = Flood Insurance Rate Map; FIS = Flood Insurance Study; NFIP = National Flood Insurance 

Program

SOURCE: FEMA, 2018n AND FEMA, 2018h

Table 2-2: Building Elevation Requirements in Effect Prior to Hurricane Harvey

Community

Building Elevation Requirements (Before Harvey)

Building Code Residential Non-residential (a)

Manufactured 

Housing

Critical 

Facility

Harris 

County 

(defines 

“habitable 

floor” rather 

than “lowest 

floor”)

Zone A: Floor 18 inches 

above BFE (or depth 

number in Zone AO) or 

to the level of crown of 

nearest public street, 

whichever is higher

All Zone A:

• Elevated: 

same as 

residential

• Dry 

Floodproofed: 

BFE (implied 

only with 

basement)

All Zone A: 18 

inches above 

BFE

All Zones: 3 

feet above 

BFE

2012 IBC and “IRC 

... as adopted by 

state law,” with 

amendments.

Zone A, floodway: 

bottom of lowest 

supporting member 18 

inches above BFE 

Unnumbered A zone and 

Zone AO without depth 

number: 3 feet above 

highest adjacent grade

Zone V: 18 inches above 

BFE

Zone V: 18 

inches above 

BFE

Zone V: 18 

inches above 

BFE

Houston, 

City 

BFE + 12 inches BFE + 12 inches BFE + 12 

inches

12 inches 

above 500-

year

2012 IBC and IRC. 

Amended to remove 

flood provisions and 

refer to floodplain 

management 

regulations.

Bellaire

(Harris 

County)

BFE + 1 foot • Elevated: BFE 

+ 1 foot

• Dry 

Floodproofed: 

BFE

BFE + 1 foot N/A “Current edition” of 

IBC, IRC, and “all 

appendices.”

Port 

Aransas 

(Aransas/

Nueces 

Counties)

BFE BFE BFE N/A 2003 IBC and IRC, 

and 1997 “Standard 

Existing Building 

Code,” “together with 

all future revisions.”

(a) Building, Residential, and Existing Building only

(b) Where full elevation required (i.e., not in pre-FIRM MH park/subdivision and not if Substantially Damaged by flood)

BFE = base flood elevation; IBC = International Building Code; IRC = International Residential Code
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-11

BUILDING CODES, STANDARDS, AND REGULATIONS

2.1.3.1 Harris County

The Regulations of Harris County, Texas for Flood Plain Management (adopted November 2011) were in 

effect prior to Hurricane Harvey. The regulations apply to all unincorporated areas (not restricted 

to the SFHA), and thus also serve as the basis for enforcement of the residential building code. The 

regulations were amended on December 5, 2017 and effective January 1, 2018. The MAT made the 

following observations regarding the pre-Harvey regulations:

+ Creates Class “I” and Class “II” permits (refer 

to text box).

+ Adopts a requirement for buildings to be 

elevated higher than the BFE (see Table 2-2), 

while permitting non-residential buildings to 

be dry floodproofed to the BFE. (The MAT 

did not determine the effective date of the 

freeboard requirements listed in Table 2-2.) 

+ Adopts the “Flood Insurance Study (FIS) 

and Flood Insurance Rate Map (FIRM) 

adopted on June 18, 2017” and subsequent 

amendments and revisions and “adopts as its 

regulatory floodways the floodways shown on the said FIRM.”

+ Requires “Certificates of Non-Compliance” to be issued by the County Engineer to advise 

owners when sites are not in compliance with the regulations of the County; advises that 

legal action may be taken and a request for denial of flood insurance may be processed with 

FEMA. Certificates may be filed in the real property records. 

+ Defines “habitable floor” (includes bathrooms, utility rooms, and storage areas greater than 

150 square feet), and uses it instead of “lowest floor.” The implication is that only storage 

areas less than 150 square feet are permitted below the required elevation.

+ Does not define “lowest floor”; this term is used for recreational buildings, critical facilities, 

and manufactured housing.

+ Embeds the definition of “substantial damage” in the definition for “substantial 

improvement.” Among triggers for substantial damage is “[i]n cases where the structure is 

covered by insurance and the insured losses for damage to the structure (excluding contents) 

amount to over 95 percent of the value of the structure, the structure shall be deemed 

substantially damaged regardless of any other data submitted.”

+ Specifies in Section 3.02 that if land is lower than the BFE, the ground elevation serves as the 

basis for regulation even if the FIRM shows otherwise. 

+ Cites FEMA Bulletins 1-93, 2-93, and 3-93 in Sections 4.05(b)(3), 4.05(b)(4), and 4.05(j) and 

states that these editions “or subsequent revisions will serve as guidance” for methods and 

practices that minimize flood damage and for materials.

+ Places limits on fill in Section 4.05(b)(9), which must be the minimum necessary to achieve 

the intended purpose, with “any excess fill material... properly mitigated on a one-for-one 

HARRIS COUNTY CLASS “I” 

AND CLASS “II” PERMITS

Class “I” permits are issued for properties 

with ground elevations above the BFE (not 

in the SFHA). 

Class “II” permits are issued for properties 

with ground elevations below the BFE 

“or subject to flooding as determined by 

these Regulations” (in the SFHA).
2-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

basis and shall not interfere with existing drainage patterns.” A maximum of 3 feet of fill is 

permitted for residential structures in subdivisions developed prior to September 16, 1976. 

+ Requires in Section 4.05(e) the “reduction in floodplain storage or conveyance capacity” 

to be offset with “hydraulically equivalent (one-to-one) volume of mitigation,” with a 

“fully hydrological and hydraulic analysis” required if mitigation is requested outside the 

boundaries of the property being developed.

+ Specifies in Section 4.05(g) that new manufactured housing parks/subdivisions are not 

permitted in floodways or Zone V.

+ Specifies in Section 4.05(m) additional requirements for floodways, including elevation using 

posts or pilings (fill not permitted). In the San Jacinto River Floodway, foundation designs 

must account for scour and requirements are detailed. This section also specifies that the area 

below the BFE shall not be enclosed, although it permits storage areas less than 150 square 

feet, provided “the walls perpendicular to flow are constructed of materials allowing the free 

flow of water and that these walls are no greater than 12 feet wide.”

+ States in Section 4.05(o) that structures in Zone V must be “on posts or pilings” and specify 

piling depth. This section also requires “the bottom of the lowest horizontal structural 

member of the structure” to be elevated (rather than the lowest horizontal structural member 

“of the lowest floor,” as specified in the NFIP regulations). It does not use the defined term 

“habitable floor” and does not limit the size of enclosures. It requires development (not 

just new construction) to be landward of the reach of mean high tide and does not permit 

alteration of sand dunes and mangrove stands. 

2.1.3.2 City of Houston

The Code of Ordinances for the City of Houston, 

Texas, including Chapter 1, General Provisions, 

and Chapter 19, Floodplain, were in effect prior 

to Hurricane Harvey. Chapter 19 was amended 

by Ordinance No. 2018-258 on April 4, 2018. 

The MAT made the following observations 

regarding the pre-Harvey regulations:

Chapter 1, General Provisions: 

+ Defines “Construction Code” to mean 

“the Building Code, the Plumbing Code, 

the Electrical Code, or the Mechanical 

Code.” Further, “[a]lthough they do not 

constitute part of the Construction Code 

for other purposes, the International 

Residential Code and the International Energy Conservation Code, both as adopted by 

state law and amended by the city, shall be considered to be included within the term 

‘Construction Code.’” 

+ Amends the 2012 IBC and IRC to delete the flood provisions and instead, refer to Chapter 19 

(floodplain regulations). 

HOUSTON FLOODPLAIN “GUIDELINES”

The City produces a “Guidelines” version 

of Chapter 19 containing text in gray boxes 

intended to “establish an operational and 

procedural framework for administration.” The 

guidelines refer to the 1993 editions of FEMA 

NFIP Technical Bulletins 1, 2, and 3. Despite 

the City’s intent that the guidelines provide 

guidance, the City enforces compliance with 

the out-of-date technical bulletins.

The “Guidelines” are available at edocs.

publicworks.houstontx.gov/engineering-andconstruction/flood-plain-guidelines.html.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-13

BUILDING CODES, STANDARDS, AND REGULATIONS

Chapter 19, Floodplain: 

+ Adopts requirement for buildings to be elevated higher than the BFE (see Table 2-2), while 

permitting non-residential buildings to be dry floodproofed to the BFE. (The MAT did not 

determine the effective date of date the freeboard requirement listed in Table 2-2.) 

+ Defines “repetitive loss” and includes it in the definition of “substantial improvement.” 

+ Requires operators of manufactured housing parks and subdivisions to file evacuation plans 

indicating alternate vehicle access and escape routes prior to obtaining permits.

2.1.3.3 City of Bellaire

The Code of Ordinances for the City of Bellaire, Texas, Chapter 9, Buildings, includes Article II, Building 

Codes, and Article II-A, Flood Damage Prevention. The regulations were in effect prior to Hurricane 

Harvey. The MAT made the following observations regarding the pre-Harvey regulations:

Chapter 9, Buildings, Article II, Building Codes:

+ Section 9-18, “Drainage requirements for residential construction,” specifies “fill credit,” a 

form of limiting fill.

– Outlines requirements for structures in the SFHA that are elevated with and without fill 

with respect to how the fill credit is applied. 

– Outside the SFHA, limits fill to that necessary to achieve adequate drainage.

– For all residential projects, requires an “as-built” elevation survey and an engineer’s 

statement of conformance with site and drainage plans prior to issuance of certificates of 

occupancy.

Chapter 9, Article II-A, Flood Damage 

Prevention (adopted October 6, 2014):

+ Does not explicitly reference the 

adopted building codes, which have 

flood provisions.

+ Adopts requirement for buildings to be 

elevated higher than the BFE (see Table 

2-2), while permitting non-residential 

buildings to be dry floodproofed to 

the BFE. (The effective date of the 

freeboard requirements noted in Table 

2-2 has not been verified.) 

+ “Lowest Floor” definition refers to the “nonelevation design requirement of section 60.3” 

rather than the City’s regulations. Adds the following non-standard and partially incorrect 

description of how lowest floor elevations are “measured” for residential structures: (a) 

concrete slab (lowest point on the exterior perimeter of the slab, excluding ledges for 

facades); (b) crawl space (top of the wood sub-flooring); (c) with basement (top surface of the 

basement floor; wine cellars and elevator pits are basements). The MAT notes FEMA has not 

granted the City of Bellaire a “basement exception” to allow residential basements in SFHAs.

BELLAIRE: COSTS OF REPAIRS

A 2017 document published on the City of 

Bellaire, Texas Official Nextdoor Page, “How 

Does the City Apply the ‘50%’ Rule?” (referring 

to the Substantial Improvement and Substantial 

Damage requirements), states “non-floodrelated renovation or remodeling costs will 

no longer be counted toward the ‘50% rule.’ 

Only previous flood-related repair costs, plus 

Harvey-related repair costs, will be included.”
2-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

+ Adopts the “Flood Insurance Study (FIS) for the City of Bellaire, Texas,” dated June 28, 

2007, “and any revisions thereto.” (The NFIP Community Status Book identifies the FIS 

date of June 18, 2007 and the Map Service Center shows the City of Bellaire is included in 

the January 6, 2017 FIS. The City’s only FIRM is dated June 18, 2007; thus, the date in the 

regulations appears to be in error.)

+ States that residential and non-residential construction “shall have lowest floors elevated as 

a minimum, to one foot above the highest of the base flood elevation shown on the effective 

FIRM and the flood hazard recovery data map.”

+ Non-residential construction, if not elevated, must “be designed so that below the base flood 

level the structure is watertight with walls substantially impermeable ....”, thus not requiring 

freeboard for dry floodproofed structures.

2.1.3.4 City of Port Aransas

The City Code of Port Aransas, Texas, including Chapter 5, Buildings and Building Regulations, and 

Chapter 8, Flood Damage Prevention, were in effect prior to Hurricane Harvey. The MAT made the 

following observations regarding the pre-Harvey regulations:

Chapter 5, Buildings and Building Regulation: 

+ Section 5-2, requires that “[a]ny work or repair costing more than a total set by resolution by 

the city council shall be required to have a permit.” 

+ Section 5-52, states that, in the event of “hurricane disaster,” the Building Official is required

to “waive building codes for a period of up to one (1) year in order to allow lots to be cleaned 

and temporary housing to be placed on site during the rebuilding process” (emphasis added).

+ Section 5-83, states that “any person wishing to make minor repairs or remodeling must 

make application for a permit,” except if the total cost is less than $1,500; there is no major 

structural change in size, shape, or location of the building; and the person doing the work 

“complies with this chapter as a homeowner.” 

Chapter 8, Flood Damage Prevention (amended January 15, 2015):

+ Does not explicitly reference the adopted building codes, which have flood provisions.

+ “Lowest Floor” definition refers to the “nonelevation design requirement of section 60.3” 

rather than comparable provisions in the City’s regulations.

+ Adopts the FIS for Aransas County (May 4, 1992) and Nueces County (May 4, 1992) “and any 

revisions thereto.” (Current effective date for Aransas County is February 17, 2016.)

2.2 Building Code Wind Requirements

Model building codes provide criteria for designers on the minimum loads buildings and other 

structures must be designed to withstand, including minimum elevation requirements for buildings 

located in flood hazard areas. The most widely adopted building codes in the United States are the 

IBC and the IRC, which are updated every 3 years, with the 2018 being the most recent edition. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-15

BUILDING CODES, STANDARDS, AND REGULATIONS

The State of Texas does not mandate the adoption and enforcement of building codes throughout the 

State; therefore, municipalities can choose to adopt and enforce any or none of the model building 

code editions (refer to the beginning of this chapter for more information on statutory requirements 

for building code adoption in Texas). Because of this, the jurisdictions impacted by Hurricane Harvey 

had adopted different editions of the IBC and IRC, ranging from the 2009 editions to the 2015 

editions (see Table 2-3). However, the Texas Windstorm Inspection Program, through the TDI, wields 

a significant influence on construction and building codes in the coastal counties. TDI refers to these 

counties as “Designated Catastrophe Areas” or “First Tier Counties.” TDI requires compliance with 

the 2006 IBC and IRC with Texas Revisions, which are based on and reference ASCE 7-05 for wind 

loads. As discussed in Sections 2.2.1 and 2.2.2, wind loads are generally higher in ASCE 7-05 than 

ASCE 7-10, which is referenced in the 2012 and 2015 IBC and IRC. For more information on the Texas 

Windstorm Inspection Program, refer to Section 2.2.3 on the Texas Windstorm Program.

Table 2-3: Building Codes in Effect at the Time of Hurricane Harvey for Selected Cities in Texas Impacted by High Winds

1 A comprehensive discussion of all the changes to the wind provisions in ASCE 7-10 can be found in Significant Changes to the Wind Load 

Provisions of ASCE 7-10, An Illustrated Guide, published by ASCE Press (Stafford, 2010).

City Building Codes

Fulton 2009 IBC and 2009 IRC

Rockport 2012 IBC and 2012 IRC

Aransas Pass 2012 IBC and 2012 IRC

Corpus Christi 2015 IBC and 2015 IRC

Port Aransas 2015 IBC and 2015 IRC

City Building Codes

Woodsboro None

Holiday Beach None

Houston 2012 IBC and 2012 IRC

Victoria 2015 IBC and 2015 IRC

IBC = International Building Code, IRC = International Residential 

Code

2.2.1 International Building Code and ASCE 7

Various editions of the IBC were adopted in the areas impacted by Hurricane Harvey, as indicated 

in Table 2-3. The 2006 and 2009 IBC primarily reference ASCE 7-05 for determining wind loads 

for the design of buildings. The 2009 IBC also contains a simplified or alternate procedure for 

determining wind loads, but the method is based on ASCE 7-05 and results in generally the same 

loads as ASCE 7-05. 

One significant wind load-related difference between the 2006 IBC and the 2009 IBC pertains to 

the use of wood structural panels as glazed opening protection in wind-borne debris regions. The 

2009 IBC requires attachment hardware for wood structural panels used as opening protection to 

be permanently installed on the building, whereas the 2006 IBC permitted the use of No. 6 or No. 

8 screws directly fastened into the wall framing. Also of note, the 2006 IBC and subsequent editions 

prohibit the use of aggregate, gravel, or stone on roofs in hurricane-prone regions because the 

roofing material often becomes wind-borne debris.

The 2012 IBC references ASCE 7-10 for determining wind loads for the design of buildings. The 

wind provisions of ASCE 7-10 were significantly revised from ASCE 7-05.1 The most notable change 

was to the wind speed maps. A summary of the changes to the wind speed maps is as follows:

+ The wind speed maps were changed to reflect strength design-level values instead of the 

allowable stress design (ASD) levels in ASCE 7-05 and earlier editions. (The 2012 and 2015 

editions of the IBC refer to these strength design-level wind speeds as ultimate design wind 

speeds, or Vult.) 
2-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

+ The wind speed maps were provided according to Risk Category, which eliminated the need 

for Importance Factors to adjust the mean recurrence interval (MRI).

+ Wind speeds were updated based on new hurricane data and new analysis of hurricane wind 

speeds, which resulted in lower design pressures for the hurricane-prone region.

As a result of the updates, wind speeds shown on the maps in ASCE 7-10 are higher than those in 

ASCE 7-05. However, after using the appropriate strength design/ASD conversions, the design wind 

loads (pressures) for hurricane-prone regions in ASCE 7-10 are generally lower (significantly lower 

in some areas) than ASCE 7-05. 

Another significant change in ASCE 7-10 that affected wind loads was the re-introduction of 

the applicability of Exposure Category D in hurricane-prone regions. In ASCE 7-05, Exposure 

Category D did not apply in hurricane-prone regions. Buildings and other structures classified as 

being in Exposure Category D in hurricane-prone regions in ASCE 7-10 would qualify as Exposure 

Category C in ASCE 7-05. The impact on design pressures of being classified as Exposure Category 

D as opposed to Exposure Category C diminishes as mean roof height increases (design pressure 

increases approximately 23 percent at a mean roof height of 15 feet and 13 percent at a mean roof 

height of 100 feet).

One way to realize the impact of the changes to the basic wind speeds in ASCE 7-10 is to convert the 

strength design-level wind speeds to ASD and overlay the converted wind speeds on the ASCE 7-05 

basic wind speed map. Figure 2-2 shows how comparable wind speeds have changed between ASCE 

7-05 and ASCE 7-10 for Risk Category II structures. The red contours on the map are the ASCE 7-05 

wind speeds (ASD). The blue contours are ASCE 7-10 wind speeds for Risk Category II structures 

converted to an ASD level. The strength design level wind speeds in ASCE 7-10 are converted to an 

ASD level by dividing by the square root of the load factor on wind load for strength design in ASCE 

7-05 (divided by √1.6).

Another way to assess the impacts of the changes to the wind speed maps is to look at changes to 

comparable design pressures. Because ASCE 7-10 wind speeds are strength design-level, calculated 

design wind pressures have to be converted to ASD for comparison to ASCE 7-05 (alternatively, 

the ASCE 7-05 wind pressures could be converted to strength design). The governing equations 

for determining design wind pressures in ASCE 7-10 have not changed from ASCE 7-05. Similarly, 

pressure coefficients and other variables used to calculate design wind pressures for buildings did 

not change in ASCE 7-10 (except for a few clarifications). Therefore, the changes in design pressures 

can be determined by taking the square of the ASCE 7-10 wind speeds and multiplying it by 0.6 (to 

convert it to ASD) and then dividing by the square of the ASCE 7-05 wind speed. For Risk Category 

II buildings sited in Exposure Categories B or C, the percent change in design pressures can be 

shown as follows:

Percent Change in Design Pressures from ASCE 7-05 to ASCE 7-10 =

[((ASCE 7-10 Wind Speeds)2 x 0.6) / (ASCE 7-05 Wind Speeds)2] −1

For areas where Exposure D now applies, an additional factor is needed. As previously mentioned, 

the effect of changing from a C Exposure to a D Exposure diminishes as the height of the 

building increases. For buildings with a mean roof height up to 30 feet, the effect of Exposure D is 

approximately 18 percent higher than Exposure C. Therefore, for buildings with a mean roof height 

of 30 feet located where Exposure D now applies, the percent change in design pressures from 

ASCE 7-05 to ASCE 7-10 can be shown as follows:

[((ASCE 7-10 Wind Speeds)2 x 0.6 x 1.18) / (ASCE 7-05 Wind Speeds)2] −1
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-17

BUILDING CODES, STANDARDS, AND REGULATIONS

Figure 2-2: Comparison of ASCE 7-05 (red contours) and ASCE 7-10 basic wind speeds for Risk Category II buildings 

converted to ASD (blue dotted contours) 

(SOURCE: MODIFIED FROM STAFFORD, 2010)

Table 2-4 summarizes the percent change in design wind pressures from ASCE 7-05 to ASCE 7-10 

for Risk Category II buildings at a mean roof height of 30 feet for select cities impacted by Hurricane 

Harvey.

Table 2-4: Design Wind Pressures from ASCE 7-05 and ASCE 7-10, Risk Category II Buildings

Location

Basic Wind Speed(a)

ASCE 7-05

Basic Wind Speed(a)

ASCE 7-10

Percent Change in Comparable Design 

Pressures from ASCE 7-05 to ASCE 7-10

Exposures B and C Exposure D(b)

Aransas Pass 130 147 -23% -9%

Corpus Christi 125 143 -21% -7%

Fulton 129 147 -22% -8%

Holiday Beach 126 146 -19% -5%

Port Aransas 135 149 -27% -14%

Refugio 116 140 -13% +3%

Rockport 130 147 -23% -9%

Victoria 119 142 -15% +1%

Woodsboro 116 140 -13% +3%

(a) Basic wind speeds were obtained from the Applied Technology Council wind speed database at hazards.atcouncil.org.

(b) Percent change reflects the increase/decrease in design pressures resulting from structures being classified as being in Exposure 

Category D in ASCE 7-10 as opposed to Exposure Category C in ASCE 7-05.
2-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

For example, the ASCE 7-05 basic wind speed for Rockport, TX, is 130 mph (ASD-level). The ASCE 

7-10 basic wind speed for Risk Category II buildings in Rockport is 147 mph (strength design level). 

Although the actual wind speed is higher, when the proper conversions are applied, the ASCE 7-10 

design pressures for Risk Category II buildings in Exposures B or C are approximately 23 percent 

lower than those in ASCE 7-05.

2.2.2 International Residential Code

The IRC addresses environmental loads, such as wind, in a more prescriptive manner so that oneand two-family dwellings can be built without individual designs by architects or engineers being 

required. However, the use of the prescriptive construction criteria in the IRC is limited. The 

prescriptive provisions in the 2006 and 2009 IRC apply to areas where the basic wind speed is 100 

mph or less. The 2006 and 2009 IRC reference ASCE 7-05, and the wind speed map in the IRC is a 

reprint of the basic wind speed map in ASCE 7-05. Therefore, where the design wind speed exceeds 

100 mph, residential buildings have to be designed in accordance with ASCE 7-05, or in accordance 

with one of the prescriptive high-wind standards referenced by the 2006 and 2009 IRC, such as 

the American Wood Council’s Wood Frame Construction Manual (2001), the American Iron and Steel 

Institute’s AISI S230, Standard for Cold-Formed Steel Framing: Prescriptive Method for One- and Two-Family 

Dwellings (2001, including 2004 supplement; 2007, including Supplement 2 dated 2008), and the 

International Code Council’s SSTD 10, Hurricane Resistant Construction Standard (1999; referenced 

only in the 2006 IRC), and the International Code Council’s ICC 600-08, Standard for Residential 

Construction in High Wind Regions (2008; referenced only in the 2009 IRC).

The 2012 IRC took a slightly different approach to ASCE 7-10 than the 2012 IBC. While the 2012 

IRC references ASCE 7-10, the wind speed map in the 2012 IRC is an ASD-level version of the ASCE 

7-10 wind speed map. In addition, a new map was added that identifies areas where wind design is 

required (see Figure 2-3). In these areas, the prescriptive provisions of the IRC are not permitted; 

rather, residential buildings must be designed in accordance with ASCE 7-10 or in accordance with 

one of the prescriptive high-wind standards. The “Wind Design Required” region in the 2012 IRC 

corresponds roughly to the areas on the ASCE 7-10 Risk Category II map where the wind speed is 130 

mph and greater (in the extreme northeastern areas of the United States and Alaska, it corresponds 

to 140 mph and greater).

The 2015 IRC also references ASCE 7-10, but uses the wind speed maps from ASCE 7-10, in addition 

to providing a map identifying regions where wind design is required. Like the 2012 IRC, the “Wind 

Design Required” region in the 2015 IRC corresponds roughly to the areas on the ASCE 7-10 Risk 

Category II map where the wind speed is 130 mph and greater (and in the extreme northeastern 

areas of the United States and Alaska, it corresponds to 140 mph and greater). 

2.2.3 Texas Windstorm Program

In 1971, as a response to the devastation caused along the Texas coast by previous hurricanes 

and by Hurricane Celia (1970), the Texas Legislature established the Texas Catastrophe Property 

Insurance Association (TCPIA) as an insurer of last resort for those unable to obtain windstorm 

and hail insurance in the private market. The association was renamed and became the Texas 

Windstorm Insurance Association (TWIA) in 1997. All insurers who provide windstorm insurance 

in Texas are required to become members of TWIA. Excess premiums and investment income on 

those premiums are deposited into the Texas Catastrophe Reserve Trust Fund, which is used to pay 

for excess losses. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-19

BUILDING CODES, STANDARDS, AND REGULATIONS

Figure 2-3: 2012 IRC Wind Design Required map 

SOURCE: ICC, USED WITH PERMISSION

TWIA operates only in First Tier coastal counties along the 367-mile Texas Gulf Coast, as shown 

in Figure 2-4. Along with the counties shown in Figure 2-4, TWIA also provides windstorm and 

hail coverage in certain specifically designated communities in Harris County that are east of 

State Highway 146. These communities include La Porte, Morgan’s Point, Pasadena, Seabrook, and 

Shore Acres.

2.2.3.1 Texas Department of Insurance

At the same time the TCPIA was established, the Texas Legislature adopted the TCPIA Building 

Code for Windstorm Resistant Construction, which was based on the wind load provisions of 

the 1971 Standard Building Code. Various other codes were adopted in later years. Successive 

hurricanes caused damage that revealed that these code requirements were not being enforced. 

This lack of enforcement led to the creation of the Windstorm Inspection Program at the TDI 

in 1988. The Windstorm Inspection Program is currently responsible for providing product 

evaluations, construction inspection services, and certification that buildings are in accordance 

with the adopted codes.

2.2.3.2 Basic Tenets of the Texas Windstorm Code

The TDI has adopted various codes for windstormrelated design since the TCPIA was established. In 

2003, the TDI adopted the 2000 IRC and 2000 IBC 

directly rather than modifying the Standard Building 

Code, as was done previously. In 2005, the TDI adopted 

TEXAS DEPARTMENT OF 

INSURANCE

For more information about the Texas 

Department of Insurance, visit www.

tdi.texas.gov/wind/index.html.
2-20 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

BUILDING CODES, STANDARDS, AND REGULATIONS

the 2003 IRC and 2003 IBC, and in 2008, the 2006 IRC and 2006 IBC were adopted. TDI has also 

established a set of revisions to the adopted codes (referred to as the Texas Revisions) that are also 

required.

Since 1998, the TDI has divided the Texas counties in the Designated Catastrophe Area along the 

Gulf of Mexico into three zones, described as Inland (II), Inland (I), and Seaward. The TDI adopts 

different wind speed requirements for each zone that roughly follow the wind speed contours in 

ASCE 7-05. Figure 2-4 illustrates the three zones, as well as the adopted wind speed requirements 

applicable to each zone. Notable Texas Revisions to the 2006 IRC and 2006 IBC regarding 

protection of glazed openings from wind-borne debris are shown in Table 2-5. Additionally, design 

wind pressures are provided for specific sizes of garage doors for various wind speeds. The Texas 

Revisions also provide specific requirements for corrosion resistance for Inland II, Inland I, and 

Seaward areas. 

Figure 2-4: Texas Windstorm Designated Catastrophe Areas

ADAPTED FROM: TDI, 2018
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 2-21

BUILDING CODES, STANDARDS, AND REGULATIONS

The TDI requires building products to be tested to and comply with the test standards and criteria 

specified in the IRC, the IBC, and the Texas Revisions. Manufacturers who sell products that meet 

these standards and criteria may request to have their products evaluated by TDI and listed on the 

TDI website. The TDI also evaluates and lists some types of building products that have passed test 

criteria specified for the High-Velocity Hurricane Zones in the Florida Building Code. 

Table 2-5: Texas Revisions to 2006 IRC and IBC for Protection of Glazed Openings from Wind-Borne Debris 

Location

Texas Revisions

Opening Protection Requirement Exceptions

Inland (II) No protection required Not applicable

Inland (I) All glazed openings must be protected with 

products meeting ASTM 1886 and ASTM 1996, 

or ANSI/DASMA 115 (Garage Doors)

Exception permits the use of plywood with 

a minimum thickness of 15/32 inches and 

maximum span of 8 feet

• Limited to one- and two-story buildings

• Requires attachments to be designed in

accordance with IRC simplified loads, ASCE

7, or the prescriptive attachment method

provided

• Installation instructions are required to be

provided

• Attachment is required to be secured to the

wall framing

Seaward All exterior openings (windows, doors, 

skylights, and garage doors) must be protected 

with products meeting ASTM 1886 and ASTM 

1996, or ANSI/DASMA 115 (Garage Doors)

Exception permits the use of plywood with 

a minimum thickness of 15/32 inches and a 

maximum span of 8 feet

• Limited to one- and two-story buildings

• Installation instructions are required to be

provided

• Requires panels and attachments to meet

ASTM E 1886 and ASTM E 1996 or an

“approved impact-resisting standard”

• Requires panels to be tested for uniform

static wind resistance in addition to windborne debris resistance

Windborne 

Debris 

Regions

Requires skylights in wind-borne debris regions 

to meet ASTM E 1886 and ASTM E 1996, or 

AAMA 506, Voluntary Specifications for Impact 

and Cycle Testing of Fenestration Products

None

AAMA = American Architectural Manufacturers Association

ANSI = American National Standards Institute

ASCE = American Society of Civil Engineers

DASMA = Door & Access Systems Manufacturers Association, International

IBC = International Building Code

IRC = International Residential Code
Flood-Related Observations

Most of Hurricane Harvey’s damage was caused by flooding 

originating from the historic rainfall in Southeastern Texas and 

by the storm surge at its three landfalls. 

The heavy rainfall caused significant riverine and sheet flow flooding, which resulted in inundation 

damage to hundreds of thousands of residential and non-residential buildings and billions of dollars 

in damage across 42 counties. The MAT visited both residential and non-residential buildings and 

the focus for each was different, as described in the paragraphs that follow. 

The mission of the MAT was to assess the performance of residential and non-residential buildings 

affected by flooding. For residential buildings, the MAT was tasked with identifying neighborhoods 

containing a mixture of new and old construction, with high participation in the NFIP, for use 

in a desktop analysis. The desktop analysis assessed the effect of floodplain regulations on flood 

insurance claims in those neighborhoods. For non-residential buildings, the MAT was tasked with 

assessing the performance of dry floodproofing mitigation measures installed in buildings within 

Harris County, including the Texas Medical Center (TMC). 

Residential buildings. Within Harris County alone, 154,170 single-family houses and thousands of 

apartment units, condos, and townhouses flooded. The widespread extent of the flooding revealed 

a large variability in the performance of residential buildings. The MAT focused on houses within 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-1

3
the mapped 1-percent-annual-chance and 0.2-percent-annual-chance event flood hazard areas to 

determine whether there was any correlation in the flood damage observed and age of the house. 

FLOODWAY DEVELOPMENT

In Harris County, 20,000 parcels worth $13.5 billion are located in or along floodways. 

Approximately 75% of buildings on those 20,000 parcels were built before the first 1.0-percentannual-chance probability flood elevations for Harris County were published in 1985. About 1,400 

structures, on floodway parcels valued at $4.2 billion, have been built in the City of Houston and 

Harris County since 2008, 7 years after Tropical Storm Allison exposed the City’s vulnerabilities to 

severe rainfall events. After Tropical Storm Allison, a prohibition against construction in the floodway 

was passed; however, after numerous lawsuits against the ban, Houston eliminated the prohibition 

on floodway development in 2008.

3-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Non-residential buildings. Within Harris County 

alone, approximately 15,000 non-residential 

buildings were flooded. Unlike residential 

buildings, floodplain management regulations and 

building codes allow non-residential buildings to 

be dry floodproofed to protect the building from 

flood damage. Given the frequency and severity 

of flooding in Harris County, the practice of 

dry floodproofing is common in non-residential 

buildings. In fact, following Tropical Storm Allison 

in 2001, several million dollars in dry floodproofing 

projects were funded under the FEMA Public 

Assistance program as hazard mitigation measures 

in conjunction with repairs to public buildings. 

Floodplain management regulations allow nonresidential buildings to be dry floodproofed. To 

receive a dry floodproofing rating credit under the 

NFIP, the floodproofing measure must protect to 

a minimum of 1 foot above the BFE. For buildings 

that were repaired or constructed after Tropical 

Storm Allison, dry floodproofing protection was 

implemented to 2 feet above the measured water 

surface elevation recorded during that event. 

The severity and area impacted by Hurricane 

Harvey resulted in numerous dry floodproofed 

buildings being exposed to floodwater, allowing the 

MAT to visit and assess the performance of various 

dry floodproofing systems. The performance of 

dry floodproofed buildings the MAT visited in 

Harris County varied significantly, allowing lessons 

to be gleaned from both successes and failures of 

dry floodproofing mitigation. 

FLOODPROOFING TERMINOLOGY 

Dry floodproofing entails the 

strengthening a building’s foundation, 

floor, and walls to withstand flood forces 

while making the structure watertight.

Wet floodproofing entails making 

utilities, structural components, and 

contents flood- and water resistant during 

periods of flooding within the structure.

NFIP TERMINOLOGY 

Special Flood Hazard Area (SFHA):

The land area covered by the floodwater 

of the base flood as delineated on NFIP 

maps. The SFHA is the area where 

the NFIP’s floodplain management 

regulations must be enforced and the 

area where the mandatory purchase of 

flood insurance applies. 

Regulatory Floodway: Delineated 

within the SFHA on NFIP maps; it is the 

channel of a river or other watercourse 

and the adjacent land areas that must be 

reserved in order to discharge the base 

flood without cumulatively increasing 

the water surface elevation more than a 

designated height.
MAT observations. Evaluating buildings to observe performance of residential buildings and 

dry floodproofed non-residential buildings was one of the MAT’s main goals. Although the MAT 

believes its assessments of buildings described in this chapter are correct, statements made herein 

are not intended to represent final judgments as to the cause of damage to individual buildings; 

further investigations by others may refine or alter judgments made by the MAT. Nevertheless, 

general damage patterns and trends the MAT observed are valid and can be used as the basis 

for recommendations to improve residential design and construction and non-residential dry 

floodproofing design and construction. 

Chapter organization. The MAT observations of flood-impacted buildings are divided into two main 

sections: Residential Buildings (Section 3.1) and Non-Residential Buildings with Dry Floodproofing 

(Section 3.2). Section 3.1 is presented by topic areas identified as of particular concern and Section 

3.2 is presented by individual buildings. 

3.1 Residential Buildings

The MAT visited select residential buildings 

(primarily single-family buildings) that were 

flooded by Hurricane Harvey in Aransas, Harris, 

and Nueces Counties. The Hurricane Harvey 

MAT emphasized identifying newly constructed 

or elevated houses that were adjacent to nonelevated houses with a wide range in age of 

construction to help evaluate the performance 

of buildings constructed to minimum floodplain 

management standards versus those constructed 

to higher standards. Additionally, the MAT endeavored to identify any areas of building performance 

in newer construction that could benefit from improvements in existing design and construction 

requirements.

Because of limited access and ongoing recovery efforts, most of the residential building performance 

was studied by analyzing NFIP flood insurance claims information in locations identified from MAT 

windshield assessments or other damage assessment surveys. The assessment focused on collecting 

location-specific information, including the flood zone and BFE, the year the residence was built, 

the foundation type, the estimated flood depth, and the total flood insurance claim payment 

amount. This information was gathered from a variety of sources. For example, the year built and 

foundation type (e.g., crawlspace versus slab) was gathered from county parcel data, the flood zone 

and BFE were collected from the National Flood Hazard Layer, and the flood insurance claim data 

were collected from the FEMA Federal Insurance Directorate based on closed claims as of June 

30, 2018. Building characteristics, particularly the foundation type, were verified based on data 

collected during windshield assessments. 

An example of a representative neighborhood visited by the MAT is shown in Figure 3-1, which 

shows part of an image taken by the Texas Civil Air Patrol on September 6, 2017. The neighborhood 

pictured had a range of old and new construction slab-on-grade houses and residences elevated on 

a crawl space. As shown in the figure, the newer elevated houses (shown with red arrows on Figure 

3-1) had little to no debris in front of them, whereas the older non-elevated structures had large piles 

of debris (shown outlined in yellow) in front of them indicating extensive damage to the building 

NIFP CLAIM PAYMENTS

For this report, NFIP claim payments were 

used as proxies for the estimated cost of 

repair. The claim payments do not reflect 

the deductible or items that were not 

covered under the policy.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-3

FLOOD-RELATED OBSERVATIONS
and contents. The entire area is in Zone AE based 

on the FIRM (effective June 2017). Of the 30 parcels 

along the highlighted route in Figure 3-1 (dashed 

blue line), 19 had an active flood insurance policy 

under the NFIP, 16 of the residences were built in 

the 1950s, and three were built after 2007. 

DEBRIS

The MAT observed debris piles as it 

drove through neighborhoods. The 

size of the debris piles outside each 

building is considered an indicator of 

the extent of building and contents 

damage.

Figure 3-1:

Representative residential 

neighborhood visited by the 

MAT [Zone AE]

PHOTO COURTESY OF TEXAS 

CIVIL AIR PATROL

3-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Of note: 

+ Of the 16 residences built before the community joined the NFIP, 12 currently have a closed 

insurance claim. The average total payment (building and contents) was approximately 

$181,750. Most of the claims are close to meeting the Substantial Damage 50 percent 

threshold. 

+ Two of the three residences built after communities started regulating development in the 

SFHA had closed claims. One had a total payment of approximately $12,050 and the other 

was closed without a payment (due to minimal to no damage).

3.1.1 General Observations

Building elevation was a universal indicator of performance: many older buildings built before 

communities joined the NFIP and began regulating SFHA development were inundated 3 to 6 feet, 

while newer elevated residential buildings performed much better, in some cases with no inundation 

and other cases with less than 1 foot of flooding above the lowest floor. Figure 3-2 through Figure 

3-5 are representative examples of flood inundation depths, as indicated by HWMs, and damage 

observed by the MAT.

Figure 3-2:

An approximately 5-foothigh HWM (shown as the 

dotted red line) observed 

by the MAT while assessing 

residential buildings on 

September 9 in Harris 

County [Zone AE]

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-5

FLOOD-RELATED OBSERVATIONS
Figure 3-3: Residential building located within the Limit of Moderate Wave Action (LiMWA) based on the February 2016 

effective FIRM [Zone AE]

3-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-7

FLOOD-RELATED OBSERVATIONS

Figure 3-4: A 54-inch-high HWM on residential buildings in Nueces County [Zone A]
3-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-5: A 42-inch-high HWM on a house in Harris County built in 1955 [Zone AE]

The one-story apartments in Figure 3-6 were built in phases starting in 2011. The apartments, which 

are located within the SFHA, were built to the minimum NFIP requirements without any freeboard. 

During Hurricane Harvey, the apartments were flooded with approximately 6 inches of water; most 

of the damage likely could have been avoided if the slab foundations had been elevated 1 foot as 

required by the model building codes and standards. Based on input from the repair contractor, 

most of the exterior condenser units were not sufficiently inundated to cause damage; however, 

some did have to be repaired, and in rare circumstances they had to be entirely replaced. One 

challenge noted by the MAT was the difficulty in repairing the party wall between apartment units. 

The damaged material was removed, but there is no practical way to replace the inner sheets with 

new material.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-9

FLOOD-RELATED OBSERVATIONS

Figure 3-6: Flood damage to Nueces County apartments [Zone AE]

Figure 3-7 illustrates an elevated residence the MAT observed in Harris County. While not many 

residences were elevated in neighborhoods that the MAT visited, those that were elevated performed 

better than adjacent, older houses built before communities began regulating SFHA development. 

The elevated residences were randomly distributed and often surrounded by slab-on-grade 

structures, allowing a comparison of new and old construction. Figure 3-8 illustrates three houses 

that were adjacent or immediately across from the elevated residence in Figure 3-7. All four houses 

are in Zone AE. The elevated residence was built in 2002, while the three slab-on-grade structures 

were built in 1955. The MAT measured a HWM at 42 inches above the slabs along this street. The 

homeowner of the elevated residence (shown in Figure 3-7) stated that the water reached the top 

step of their entrance but did not inundate the habitable space. The elevated residence had a flood 

insurance claim payment of approximately $18,000 (primarily due to having non-flood damageresistant materials in the garage and crawlspace), while the three slab-on-grade structures had an 

average claim payment of $136,000. 
Figure 3-7: 

This elevated house built 

in 2002 (HWM, shown as 

the dotted red line) had 

much less damage than 

surrounding older slabon-grade houses (example 

shown in Figure 3-8) 

[Zone AE]

3-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-8: 

Slab-on-grade house 

(located across the street 

from the elevated residence 

shown in Figure 3-7) has 

large debris pile [Zone AE] 

Flood damage to buildings was not limited to properties in mapped 1.0-percent-annual-chance 

probability floodplains (SFHA). For example, the elevated Aransas County single-family residence 

in Figure 3-9 built in 2016 in Zone X had approximately $12,000 in damages due to lack of flood 

damage-resistant materials below the elevated floor. In Harris County, aerial imagery revealed 

that about one-third of the county was under water at one point, and approximately half of the 

inundated area was outside of the FEMA-mapped 0.2-percent-annual-chance probability floodplain 

and therefore outside the SFHA.
The MAT observed recently built houses that met or exceeded the minimum NFIP elevation 

requirements (but not requirements for enclosures) and had minimal structural damage, but still 

required some repair to interior finishing. For example, the Zone AE residence in Figure 3-10 was 

built in 2016 with insufficient flood openings; it appeared to have limited flood damage from the 

exterior, yet an NFIP insurance claim was filed for this residence. In addition to flood damage 

related to its elevation, the house had damage to the building envelope from hurricane-force winds, 

including loss of siding and soffit covering, which may have caused interior damage from leaking 

around those openings.

Figure 3-9: Elevated residence built in 2016 with flood damage (approximately $12,000) [Zone X]

Figure 3-10: Relatively new house built in 2016 had limited exterior flood damage, yet interior repairs were required due 

to flood inundation and penetration of wind-driven rain [Zone AE]

3.1.2 Enclosures Below Elevated Buildings

For floodplain management purposes, an enclosure is a confined area below the lowest elevated 

floor of a building that is formed by walls on all sides of the enclosed space. Enclosed areas that 

are used solely for parking of vehicles, building access, or storage are permissible below the lowest 

elevated floor. However, floodplain management regulations for Zone A/AE require enclosures to 

be built with flood damage-resistant materials and have openings in walls to allow free entry and exit 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-11

FLOOD-RELATED OBSERVATIONS
of floodwater. If an enclosure is not properly constructed with adequate openings (refer to FEMA 

Technical Bulletin 1, Openings in Foundation Walls and Walls of Enclosures [2008d]), it can transfer 

flood forces to the main structure and possibly lead to structural damage or collapse. 

Most of the enclosures the MAT observed were in Aransas and Nueces Counties. Although no 

damage to enclosures with compliant flood openings was observed, compliance with floodplain 

management requirements was inconsistent. For example, a recently constructed (2016) singlefamily residence in Zone AE had a two-car garage enclosure and another enclosure for access to the 

house. The two-car garage had openings along two sides (top row of images in Figure 3-11), but the 

enclosure for access to the house had no openings (bottom row of images in Figure 3-11).

Figure 3-11: Elevated residence built in 2016 in Aransas County [Zone AE]

3-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
FEMA Technical Bulletin 1, Openings in Foundation Walls and Walls of Enclosures (2008d), outlines 

the requirements and guidance for the installation of openings. The Technical Bulletin includes 

requirements for an enclosure’s minimum size, as well as guidance on limiting covers or devices that 

could impede the free flow of floodwater into and out of the enclosed area. Some enclosures were 

observed to have the compliant number of openings, but the openings did not necessarily meet all 

the requirements. For example, the elevated single-family residence built in 2009 in Zone AE shown 

in Figure 3-12 had an enclosure that appeared to be for storage; it had an engineered opening on 

one wall, but on the other wall it had a less than 3-inch by 6-inch cutout opening covered by an 

air vent faceplate with a screen along the interior. The smaller opening was not a compliant flood 

opening. While the MAT did not identify a HWM in this area, and access was not provided to the 

interior of this enclosure, the presence of piles of insulation and other garbage in the debris pile 

adjacent to the elevated residence (upper left image of Figure 3-12) suggests that the interior of the 

enclosure sustained damage because flood damage-resistant materials were not used.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-13

FLOOD-RELATED OBSERVATIONS

Figure 3-12: Elevated residential building non-compliant flood opening [Zone AE]
In Port Aransas, the MAT observed two elevated houses approximately 300 feet apart along the 

same street within the SFHA in Zone AE; the two sites experienced the same flood conditions 

during Hurricane Harvey. One house was built in 1982 and the other in 2014. Both had enclosures 

below the elevated building, but only the enclosure below the newer house had flood openings. The 

performance and extent of damage within the enclosure of these two buildings was considerably 

different, with the enclosure of the older house suffering extensive damage (see Figure 3-13), while 

the newer house required much less repair (see Figure 3-14).

Figure 3-13: Extensive damage to the enclosure of an older (1982) elevated residence in Port Aransas; the enclosure did 

not have flood openings [Zone AE]

3-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-14: 

The enclosure of a newer elevated residence in Port 

Aransas with compliant flood openings on each side 

of the house (see insets) suffered only limited damage 

to its contents [Zone AE]
The MAT observed recently built elevated houses in Nueces County with enclosures that were 

permitted under the effective 1992 FIRM but whose flood zone determination will likely change 

based on the preliminary map. The elevated residence in Figure 3-15 had flood openings, but there 

were not enough openings based on the enclosure size. In addition, based on the preliminary FIRM, 

this house will be reclassified from Zone AE to Zone VE. Without breakaway walls and based on the 

enclosure size, the house is susceptible to damage from wave action. Although a HWM was not 

identified by the MAT during the windshield assessment, preliminary damage assessment and flood 

insurance claims information obtained by the MAT indicate there was about $3,000 in damage 

within the enclosure.

Figure 3-15: Elevated residence built in Nueces County in 2016 to Zone AE floodplain management requirements [Zone 

VE, per updated preliminary FIRM]

3.1.3 Perimeter Wall Foundations (Crawlspace)

Perimeter wall foundations (also called crawlspaces) were present in many of the newer elevated 

buildings the MAT observed, especially in Harris County. The foundations were predominantly pier 

and beam construction and ranged from 2 to 6 feet above grade. Like enclosures, crawlspaces must 

have flood openings to allow the equalization of flood forces. Figure 3-16 shows a representative 

crawlspace observed by the MAT.

Figure 3-16: 

Residential crawlspace 

observed by the MAT in a 

Harris County house built in 

2002 where the insulation 

along the elevated floor had 

to be removed [Zone AE]

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-15

FLOOD-RELATED OBSERVATIONS
One common performance issue the MAT observed in crawlspace foundations was the use of nonflood damage-resistant materials, particularly insulation. The MAT observed relatively small piles 

of debris adjacent to several of the elevated buildings in Harris County, and the observed debris 

appeared to be non-flood damage-resistant materials likely removed from crawlspaces and garages, 

as illustrated in Figure 3-17. 

Based on MAT observations, some property owners used fiberglass insulation or other non-flood 

damage-resistant insulation materials below the elevated lowest floor. Use of such materials requires 

an additional factor of safety be incorporated into the foundation design flood elevation, or 

freeboard, to reduce the risk of flood damage.

Figure 3-17: 

Non-flood damage-resistant 

materials removed from 

the crawlspace of the 

adjacent elevated Harris 

County building built in 2014 

[Zone AE]

3.1.4 Ongoing Slab-on-Grade Elevation Project

The MAT observed one residential elevation project that was underway at the time Hurricane 

Harvey struck (see Figure 3-18 through Figure 3-20). The project was located in the SFHA (Zone 

AE) and was partially funded under FEMA’s Hazard Mitigation Assistance programs, and the house 

was scheduled to be lifted days before Hurricane Harvey made landfall. Because of the storm, 

the contractor had to put the lift on hold. Damage to the house was significant and resulted in a 

maximum coverage NFIP claim from Hurricane Harvey. 

Because the project was underway at the time the MAT visited, this house offers a case study in 

elevating a slab-on-grade foundation. The house was elevated more than 4 feet after Hurricane 

Harvey. 

Elevation method and foundation system. The elevated slab is supported by mini-piers consisting 

of concrete blocks connected to one another with a series of threaded steel dowel rods or other 

material running through a hole in the center of each block (see Figure 3-18 for representative 

examples of mini-piers). 

The homeowner stated that a structural engineer evaluated the slab and recommended the pier 

spacing. In some parts of the house a steel beam was used to support the slab to limit the pier 

spacing, although pier spacing varied greatly. Most spans were approximately 8 to 10 feet; some 

exceeded 12 feet. 

3-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
The MAT did not observe any evidence of a continuous load path connection between the piers 

and the steel beam or the concrete slab to the piers around the perimeter wall. Figure 3-18 shows 

representative images from the crawlspace illustrating the foundation system.

Figure 3-18: Recently elevated slab-on-grade foundation where steel beams were used to support the elevated slab and 

limit pier spacing [Zone AE]

Finish. A perimeter wall finish with flood openings (as seen in Figure 3-19) was placed around the 

base of the elevated houses to provide an aesthetic covering for the raised slab. The homeowner 

stated that the contractor sprayed the bottom of the slab with closed-cell foam to insulate it. Closedcell foam was also sprayed throughout all the exterior walls, shown in Figure 3-20. The closed-cell 

foam was sprayed directly on the existing fiberboard and wood framing adhering the components 

into an assembly. If the house is elevated above the BFE with sufficient freeboard to make sure 

that it has minimal flood risk, this approach will likely result in a more energy efficient house. It is 

important to inspect the fiberboard to make sure that it was not damaged during previous flood 

events and that the moisture content of the fiberboard is within the manufacturer’s recommended 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-17

FLOOD-RELATED OBSERVATIONS
limits. If the fiberboard sheathing is damaged and no longer maintains its structural properties, 

the proposed assembly (which includes the closed cell foam), should be evaluated by an engineer 

to verify that it can sufficiently resist lateral loads and that the exterior sheathing does not need 

to be replaced. Although closed-cell foam is considered an acceptable flood damage-resistant 

material, applying it directly to the existing fiberboard, which is not flood damage-resistant, could 

be problematic because any trapped moisture from floodwater would be difficult to dry out. Such 

assemblies, which include porous exterior sheathing materials, could be susceptible to mold growth 

or other damage that is difficult to inspect and should therefore be avoided in floodprone areas.

Figure 3-19: 

Exterior of new masonry 

perimeter foundation wall 

adjacent to piers supporting 

the elevated slab [Zone AE]

Figure 3-20: Closed-cell foam was applied to all exterior walls when this slab-on-grade house was elevated

3-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
3.1.5 Floodplain Management Requirements versus Damage

The MAT visited neighborhoods similar to that shown in Figure 3-21, where there are side-by-side 

new and old residences as well as new construction that exceeds the NFIP requirements. Visiting 

such neighborhoods provided the MAT with a unique opportunity to evaluate the effectiveness of 

elevating houses to mitigate flood damage.

Figure 3-21:

Example of neighborhood in 

Harris County where newer 

elevated residences (house 

on left was built in 2013) 

are situated next to older 

residences (non-elevated 

older residence on right was 

built in 1948) [Zone AE]

Figure 3-22: 

Example of an elevated 

residence (left side) next to a 

non-elevated residence (right 

side); the elevated house 

sustained much less damage 

during Hurricane Harvey

3.1.5.1 Proof of Benefit of Building Elevation

The MAT was able to identify some situations where adjacent elevated and non-elevated buildings 

both had active NFIP flood insurance policies before Hurricane Harvey and their claims were 

closed or paid. Having NFIP claims for adjacent (or nearby) structures allowed the MAT to compare 

flood damage cost based on current floodplain management requirements as well as design and 

construction practices. One example is illustrated in Figure 3-22 where the recently constructed 

elevated residence had approximately $4,000 in damage, while the non-elevated structure had over 

$96,000.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-19

FLOOD-RELATED OBSERVATIONS
3.1.5.2 Proof of Benefit of NFIP Construction 

Most of the neighborhoods visited in Harris County were in two NFIP-participating communities: 

Bellaire and Houston. Based on the information collected in the field, as well as a desktop 

assessment of parcel data attributes including year built and foundation type, the MAT identified 

groups of houses with a high percentage of active NFIP flood insurance policies to compare building 

performance. 

Within the specific neighborhoods visited and analyzed, there were 1,280 active NFIP policies, of 

which 673 had closed claims from Hurricane Harvey. Table 3-1 provides a summary of these closed 

flood insurance claims. The distribution was almost evenly split between houses built before (54 

percent) and after (46 percent) the communities began regulating SFHA development in 1982. The 

average claim for houses built after the communities adopted floodplain management regulations 

was half that compared to those built before. 

Table 3-1: Summary of Closed Flood Insurance Claim Data for Neighborhoods Analyzed by MAT 

Construction Date Number of Houses Average Claim

Before 1982 663 $181,258

After 1982 572 $89,906

Note: 1982 is the year the community adopted floodplain management regulations

SOURCE: CLAIMS BASED ON NFIP DATA THROUGH JUNE 2018 (FEMA, PERSONAL COMMUNICATION) AND YEAR BUILT BASED ON HARRIS 

COUNTY APPRAISAL DISTRICT REAL AND PERSONAL PROPERTY DATABASE (2018)

3.1.5.3 Proof of Benefit of NFIP Participation

One residential area associated with the 1,280 NFIP policies the MAT studied consisted of 334 

residences, all of which were in Zone AE. This representative neighborhood is illustrated in 

Figure 3-23. As shown on Figure 3-23, the neighborhood is composed of houses built on slabs and 

crawlspaces and includes houses of varying ages. The relatively close proximity of these residences 

provided an opportunity for the MAT to compare residences that were subject to similar flood 

conditions during Hurricane Harvey and analyze damage (as represented by claim payments) with 

respect to homeowner maintenance of an active flood insurance policy, presence of a new FIRM, 

and foundation type. 

Effect of Active Flood Insurance Policy

Of the 334 residences, 161 (48 percent) had an active flood insurance policy. The 48 percent rate 

for having an active flood insurance policy within the SFHA is representative of the neighborhoods 

analyzed (the overall rate was about 50 percent). At the time this report was written, 157 of the 161 

flood insurance policies in this residential area had a closed claim. The average total (building and 

content) closed claim payment was approximately $98,182. Of the 157 structures with closed claims, 

62 were built prior to 1982 and the remaining 95 were built after 1982. 

Within this specific neighborhood, the average total claim payment for the houses built prior to 

when the community began regulating SFHA development was approximately $146,800, whereas 

those built after 1982 had an average total claim of approximately $66,450 (see Table 3-2). 

3-20 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
$

2008

$

2007

$$

2007

$

2004

—

1996

$$$

1955

$$$$1982

2015

$$

2004

$$$$1947

$

2011

$$$

1946

$$$$$

1952

$$$$$

1989

$$$$$

1997

$$$$1950

$$$$1950

$$$$1950

$$$$1950

$$$$2000

$$$$1950

$$$$2003

$$$

1950

$$

2010

$$

2007

$$

1950

$$$

1950

$$$

1950

$$$

1954

$$$

1953

$$$$$

1996

$$$$$

1952

$$$

1998

$$$$1947

$$$$$

1950

$$$$2000

$$$$1947

$$$

1950

$$$

1950

$$$$1950

$$$$1994

$$$$1997

$$$$1947

$$$$2001

$$$

1950

$$

1950

$$$

1998

$$$

1950

$

2006

$$$$1993

$$$$1998

$$$$1951

$$$$1951

$$$$1963

$$$$$

1950

$$$$1950

$$

1997

$$

2006

$$$$$

1955

$$$$1963

$$$

1950

$

1994

$$$$1999

$$$$1954

$$

1989

$$$

1947

$$$$$

2000

$$$$$

1951

$$$$1950

$$$$1950

$$$

1952

$$$

1951

$$$$1950

$$$$1953

$$$$1950

$$$$1954

$$$$1953

$$$

2003

$$$$1988

$$$$1953

$$$

1991

$$$

1950

$$$

1950

$

2005

—

2003

$$$$$

1989

$$$

1950

$$$

1950

$$$$$

1954

$$$$$

1950

$

2006

—

2006

—

1951

$

2008

$$$$1999

$$$

1990

$

2005

$$

1990

$

2006

$$

2007

$$

1950

$$$

1998

$$

1950

$$$$$

2001

$

2002

$$$$$

2002

$$$$1992

$$$$1950

$$$$1951

$$$$$

$$$

1989

1953

$$$

1990

$$$$1951

$$

2005

$$$

2002

$$$

1997

$$

1950

$$$

1950

$$$

1969

$

2016

—

2010

$

2012

$

2010

$

2012

$

2006

$

2012

$$

2006

$

2014

$

2011

$

2014

—

2015

$

2006

$

2015

$

2006

—

2006

$

2014

$

2010

—

2015

$

2007

$

2012

$

2014

$

2013

$

2006

$$

2012

$

2013

$$

2008

—

2013

—

2014

$$

2012

$$$

2014

—

2014

$$

2014

—

2015

—

2015

—

2014

$

2014

$$

2015

Insurance Claims (data as of June 2018):

LEGEND

####

CrawlspaceSlabNo NFIPpolicy

Year built

—

 1–10,00010,000–50,00050,000–125,000125,000–225,000225,000+

$

$$

$$$

$$$$

$$$$$

Closed w/o payment

RESULTS

CLAIM AMOUNTS FOUNDATION TYPE YEAR BUILT

Quantity Percent Crawlspace Slab Pre-19821 Post-1982 1982-2000 Post-20002

0 16 10% 13 3 0 16 1 15

$ 31 20% 18 13 0 31 1 30

$$ 24 15% 6 18 7 17 4 13

$$$ 27 17% 1 26 19 8 5 3

$$$$ 40 26% 0 40 27 13 11 2

$$$$$ 19 12% 0 19 9 10 9 1

Total 157 100% 38 119 62 95 31 64

1 Initial FIRM is dated 1981; structures built 1982 and later would comply with NFIP requirements per the initial FIRM.

2 Updated FIRM for the area studied is dated 1999; structures constructed 2000 and later would comply with updated 

zone information shown on the 1999 or latest effective FIRM.

Figure 3-23: Distribution of residences analyzed in the representative residential area, as of June 2018

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-21

FLOOD-RELATED OBSERVATIONS
Table 3-2: Summary of Closed Flood Insurance Claim Data for the Representative Residential Area

Description Houses Built Before 1982 Houses Built After 1982 All Houses

Total number of policies 66 95 161

Total number of closed claims 62 95 157

Average closed building claim $117,506 $57,034 $80,915

Average closed content claim $29,924 $9,418 $17,267

Average closed total claim $146,800 $66,452 $98,182

Claims closed without 

payment ($0) 0 16 16

SOURCE: CLAIMS BASED ON NFIP DATA THROUGH JUNE 2018 (FEMA, PERSONAL COMMUNICATION) AND YEAR BUILT BASED ON HARRIS 

COUNTY APPRAISAL DISTRICT REAL AND PERSONAL PROPERTY DATABASE [2018]

Effect of New FIRM on Damage

While the year built relative to the initial adoption of floodplain management regulations was a key 

indicator in differentiating building performance, the MAT found during its analysis that newer 

construction built to meet the latest FIRM as well as the latest floodplain management requirements 

(including freeboard) was an indicator as well. 

In the representative neighborhood introduced in the previous subsection, 15 of the 16 claims 

closed without payment were built in 2001 or later. The average claim for a post-2000 (effective 

date of previously effective FIRM) residence was approximately $19,335, almost 90 percent less than 

those built from 1982 through 2000. Table 3-3 shows a summary of claims comparing post-2000 

construction to those built from 1982 through 2000. 

Table 3-3: Closed Flood Insurance Claim Data for Post-1982 Construction in the Representative Residential Area

Description Houses Built 1982–2000 Houses Built After 2000 All Houses

Total number of policies 31 64 95

Total number of closed claims 31 64 95

Average closed building claim $139,514 $17,083 $57,034

Average closed content claim $24,214 $2,252 $9,418

Average closed total claim $163,728 $19,335 $66,452

Claims closed without 

payment ($0) 1 15 16

SOURCE: CLAIMS BASED ON NFIP DATA THROUGH JUNE 2018 (FEMA, PERSONAL COMMUNICATION) AND YEAR BUILT BASED ON HARRIS 

COUNTY APPRAISAL DISTRICT REAL AND PERSONAL PROPERTY DATABASE [2018]

3-22 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Representative Neighborhood – Effect of Foundation Type on Damage

One additional indicator of building performance found during the MAT’s analysis was the 

foundation type. Buildings constructed on crawlspaces had significantly lower claims than those 

with a slab-on-grade foundation. The average claim for a house with a crawlspace was approximately 

$8,800, about 93 percent less than those built on a slab. Table 3-4 shows a summary of the flood 

insurance claims based on foundation type. 

Table 3-4: Closed Flood Insurance Claim Data for Slab-on-Grade versus Crawlspace Construction in the Representative 

Residential Area

Description Slab-on-Grade Crawlspace All

Total number of policies 123 38 161

Total number of closed claims 119 38 157

Average closed building claim $104,042 $8,490 $80,915

Average closed content claim $22,670 $347 $17,267

Average closed total claim $126,712 $8,837 $98,182

Claims closed without payment ($0) 3 13 16

SOURCE: CLAIMS BASED ON NFIP DATA THROUGH JUNE 2018 (FEMA, PERSONAL COMMUNICATION) AND YEAR BUILT BASED ON HARRIS 

COUNTY APPRAISAL DISTRICT REAL AND PERSONAL PROPERTY DATABASE [2018]

3.2 Non-Residential Buildings with Dry Floodproofing

Unlike residential buildings, non-residential buildings can use dry floodproofing to protect the 

building from flooding. Many non-residential buildings in Harris County have dry floodproofing 

measures installed to prevent damage from the frequent flooding experienced in the county. With 

its record-breaking rainfall amounts, Hurricane Harvey tested dry floodproofing measures installed 

at buildings throughout Harris County. 

One goal for the MAT was to evaluate the performance of these measures to assess which methods 

worked and which did not, and why. To accomplish this goal, the MAT visited private commercial 

buildings, government buildings, and the TMC in Harris County. Table 3-5 lists the buildings visited 

that are described in this report (the MAT visited some non-residential buildings not described 

herein) and the pertinent subsection number.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-23

FLOOD-RELATED OBSERVATIONS
Table 3-5: Facilities and Buildings Assessed by MAT in Harris County

Facility Name

MAT 

Section

Private 

Commercial Government NFIP Flood Zone

Harris County Jail 3.2.1.1 X Zone AE

Harris County Criminal Justice Center 3.2.1.2 X Zone X

Jury Assembly Building 3.2.1.3 X Zone X

Harris County Civil Courthouse 3.2.1.4 X Zone X

City of Houston Public Works 3.2.2 X Unshaded Zone X

Wortham Theater and Underground 

Parking and Tunnel Complex 3.2.3 X Zone AE

Energy Corridor Office Building #1 3.2.4 X Zone X

Energy Corridor Office Building #2 3.2.5 X Unshaded Zone X

Houston Galleria Office Tower 3.2.6 X Unshaded Zone X

Four Leaf Towers 3.2.7 X Unshaded Zone X

Starbucks at 4660 N. Braeswood 3.2.8 X Zone AE

Texas Children’s Hospital 3.2.9.1 X Zone X

The University of Texas MD Anderson 

Cancer Center 3.2.9.2 X Zone AE and 

Zone X(a)

Harris Health System Ben Taub Hospital 3.2.9.3 X Zone X

Baylor College of Medicine 3.2.9.4 X Zone X

CenterPoint Energy Grant Substation 3.2.9.5 X Zone AE

Thermal Energy Corporation (TECO) 

Paul G. Bell, Jr. Energy Plant 3.2.9.6 X Zone AE

Note: All buildings are located on the Harris County Community FIRM panels

(a) The MD Anderson Cancer Center has numerous buildings on the TMC campus, with some of the buildings located in Zone AE and others located in Zone X.

MAT = Mitigation Assessment Team; NFIP = National Flood Insurance Program

3-24 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
General Observations

The performance of dry floodproofing 

measures was highly variable, ranging from 

effective to complete failure. However, the 

dry flood proofing systems evaluated that 

performed well (or failed) shared similar 

characteristics. In buildings where the 

dry floodproofing failed, critical building 

systems located in basements and first floors 

were damaged and rendered inoperable. 

In addition to failures, the MAT observed 

numerous instances of “near misses.” In 

these cases, the dry floodproofing measures 

or human intervention prevented widespread 

flood damage, but if flood levels had been 

only slightly higher or if building managers 

had not taken action before the onset of 

flooding, many of these successes would have 

KEY DRY FLOODPROOFING TERMINOLOGY

Flood Barrier: The physical barrier, composed of opening protection, floor slab, and wall system, 

that separates floodwater from the dry floodproofed portion of the building.

Opening Protection: A cover, shield, or door that covers a window, doorway, loading dock access, 

or other opening in a building wall or floor. Sometimes called “closure device.”

Active: A dry floodproofing opening protection system that requires human intervention to install 

the physical barrier. These systems are effective only if there is enough warning time to mobilize 

the labor and equipment necessary to implement them and then safely evacuate.

Passive: A dry floodproofing opening protection system that does not require human intervention to deploy the physical barrier.

Floodwall: A constructed barrier of flood-damage-resistant materials to keep water away from or 

out of a specific area. Floodwalls surround a building and are typically offset from the exterior walls 

of the building; some floodwalls can be integrated into the building envelope. Floodwalls are considered a component of the overall flood barrier. 

Flood Entry Point: Any opening, joint, gap, crack, low point, or other location through or over 

which floodwater can enter the dry floodproofed area.

Substantially Impermeable: According to USACE, a wall is considered substantially impermeable 

if it limits water accumulation to 4 inches in a 24-hour period (USACE, 1995). In addition, sump 

pumps are required to control any seepage, and flood-resistant materials must be used in all areas 

where seepage is likely to occur. As stated in FEMA’s Technical Bulletin 3, FEMA adopted the 

USACE’s standard for defining substantially impermeable. ASCE 24 is the minimum requirement; it 

is possible to achieve lower seepage rates, which is strongly encouraged by FEMA, particularly in 

new construction.

TROPICAL STORM ALLISON 

COMPARED TO HURRICANE HARVEY

Similar to Hurricane Harvey, Tropical Storm 

Allison lingered over eastern Texas for 5 

days before travelling eastward toward North 

Carolina and Virginia. In Houston, total rainfall 

from Tropical Storm Allison was recorded 

between 5 and 35 inches; east of Houston, 

some areas recorded rainfall totals that 

exceeded 40 inches. 

By comparison, all of Harris County received a 

minimum of 25 inches of rain, with a maximum 

of 54 inches of rain, during Hurricane Harvey. 

For additional information, refer to Chapter 1.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-25

FLOOD-RELATED OBSERVATIONS
been failures. Table 3-6 summarizes the key observations by the MAT on the performance of dry 

floodproofing systems and the amount of downtime and damage that occurred at the buildings 

visited by the MAT.

Owners of the buildings visited understood their 

vulnerability based on their location on the FIRM 

and as a result of having sustained flood damage from 

Tropical Storm Allison (or from more recent flooding 

events such as the Memorial Day Flood in 2015 or 

the Tax Day Flood in 2016). Most of the buildings 

that the MAT visited initiated dry floodproofing 

mitigation measures and annual preparedness 

training performed by their employees in response to 

the damage sustained during Tropical Storm Allison 

in 2001.

Organization of Non-Residential Dry Floodproofing Observations

The remainder of this section first describes MAT observations related to planning and 

implementation of dry floodproofing systems, followed by the observed damage and performance 

of dry floodproofing systems organized by building or facility, rather than by damaged component. 

The presentation of the information is ordered by grouping together buildings based on their 

location within Harris County. Building locations are grouped into the following areas: 

+ Downtown Houston (Sections 3.2.2 to 3.2.4)

+ Energy Corridor (Sections 3.2.5 and 3.2.6)

+ Houston Galleria (Section 3.2.7 and 3.2.8)

+ Brays Bayou Watershed (Section 3.2.9)

+ Texas Medical Center (TMC) (Section 3.2.10)

The following information is presented for each location 

visited: brief discussion of the building(s) and the flood risk at 

the site, dry floodproofing mitigation measures in place prior 

to Hurricane Harvey, the performance of the building during 

Hurricane Harvey and its effect on operations, and a summary 

of observations by the MAT. 

FEMA MITIGATION FUNDING

Many of the Harris County buildings, 

TMC buildings, and the Theater 

District received a FEMA Public 

Assistance (406 mitigation) grant after 

Tropical Storm Allison to install dry 

floodproofing measures to protect 

against future events.

NAVD 88 

All flood elevations in this 

section are referenced to 

the North American Vertical 

Datum of 1988 (NAVD 88).

3-26 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

3.2.1 Planning and Implementation of Dry Floodproofing Systems

Most of the buildings visited as part of the field investigation had well-organized and thorough 

emergency operations plans on how to prepare the building and implement dry floodproofing 

measures before the arrival of severe weather. 

Buildings that survived Hurricane Harvey with minimal impact had building managers who had 

learned from previous failures and instilled a culture of preparedness and redundancy. These 

building managers reported holding annual training exercises to ensure that building engineering 

and maintenance staff knew how to deploy dry floodproofing measures and that institutional 

knowledge was shared with everybody responsible for protecting the building. The annual exercises 
Table 3-6: Dry Floodproofing Key Observations Crosswalk with Report Section

Key Observations

Report Section

3.2.2.1

3.2.2.2

3.2.2.3

3.2.2.4

3.2.3

3.2.4

3.2.5

3.2.6

3.2.7

3.2.8

3.2.9

3.2.10.1

3.2.10.2

3.2.10.3

3.2.10.4

3.2.10.5

3.2.10.6

Building managers instilled a culture of preparedness and have extensive emergency operations plans 

    

Flood damage-resistant materials were not used below the DFE          

Freeboard was above code-recommended values    

Freeboard based on previous events instead of tied to an MRI flood event     Independent verification of dry floodproofing systems performed      Material not designed to resist hydrostatic forces used in the flood barrier  Successful performance of passive flood barriers    Redundant dry floodproofing systems were in place         

Seepage occurred around pipe penetrations and though cracks in walls       

Stormwater piping issues resulted in flood damage    Dry floodproofing system considered to be Substantially impermeable        

Submarine door or floodgate seepage issue or failure occurred  Sump pump not provided to remove seepage through flood barriers         

Water flowed in utility/electrical conduits    

DFE = design flood elevationMRI = mean recurrence interval

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-27

FLOOD-RELATED OBSERVATIONS
had the added benefit of allowing participants 

to identify broken or missing components in 

the dry floodproofing system. After Hurricane 

Harvey, these same building managers had 

meetings about lessons learned and how their 

emergency management plan and training 

should be modified as a result. 

Preparation for the potential impact of 

Hurricane Harvey started a week before the 

storm made landfall. Long-range forecasts 

showed the potential of a hurricane in the 

Gulf of Mexico, which is often the trigger for 

implementing emergency operations plans 

for buildings in Texas. Preparation activities 

included filling the fuel tanks of the backup 

generators, emptying dumpsters, cleaning up 

trash and debris from around the building, 

checking sump pumps and renting back up pumps in case of failure, and verifying that backflow 

preventers were functioning. Some building owner and operators went as far as to stockpile common 

building materials, such as drywall, to speed up recovery efforts after an event, since those supplies 

are often in short supply after an event.

The timing for when facility managers began to deploy active opening protection depended on the 

size of the building. Deployment in larger buildings began 2 days before Hurricane Harvey made 

landfall, whereas managers of smaller buildings waited until the day before or after Harvey made 

landfall. Buildings with passive opening protection had the option to either let the barrier function 

as designed or manually open the barrier. 

The buildings visited by the MAT that were located in Unshaded Zone X and critical government 

facilities that could not be fully evacuated had teams of building engineers or maintenance 

staff positioned on upper floors during Hurricane Harvey to respond to any issues with the dry 

floodproofing systems. In at least three cases, building engineers and maintenance staff were able to 

respond to issues, minimizing damage or preventing a catastrophic failure in the dry floodproofing 

system. 

EMERGENCY OPERATIONS PLANS

All emergency operations plans start with 

a clear understanding of the flood hazard, 

identifying where floodwater may originate 

and how it can enter the building. As a best 

practice, these plans should be updated or 

refined every year after failures or successes 

are identified with the intent of minimizing the 

impact flooding has on the building. Texas 

Recovery Advisory 1, Dry Floodproofing: 

Planning and Design Considerations (2018g), 

included in Appendix A, provides an overview 

of flood vulnerability assessments and how 

to use the information obtained.

3-28 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

3.2.2 Judicial and Correctional Facilities – Downtown Houston

Several Harris County judicial and correctional facilities are located near downtown Houston. 

Many are within 1⁄4 mile of where White Oak Bayou flows into Buffalo Bayou (see Figure 3-24). 

The MAT visited eight judicial and correctional buildings in the area. The four buildings discussed 

herein both sustained flood damage and had sources of floodwater entry into the building that 

were examples of overall issues with the dry floodproofing design. Three of the four facilities—the 

Criminal Justice Center, Jury Assembly Building, and the Civil Courthouse—are clustered within 

300 feet of each other; the fourth, the Harris County Jail, is approximately 1,200 feet to the north.
Figure 3-24: Map of Downtown Houston showing the confluence of White Oak Bayou with Buffalo Bayou, and the four 

Harris County facilities visited by the MAT discussed in this subsection

Milam Street

Main Street

San Jacinto Street

Commerce Street

Congress Avenue

Franklin Street

J

Mi

Mai

n J

Sa Street

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-29

FLOOD-RELATED OBSERVATIONS

A HCFCD stream gage is located near the Milam Street Bridge (see Figure 3-24) approximately 900 

feet upstream of the confluence of the White Oak and Buffalo Bayous. The Milam Street gage is the 

closest stream gage to, and is just upstream of, the four Harris County buildings discussed in this 

section and is 2,100 feet downstream of the Wortham Theater (see Section 3.2.3). 
Historic Flood Levels at Harris County Judicial and Correctional Facilities in Houston

Historic flood levels were compared to published flood elevations to determine the approximate 

MRIs for those events at the Milam Street Bridge stream gage. The HCFCD had determined the 

flood elevations for various MRIs, as shown in Table 3-7. Table 3-8 shows the highest flood levels 

recorded by the Milam Street Bridge gage for the six largest severe weather and flooding events 

within the last 20 years and their approximate MRIs. Based on the Milam Street Bridge stream gage, 

the recorded HWM of 37.8 feet for Hurricane Harvey was the highest recorded event, but was less 

than a 0.2-percent-annual-chance event. 

Table 3-7: Flood Levels, Probabilities, and Associated Recurrence Intervals at the Milam Street Bridge

Milam Street Flood Elevations for Various Flood Events

Annual Chance of Exceedance 10% 2% 1% 0.2%

Mean Recurrence Interval (years) 10 50 100 500 

Flood Elevation (feet) 27.1 32.6 35.6 41.3 

Table 3-8: Summary of Data Based on Milam Street Bridge Gage

Event

Maximum Flood 

Elevation (feet)

Approximate 

MRI(a) (years)

Percent Annual Chance 

of Exceedance

Harvey (2017) 37.8 197 0.5

Allison (2001) 35.9 117 0.85

Memorial Day (2015) 31.3 33 3

Fran (1998) 30.4 26 3.8

Tax Day (2016) 28.7 16 6.3

Ike (2008) 27.8 13 7.7

(a) The MRIs (mean recurrence intervals) were determined using regression analysis whereby a best-fit curve was selected to model 

the data and then compared to the published flood elevations. A logarithmic curve was selected, which produced a coefficient of 

determination (R2 value) of 99.8 percent. 

SOURCE: HCFCD, 2018A

3.2.2.1 Harris County Jail – 701 N. San Jacinto Street, Houston, TX 

Harris County Jail is a 650,000-square-foot, seven-story building 

with an additional basement level located in downtown Houston 

near the confluence of White Oak Bayou and Buffalo Bayou. 

Originally a cold storage warehouse constructed in the 1920s, 

the building was heightened by two stories and opened as a 

correctional facility in 1991. Per the FIRM effective in 1985, the 

area was classified as Zone AE; however, whether any measures 

were taken to mitigate the flood risk to the building as part of the conversion from a cold storage 

warehouse to a correctional facility is unknown. The building site is exposed to flooding from the 

White Oak and Buffalo Bayous and is located in Zone AE with a BFE of 34 feet. The west elevation 

of the building is adjacent to the regulatory floodway (see Figure 3-25). Figure 3-26 shows the 

building’s location on the effective FIRM. 

The building’s first floor is approximately 4 feet above grade on the south, east, and north. The 

basement is near grade on the west. An underground inmate tunnel connects the Harris County Jail 

to other correctional facilities and government buildings to the southeast.

HARRIS COUNTY JAIL

FIRM = Zone AE

BFE = 34 feet

(see Figure 3-26)

3-30 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-25: 

Harris County Jail as viewed 

from the Main Street Bridge

Commerce Street

San Jacinto Street

Main Street

S

C

eet HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-31

FLOOD-RELATED OBSERVATIONS

Figure 3-26: 

FIRM for Harris County Jail in 

the City of Houston
Dry Floodproofing Mitigation Measures 

At the time of the MAT, the Harris County Jail did not have any dry floodproofing mitigation 

measures to provide protection from flooding. The first floor elevation is above the mapped 

0.2-percent-annual-chance flood elevation. Given the nature of the building’s function, there are 

few openings in the building (though the basement level has utility penetrations and a connection 

to the inmate transfer tunnel). 

Performance during Harvey

Hurricane Harvey’s extreme rainfall caused both the Buffalo and White Oak Bayous to overtop 

their banks. Water from the White Oak Bayou flowed around the north and east sides of the 

building, effectively creating an island of the jail. Data from the Milam Street Bridge stream gage 

approximately 900 feet upstream indicate flood levels reached 37.8 feet during Harvey (see Table 

3-8). At the jail, staff reported water was 2 feet deep on N. San Jacinto Street (see Figure 3-27), 

which is nearly 18 feet above the elevation of the basement floor. To the west (see Figure 3-28), water 

levels in the bayou were reported to be 6 feet lower, or approximately 12 feet above the basement 

floor. The jail was not evacuated before the storm.

Figure 3-27: 

View of east wall of jail along 

N. San Jacinto Street where 

water levels reached the top 

of the concrete wainscot (red 

line)

3-32 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-28: 

View of west side of the jail 

along White Oak Bayou

Basement. Staff reported that the building experienced “excessive seepage.” Water was described 

as flowing in sheets down the basement walls and flowing through the joint between the basement 

walls and the basement floor. Water entry was described as being dispersed throughout, but 

there were several areas where water entry was concentrated and flowed freely into the basement, 

particularly where utilities penetrated the basement walls. One area of concentrated floodwater 

entry was where electrical conduits containing communication cabling penetrated the east wall of 

the basement (see Figure 3-29 and Figure 3-30); the communication conduits originate in a belowgrade communications vault on N. San Jacinto Street. Concentrated floodwater flow also entered 

where water service piping and gas piping enter the basement. Water stains and corrosion patterns 

suggest that water flowed around water and gas piping but through electrical conduits.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-33

FLOOD-RELATED OBSERVATIONS

Figure 3-29: 

Location of below-grade 

communication vault (red 

circle) on N. San Jacinto 

Street
Figure 3-30: Concentrated floodwater entry points

The water from seepage and the utility penetrations collected in the lowest areas of the basement, 

reaching a depth of up to 8 inches in places. This depth of floodwater was within inches of 

overtopping the base of critical equipment, including the electrical service switchboard (see Figure 

3-31), which was elevated slightly on a short concrete service slab, and the Houston Lighting and 

Power (now Reliant) electrical vault.

Figure 3-31: 

Maximum water depth at the 

electrical service equipment

3-34 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Water did not flow freely into openings in the building’s exterior, but floodwater appeared to 

have risen within inches of a ventilation grate in an alley along the north side of the building (see 

Figure 3-32) that provides combustion air and ventilation for the building’s emergency generator. 

Rainwater falling though this grill collected in the vaults and seeped into the standby generator 

room located in the basement, but did not reach the generator itself.
Figure 3-32: 

At-grade ventilation grill on 

north side of the building 

that was not inundated

Inmate transfer tunnel. Floodwater also entered the building’s perimeter through an inmate 

transfer tunnel (see Figure 3-33). At its highest level, floodwater depths where the tunnel enters the 

jail exceeded 5 feet and nearly filled the tunnel. When water levels rose in the inmate transfer tunnel 

and began to flow into the building, staff placed heavy furniture next to the door in an attempt to 

resist flood loads. However, the barricades were insufficient, and the door failed during the flood. 

Fortunately, the point where the tunnel connects to the jail is below the basement, so large volumes 

of floodwater did not flow into the basement itself. 

Staff installed temporary sump pumps and attempted to remove floodwater that entered the 

building. They reported that efforts were hampered because no low areas or sump pits existed where 

pumps could be placed to more effectively remove floodwater.

Figure 3-33: 

Inmate transfer tunnel door

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-35

FLOOD-RELATED OBSERVATIONS
Effect on operations. During Hurricane Harvey, the basement spaces (containing the medical 

facilities, print shop, and electrical rooms) were not occupied. The use of flood damage-resistant 

materials in the basement allowed normal function to resume after the floodwater receded and the 

water in the basement was removed. 

Summary of MAT Observations

+ The Harris County Jail is located in Zone AE, adjacent to the floodway, and has a BFE of 34 

feet. Buildings located in Zone AE should follow the flood provisions of model codes and 

standards such as the IBC and ASCE 24.

+ The below-grade portions of the building were not substantially impermeable and allowed 

floodwater to enter the building in areas where floodwater rose above the basement floor.

+ Water entered the basement through joints between construction materials, such as between 

basement walls and footings and basement walls and upper floors. Construction drawings 

were not available to confirm this, but the MAT suspects that construction details such as 

waterstops to limit migration of fluids across construction joints were not used.

+ The amount of floodwater that entered along any given length of construction joint was likely 

limited, and per-foot flowrates were likely modest; however, the total length of construction 

joints in the building that were exposed to floodwater allowed enough water to enter the 

building to disrupt operations and threaten critical equipment. 

+ Water entered the basement around or through utility penetrations. The number of water 

entry points was relatively low, but flowrates in those that existed were relatively high.

+ There were no sump pits located in the lowest portion of the basement where floodwater flow 

could be concentrated, resulting in a large amount of floodwater accumulating within the 

building basement before it could be removed. 

+ Even though floodwater entered the building, the use of flood damage-resistant materials in 

the basement limited the disruption to operations after floodwater receded. 

3.2.2.2 Harris County Criminal Justice Center – 1201 Franklin Street, Houston, TX

Constructed in 1999, the Harris County Criminal Justice 

Center is a 20-story building, with an additional basement 

level, located northeast of the intersection of Franklin 

Street and San Jacinto Street about a block and a half 

south of Buffalo Bayou. The main entrance to the building 

is on Franklin Street (south side of building), and smaller 

public entrances are on San Jacinto Street (west side) and 

Caroline Street (east side). Service entrances are along San 

Jacinto Street and Commerce Street (north side) and the former Harris County Jail is to the east. 

The building is in Shaded Zone X outside of the SFHA but exposed to the 0.2-percent-annualchance flood (see Figure 3-34). Figure 3-35 shows the Criminal Justice Center as viewed from the 

intersection of Franklin Street and San Jacinto Street. 

HARRIS COUNTY CRIMINAL 

JUSTICE CENTER

FIRM = Shaded Zone X

(see Figure 3-34)

3-36 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Commerce Street

Franklin Street

Congress Avenue

San Jacinto Street 

Caroline Street 

eet 

aroline S aroline S

eet

S

Car

Figure 3-34: FIRM for Harris County buildings on south side of Buffalo Bayou in the City of Houston

Figure 3-35: 

Harris County Criminal 

Justice Center viewed from 

the southwest

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-37

FLOOD-RELATED OBSERVATIONS
The first floor of the building is approximately 2 feet above street level along Franklin Street and is 

slightly higher above street level on the west and north. The building is constructed over a basement 

that extends one level below the first floor, with the south wall of the basement extending beyond 

the footprint of the first floor. 

Between 2009 and 2012, an underground pedestrian tunnel was constructed that connects the 

Harris County Criminal Justice Center to the Jury Assembly Building, the Harris County Civil 

Courthouse, and the Harris County Juvenile Justice Center, all located to the south. As part of the 

construction of the pedestrian tunnel, submarine doors were installed where the tunnel ties into 

the basement of the Harris County Criminal Justice Center, to the Jury Assembly Building, and the 

Harris County Civil Courthouse.

Dry Floodproofing Mitigation Measures

Shortly after Harris County Criminal Justice Center’s dedication 

in 1999, Tropical Storm Allison (June 2001) struck. Floodwater 

from Tropical Storm Allison entered the building and destroyed 

critical equipment, much of it located in the basement level. 

Damage was extensive, exceeding $11.1 million, and repairs 

reportedly took nearly a year to complete. A design flood 

elevation (DFE) was established at an elevation 39 feet, 3 

feet above the reported Tropical Storm Allison HWM. The 

mitigation involved adding 13 flood shields, each 3.5 feet tall, 

at all first-floor openings around the building; elevating critical 

equipment, such as the main electrical service equipment, several feet above the basement floor; 

and installing a backflow prevention valve in the main sanitary sewer lateral. The entrance to the 

underground parking area at the southeast corner of the building was elevated and fitted with an 

automatic floodgate at the top of the ramp (see Figure 3-36). If floodwater reaches the gate, buoyant 

forces of the water raise the gate into position.

FEMA MITIGATION 

FUNDING

Approximately $3.1 million 

in FEMA Public Assistance 

Program mitigation funding 

was used for the repairs.

Figure 3-36: 

Flood shield that 

automatically deploys as 

waters rise at ramp to 

underground parking garage

3-38 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
The building has a sanitary sewer lift system that serves plumbing fixtures in the basement. Those 

fixtures are below the elevation of the sewer line lateral, which exits the building near the basement 

ceiling. Sewage from the basement fixtures is collected in a sanitary sewer sump, which contains two 

lift pumps that discharge into the sanitary sewer lateral. Both pumps are equipped with check valves 

that prevent sewage from flowing back into the sump (see Figure 3-37). 

Figure 3-37: 

Check-valve in sanitary 

sewer lateral

The building has a separate system to collect and discharge groundwater and stormwater from 

underground portions of the building. Water from drains in the basement floor and in the 

underground parking garage collects in the stormwater sump. Like the sanitary sewer lift pumps 

that serve the basement plumbing fixtures, the stormwater sump has two pumps that discharge into 

the municipal stormwater sewer lateral.

Performance during Harvey

In preparation for Hurricane Harvey, staff deployed all of the flood shields and closed the 

submarine doors to the pedestrian tunnel with emergency staff remaining in the building during 

the hurricane. 

Water from the Buffalo Bayou overtopped its banks, spilling into the streets of Downtown Houston. 

Because of the slight hills in the area around the Harris County buildings, floodwater depths in 

the street ranged from no floodwater accumulation in the street at the intersection of Franklin 

Street and Austin Street to the east of the Criminal Justice Center to approximately 4 feet at the 

intersections of Franklin Street with San Jacinto Street, Commerce Street, and Caroline Street, to 

the north, west, and south of the Criminal Justice Center. 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-39

FLOOD-RELATED OBSERVATIONS
Flood shields. The flood shields functioned as intended and prevented water from entering 

the building where they were installed. Flood shields along Franklin Street were exposed to 

approximately 2.5 feet of flooding (see Figure 3-38), leaving approximately 1 foot of freeboard 

for the shield. Shields along San Jacinto and Commerce Streets were exposed to slightly deeper 

floodwater.

Figure 3-38: 

View of the Criminal Justice 

Center from the southeast 

with approximate depth of 

flooding indicated by dotted 

red line

Pedestrian tunnel. The pedestrian tunnel network connecting the Harris County Criminal Justice 

Center with the Jury Assembly Building, Harris County Civil Courthouse, and the Harris County 

Juvenile Justice Center was fully inundated with floodwater.

Basement. Emergency staff reported that floodwater entered the basement around the submarine 

door that separates the pedestrian tunnel from the Criminal Justice Center. Videos taken during 

the flood show that water entered around the frame of the submarine door, not past the pneumatic 

seals. Water flow was concentrated around the bolt penetrations that secure the door frame to the 

adjacent wall (see Figure 3-39). The video shows that leakage was significantly more intense near 

the bottom of the door, where hydrostatic pressures would be greatest.

3-40 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-41

FLOOD-RELATED OBSERVATIONS

Figure 3-39: 

Floodwater seepage at 

submarine door

Staff also reported that water entered where the south wall of the basement meets the basement 

ceiling. They described water as flowing freely down that wall. That portion of the basement extends 

beyond the footprint of the first floor, so floodwater along Franklin Street rushed over the basement 

ceiling in that area. Although construction drawings were not available, the MAT suspects that 

construction details such as waterstops to limit migration of fluids across construction joints were 

not used. Not using such waterstops is common for buildings not designed to retain fluids. Because 

much of the flood mitigation was completed for the building after original construction, installing 

features to reduce the permeability of the basement would be difficult.

Water depths in the basement reached 12 inches. Floodwater did not reach the critical equipment 

that had been elevated after Tropical Storm Allison (see Figure 3-40) but did cause widespread 

damage to the lower portions of interior partitions and finishes. Most of the areas exposed to 

floodwater were not constructed with flood damage-resistant materials. 
Figure 3-40: 

Floodwater did not reach 

critical equipment that 

was elevated after Tropical 

Storm Allison

3-42 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

However, floodwater did reach electronic equipment that controls the domestic water booster 

pumps and caused the booster pumps to over-pressurize the domestic water system. As a result, 

pneumatically controlled domestic water valves failed on the 17th floor.

First floor. Sewage flowed out of plumbing fixtures on the first floor. In some portions of the first 

floor, flood depths of approximately 1 inch were reported. Much of the first floor was contaminated 

by effluent, necessitating the removal of the lower portions of drywall to allow the area to be cleaned 

and disinfected (see Figure 3-41).

Effect on operations. During the MAT visit 21⁄2 months after Harvey made landfall, the facility was 

still undergoing repairs and will remain unoccupied until repairs are complete. Prior to the MAT’s 

site visit, the booster pump controls had been elevated. Wall finishes on both the first floor and 

basement had been removed and had yet to be replaced.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-43

FLOOD-RELATED OBSERVATIONS

Figure 3-41: 

Wall finishes were removed 

from the first floor as a 

result of sewage leakage

Summary of MAT Observations 

+ The Harris County Criminal Justice Center is located in Shaded Zone X, outside of the 

SFHA, and is thereby exempt from the flood provisions of model codes and standards such as 

the IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding.

+ The mitigation actions taken after Tropical Storm Allison, dry floodproofing 3 feet above the 

Tropical Storm Allison HWM to elevate to 39 feet, were effective at reducing flood damage. 

Since readings from the local stream gage suggest that flood levels during Hurricane Harvey 

were nearly 2 feet higher than during Tropical Storm Allison, the damage would likely have 

been more extensive if mitigation actions had not been completed. 

+ The primary area of water entry appeared to have been limited to (or at least concentrated 

in) an area where the basement extends beyond the footprint of the first floor. In that area, 

the ceiling of the basement and the top of the basement wall were exposed to floodwater. 

+ During Hurricane Harvey, the network of pedestrian tunnels connecting the Criminal Justice 

Center to the Jury Assembly Building and other Harris County-operated buildings in the 

area was fully inundated with water (refer also to Section 3.2.1.3). A submarine door located 

between the basement of the Criminal Justice Center and the pedestrian tunnel leaked at 

many of the bolted connections securing the door to a concrete masonry unit (CMU) wall.

+ Significant flood damage resulted from the inability of the building’s drain waste and vent 

system to function during Hurricane Harvey. As a result, much of the damage to the building 

was caused by internal sources, not floodwater or effluent that originated outside of the 

building. MAT observations suggest that flooding caused sewage levels in the municipal 

system to rise to a level that prevented effluent from being discharged from the building. The 
building was occupied, and effluent was likely being generated. Without the ability to drain, 

effluent rose in the drain waste and vent piping until it reached the level of the first floor 

plumbing fixtures. At that point, effluent flowed out of those fixtures and contaminated the 

building interior. The backflow valve installed on the sewer line after Tropical Storm Allison 

likely prevented municipal system sewage from back-flowing into the building but could not 

prevent effluent generated within the building from overflowing out of the lowest gravity-fed 

fixtures. Plumbing fixtures in the basement are several feet below those on the first floor, but 

they do not rely on gravity to discharge effluent and are isolated from the gravity-fed portions 

of the system by the check valves on the discharge piping of the sewer lift pumps.

+ Approximately 12 inches of water accumulated in the basement. The MAT was not able 

to determine how long the floodwater was present in the basement, but if design flood 

conditions persisted for at least 3 days, the seepage the building experienced would meet 

ASCE 24 criteria for requiring a structure to be substantially impermeable (which limits 

seepage to 4 inches during a 24-hour period). Because the basement was not equipped with 

sump pumps to remove the seepage that occurred, the requirements of ASCE 24 were not met 

to consider this building substantially impermeable. 

+ The portions of the building interior exposed to floodwater were not constructed with flood 

damage-resistant materials, and damaged materials had to be removed and replaced. Damage 

prevented the building from being functional for several months.

3.2.2.3 Jury Assembly Building – 1201 Congress Street, Houston, TX

The Jury Assembly Building is a one-story building, with 

an additional basement level, constructed between 2009 

and 2012 (see Figure 3-42). It is situated on a small hill due 

south of the Criminal Justice Center and due west of the Civil 

Courthouse, and lies approximately 700 feet south of Buffalo 

Bayou (see Figure 3-24 for placement relative to other Harris 

County buildings). The Jury Assembly Building has one 

5,000-square-foot floor above grade and one 30,000-square-foot floor below grade. The below-grade 

portion of the building contains four large auditoriums for potential jurors. The building is in 

Shaded Zone X outside of the SFHA but exposed to the 0.2-percent-annual-chance flood.

The upper floor of the Jury Assembly Building is approximately 13 feet above the first floor of the 

Criminal Justice Center (refer to Section 3.2.1.2). 

The building is connected to an underground pedestrian tunnel that provides access to the Criminal 

Justice Center to the north, the Civil Justice Center to the east, and the Juvenile Justice Center to 

the south. It is also connected to an underground utility tunnel that contains steam, condensate, 

and supply and return chilled water lines that originate in a central plant one block to the south. 

The central plant provides heating and air conditioning to several judicial buildings in the area, 

including the Harris County Jail, Harris County Criminal Justice Center, Jury Assembly Building, 

and Harris County Civil Courthouse. 

The basement walls of the Jury Assembly Building are reinforced concrete. They encompass the 

entire underground portion of the building, including a utility vault. The underground electrical 

utility vault is located at the southeast corner of the building. The vault was installed and operated 

by Houston Lighting and Power (now called Reliant). The vault can be accessed from within the 

JURY ASSEMBLY BUILDING

FIRM = Shaded Zone X

(see Figure 3-34)

3-44 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-42: 

Jury Assembly Building 

viewed from the south

Jury Assembly Building (see Figure 3-43) and from 

an at-grade access cover above the vault. Because 

of its proximity to the Jury Assembly Building, the 

MAT assumes the electrical utility vault contains 

transformers that supply the building. Based on its 

size as indicated on the architectural drawings, it 

may also contain electrical distribution equipment 

that supplies the area. The electrical utility vault 

is separated from the Jury Assembly Building 

auditorium by fire-rated masonry walls. The 

basement walls contain an access door to the 

electrical utility vault, which is not designed to 

resist floodwater (see Figure 3-43).

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-45

FLOOD-RELATED OBSERVATIONS

Figure 3-43: 

Door to the electrical 

utility vault, which is 

not designed to prevent 

floodwater entry
Dry Floodproofing Mitigation Measures

Two submarine doors isolate the underground portion of the Jury Assembly Building from the 

underground pedestrian tunnel (see Figure 3-44). A third submarine door separates the Jury 

Assembly Building from the underground utility tunnel. Like the submarine doors in the Criminal 

Justice Center, each door is equipped with two seals, valves to inflate them, and gauges that indicate 

the air pressure within the seals.

The building is equipped with two sanitary sewer lift pumps that collect effluent from basement 

plumbing fixtures and pump it to the municipal sewer system. Each pump is equipped with a check 

valve on its discharge line to prevent backflow. 

The building has a separate system to collect and discharge groundwater and stormwater. Water 

from drains in the basement floor and the surface drain that collects roof runoff accumulates in 

the stormwater sump. Like the sanitary sewer lift pumps, the stormwater sump has two pumps that 

discharge into the municipal storm sewer. The stormwater collection system has an electrically 

operated valve placed in the line that collects roof runoff. The pump controls automatically close the 

valve if water levels in the stormwater sump exceed a preset level. These controls prevent stormwater 

inflow from exceeding the capacity of the discharge pumps. 

Both the sanitary sewer pumps and the stormwater pumps are powered from an automatic standby 

generator. The generator is located on a mezzanine above the ground level floor, above the elevation 

for a 1-percent-annual-chance flood event.

3-46 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-44: 

Submarine door separating 

the Jury Assembly Building 

from the underground 

pedestrian tunnel
Performance during Harvey

Staff reported that prior to floodwater levels rising, the three submarine doors connected to the 

underground tunnels were closed with pairs of inflated pneumatic seals. On one of the doors, one 

of the seals failed to maintain air pressure, but the other seal maintained pressure and was able to 

form a watertight seal.

In the areas around the Jury Assembly Building, HWMs were several feet below the first floor 

elevation. Additionally, floodwater approached, but did not reach, the at-grade access cover of the 

utility vault. 

Pedestrian tunnels. The pedestrian tunnel network connecting the Jury Assembly Building with 

the Harris County Criminal Justice Center, Harris County Civil Courthouse, and the Harris County 

Juvenile Justice Center was fully inundated by floodwater. 

Basement. Floodwater reached a depth of nearly 8 feet in the basement, nearly submerging that 

level of the building. Floodwater did not reach the ceiling of the basement, but nearly all interior 

finishes, wiring, and equipment, was submerged. Cleaning and decontamination were ongoing 

during the MAT site visit. The basement was flooded even though floodwater did not rise to the 

elevation of the entrances to the Jury Assembly Building; the MAT was not able to identify the 

source of the basement flooding. 

Effect on operations. During the MAT visit 2.5 months after Harvey made landfall, the facility was 

still undergoing repairs and will remain unoccupied until repairs are complete. 

Summary of MAT Observations

+ The Harris County Jury Assembly Building is located in Shaded Zone X, outside of the SFHA, 

and is thereby exempt from the flood provisions of model codes and standards such as the 

IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding.

+ The damage to the interior was to materials that were not flood damage-resistant. 

+ The building experienced a failure of measures designed to prevent floodwater entry. The 

MAT could not definitively determine how floodwater entered the building. Since stream 

gage data suggest that Hurricane Harvey caused flooding in the area that far exceeded design 

conditions, even properly designed flood control systems could have been overwhelmed. 

During the MAT site visit, the submarine doors were intact and there was no indication 

of structural failures in the basement walls, ceilings, floors, or other portions of the flood 

protection boundary. At the time of the site visit, the MAT verified that the check valves on 

the stormwater pumps were functioning even though the controls for the pumps had been 

destroyed by floodwater. There was no indication that floodwater entered the basement 

from above or reached the first floor of the building. No ceiling tiles were damaged in the 

basement, suggesting that water entered from the floor. Security video from inside the 

building shows water slowly rising but does not show the source of flooding, so the exact 

failure mode could not be determined. 

+ The MAT observed a floor drain in the electric utility vault that may have been a possible 

floodwater entry point. The floor drain in the electrical utility vault connects to the floor 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-47

FLOOD-RELATED OBSERVATIONS
drains in the pedestrian tunnel that runs under Franklin Street on the opposite side of 

the submarine door. When the pedestrian tunnel became fully inundated with floodwater, 

water could have backflowed through the floor drain into the electrical utility vault. The 

electric utility vault is within the flood protection boundary, and any drain not isolated by 

a check valve or other means to prevent storm water from backflowing through the drain is 

a potential point of floodwater entry. Staff reported that after floodwater receded and the 

building could be entered, they found the door to the electrical utility vault open. 

Investigation of this door by the MAT indicated that the door deformed, bowing slightly 

outward toward the interior of the Jury Assembly Building. The depth of flooding within 

the basement level of the building closely correlates with the observed HWMs on Franklin 

Street between the Criminal Justice Center and the Jury Assembly Building, suggesting that 

floodwater flowing into the basement of the Jury Assembly Building was able to equalize with 

floodwater near the building.

3.2.2.4 Harris County Civil Courthouse – 

201 Caroline Street, Houston, TX 

Constructed between 2003 and 2005 and dedicated in 2006, the 

Harris County Civil Courthouse is an 18-story building, with 

an additional basement level, located east of the intersection of 

Congress Street and Caroline Street, one block southeast of the 

Jury Assembly Building (see Figure 3-24 

for placement relative to other Harris 

County buildings). The main entrance 

to the building is on Caroline Street and 

is approximately 8 feet above the street 

level. The building is constructed over a 

basement that extends one level below the 

first floor. The building is approximately 

650 feet south of Buffalo Bayou and is 

situated in the Shaded Zone X, outside of 

the SFHA, but exposed to the 0.2-percentannual-chance flood. Figure 3-45 shows 

the Civil Courthouse when viewed from 

the southwest.

HARRIS COUNTY 

CIVIL COURTHOUSE

FIRM = Shaded Zone X

(see Figure 3-34)

3-48 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-45: 

Harris County Civil Courthouse 

viewed from the southwest
Figure 3-46: 

Submarine door that 

separates the Civil 

Courthouse basement from 

the underground pedestrian 

tunnel

Like several other judicial buildings in the area, the Civil Courthouse connects to an underground 

pedestrian tunnel that provides access to the Jury Assembly Building, the Criminal Justice Center, 

and the Juvenile Justice Center. The elevation of the pedestrian tunnel is approximately 6 feet below 

the basement floor level of the Civil Courthouse; a corridor with a ramp extends from the basement 

level of the building to the pedestrian tunnel. 

Dry Floodproofing Mitigation Measures 

Because the Civil Courthouse was constructed after Tropical Storm Allison, the building contains 

several design features that reduce its vulnerability to floods. These include:

+ Submarine door. A submarine door isolates the pedestrian tunnel from the corridor that 

extends from the basement of the Civil Courthouse (see Figure 3-46). 

+ Floodgate. An automatic floodgate (see Figure 3-47) at the top of the vehicle access ramp to 

protect an underground garage that is on the same level as the basement. 

+ Elevation. Electrical and heating, ventilation, and air conditioning (HVAC) equipment is 

elevated to keep it away from floodwater:

– The electrical service equipment is located on the first floor. It is placed on concrete slabs

that elevate it nearly 18 inches above the first floor level.

– Electrical equipment is “top fed,” meaning conduits and bus ducts enter and exit the top

of the electrical service and distribution equipment rather than extending below the

electrical equipment where flood risks are greater.

– Standby power for the facility, the two pad-mounted transformers that supply power to the

building, and the utility company’s distribution equipment are elevated several feet above

street level.

– Much of the central HVAC equipment is elevated above flood levels because it is located on

the building’s penthouse level.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-49

FLOOD-RELATED OBSERVATIONS
Figure 3-47: 

Automatic floodgate at ramp 

to basement parking garage

Performance during Harvey

Floodwater from Hurricane Harvey surrounded the Civil Courthouse, but was approximately 8 feet 

below the elevation of the first floor (see Figure 3-48). Floodwater did not reach the automatic 

floodgate at the ramp for the parking garage below the building and the gate did not deploy. 

Pedestrian tunnel. The pedestrian tunnel 

network connecting the Harris County 

Criminal Justice Center with the Jury Assembly 

Building, Harris County Civil Courthouse, and 

the Harris County Juvenile Justice Center was 

fully inundated with floodwater. Floodwater 

from the pedestrian tunnel entered the 

corridor that extends from basement to the 

pedestrian tunnel. The submarine door 

separating the building from the tunnel was 

submerged; flood depths in the corridor at the 

submarine door approached 8 feet, reaching 

a depth that allowed floodwater to overcome 

the ramp and spill into the basement of 

the courthouse (see Figure 3-49). Building 

engineers identified the unsealed conduit and 

utility penetrations in the flood barrier wall 

3-50 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-48: 

Flood level at the Civil 

Courthouse during Hurricane 

Harvey (red dotted line)
Figure 3-49: 

Civil Courthouse corridor

that separates the basement corridor from the utility tunnel as likely floodwater entry points (see 

Figure 3-50). The penetrations were sealed after the flooding, prior to the MAT visit. Insufficient 

information exists to confirm that unsealed penetrations were the only sources of floodwater entry, 

but they did at least contribute to floodwater entry and resulting damage.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-51

FLOOD-RELATED OBSERVATIONS
Figure 3-50: 

Floodwater entry through unsealed penetrations 

PHOTOGRAPH ON THE RIGHT COURTESY OF FACILITIES AND PROPERTY MAINTENANCE, HARRIS COUNTY ENGINEERING DEPARTMENT.

3-52 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Basement. Within the courthouse basement, water levels reached approximately 4 inches deep. 

Floodwater completely filled the elevator pits, which extend below the level of the basement. The 

pits remained full until staff could return to pump out the water. Floodwater damaged interior 

finishes in the basement, but during the MAT’s site visit, repairs were nearly completed. 

Effect on operations. Flood damage limited building function for several weeks after the event 

while repairs were completed.
Summary of MAT Observations

+ The Harris County Civil Courthouse is located in Shaded Zone X, outside of the SFHA, 

and is thereby exempt from the flood provisions of model codes and standards such as the 

IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding.

+ Flood damage from Hurricane Harvey was relatively limited and generally involved noncritical components such as interior finishes. The damage to the interior was to materials that 

were not flood damage-resistant. 

+ The flooding in the building resulted, in part, from a failure to maintain the integrity of 

the flood barrier. While most penetrations that the MAT observed in the flood barrier had 

been sealed and were apparently effective at preventing or limiting floodwater entry, other 

penetrations were not sealed and allowed floodwater to enter the building. 

3.2.3 City of Houston Public Works Building - 611 Walker Street, Houston, TX

Constructed in 1968, the City of Houston Public Works 

Building is a 27-story office building, with two below-grade 

levels, located in Downtown Houston and east of Buffalo 

Bayou. The main entrance is located on the south side of the 

building along Walker Street (see Figure 3-51). 

PUBLIC WORKS BUILDING

FIRM = Unshaded Zone X

(see Figure 3-52)

Figure 3-51: 

City of Houston Public Works 

Building; red outline denotes 

an open-air courtyard on the 

south side of the building

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-53

FLOOD-RELATED OBSERVATIONS
The deepest below-grade level contains the MEP systems for the building. The first below-grade 

level, one level below street level, contains an open-air courtyard on the south side of the building 

and the access from the Downtown Houston tunnel network that connects most of the buildings 

in Downtown Houston to one another (see red outline on Figure 3-51). The Downtown Houston 

tunnel network at the public works building is located on the south side of the building running in 

a west-to-east direction. The west side of the tunnel connects to the Tranquility Park Parking Garage 

and the rest of the Downtown Houston tunnel network. The Public Works Building is located in 

Unshaded Zone X, approximately 600 feet from the nearest regulated floodplain (see Figure 3-52).

During Tropical Storm Allison in 2001, the Public Works Building flooded (as with many others 

in Downtown Houston) when the Tranquility Park Parking Garage became inundated and water 

flowed into the connecting Downtown Houston tunnel network (see Figure 3-53).

Figure 3-52: 

FIRM for the City of Houston 

Public Works Building

3-54 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-53: Tranquility Park Parking Garage and tunnel network (left); partial-height flood door installed in the tunnel 

network (right)

MAP SOURCE: HOUSTON FIRST, USED AND MODIFIED WITH PERMISSION

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-55

FLOOD-RELATED OBSERVATIONS
Dry Floodproofing Mitigation Measures

In response to Tropical Storm Allison in 2001, a partial-height flood door was installed in the tunnel 

network on the east side of Tranquility Park Parking Garage, approximately 50 feet away from the 

basement entrance to the Public Works Building (see Figure 3-53). The MAT did not observe any 

redundant flood barriers in the tunnel network beyond this barrier. 

Performance during Harvey

During Hurricane Harvey, this area of Downtown Houston received approximately 30 to 35 inches 

of rain, but floodwater from Buffalo Bayou did not extend far enough from its banks to reach the 

Public Works Building. 

Basement. The rain stripped a considerable amount of leaves from the trees and plants in the openair courtyard. The fallen vegetation, mixed with trash that was blown into the courtyard, clogged 

the floor drains in the courtyard, which then caused stormwater to flow into the lower of the two 

levels of the Public Works Building, damaging interior finishes.

Tranquility Park Parking Garage. The Tranquility Park Parking Garage was completely inundated 

as a result of numerous breaches in the flood barriers from the Theater District and connected 

parking garages (refer also to Section 3.2.3). The partial-height flood door shown in Figure 3-53 is 

74 inches tall; the water reached a maximum height of 70.75 inches, nearly overtopping it.

Effect on operations. Because of stormwater flooding, both basement levels of office space lost their 

useful function for several months while damage to interior finishes were repaired. 

Summary of MAT Observations 

+ The Public Works Building is located in Unshaded Zone X, outside of the SFHA, and is 

thereby exempt from the flood provisions of model codes and standards such as the IBC and 

ASCE 24. Although not required, flood-resistant features are recommended as a best practice 

even for buildings located outside the SFHA, especially those with a history of flooding. 

+ Although the Public Works Building was spared catastrophic losses by the successful 

performance of the partial-height flood door located at the entrance to the Tranquility 

Park Parking Garage, as with many other buildings in Downtown Houston, no additional 

protection measures were in place to prevent the full inundation of the tunnel network and 

connecting basements if the water had reached its full 74-inch height. If this partial-height 

flood barrier had been overtopped, the damage that occurred in 2001 from Tropical Storm 

Allison would have recurred, flooding a large portion of the pedestrian tunnel network, the 

basement of the Public Works Building, as well as the basements of numerous other buildings. 

3.2.4 Theater District and Underground 

Parking and Tunnel Complex

The Theater District is located along the east bank of Buffalo Bayou 

in Downtown Houston. The Theater District includes the Alley 

Theater, Jones Hall, Hobby Center for the Performing Arts, Houston 

Ballet, Bayou Place, Wortham Theater and underground parking 

garages. Because of the recovery efforts being conducted at the time 

THEATER DISTRICT

FIRM = Zone AE

BFE = 36 to 37 feet

(see Figure 3-54)

3-56 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
of the MAT deployment, the MAT was only able to assess the performance of dry floodproofing 

components at the Wortham Theater, Green Parking Garage, Little Tranquility Park Parking 

Garage, and Tranquility Park Parking Garage. 

The Theater District has buildings that are located in the regulatory floodway, Zone AE, Shaded 

Zone X, and Unshaded Zone X. The Wortham Theater is located in Zone AE, with a BFE of 37 feet. 

Figure 3-54 shows the FIRM for the Theater District area and the approximate locations of the flood 

breaches discussed in this report (each breach is numbered uniquely for discussion purposes). 

The Theater District buildings are connected to a network of below-grade parking garages that are 

connected to one another via a pedestrian tunnel network. The pedestrian tunnel network also 

ties into the Downtown Houston tunnel network via a tunnel extending from the east end of the 

Tranquility Park Parking Garage and the south end of the Civic Center Parking Garage adjacent 

to Jones Hall. As shown on Figure 3-54, the Wortham Theater is located on the north side of the 

Rusk Street

Capitol Street

Texas Avenue

Louisiana Street

Prairie Street

Milam Street

§ ̈¦45

P

Figure 3-54: FIRM for the Theater District; approximate locations of flood breaches are shown (uniquely numbered from 

1 to 9)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-57

FLOOD-RELATED OBSERVATIONS
Theater District and the Alley Theater and Jones Hall are located to the south and east of the 

Wortham Theater.

The Wortham Theater, located at 501 Texas Avenue, is a 437,500-square-foot facility that was 

constructed in 1987. It has an extensive basement level that contains rehearsal areas, costume storage, 

facilities to construct stages and sets, and dressing rooms. The at-grade and above-grade portions 

of the theater contain the stage, seating, and means to enter the theater, as well as other amenities 

such as restrooms and concessions. Extending south from the Wortham Theater and connected via 

a pedestrian tunnel is the Civic Center (also known as the Green Parking Garage), which is located 

beneath the Bayou Palace Complex. Further south are the Little Tranquility Park Parking Garage 

and the Tranquility Park Parking Garage. From the Tranquility Park Parking Garage, pedestrian 

tunnels extend to Houston City Hall, the City Hall Annex, and 611 Walker Building which includes 

the City of Houston Public Works Department. 

3.2.4.1 Dry Floodproofing Mitigation Measures 

During Tropical Storm Allison in 2001, the Theater District, 

including the Wortham Theater and the surrounding 

underground parking complex and pedestrian tunnels, was 

severely flooded. In response, numerous floodgates were 

installed at entrances to the Wortham Theater, street entrances 

for vehicles into the parking garages, at pedestrian entrances 

into the parking garages, and between different parking 

garage sections. Six submarine doors and 38 floodgates were 

installed in the Theater District to protect against future 

flooding (see Figure 3-55 for examples of floodgates installed 

at pedestrian and vehicle entry points to the below-grade 

parking garages). All of the gates installed are active systems, 

meaning they must be manually set in place prior to an event. 

3-58 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

FEMA MITIGATION 

FUNDING

Mitigation measures in the 

Theater District were installed 

using approximately $1.2 

million of funding provided 

under FEMA’s Public 

Assistance Program for 

hazard mitigation (e.g., 406 

Hazard Mitigation).

Figure 3-55: Examples of the floodgates installed to protect the Theater District and underground tunnels and parking 

garages
The elevation of the floodgates was reportedly selected to provide protection from a flood event 

that would cause flood levels 2 feet higher than those experienced during Tropical Storm Allison, or 

approximately 39.3 feet, but were not tied to a recurrence interval for Buffalo Bayou.

3.2.4.2 Performance during Harvey

Hurricane Harvey was the most severe event to impact the Theater District Complex in terms of 

HWM, exceeding the HWM of Tropical Storm Allison by approximately 2.0 feet. During Hurricane 

Harvey, the estimated HWM at the Wortham Theater was 39.63 feet based on a HWM surveyed 

along Preston Street. The FIS for the Prairie Street Bridge crossing of Buffalo Bayou indicates that 

the 0.2-percent-annual-chance flood elevation is 41.8 feet and the 1-percent-annual-chance flood 

elevation is 36.15 feet, making the severity of Hurricane Harvey an approximately 0.36-percentannual-chance probability event. 

During Hurricane Harvey, floodwater entered the Wortham Theater, Alley Theater, the basement 

of Jones Hall, and the Green, Little Tranquility Park, and Tranquility Park parking garages. In 

total, staff reported that approximately 270 million gallons of water was pumped out of the Theater 

District. 

Breaches in the Dry Floodproofing System

In preparation for Hurricane Harvey, the floodgates protecting the Theater District were deployed 

starting on Thursday, August 24 and completed on August 25. Eventually the water of Buffalo Bayou 

overtopped the majority of the floodgates installed to protect the Wortham Theater and entrances 

into the underground parking and tunnel complex. Prior to the overtopping of the floodgates, 

nine significant breaches occurred in the dry floodproofing system. Figure 3-56 shows a map of 

the underground portions of the Theater District and the approximate locations of the nine flood 

breaches.

Breach No. 1: Foundation Wall Infill Patch

Breach No. 1 is believed to be the first breach in the dry floodproofing system and was one of 

the largest in the Theater District, occurring in the foundation wall of the Green Parking Garage, 

beneath Bayou Place. The Green Parking Garage is an extensive three-level underground parking 

garage. During a past construction or capital improvement project, a large opening had been 

cut through the foundation wall of the garage to provide temporary access. After the project was 

completed, the 6-foot by 6-foot opening was infilled with metal stud framing and gypsum wall 

board, but not reconstructed with substantially impermeable material or with sufficient strength to 

reestablish the foundation wall load path. 

The foundation for Bayou Place consists of a deep foundation system using drilled concrete piers 

and grade beams. The floor system for Bayou Place consists of precast concrete that spans between 

the grade beams. The foundation system includes a cavity between the precast concrete floor and 

the soil within which plumbing and stormwater pipes are supported from the precast concrete using 

pipe hangers. 

The roof stormwater drain network collects water and conveys the stormwater to a system of interior 

stormwater drain lines that are suspended from the precast concrete floor system. These stormwater 

drain lines discharge into Buffalo Bayou. On the west side of Bayou Place, along the east bank of 

Buffalo Bayou, one of the roof stormwater drains had disconnected from the stormwater drain line 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-59

FLOOD-RELATED OBSERVATIONS
Figure 3-56: Underground components of the Theater District, parking garage network, and tunnels are shown in 

relationship to the approximate locations of the nine significant flood breaches that occurred

MAP SOURCE: HOUSTON FIRST, USED AND MODIFIED WITH PERMISSION

3-60 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

at the top of the bank of Buffalo Bayou; when this disconnection occurred is unknown. During 

Hurricane Harvey, the significant amount of stormwater flow eroded the bank of Buffalo Bayou 

at the location of the disconnected pipe, exposing the cavity beneath the floor slab. When the 

floodwater in Buffalo Bayou reached the level of the exposed cavity, floodwater filled the cavity and 

resulted in hydrostatic pressure against the patched 6-foot by 6-foot opening infilled with metal 

stud framing and gypsum wall board. The bottom of the 6-foot by 6-foot opening was at elevation 

26.50 feet, while the HWM of Buffalo Bayou was reported to reach 38.63 feet. Since the infill patch 

was not constructed from substantially impermeable material, nor did it have adequate structural 
capacity to re-establish the load path in the foundation wall, the infill patch in the foundation wall 

failed due to the hydrostatic forces, resulting in the complete inundation of the Green Parking 

Garage (see Figure 3-57).

Buffalo Bayou Buff

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-61

FLOOD-RELATED OBSERVATIONS

Figure 3-57: A disconnected pipe allowed stormwater to enter the cavity under the Green Parking Garage floor slab, 

resulting in the complete inundation of the garage
Breach No. 2: Submarine Door

Breach No. 2 occurred at the submarine door that isolates the Little Tranquility Park Parking 

Garage and Tranquility Park Parking Garage from the underground structures to the north. Both 

of these garages are three-level underground parking garages located beneath the parks bearing 

the same name. As the floodwater from Breach No. 1 filled the Green Parking Garage, it eventually 

reached the submarine door shown in Figure 3-58. 

The loading from the floodwater caused the submarine door to experience a structural failure in 

the midpoint of the steel face plate adjacent to a vertical stiffening rib, leaving half of the submarine 

door remaining intact in the door frame (see Figure 3-59 and Figure 3-60). The water elevation in 

Buffalo Bayou when the submarine door failed is not known. The failure of this submarine door 

resulted in the complete inundation of the Little Tranquility Park Parking Garage and Tranquility 

Park Parking Garage.

Figure 3-58: Submarine doors on the road that connects the Green Parking Garage to the Little Tranquility Park Parking 

Garage being deployed in preparation for Hurricane Harvey 

PHOTOGRAPH COURTESY OF CARLOS GUTIERREZ, CSF CONSULTING

3-62 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-59: Submarine door shown in Figure 3-58 after its failure

PHOTOGRAPHS COURTESY OF CARLOS GUTIERREZ, CSF CONSULTING

Floodwater inundating the Little Tranquility Park Parking Garage and Tranquility Park Parking 

Garage eventually reached the floodgate that protects the Downtown Houston tunnel network—

that floodgate did not fail and successfully prevented additional flooding in the tunnel network 

(refer to Section 3.2.3 and Figure 3-55 for more information).

Breach No.3: Glass Block Wall

Breach No. 3 occurred when the floodwater on the streets in the area continued to rise, eventually 

cresting a small hill that surrounds Little Tranquility Park. Inside Little Tranquility Park, a glass 

block wall had been installed to fill the gap between a concrete walkway and the bottom of the 

overpass for Rusk Street. When Little Tranquility Park began to fill with floodwater, the glass block 

wall was loaded by hydrostatic forces. With no structural capacity to resist hydrostatic forces, the 

wall collapsed, resulting in a second floodwater entry point into the underground parking garage 

network (see Figure 3-60). 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-63

FLOOD-RELATED OBSERVATIONS
3-64 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-60: Glass block wall that failed when exposed to floodwater pressures (left); floodwater entering through 

Breach No. 3 (right)

RIGHT PHOTOGRAPH COURTESY OF CARLOS GUTIERREZ, CSF CONSULTING

Even if the submarine door between the Green Parking Garage and Little Tranquility Park Parking 

Garage had remained intact (Breach No. 2), this breach of the glass block wall still would have 

resulted in the complete inundation of both the Little Tranquility Park Parking Garage and the 

Tranquility Park Parking Garage.

Breach No. 4 and 5: Tranquility Parking Garage Vehicle Ramp 3

Breaches No. 4 and No. 5 both occurred at vehicle ramp 3 to the Tranquility Park Parking Garage. 

Vehicle ramp 3 is protected from flooding with retaining walls, acting as floodwalls, on the east and 

west side with a floodgate across the top of the ramp to the south. 

West side of ramp. Breach No. 4 occurred on the west side of the vehicle ramp. This retaining 

wall abuts the wall and foundation for a stairwell and elevator shaft that provides access to Little 

Tranquility Park Parking Garage, but is not physically connected to the wall. Over time, the top of 

the retaining wall has deflected, opening a 2-inch-wide gap between the edge of the retaining wall 

and the foundation wall that allowed water to enter the parking garage (see Figure 3-61).

East side of ramp. Breach No. 5 occurred along the east side of the Tranquility Park Parking 

Garage vehicle ramp 3. Prior to Hurricane Harvey, a portion of the retaining wall and stairwell 

that led from a Federal Building to the Tranquility Park Parking Garage had been temporarily 

demolished to accommodate construction at the Federal Building. When Hurricane Harvey struck, 

the construction was not complete, and floodwater was able to enter the parking garage (see Figure 

3-62). At the time of the MAT site visit, the opening in the retaining wall had been repaired.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-65

FLOOD-RELATED OBSERVATIONS

Figure 3-61: Floodwater entry point at a gap in a retaining wall 

RIGHT PHOTOGRAPH COURTESY OF CARLOS GUTIERREZ, CSF CONSULTING
Figure 3-62: 

Floodwater entry point at 

demolished retaining wall 

section

PHOTOGRAPH COURTESY 

OF CARLOS GUTIERREZ, CSF 

CONSULTING

3-66 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Breach No. 6: Seepage through Wortham Theater Building Envelope

Breach No. 6 consists of numerous points of water seepage through the building envelope and 

through two floodgates on the west side of the Wortham Theater, along the bank of Buffalo Bayou. 

Seepage through foundation. Water reportedly entered though an unsealed joint between the top 

of the concrete foundation and the reinforced masonry wall with granite façade, shown in Figure 

3-63, and in locations where there was a separation between waterproofing and the foundation wall. 

The HWM of Buffalo Bayou was approximately 6 feet above this joint in the building envelope. 

Floodgates. On the west side of the Wortham Theater there are two emergency exits protected 

by sliding floodgates. The top of these floodgates, which have an elevation of 39.30 feet, were 

overtopped by floodwater when it reached its maximum elevation of 39.63 feet. However, even 

before the floodgates were overtopped, leaks in the seals of the floodgates, coupled with the lack of 

a seepage collection system, allowed water to infiltrate the building (see Figure 3-64).
Figure 3-63: 

Unsealed joint between the 

concrete foundation wall 

and reinforced masonry wall 

with granite façade where 

significant seepage into the 

Wortham Theater occurred

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-67

FLOOD-RELATED OBSERVATIONS

Figure 3-64: 

Floodgate protecting 

emergency exit along 

Buffalo Bayou

RIGHT PHOTOGRAPH COURTESY 

OF CARLOS GUTIERREZ, CSF 

CONSULTING
Breach No. 7 and 8: Seepage Though Glass Doors

Fish Plaza glass door entrance. Breach No. 7 occurred through the glass doors that make up 

the entryway to the Wortham Theater from Fish Plaza, located along Texas Street. Floodwater 

inundated Fish Plaza and seeped around the edges of the glass doors into the building. Once inside 

the building, the water began to flow down a stairwell to the basement and collected in the tunnel 

that connects the Wortham Theater to the Green Parking Garage. This tunnel has a submarine door 

(see Figure 3-65) that isolates the Wortham Theater from the Green Parking Garage, which was 

fully inundated with water from Breach No. 1. The tunnel inside the Wortham Theater eventually 

filled up to the tunnel ceiling and up to the first landing in the stairwell. The water that filled this 

tunnel section was the combination of the water that was able to seep around the glass doors and 

floodwater from the Green Parking Garage. This tunnel section contains a trench drain that was 

located behind a sheetrock wall, which connects to floor drains in the Green Parking Garage. When 

the Green Parking Garage became fully inundated, floodwater backflowed within this trench drain, 

bypassing the submarine door, and filled the tunnel.

Figure 3-65: 

Submarine door that isolates 

the Wortham Theater from 

the Green Parking Garage

Preston Street glass door entrance. Breach No. 8 occurred at a glass door entryway along Preston 

Street, on the north side of the Wortham Theater. Breach No. 8 highlights the difficulties associated 

with establishing and maintaining a continuous barrier to prevent the entry of floodwater at the 

Wortham Theater. Although the majority of building entrances below the established DFE were 

protected by a floodgate, not all of the entrances were protected. A large rollup garage door for 

the loading dock located on the north side of the Wortham Theater was protected by a floodgate, 

but a glass door entryway 20 feet to the east did not have any installed dry floodproofing protection 

measures (see Figure 3-66). Inside the glass door entryway is a small vestibule and a short staircase 

leading up to the main lobby, which is approximately 3.5 feet above the street level. During 

Hurricane Harvey, floodwater entered the building at the glass door entryway, overtopped the stairs, 

and flowed into the Wortham Theater.

3-68 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-66: Floodwater entry point though glass door entryway

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-69

FLOOD-RELATED OBSERVATIONS

Breach No. 9: Missing Floodgate

Breach No. 9 occurred on the east side of the Wortham Theater, along South Smith Street, at 

an emergency exit. This emergency exit, while located below the DFE, was not protected with a 

floodgate (see Figure 3-67). A similar emergency exit, located 50 feet to the north, at a similar 

elevation, was fitted with a floodgate that successfully kept floodwater from entering the building.

Miscellaneous Ground-Level Floodwater Entry Points

In addition to the nine breaches described in detail, floodwater entered the area protected by dry 

floodproofing mitigation measures at other ground-level entry points. 

Floodgates. Of the 16 pedestrian and vehicle entrances into the garages, two locations did not 

have floodgates installed. The other 14 entrances were protected by floodgates, but they were all 

overtopped due to the depth of the floodwater in the Theater District. Additionally, two of the 

floodgates at pedestrian entrances had issues with their seals, allowing significant seepage prior to 

overtopping. 

Unsealed penetrations. In the Wortham Theater, floodwater seeped into the building through 

unsealed pipe and conduit penetrations through the walls and ceiling of below-grade areas and 

through cracks in walls and ceilings of below-grade areas. 
Figure 3-67: 

Emergency exit door 

along the east side of 

the Wortham Theater; 

the red line indicates the 

approximate HWM during 

Hurricane Harvey

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FLOOD-RELATED OBSERVATIONS

Effect on Operations 

During the MAT visit 21⁄2 months after Hurricane Harvey made landfall, the cleanup and debris 

removal stage of recovery was ongoing. The Wortham Theater partially reopened on September 26, 

2018, a little more than 1 year after Hurricane Harvey. The parking garages took approximately 3 

months after Hurricane Harvey to resume regular operation but took approximately 16 months to 

be fully restored. 

3.2.4.3 Summary of MAT Observations

Theater District and Garages

+ The Theater District contains buildings that are located in the regulatory floodway, Zone AE, 

Shaded Zone X, and Unshaded Zone X. The Wortham Theater is located in Zone AE, with 

a BFE of 37 feet. Buildings located in Zone AE should follow the flood provisions of model 

codes and standards such as the IBC and ASCE 24. Although not required, flood-resistant 

features are recommended as a best practice even for buildings located outside the SFHA, 

especially those with a history of flooding.

+ The DFE, which is the water surface elevation of Tropical Storm Allison plus 2 feet of 

freeboard, was not correlated to a recurrence interval-based flood elevation such as the 

1-percent-annual-chance probability event or 0.2-percent-annual-chance probability flood 

elevation. Although many dry floodproofing systems installed in Houston after Tropical 

Storm Allison used this metric, the floodplain profile of the different watersheds in Houston 

are not the same. Two feet of freeboard in a wide floodplain such as Brays Bayou provides a 

significant level of protection, whereas 2 feet of freeboard provided in the narrower and more 

restricted floodplain of Buffalo Bayou does not provide the same level of protection. 
After Hurricane Harvey, HoustonFirst, the managers of the Houston Theater District, hired an 

independent engineering consultant to perform a comprehensive flood vulnerability assessment. 

The summary report, developed by CSF Consulting, L.P. on the events of Hurricane Harvey and 

findings, is titled Tropical Storm Harvey Flood Investigation (2018). To protect the Houston Theater 

District from future flooding events, HoustonFirst is evaluating the benefits and costs of three 

different potential DFEs: the Hurricane Harvey HWM plus 1 foot of freeboard, the 0.2-percentannual-chance event flood elevation plus 1 foot of freeboard, and the 0.2-percent-annual-chance 

event flood elevation plus 2 feet of freeboard.

3.2.5 Energy Corridor Office Building #1 

Constructed in the early 1980s, this office building complex 

located in the Energy Corridor near Buffalo Bayou consists of 

a 28-story high-rise tower, on the west side of the complex, that 

connects to a five-story building in the center of the complex 

(see Figure 3-68). On the east side of the complex is a ninelevel parking garage. The five-story building has an additional 

basement level containing a loading dock. The loading dock can 

be accessed via a vehicle ramp constructed on the north side of the complex, between the parking 

garage and five-story building. Some portions of the parking garage are within the Shaded Zone X 

(see Figure 3-69), but most of the complex is located in Unshaded Zone X.

Figure 3-68: 

Aerial image of Energy 

Corridor Office Building #1 

(taken on August 30, 2017) 

showing floodwater around 

the office complex

BUILDING #1

FIRM = Unshaded Zone X

(see Figure 3-70)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-71

FLOOD-RELATED OBSERVATIONS
Figure 3-69: 

FIRM for the Energy Corridor 

Office Building #1

3-72 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Dry Floodproofing Mitigation Measures 

These office buildings have not sustained significant flood damage in the past, but have experienced 

several minor flooding events caused by stormwater sheet flow flooding collecting in the loading 

dock. As a result, a passive floodgate was installed to protect the loading dock from sheet flow 

entering from the street. The passive floodgate was tied into a concrete wall on each side of the 

loading dock, forming a flood barrier along the north side of the office building complex. In 

anticipation of flooding associated with Hurricane Harvey, temporary flood barriers composed of 

water-filled bladders were installed along the eastern portion of the parking garage.

Performance during Harvey

During Hurricane Harvey, the area around the Energy Corridor Office Building #1 complex 

experienced minor flooding cause by stormwater that receded as bands of heavy rainfall passed 

by. However, the building experienced significant flooding on August 29, 2017, 4 days after Harvey 

made landfall. On August 28, the U.S. Army Corps of Engineers (USACE) was forced to start 

releasing water from Addicks Reservoir and Barker Reservoir to prevent a catastrophic failure of the 

dams. The Addicks and Barker Reservoirs mark the northern and western boundary of the Energy 

Corridor. Both reservoirs discharge into Buffalo Bayou, which runs through the southern portion of 

the Energy Corridor. After the release, a flood gage along Buffalo Bayou at the Dairy Ashford Road 
Bridge located approximately 2 miles downstream from the Energy Corridor indicated a HWM of 

76.90 feet on August 30, which exceeds the 0.2-percent-annual-chance flood elevation of 74.70 feet 

by 2.2 feet.

Parking garage. In anticipation of Hurricane Harvey, temporary flood barriers were installed 

along the eastern portion of the parking garage to protect the complex from floodwater that would 

approach from the southeast. However, as the floodwater rose, the temporary flood barriers were 

overtopped, allowing water to flow into the parking garage (see Figure 3-70). As the parking garage 

filled with water, its walls were overtopped and floodwater started to fill the loading dock area. 

The automatic passive floodgate protecting the loading dock deployed as designed when floodwater 

reached the north side of the building complex (see Figure 3-71). 

Figure 3-70: 

Civil Air Patrol photo 

showing the east side of the 

parking garage

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-73

FLOOD-RELATED OBSERVATIONS
Figure 3-71: 

Deployed passive floodgate 

at the top of the loading dock 

ramp (red outline) 

3-74 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Office building basement. An at-grade vault on the north side of the five-story building once 

provided access to a below-grade ventilation opening for an electrical room whose components were 

relocated during a project several years prior to Harvey. The opening in the foundation wall was 

filled in with unreinforced masonry. When floodwater entered the vault, the unreinforced masonry 

wall failed as a result of the hydrostatic loading, allowing water to enter the basement and fully 

inundate it.

Office building first floor. Floodwater from Hurricane Harvey eventually reached 1.2 feet above the 

first floor of both the five-story building and the 28-story high-rise tower, damaging interior finishes 

on the first floors.

Effect on operations. During the MAT visit 21⁄2 months after Harvey made landfall, this complex 

was still undergoing repairs and still unoccupied and will remain so until repairs are complete.

Summary of MAT Observations

+ The Energy Corridor Office Building #1 is located in Unshaded Zone X, while the parking 

garage is located in Shaded Zone X. All of the buildings are located outside of the SFHA and 

thereby exempt from the flood provisions of model codes and standards such as the IBC and 

ASCE 24. Although not required, flood-resistant features are recommended as a best practice 

even for buildings located outside the SFHA, especially those with a history of flooding.
+ The passive floodgate was installed to protect against stormwater sheet flow from flooding 

into the loading dock. It was not designed for an event as severe as Hurricane Harvey, which 

exceeded the 0.2-percent-annual-chance event. The passive gate performed as designed and 

was not overtopped.

+ Floodwater entered the dry floodproofed area behind the passive floodgate by overtopping 

an unidentified low point in the office building complex via the parking garage and by 

overloading an unreinforced masonry wall used to infill a below-grade wall penetration to an 

unused utility vault. 

+ When protecting existing buildings, understanding the potential source of flooding is critical. 

The entire flood barrier should be set to the same elevation without any low points that can 

lead to overtopping, and all components of the flood barrier should be capable of resisting 

the hydrostatic forces associated with the DFE.

3.2.6 Energy Corridor Office Building #2 

Constructed in the early 1980s, this office building located in the 

Energy Corridor near Buffalo Bayou is a 17-story commercial office 

building with an additional basement level containing a loading 

dock. The loading dock is accessed via a vehicle ramp constructed 

on the south side of the building. A passive floodgate is installed at 

the top of the loading dock ramp (see Figure 3-72). A majority of the 

building systems (MEP components, potable water supply pumps, 

BUILDING #2

FIRM = Unshaded Zone X

(see Figure 3-74)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-75

FLOOD-RELATED OBSERVATIONS

Figure 3-72: Energy Corridor Office Building #2 (left image) and loading dock and ramp (right image)
fire suppression equipment, and backup generator and fuel) are located in a mechanical room in the 

basement; a ventilation vault is located on the north side of the building to provide ventilation for this 

equipment. There are two pad-mounted transformers in the loading dock area and a switchgear with 

conduits that run into an electrical manhole located in the street beyond the loading dock ramp. The 

office building is located in an Unshaded Zone X, approximately 0.1 mile from the nearest regulated 

floodplain (see Figure 3-73).

Figure 3-73: 

FIRM for Energy Corridor 

Office #2

3-76 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Dry Floodproofing Mitigation Measures

This office building sustained significant flood damage when a severe thunderstorm in 2009 

resulted in the complete inundation of the basement and loading dock (see Figure 3-74) and has 

experienced several minor flooding events caused by stormwater sheet flow collecting in the loading 

dock. As a result, a passive floodgate was installed at the top of the loading dock ramp to prevent 

stormwater sheet flow from flooding the loading dock. Within the loading dock is a large sump 

pump, with a connection for a redundant pump, to remove any rainwater that may collect at the 

base of the loading dock; the water is discharged over the wall into a pond. The passive floodgate 

and the sump pump are shown on Figure 3-72).

Additionally, a 1-foot-tall concrete curb wall was installed on the top of an existing ventilation vault 

that provides ventilation to the MEP systems located in the basement mechanical room. The new 

wall elevation matches the wall height at the loading dock and that of the passive floodgate. 

Figure 3-74: 

Flooding of the loading 

dock during a severe 

thunderstorm in 2009

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-77

FLOOD-RELATED OBSERVATIONS

Performance during Harvey

During Hurricane Harvey, the area around the Energy Corridor Office Building #2 experienced 

minor flooding cause by stormwater that receded as bands of heavy rainfall passed by, but 

experienced significant flooding on August 29, 2017, 4 days after Harvey made landfall. On August 

28, the USACE was forced to start releasing water from Addicks Reservoir and Barker Reservoir to 

prevent a catastrophic failure of the dams. The Addicks and Barker Reservoirs mark the northern 

and western boundary of the Energy Corridor. Both reservoirs discharge into Buffalo Bayou, 

which runs through the southern portion of the Energy Corridor. After the release, on August 

30, a flood gage along Buffalo Bayou at the Dairy Ashford Road Bridge located approximately 2 

miles downstream from the Energy Corridor indicated a HWM of 76.90 feet, which exceeds the 

0.2-percent-annual-chance flood elevation of 74.70 feet by 2.2 feet.

Floodgates. Prior to the release of water from Addicks Reservoir and Barker Reservoir, the passive 

floodgates deployed at least one time on August 26, but when floodwater receded, the gates lowered. 

On August 29, floodwater caused the passive floodgate to rise again; it reached its fully deployed 

position in approximately 30 minutes (see Figure 3-75). Floodwater did not recede in the area 

around the building until September 5, 2017.
Figure 3-75: Flooding around Energy Corridor Office Building #2 August 29 to August 30 

RIGHT SIDE PHOTOGRAPHS COURTESY OF ANDREW HOYNS, HICKS VENTURES

3-78 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

At its maximum elevation, the floodwater rose to within about 7 inches of the top of the floodgate. As 

a precaution, sandbags were placed on the top of the passive floodgate and adjoining concrete walls 

when the on-site maintenance personnel received information that the floodgates at neighboring 

office buildings were being overtopped. Floodwater did not overtop the gate, nor was excessive 

leakage past the gate reported, even though the rubber gasket at the base of the passive gate was 

cracked. 

Switchgear conduit. Shortly after the passive floodgates were fully deployed, water flowed into 

the area of the loading dock ramp behind the floodgate. Water appeared to be flowing within the 

underground duct bank/conduit that runs between the utility switchgear in the loading dock area 

(see Figure 3-76, left) and the underground electrical manhole located in the street to the west of 

the building (see Figure 3-76, right). Maintenance personnel who were on site during Hurricane 

Harvey placed plastic lining and sandbags on the electrical manhole cover to reduce the rate of 

floodwater flowing into the loading dock to a rate at which the sump pumps in the loading dock 

were able to keep up.

Basement. Floodwater reportedly seeped over and down into the basement at the construction 

joint between the exterior pre-cast concrete panels and the first floor slab. This construction 

joint likely did not have a waterstop, or if the waterstop was installed, it had been compromised. 

Reportedly, no other portions of the basement experienced noticeable seepage. The water seeping 
Figure 3-76: Floodwater entering protected area flowing within utility switchgear conduit 

RIGHT PHOTOGRAPH COURTESY OF ANDREW HOYNS, HICKS VENTURES

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-79

FLOOD-RELATED OBSERVATIONS

into the basement was located near a sump pit that removes roof stormwater drainage; the sump 

was able to accept and remove the seepage. The stormwater sump pit was previously connected to a 

perimeter drain system, but it was disconnected a few years ago because it caused the sump pumps 

to continually run. Disconnecting the perimeter drain system prevented a considerable source of 

water from entering the building, one that could have overwhelmed the sump pump system during 

Hurricane Harvey.

Effect on operations. Due to the performance of the dry floodproofing systems and the ability of 

on-site maintenance personnel to identify a source of floodwater, this building was one of the few 

buildings in the area that was able to resume normal operations after floodwater receded. Minimal 

damage was reported during the MAT visit.

Summary of MAT Observations

+ The Energy Corridor Office Building #2 is located in Unshaded Zone X, outside of the 

SFHA, and is thereby exempt from the flood provisions of model codes and standards such as 

the IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding. 

+ The flood damage to this office building should be considered a near miss. The passive 

floodgate performed as designed, but water entered the dry floodproofed area from the 
electrical manhole through a duct bank/conduit to the utility switchgear and through 

horizontal piping passing through the basement foundation wall. If on-site maintenance 

personnel were not present to observe the inflow of water from beneath the utility switchgear 

and through piping, identify its source, and mitigate the source of water, this water flow could 

have overwhelmed the sump pump and flooded the basement. 

+ The passive floodgate was not designed to protect against a DFE flood level, and there was 

no flood vulnerability assessment for the building that identified possible sources of water 

infiltration. The gate was installed to protect against stormwater sheet flow flooding and was 

not designed for an event as severe as Hurricane Harvey. The passive floodgate performed as 

designed and was not overtopped.

+ Seepage was directed towards a stormwater sump pit located in the basement that successfully 

removed the seepage with minor impact to the building’s operating capabilities.

3.2.7 Houston Galleria Office Tower

This 20-story office building was constructed in 1977 in the 

Houston Galleria District (see Figure 3-77). This building 

contains a basement with a loading dock, which is accessed via 

a vehicle ramp constructed on the south side of the building. 

A majority of the building systems (MEP components, potable 

water supply pumps, and fire suppression equipment) are 

located in the basement. 

The office building is located in an Unshaded Zone X, approximately 1.5 miles from the nearest 

regulated floodplain. Although not in close proximity to a regulated floodplain, this building was 

severely flooded by both Tropical Storm Allison and the 2015 Memorial Day Flood as a result of 

stormwater sheet flow flooding (see Figure 3-78).

Dry Floodproofing Mitigation Measures 

After sustaining considerable damage in the 2015 Memorial Day Flood, the building owners 

promptly began the repairs to restore the building to its pre-flood condition. A flood vulnerability 

analysis was performed to quantify flood risks and identify areas and the elevation where floodwater 

could enter. With the information obtained during the flood vulnerability analysis, a comprehensive 

approach was taken to mitigate the identified source for water intrusion. Where critical building 

systems could not be relocated, redundant dry floodproofing systems with alarms were installed 

to provide the desired level of protection. When a repair was made, the repair was independently 

verified to ensure the repair was properly constructed and to ensure proper performance for 

protection against future flooding events. 

Flood mitigation included a multi-pronged approach and redundant systems. Independent testing 

of the dry floodproofing mitigation measures ensured that the components would properly function 

when tested by a flooding event. Numerous measures were undertaken by the building managers, as 

follows:

+ DFE. Establishing a DFE to be used for the entire site.

+ Flood barrier. Installing a passive floodgate at the top of the ramp to the below-grade loading 

dock (see Figure 3-79). The passive floodgate was connected to the floodwall constructed 

GALLERIA OFFICE TOWER

FIRM = Unshaded Zone X

3-80 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-77: 

Houston Galleria Office 

Tower

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-81

FLOOD-RELATED OBSERVATIONS

Figure 3-78: 

Loading dock flood during 

the 2015 Memorial Day Flood

PHOTOGRAPH COURTESY 

OF GALLERIA OFFICE TOWER 

BUILDING MANAGEMENT
around the loading dock in response to Tropical Storm Allison in 2001. The floodwall is also 

connected to the structure of the building. 

+ Redundancy. Constructing a redundant flood barrier system to protect the MEP components 

in the basement. The redundant flood barrier consists of a reinforced concrete wall with 

flood doors at the two pedestrian doors that provide access to the basement from the loading 

dock (see Figure 3-80). The reinforced concrete wall is tied into the existing structure with 

waterstops at the top and bottom of the wall. The concrete wall was designed to resist the 

hydrostatic load associated with a fully inundated loading dock and the loads transferred to 

the wall by the flood doors.

Figure 3-79: 

Passive floodgate located at 

the top of the loading dock 

ramp

+ Pony walls. Constructing pony walls west of the building to prevent water from entering the 

basement via the fresh air intake louvers and prevent water from flowing into the parking 

garage and entering elevator pit. The area within the floodwalls is sloped to drain stormwater 

to the east to a scupper that allows stormwater to drain into the loading dock where it is 

emptied via a sump pump (see Figure 3-81, left image). The equipment is elevated on 

concrete pads to keep it above any stormwater that may collect in this area.

+ Larger sump pumps. Increasing the size of the sump pumps in the loading dock. The sump 

pumps are designed to remove stormwater from the loading dock, including the stormwater 

that drains into the loading dock from the elevated equipment area. The sump pit is 

protected by a screen system to prevent debris from fouling any of the pumps (see Figure 

3-81, left image). A high water level detection and alarm system was installed in the loading 

dock to notify building security that water is starting to collect in the loading dock (see 

Figure 3-81, right image).

3-82 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-80: 

Loading dock flood doors 

(the red line is a reflective 

strip and not an indicator of 

HWM); inset shows one of 

the flood doors installed to 

protect MEP

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-83

FLOOD-RELATED OBSERVATIONS

Figure 3-81: Loading dock sump pump screen protection (left) and high water level alarm (right)
+ Sealing. Sealing around all pipe penetrations through the foundation wall. 

– Pipe penetrations into the mechanical room (see Figure 3-82) were sealed and the insides 

of electrical conduits were also sealed to prevent water from flowing inside the conduit and 

entering the mechanical room. Additionally, a wet alarm was installed in the mechanical 

room to notify security, building engineers, and building managers that water is leaking 

into the building in this area. 

– Other pipe penetrations and cracks through the foundation wall were sealed by pressure 

injecting a hydrophilic polyurethane foam to prevent water seepage. Areas with pipe 

penetrations or foundation cracks were not covered by building finishes or paint until it 

could be independently verified that the crack injection or pipe penetration sealing could 

prevent water seepage into the building.

Figure 3-82: Wet alarm (left) and sealed pipe penetration (right)

The mitigation and dry floodproofing measures 

undertaken by the building were tested during 

the 2016 Tax Day Flood. The office tower did not 

sustain any damage from flooding of streets in the 

area. The installation of the passive floodgate at 

the loading dock was completed 5 days before that 

flood. The passive floodgate at the top of the loading 

dock properly deployed, and the sump pumps in the 

loading dock were able to keep up with the rainfall, 

preventing a repeat of the damage that occurred in 

2015. The parking garage for the office tower was 

flooded by stormwater sheet flow, which damaged 

the elevator equipment in the parking garage and 

cars parked on the first level. In response to the 

flood, five additional passive floodgates, a 3-foot floodwall on the north perimeter of the garage, 

and check valves on all first- and second-level floor drains were installed around the parking garage 

(see Figure 3-83).

CONTINUED SUCCESSFUL 

PERFORMANCE

On July 4, 2018, when a severe 

thunderstorm dropped approximately 8 

inches of rainfall in 3 to 5 hours across 

portions of western Houston that 

resulted in street flooding, the passive 

floodgates successfully deployed 

and protected the loading dock and 

basement from flood damage.

3-84 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-85

FLOOD-RELATED OBSERVATIONS

Figure 3-83: 

Parking garage for the 

Houston Galleria Office 

Tower

Performance during Harvey

Basement. During Hurricane Harvey, two leaks occurred in the basement of the building. The 

first leak was through a pipe penetration in the mechanical room that allowed the intrusion of 

approximately 10 to 15 gallons of water per day. The second leak was around a conduit penetration 

in the storage room that allowed the intrusion of approximately 5 to 10 gallons of water per day. The 

water from these two leaks was directed toward the existing sanitary sewer sump pit and removed 

from the basement. 

Passive floodgates. The passive floodgates at the loading dock and at the parking garage entrances 

successfully deployed and prevented floodwater entering the protected areas. 

Effect on operations. Minimal damage was reported during the MAT visit, mainly to ceiling tiles 

and drywall from the two leaks in the basement. 

Summary of MAT Observations 

+ The Houston Galleria Office Tower is located in Unshaded Zone X, outside of the SFHA, 

and is thereby exempt from the flood provisions of model codes and standards such as the 

IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding. 
+ Damage from the 2015 Memorial Day Flood at the building resulted in the performance of 

a flood vulnerability assessment and subsequent installation of dry floodproofing mitigation 

measures. The dry floodproofing mitigation measures undertaken were extensive, addressing 

both MEP components and the structure. 

+ Independent testing of the dry floodproofing mitigation measures ensured they would 

properly function when tested by a flooding event. 

+ The dry floodproofing components and mitigation activities performed at the Houston 

Galleria Office Tower provided a comprehensive flood barrier that performed as designed 

during the 2016 Tax Day Flood and Hurricane Harvey. The building experienced only two 

minor leaks in the dry floodproofing barrier during Hurricane Harvey that did not result in 

significant damage or loss of function down time. 

3.2.8 Four Leaf Towers

The Four Leaf Towers are twin 396-unit, 42-story condominium 

towers that were constructed in 1982. The condominium towers 

are situated above the parking garage, with the first floor of the 

towers and access to the parking garage located approximately 8 

feet above the grade of the surrounding streets (see Figure 3-84). 

Figure 3-84: 

Four Leaf Towers 

Condominium Complex, 

where yellow double arrows 

indicate street-level access 

locations to the complex and 

blue dashed arrows indicate 

access to parking garage

FOUR LEAF TOWERS

FIRM = Unshaded Zone X

(see Figure 3-86)

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The condominium complex grounds contain several at-grade amenities, including a gym, tennis 

courts, a pool, restrooms, and a lounge. Additionally, on the northeast corner of the complex, an 

access ramp descends from street level to the loading dock. Within the loading dock is an access way 

to the parking garage, the waste pickup area, and the building central plant that generates steam 

and chilled water. Rooms that contain the remaining critical building systems, such as the electric 

room, potable water supply pumps, and fire suppression pumps, are located below grade in the 

garage. The condominium complex is located in Unshaded Zone X, approximately 0.4 mile from 

the nearest regulated floodplain (see Figure 3-85).

Figure 3-85: 

FIRM for Four Leaf Towers 

Condominium Complex

Dry Floodproofing Mitigation Measures 

At-grade portions of the Four Leaf Towers complex flooded from stormwater sheet flow during the 

Memorial Day and Tax Day Floods in 2015 and 2016, resulting in significant damage to the facility. 

After these two events, the property managers studied their grounds to identify areas susceptible 

to flooding or where water could enter the complex. Flood mitigation included a multi-pronged 

approach with independent testing of the dry floodproofing mitigation measures to ensure that 

the components would properly function when tested by a flooding event. Several measures were 

undertaken by the building managers, as follows:

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-87

FLOOD-RELATED OBSERVATIONS
+ Flood-resistant doors. Installing seven flood-resistant personnel doors to replace doors for 

the gym, restrooms near the complex’s at-grade level swimming pool and other amenities at 

the complex, and at pedestrian access points to the parking area.

+ Flood barrier. Installing a flood log system at the top of the loading dock ramp and in a 

stairwell that provides access to the parking garage (see Figure 3-86).

+ Training. Initiating a program of annual practice exercises. The building manager holds an 

annual exercise to implement the emergency operations plan with all building staff, including 

maintenance personnel and gardeners, to practice installing all of the dry floodproofing 

measures, recording the time it takes to install each component as well as the overall system. 

The training exercise is held in April because of its proximity to hurricane season, which 

allows any issues identified during the training, such as worn gaskets or missing components, 

to be fixed before any severe weather is likely to occur. Because flooding can occur with little 

warning, having multiple groups of people that know how to install the dry floodproofing 

measures and understand the installation time of each component is imperative.

Figure 3-86: Examples of active and passive flood barriers at Four Leaf Towers

Performance during Harvey

At-grade areas. During Hurricane Harvey, stormwater sheet flow backed up in the at-grade 

swimming pool and amenities area, resulting in a flood depth of approximately 3.5 feet. Figure 

3-87 shows the HWM that resulted from the flooding. The flood doors in those areas protected the 

restrooms and gym, which sustained only minor water seepage. 

Parking garage. Within the stairwell providing access to the parking garage, the flood logs were 

loaded with approximately 6 inches of water; no water was reported inside the parking garage. 

3-88 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Loading dock. The location of the flood log at the top of the loading dock access ramp was not 

exposed to the stormwater sheet flow and was not tested as a result. 

Effect on operations. The condominium complex escaped Hurricane Harvey with only minor 

damage to exterior finishes in the at-grade areas.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-89

FLOOD-RELATED OBSERVATIONS

Figure 3-87: 

HWM near the swimming 

pool at the Four Leaf Towers 

condominium complex

Summary of MAT Observations

+ The Four Leaf Tower condominium complex is located in Unshaded Zone X, outside of the 

SFHA, and is thereby exempt from the flood provisions of model codes and standards such as 

the IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding. 

+ Building damage from the 2015 Tax Day and 2016 Memorial Day Floods resulted in 

the performance of a flood vulnerability assessment and subsequent installation of dry 

floodproofing mitigation measures. 

+ Independent testing of the dry floodproofing mitigation measures ensured they would 

properly function when tested by a flooding event. 

+ After previous flooding events, the building manager developed an extensive emergency 

operations plan and instilled a culture of preparedness that resulted in the complex being 

well prepared for Hurricane Harvey. 
+ The dry floodproofing components and mitigation activities performed at Four Leaf Tower 

condominium complex provided a comprehensive flood barrier, performing as designed 

during Hurricane Harvey. The building experienced only minor damage to exterior finishes 

in the at-grade areas.

3.2.9 Starbucks at 4660 N. Braeswood 

The drive-through Starbucks coffee shop, constructed in 2016, is located 

along North Braeswood Boulevard. The building is located in Zone 

AE (see Figure 3-88), with a BFE of 53.2 feet and a 0.2-percent-annualchance flood elevation of 54.5 feet. The design of the coffee shop used 

both elevation on fill and dry floodproofing to achieve the desired level 

of protection at elevation 54.8 feet, which is 2.67 feet above the finished 

floor (See Figure 3-89). The 2.67 feet dry floodproofed height resulted 

in 6 inches of additional freeboard beyond the 1-foot minimum required 

by ASCE 24. Elevation was achieved by adding approximately 3 feet of soil fill to the building pad, 

which was the maximum possible increase while maintaining vehicle access to the drive-through 

from the grade of the adjacent streets. 

Sanitary sewer lines discharge by gravity to a municipal main that is reported to be “several feet” 

below grade (due to the proximity of the local wastewater treatment plant). 

Figure 3-88: 

FIRM for the Starbucks 

building at 4660 N. 

Braeswood Boulevard

STARBUCKS

FIRM = Zone AE

BFE = 53.2 feet

(see Figure 3-89)

§ ̈¦610

S Post Oak Road

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FLOOD-RELATED OBSERVATIONS
Figure 3-89: 

Shows the Starbucks 

building elevated on fill with 

dry floodproofing

Dry Floodproofing Mitigation Measures 

Several dry floodproofing measures were included in the design and construction of the Starbucks 

building, as follows: 

+ Flood barrier. A flood barrier was created by constructing the lower portions of the exterior 

walls with fully grouted, reinforced CMUs, with an exterior brick veneer. A membrane was 

installed in the cavity between the CMU and the veneer (see Figure 3-90). The remaining 

portions of the building, built on top of the CMU walls, are composed of light-gauge, steelframed walls that are not designed to prevent floodwater entry.

Figure 3-90: 

Membrane installed on the 

fully grouted and reinforced 

CMU wall

PHOTOGRAPH COURTESY KEVIN 

MYERS OF MC MANAGEMENT 

AND DEVELOPMENT; TAKEN 

DURING CONSTRUCTION AT THE 

STARBUCKS FACILITY

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-91

FLOOD-RELATED OBSERVATIONS
+ Flood doors. Three pedestrian flood doors were installed: one at the employee entrance, one 

at the store room entrance, and one at the restroom entrance (see Figure 3-91). 

+ Sealing. All of the penetrations through the flood barrier below the DFE were protected.

Figure 3-91: 

Pedestrian flood doors 

installed to access 

restrooms, storage room, 

and employee entrance

Performance during Harvey

During Hurricane Harvey, floodwater rose 

to an elevation of 54.2 feet, just below the 

0.2-percent-annual-chance flood elevation of 

54.5 feet and approximately 2 feet above the 

finished floor. The floodwater remained at 

that level for approximately 2 days (see Figure 

3-92). 

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FLOOD-RELATED OBSERVATIONS

Figure 3-92: Starbucks 

during Hurricane 

Harvey flooding

PHOTOGRAPH COURTESY 

OF KATI SOUTHERN
First floor. Water reportedly entered through floor drains that discharged into the sanitary sewer 

lines (see Figure 3-93). Water levels within the building reached about 2 inches at the southwest 

corner of the building, where the floor elevation is lowest (see Figure 3-94). 

Effect on operations. Minimal damage was reported for the coffee shop after having been exposed 

to floodwater for 2 days. Once floodwater receded and the minor water inside the coffee shop was 

cleaned up, normal business operations resumed.

Figure 3-93: Floor drains (red arrows) where floodwater entered

Figure 3-94: Approximate flood levels during Hurricane Harvey on the outside of the building (left) and inside (right)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-93

FLOOD-RELATED OBSERVATIONS
Summary of MAT Observations

+ The Starbucks at 4660 N. Braeswood is located in Zone AE, in close proximity to the 

floodway, and has a BFE of 53.2 feet. Buildings located in Zone AE should follow the flood 

provisions of model codes and standards such as the IBC and ASCE 24.

+ Numerous flood risk reduction measures were included in the design and construction of this 

building in 2016 because of the known flood risk. 

+ The building was exposed to floodwater for approximately 2 days, but experienced only 

minor water seepage into the building and minor backflow from the sanitary sewer into the 

building. 

+ The additional 6 inches of freeboard incorporated into the design beyond the code minimum 

of 1 foot of freeboard prevented the dry floodproofing measures from being overtopped and 

thereby prevented inundation of the building. 

+ The design of the coffee shop did not incorporate sump pumps or pits to collect and dispose 

of any seepage into the building. The omission of a sump pump and pit to collect and remove 

seepage is a violation of the ASCE 24 requirements for a dry floodproofed building. 

3.2.10 Texas Medical Center 

The TMC is primarily situated in southwest Houston along the north 

bank of Brays Bayou, with some facilities expanding to the other 

side; buildings on the TMC are located in either the Shaded Zone 

X or Zone AE (buildings located closer to the bayou) (see Figure 

3-95). 

The MAT selected the TMC as an example of essential hospital/

medical and support facilities that had integrated dry floodproofing 

measures into their facilities. The MAT visited six of the TMC 

member institutions. The specific TMC facilities visited were selected 

based on several factors, including size, whether the specific facility was known to have implemented 

dry floodproofing mitigation measures, whether the installed mitigation measures were tested 

during Hurricane Harvey, whether FEMA funds were used for the installed mitigation measure, and 

whether the MAT was able to arrange access. Figure 3-96 shows the locations of the facilities visited 

by the MAT.

The dry floodproofing measures at TMC were mostly implemented after Tropical Storm Allison in 

2001. Much, but not all, of the flood mitigation implemented at TMC facilities was funded through 

either FEMA Public Assistance (406 Mitigation) or the FEMA Hazard Mitigation Grant Program 

(404 Mitigation).

TEXAS MEDICAL 

CENTER

FIRM = Zone X and AE

BFE = 43.7 to 40.7 feet

(see Figure 3-96)

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FLOOD-RELATED OBSERVATIONS
TEXAS MEDICAL CENTER 

The TMC was established in the 1940s with funds from the MD Anderson Foundation and has 

grown to be the largest medical, patient care, research, and educational complex in the world. 

Currently, the TMC is made up of 59 member institutions, including world-renowned hospitals, 

academic institutions, and support service institutions. Although the overarching TMC umbrella 

organization provides a variety of services to its member institutions, including a police force, 

property management, and parking, the member institutions operate largely autonomously from 

one another.

The largest member institutions are:

•	 Baylor College of Medicine 

•	 CenterPoint Energy Grant Substation 

•	 CHI St. Luke’s Health 

•	 Harris Health System Ben Taub Hospital 

•	 Houston Methodist 

•	 Memorial Hermann 

•	 Michael E. Debakey Veterans Affairs Medical Center 

•	 Rice University 

•	 Texas A&M University Health Science Center

•	 Texas Children’s Hospital

•	 Texas Heart Institute

•	 The University of Texas Health Science Center at Houston

•	 The University of Texas MD Anderson Cancer Center

•	 The University of Texas Medical Branch at Galveston

•	 Thermal Energy Corporation (TECO) Paul G. Bell, Jr. Energy Plant

•	 University of Houston

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-95

FLOOD-RELATED OBSERVATIONS
Figure 3-95: FIRM for TMC

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FLOOD-RELATED OBSERVATIONS

Historic Flood Levels at TMC

A stream gage is located at the outlet of the Harris Gully box culvert where it feeds into Brays 

Bayou at the east side of TMC. The Harris Gully box culvert is a system of underground stormwater 

collection pipes and culverts that collects surface stormwater from throughout the TMC and Rice 

University area. The stormwater collection system was improved after Tropical Storm Allison in 2001 

to lower flood levels on the TMC campus. Data for the stream gage at the Harris Gully box culvert 

are available from the Harris County Flood Warning System website and are summarized in Table 

3-9, which shows various probability of exceedance with the associated MRI and flood elevations for 

the Harris Gully gage location. Probabilities are given as the annual chance of the site experiencing 

a flood event that meets or exceeds a given flood elevation.
Figure 3-96: Locations of facilities observed by the Harvey MAT at TMC

Table 3-9: General Flood Information Measured at Harris Gully Box Culvert 

Harris Gully Box Culvert 

Annual chance of exceedance 10% 2% 1% 0.2%

MRI 10 years 50 years 100 years 500 years

Flood elevation 34.9 feet 38.2 feet 39.9 feet 43.0 feet

MRI = mean recurrence interval

SOURCE: HCFCD, 2018A 

The MAT compared historic flood levels at the Harris Gully box culvert to published flood elevations 

to determine the approximate MRIs for those events recorded at the Harris Gully box culvert stream 

gage. Table 3-10 lists the six most severe flood events in the last 20 years, including Hurricane 

Harvey, and their approximate MRIs at the Harris Gully box culvert. Data are not available for 

Tropical Storm Allison at this stream gage. 

Based on the available data for the Harris Gully box culvert, the rainfall from Hurricane Harvey was 

a record setting event with a HWM of 41.5 feet and was a 0.42-percent-annual-chance-of-exceedance 

event. In comparison, a Harris County stream gauge along Brays Bayou just upstream of the TMC 

at South Main Street indicates a HWM of 45.70 feet, matching the 1-perecnt-annual-chance-ofexceedance event for that section of Brays Bayou and exceeding the Tropical Storm Allison HWM 

of 42.91 feet. 

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-97

FLOOD-RELATED OBSERVATIONS
Table 3-10: Past Flood Events and Their Approximate Mean Recurrence Intervals

Event Name Date

Harris Gully Box Culvert

Maximum Flood Elevation Approximate MRI(a)

Annual Chance 

of Exceedance

Hurricane Harvey 08/27/2017 41.5 feet 235 years 0.42%

[No name] 01/18/2017 35.3 feet 12 years 8.3%

Tax Day 04/18/2016 37.4 feet 33 years 3.0%

Memorial Day 05/26/2015 38.0 feet 44 years 2.3%

[No name] 01/19/2012 36.1 feet 18 years 5.5%

Hurricane Ike 09/13/2008 34.0 feet 6 years 16.7%

(a) The MRIs (mean recurrence intervals) were determined using regression analysis whereby a best-fit curve was selected to model the 

data and compared to the published flood elevations. A logarithmic curve was selected, which produced a coefficient of determination 

(R2 value) of 99.9 percent. 

SOURCE: BASED ON DATA FROM HCFCD, 2018A 

TMC Operational Impact and Response

In general, the majority of facilities at TMC suffered 

only a minimal amount of floodwater intrusion 

and damage during Hurricane Harvey. This was a 

result of the facilities owners’ proactive approaches 

to flood hazard mitigation over the past 15 to 20 

years, rigorous emergency preparedness policies 

and procedures, and the significant amount of 

channel capacity improvements to the Harris Gully 

box culvert and Brays Bayou. 

At several of the TMC facilities visited, the 

MAT discussed emergency planning activities 

and operational impacts before, during, and 

after Hurricane Harvey with key management 

contacts. As previously noted, the majority of 

the TMC facilities were damaged by Tropical Storm Allison, and facility emergency preparedness 

and response activities typically incorporated the lessons learned from that event. Given all the 

mitigations measures that had recently been implemented and/or improved upon at the respective 

TMC facilities, in combination with the lack of alternative options for critical patient care, most of 

the TMC facilities “defended in place.” Typical preparatory activities included:

+ Canceling surgeries and other procedures 2 to 3 days before Hurricane Harvey’s landfall

+ Modestly reducing patient load (10 to 20 percent per hospital)

+ Activating “ride-out” procedures and staff

ELECTRICAL UTILITY RELOCATION 

MANDATE

 After Tropical Storm Allison, TMC and 

CenterPoint Energy mandated that all 

buildings at the TMC had to elevate their 

electrical equipment to above the BFE 

if they wanted to remain connected to 

the electrical grid during a flood event 

to minimize the chance that an electrical 

failure at one building would cause 

electrical issues at another building.

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FLOOD-RELATED OBSERVATIONS

3.2.10.1 Texas Children’s Hospital (TCH)

Texas Children’s Hospital (TCH), located at 6621 Fannin Street, consists of six buildings at the 

southwest corner of the TMC campus (see Figure 3-97). All of the buildings that make up the TCH 

campus are situated in a Shaded Zone X (see Figure 3-98). The concrete buildings, with construction 

dates between 1987 and 2017, consist of the following: 
+ The Pavilion for Women (16 stories + 4 basement parking stories) 

+ Legacy Tower (26 stories + 4 basement parking stories)

+ Wallace Tower (17 stories + 4 basement parking stories)

+ West Tower (21 stories + 2 basement stories)

+ Abercrombie Building (8 stories + 2 basement stories)

+ Feigin Tower (20 stories)

TEXAS CHILDREN’S 

HOSPITAL

FIRM = Shaded Zone X

(see Figure 3-99)

Holcombe Blvd.

Fannin St.

Holcombe Blvd.

Fannin St.

Figure 3-97: Texas Children’s Hospital aerial view looking north

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-99

FLOOD-RELATED OBSERVATIONS
0 500 1,000

Feet

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FLOOD-RELATED OBSERVATIONS

TCH is the largest specialty pediatric hospital in the United States with 851 licensed beds and 

16,000 employees. It is affiliated with the Baylor College of Medicine and has three hospitals and 

eight urgent care centers. TCH is the only tertiary pediatric hospital in the region, so it had to 

remain open during Hurricane Harvey and was not able to transfer its specialty and critical patients 

because there were few other facilities in the region that could care for them. 

Pre-event activities included slightly reducing the number of patients, cancelling elective procedures 

36 hours before landfall, arranging for full staffing with staff support services, and focusing on care 

for vulnerable populations.

Figure 3-98: FIRM for Texas Children’s Hospital
Dry Floodproofing Mitigation Measures 

In the late 1990s to early 2000s, TCH installed a series of dry floodproofing submarine doors in its 

basement to address their flood vulnerability. The installation of these submarine doors was certified 

3 weeks before Tropical Storm Allison struck the area. These submarine doors in the basement 

were closed in advance of the storm and successfully isolated the flooding during Tropical Storm 

Allison to the second basement level, which filled with 8 feet of water. As a result of the flooding, 

TCH lost primary power, but was able to remain operational using back-up power systems. During 

Tropical Storm Allison, TCH accepted patients evacuated from neighboring hospitals. Flooding 

in the basement of TCH resulted in approximately $30 million in damages, whereas neighboring 

hospitals sustained damages in excess of $100 million.

After Tropical Storm Allison, another flood vulnerability assessment was performed to identify areas 

to be protected resulting in the implementation of a variety of flood mitigation measures, described 

as follows:

Formation of the Tunnel Management Group. Although TCH suffered damage during Tropical 

Storm Allison due to loss of power, the flooding that occurred in the basement of TCH during 

Tropical Storm Allison entered through the Houston Methodist Neurosensory building tunnel, 

whose gate was not completely installed prior to the event. The basement levels of TCH are 

connected to its neighbors, Houston Methodist and CHI St. Luke’s Health, via a series of tunnels. 

As a result of the flooding that occurred during Tropical Storm Allison, these three facilities 

formed a Tunnel Management Group to facilitate working together to protect the tunnel system 

from floodwater intrusion. The Tunnel Management Group has taken planning and mitigation 

steps to improve coordinated efforts, such as developing an agreement that allows any one of the 

organizations to close any of the flood doors or floodgates that protect the tunnel system.

Flood doors, floodgates, and sump pumps. Flood doors and floodgates were installed to prevent 

flooding of the tunnel system. The tunnel is designed to direct any water that enters the tunnel to 

drain to a low point where sump pumps remove the water. Additionally, the tunnel is composed of 

flood damage-resistant materials to minimize any damage that may occur (see Figure 3-99).

Figure 3-99: Flood doors in basement tunnel (left) and below-grade parking garage (right)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-101

FLOOD-RELATED OBSERVATIONS
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Additionally, surface level floodgates were installed to protect the access points to below-grade areas. 

Examples of surface level floodgates are shown in Figure 3-100.

Elevation. Utilities, MEP components, and back-up generators that were located in the basement 

were elevated. The electrical components were elevated to comply with the TMC and CenterPoint 

Energy mandate. 

Monitoring. Continuous flood monitoring systems through a 24-hour central operations facility are 

used to monitor and forecast incoming storms. Elements of TCH’s emergency plan are triggered 

at different benchmarks, but important preparations, such as ensuring the availability of sufficient 

supplies and staffing, are typically reviewed 72 to 96 hours prior to the anticipated arrival of a storm. 

TCH staff reportedly began tracking Hurricane Harvey 12 days in advance of landfall when the 

storm was first forecast as a tropical wave. 

Planning. Prior to an event, TCH undertakes advanced placement of materials and staffing. TCH 

rented additional potable water tanker trucks to supplement on-site storage tank supplies. In 

addition, construction crews and water remediation crews were placed under contract and housed 

on site during the storm. TCH also stockpiled drywall in advance of the storm so that crews could 

begin repairs immediately when the storm passed.

Preparedness. TCH management instills a culture of preparedness, including regularly scheduled 

preparedness exercises. This culture of preparedness, supporting by buy-in from executive-level 

management, contributed greatly to the successful performance of this facility and its operations 

during Hurricane Harvey.

Performance during Harvey

Staff implemented emergency preparedness procedures well in advance of the storm and were 

prepared to ride out the storm. TCH did not evacuate any patients and did not turn away any 

patients, although there appears to have been some miscommunications with emergency medical 

service providers about the hospital’s status. 

Figure 3-100: Flood log gate (left) and swing floodgate (right) at parking garage entrances
Water depth in the streets around the TCH was reported as 3 feet, but water never rose high enough 

to get close to any of the buildings or any of the flood barriers. Various leaks at the facility due 

to wind-driven rain were reported, and some floor drains in the basement and stairwells became 

overwhelmed by rainfall, but these water intrusions were effectively managed.

Effect on operations. The TCH facility was only minimally impacted by Hurricane Harvey. It never 

lost services or the ability to provide patient care during the event. TCH put numerous mitigation 

measures in place to deal with an event such as Hurricane Harvey. The mitigation measures, which 

were not fully tested by Harvey, performed well. 

Summary of MAT Observations

+ The buildings that make up the TCH are located in Shaded Zone X outside of the SFHA, 

and are thereby exempt from the flood provisions of model codes and standards such as the 

IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding.

+ Building damage from Tropical Storm Allison resulted in the performance of a flood 

vulnerability assessment and subsequent installation of dry floodproofing mitigation 

measures. 

+ Based on previous flooding events and goals of providing healthcare in all conditions, 

hospital management has instilled a culture of preparedness that is reinforced by annual 

training exercises. 

+ TCH developed an extensive emergency operations plan for hurricanes that had the hospital 

well prepared for the event. 

+ TCH installed numerous mitigation measures in place to deal with an event such as 

Hurricane Harvey. The mitigation measures, which were not fully tested by Hurricane 

Harvey, performed well. 

3.2.10.2 The University of Texas MD Anderson Cancer Center

The MD Anderson Cancer Center consists of three campuses: the 

north, mid, and south. The north campus is located north of Brays 

Bayou, within the encompassing TMC, while the mid-campus and 

south campus are both located south of Brays Bayou. The combined 

MD Anderson Cancer Center facilities at TMC consist of over 16 

million square feet of space. The MD Anderson Cancer Center is a 

specialty hospital for cancer care with more than 600 beds and 20,000 

employees. 

The north campus facilities, centered around the Main Building, are 

located at 1515 Holcombe Boulevard and consist of numerous independent buildings, including 

outpatient clinics, research facilities, and a radiation outpatient center. The buildings of the MD 

Anderson north campus are connected to one another by above-ground pedestrian walkways, but 

are not connected to any other TMC institutions (see Figure 3-101 and Figure 3-102). 

MD ANDERSON 

CANCER CENTER

FIRM = Zone AE 

and Shaded Zone X

(see Figure 3-103)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-103

FLOOD-RELATED OBSERVATIONS
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FLOOD-RELATED OBSERVATIONS

Figure 3-101: Aerial view of the MD Anderson Cancer Center north campus looking north
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-105

FLOOD-RELATED OBSERVATIONS

Figure 3-102: Map of the MD Anderson Cancer Center north campus 

MAP SOURCE: OBTAINED FROM MD ANDERSON CENTER, USED WITH PERMISSION
Most of the north campus facilities are situated in Zone AE, including the Main Building, and the 

rest are in Shaded Zone X. The facilities on the north campus have different BFEs, depending on 

location. The mid-campus administrative building and a number of research buildings at the south 

campus facility are located in Shaded Zone X and Unshaded Zone X south of Brays Bayou. The 

north and mid-campus areas are shown on Figure 3-103.

Figure 3-103: FIRM for MD Anderson Cancer Center north campus and mid-campus buildings along Brays Bayou

3-106 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Dry Floodproofing Mitigation Measures 

During Tropical Storm Allison in 2001, the MD Anderson Cancer Center lost power and experienced 

minor flooding and damage. After 2001, a flood vulnerability assessment was conducted to identify 

locations where water can infiltrate the Main Building. Subsequently, many flood mitigation 

measures have been implemented on the MD Anderson Cancer Center campus, primarily at the 

Main Building. Additionally, several of the MD Anderson Cancer Center buildings were constructed 

after Tropical Storm Allison and as a result, were designed with finish floor elevations and utilities 

elevated above the 0.2-percent-annual-chance flood elevation. These newer buildings include a 

few on the north campus (Mays Clinic, Duncan Building, and Pickens Tower), all the mid-campus 

buildings, and most of the south campus buildings. A description of implemented flood mitigation 

measures follows:

Perimeter floodwall, floodgates, and sump pumps. A complete perimeter floodwall (see Figure 

3-104) with more than 75 active and passive floodgates (see Figure 3-105) was installed to provide 

protection against a 0.2-percent-annual-chance-of-exceedance event. After installation of the 

perimeter floodwalls, sections with aquarium glass and passive floodgates were independently 

tested to ensure adequate performance. Sump ejector pumps were installed throughout the campus 

behind the flood barrier.

Figure 3-104: Marble-faced floodwall (left) and aquarium glass windows in floodwall (right) at the Main Building

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-107

FLOOD-RELATED OBSERVATIONS

Figure 3-105: Passive floodgates (red arrows) at entrances through floodwall at the Main Building
Flood doors. Basement-level flood doors (see Figure 3-106) were installed to compartmentalize 

different areas if the basement were to become subject to flooding.

Figure 3-106: Flood doors in basement that subdivide basement areas within the Main Building

Elevation. All utilities and backup generators were elevated to upper floors. The electrical 

components were elevated to comply with the TMC and CenterPoint Energy mandate. 

Monitoring. Continuous flood monitoring systems through a central operations facility, located in 

the Main Building, are used to monitor and forecast incoming storms (see Figure 3-107). Elements 

of MD Anderson Cancer Center’s emergency plan are triggered at different benchmarks, but 

important preparations, such as ensuring sufficient supplies and staffing, are typically reviewed a 

few days in advance of a predicted storm.

3-108 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-107: 

Central operations 24-hour 

facility that provides 

continuous flood monitoring
Preparedness. The MD Anderson Cancer Center management instills a culture of emergency 

preparedness, including regularly scheduled preparedness exercise. These drills are unannounced 

and timed; due to the number of gates in the dry floodproofing system, only 10 gates are 

closed during the any individual drill. These drills are conducted until each gate in the dry 

floodproofing system has been closed. Maintenance on the gates is performed twice a year, before 

and after hurricane season, and sump pump maintenance is performed quarterly. This culture of 

preparedness, supported by buy-in from executive-level management, contributed greatly to the 

successful performance of this facility and its operations.

Performance during Harvey

Four days before the storm arrived in Houston, the MD Anderson Cancer Center’s Incident 

Command team started making organizational decisions about the institution. Incident Command 

processes were in place during the storm and into recovery. Rotations were in place to allow the 

Incident Command team and others to rest during the event and through the post-storm recovery 

process. The north campus buildings are connected to one another by above-ground pedestrian 

walkways. During events such as Harvey, the outer buildings such as the Mays Clinic, Duncan 

Building, and Pickens Tower are staffed only to the extent required to maintain critical services; 

the other staff and support personnel relocate to the Main Building, which is where the in-patient 

functions are housed and is therefore critical to providing continued services. 

Two days prior to Hurricane Harvey’s landfall, MD Anderson Cancer Center personnel removed 

trash and hazardous waste from its campus; inspected the roofs of all buildings for possible debris 

sources and removed any items found; verified that rooftop equipment was properly secured; and 

began the process of installing active floodgates and manually raising the passive floodgates. 

During Hurricane Harvey, the north campus of MD Anderson Cancer Center was entirely cut off by 

floodwater for just over 2 days, with no access to additional food, supplies, or municipal water. 

Utility service and patient care. None of the buildings on any of the campuses of the MD Anderson 

Cancer Center lost utility service or the ability to provide patient care during Hurricane Harvey. 

Staff implemented their emergency preparedness procedures well in advance of the storm and were 

prepared to ride out the storm. As part of these procedures, elective procedures and admissions 

were cancelled and patients were discharged as rapidly as possible, enabling a reduction of their inpatient census to 540 patients and allowing staff to be reduced to a designated “ride-out” team of 

1,000. MD Anderson Cancer Center personnel brought patients who were being treated with daily 

chemotherapy into the main facility so that they would not miss any of their treatments as a result of 

storm-related travel impacts. They did not evacuate any patients and did not turn away any patients. 

At-grade areas. Portions of the Main Building were surrounded by approximately 3 feet of water in 

the streets (see Figure 3-108), but water never rose high enough to threaten the building or any of 

the flood barriers. Approximately 6 inches of water was reportedly up against the flood barriers in 

certain locations.

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-109

FLOOD-RELATED OBSERVATIONS
A manhole located on the dry side of the floodwall at the southwest corner pavilion drop-off area 

whose cover blew off because of overpressure from the stormwater sump pump system was a point of 

failure. This resulted in minor flooding in the building lobby. Other sources of water infiltration in 

the Main Building included:

+ Water flow through a conduit that connected to utility vault in the street on the other side of 

the floodwall. 

+ Wind-driven rain that entered the buildings in the north campus. 

Effect on operations. The MD Anderson Cancer Center was only minimally impacted by Hurricane 

Harvey. At the time of the MAT visit, all damage had been repaired and all areas were functioning 

normally. 

Thirty-five percent of the staff was directly affected by the floods and much of the staff was working 

long hours, the hospital brought in additional clinical staff (after flooding receded) from other 

hospitals, such as:

+ University of Texas (UT) Southwestern – a fellow UT system institution in Dallas

+ Banner MD Anderson Cancer Center – an MD Anderson Cancer Network® partner in 

Phoenix, AZ

+ OhioHealth – an MD Anderson Cancer Network–certified member in Columbus, OH

+ Northwell Health – a network of health care facilities based in New York

Figure 3-108: 

Water level on Bates Street 

outside of MD Anderson 

Cancer Center north campus 

at the Main Building during 

Hurricane Harvey

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FLOOD-RELATED OBSERVATIONS
Summary of MAT Observations

+ The buildings that make up the MD Anderson Cancer Center are located in Shaded Zone 

X or Zone AE; their BFEs vary, depending on their location along Brays Bayou. Buildings 

located in Zone AE should follow the flood provisions of model codes and standards such as 

the IBC and ASCE 24. Although not required, flood-resistant features are recommended as a 

best practice even for buildings located outside the SFHA, especially those with a history of 

flooding.

+ Building damage from Tropical Storm Allison resulted in the performance of a flood 

vulnerability assessment and subsequent installation of dry floodproofing mitigation 

measures. 

+ Independent testing of the dry floodproofing mitigation measures ensured they would 

properly function when tested by a flooding event. 

+ Based on previous flooding events and goals of providing healthcare in all conditions, 

hospital management has instilled a culture of preparedness that is reinforced by annual 

training exercises. The annual exercises are unannounced and the time to install each 

component and the entire dry floodproofing system is timed. 

+ MD Anderson developed an extensive emergency operations plan for hurricanes that had the 

hospital well prepared for the event. 

+ MD Anderson installed numerous mitigation measures to deal with an event such as 

Hurricane Harvey. The mitigation measures performed as designed. MD Anderson escaped 

Hurricane Harvey with only minor damage to interior finishes in the main building. 

3.2.10.3 Harris Health System Ben Taub Hospital

The Ben Taub Hospital, located at 1504 Taub Loop, is located at 

the east side of the TMC campus just west of the Houston Zoo and 

Hermann Park (see Figure 3-109). The site is situated in a Shaded 

Zone X (see Figure 3-110). The hospital has one basement story 

and six above-ground stories. The building was originally built in 

1963, with an addition in 1990 and major remodel in 2014. 

The Ben Taub Hospital is a 586-licensed-bed facility (450 staffed) 

with an elite Level 1 trauma center that is part of the Harris County Hospital District Ben Taub 

is staffed by the faculty, residents, and students from Baylor COM and is one of the most active 

hospitals in southeast Texas, with over 100,000 emergency department visits annually. Ben Taub is 

also an important psychiatric facility for the region.

BEN TAUB HOSPITAL

FIRM = Shaded Zone X

(see Figure 3-111)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-111

FLOOD-RELATED OBSERVATIONS
Figure 3-109: Harris Health System Ben Taub Hospital aerial view looking north

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Dry Floodproofing Mitigation Measures

During Tropical Strom Allison, Ben Taub Hospital temporality lost power but did not sustain any 

flood damage. The hospital does not have any surface floodgates or surface dry floodproofing 

measures; it is located on the highest grade elevation in the TMC. The Harris County Emergency 

Management Office provides much of the hazard mitigation planning and flood control at the site. 

The hospital is connected with the Baylor COM building through a single basement tunnel. This 

tunnel is equipped with a submarine door designed to protect Baylor’s basement from flooding with 

water from the Ben Taub tunnel (see Figure 3-111) or vice versa.

Figure 3-110: FIRM for Ben Taub Hospital and Baylor College of Medicine

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-113

FLOOD-RELATED OBSERVATIONS
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Figure 3-111: 

Basement tunnel submarine 

door between Ben Taub 

Hospital and the Baylor 

College of Medicine (viewed 

from Ben Taub)

Performance during Harvey

During Hurricane Harvey, floodwater came within approximately 6 inches of the first floor elevation 

of Ben Taub Hospital but did not breach the perimeter. 

Basement. Portions of the basement flooded as a result of two pipe breaks caused by backflow 

overpressures. Stormwater from the Ben Taub and other at-grade storm drains discharge to 

a stormwater tank operated by Harris County. When water levels in Brays Bayou prevent gravity 

drainage, stormwater collects in a tank and is then pumped into Brays Bayou. During Hurricane 

Harvey, the pumps to remove the stormwater from the tank malfunctioned, causing the tank to 

completely fill with water, pressurizing all of the connecting stormwater lines and causing the two 

stormwater pipes inside Ben Taub Hospital to break. After the pipe break, maintenance personnel 

from Harris County were contacted and dispatched to manually start the stormwater pumps. Once 

back pressure in the system was reduced, hospital facility engineers were able to repair the broken 

pipes and stop the flow of water. 

Food service. Floodwater in the basements from the broken pipes destroyed approximately 30 

percent of the hospital’s food stores and other service-related items. As a result of the losses to the 

food stores and other supplies, hospital staff attempted to transfer five patients in the Intensive Care 

Unit. However, the intense flooding throughout the Harris County region forced them to bring 

three of the transfers back to the hospital within 2 hours of their original departure. The hospital 

was unable to admit new patients or conduct procedures for 7 days following the event.

Utility service. Water from the broken pipes damaged an electrical panel that controls the production 

of chill water. Chill water production halted, forcing the air conditioning in the hospital to turn off. 

In the days after Hurricane Harvey, indoor temperatures reached 88 degrees Fahrenheit (°F). 
Effect on operations. Water also came close to other electrical equipment, which could have cut 

off all electricity to portions of the hospital and would have resulted in an extended shutdown of 

the hospital. Fortunately, hospital facility engineers were able to channel the floodwater into an 

auditorium and subbasement areas to protect this electrical equipment and other areas of the 

basement from floodwater (see Figure 3-112). During the MAT visit, repairs in the basement were 

still underway, but the hospital was operational.

Figure 3-112: Basement auditorium used as water retention area (left) and reported water level in subbasement 

indicated by staff member (right)

Summary of MAT Observations

+ The buildings that make up the Ben Taub Hospital are located in Shaded Zone X. All of the 

buildings are located outside of the SFHA and thereby exempt from the flood provisions 

of model codes and standards such as the IBC and ASCE 24. Although not required, floodresistant features are recommended as a best practice even for buildings located outside the 

SFHA, especially those with a history of flooding.

+ The failure of stormwater piping resulted in damage to 30 percent of the food supply in the 

hospital and shorted out an electrical panel that controlled chill water production. 

+ Hospital facility engineers were able to fix the broken pipes and prevented the floodwater 

from damaging electrical equipment that would have caused a significant power failure in the 

hospital. 

3.2.10.4 Baylor College of Medicine (COM)

The Baylor College of Medicine (COM) is located at 1 Baylor Plaza 

(see Figure 3-113). The site is situated in Shaded Zone X (see 

Figure 3-110). The Baylor COM Cullen Building was completed in 

BAYLOR COLLEGE 

OF MEDICINE

FIRM = Shaded Zone X

(see Figure 3-111)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-115

FLOOD-RELATED OBSERVATIONS
1947 and is one of the oldest buildings at the TMC. The campus now contains numerous other 

buildings providing educational and research facilities for approximately 800 medical students, 

1,000 graduate students, 1,000 residents, and 300 allied health students. All of the Baylor COM 

buildings are immediately adjacent to one another and interconnected by basement tunnels. Baylor 

COM is connected to the adjacent Ben Taub Hospital (Section 3.2.9.3) via a single underground 

tunnel.

Dry Floodproofing Mitigation Measures 

Baylor COM was significantly impacted by Tropical Storm Allison in 2001. The entire basement 

flooded because the flood log gates were not installed at the time. Primary and backup power failed, 

and critical storage freezers stopped, resulting in the loss of 60,000 tumor samples and other critical 

research specimens that were housed in the basement. Damages from Tropical Storm Allison were 

estimated at nearly $500 million. With assistance from FEMA’s Public Assistance Program (e.g., 406 

Hazard Mitigation), approximately $9.1 million was provided to fund dry floodproofing mitigation. 

Since Tropical Storm Allison, Baylor COM conducted a flood vulnerability assessment and has 

implemented several flood hazard mitigation projects, as follows:

Floodwall, floodgates, and flood doors. Floodwalls, floodgates, and flood doors were installed to 

block the intrusion of floodwater (see Figure 3-114). The floodwall surrounding the entire campus 

was designed and constructed to meet the 0.2-percent-annual-chance probability flood elevation 

plus 2 feet of additional freeboard. The floodgates in many locations are well designed into the 

architecture of the site and are not readily apparent.

Figure 3-113: Baylor COM aerial view looking north

3-116 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Sump pumps. The basement has eight different sump pits that are sized to handle water intrusion 

into the basement (see Figure 3-115). Each sump pit is sized and fitted with a redundant pump. The 

basement is constructed from flood damage-resistant materials in the areas where water is directed 

to the sump pits.

Figure 3-114: Swing flood door (left) and guillotine floodgate (right)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-117

FLOOD-RELATED OBSERVATIONS

Figure 3-115: Typical sump pit in basement (left) and ejection pipes over floodwall (right)
Elevation. Mechanical and electrical utilities were elevated to protect against floodwater (see Figure 

3-116 and most research facilities were elevated. The electrical components were elevated to comply 

with the TMC and CenterPoint Energy mandate.

Figure 3-116: 

Elevated central plant 

structure (in red outline)

Performance during Harvey

Baylor COM facilities were only minimally impacted by Hurricane Harvey. All classes were cancelled 

during the storm to allow students and staff to stay away from campus during the event. The 

facilities management personnel were stationed on campus to ride out the storm and help set up 

and maintain the flood mitigation devices to protect the campus. Although management personnel 

had been monitoring Hurricane Harvey’s development several days prior to the arrival of the storm 

and implementing initial preparedness measures, they did not begin final preparations until the 

morning of August 26, when it appeared that the impact of Hurricane Harvey was going to be 

greater than originally forecast. 

At-grade. During Hurricane Harvey, the water around the campus was approximately 1 foot above 

grade at the floodwalls and gates. The seal at one gate failed; however, the water seepage flowed to a 

sump pit located near the gate. 

Basement. A 1940s-era cleanout inside the basement failed due to backflow pressures; the failure 

was adjacent to one of the new sump pits installed in response to Tropical Storm Allison and it 

prevented the water from spreading throughout the basement. A mechanical room sump pit failed 

because a conduit penetration through the floodwall was not properly sealed and leaked water onto 

the control panel. Water from this area was removed by the redundant pump. The penetration has 

since been sealed and the control panel has been moved away from the wall. Baylor COM is in the 

process of relocating all control panels to the interiors of rooms. There was also a small amount of 

water intrusion into the research area, but staff used a squeegee to move the water to one of the 

sump pits. 

Effect on operations. The facilities never lost any services on site. 

Summary of MAT Observations

+ The buildings that make up the Baylor COM are located in Shaded Zone X. All of the 

buildings are located outside of the SFHA and thereby exempt from the flood provisions 

3-118 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
of model codes and standards such as the IBC and ASCE 24. Although not required, floodresistant features are recommended as a best practice even for buildings located outside the 

SFHA, especially those with a history of flooding.

+ Building damage from Tropical Storm Allison resulted in the performance of a flood 

vulnerability assessment and subsequent installation of dry floodproofing mitigation 

measures. 

+ The dry floodproofing components and mitigation activities performed at the Baylor COM 

provided a comprehensive flood barrier that performed as designed during Hurricane 

Harvey. Though the building experienced minor areas of water intrusion and pipe breaks 

there was no significant damage or downtime due to loss of function. 

+ Providing redundant sump pumps in each sump pit prevented damage from occurring when 

pumps failed. 

3.2.10.5 CenterPoint Energy Grant Substation

The CenterPoint Energy Grant Substation is located along the 

southern edge of the TMC adjacent to Brays Bayou (see Figure 

3-117). The site is situated in Zone AE, with a BFE of 43.0 feet, on 

the north bank of Brays Bayou adjacent to the floodway (see Figure 

3-118). This substation supplies electric service to all TMC facilities. 

It contains three transformers, but on-site personnel reported that 

a single transformer can carry the full TMC load, if needed.

GRANT SUBSTATION

FIRM = Zone AE

BFE = 43.0 feet

(see Figure 3-119)

Figure 3-117: CenterPoint Energy Grant Substation and TECO Paul G. Bell, Jr. Energy Plant; aerial view looking northeast

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-119

FLOOD-RELATED OBSERVATIONS
3-120 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS

Figure 3-118: FIRM for CenterPoint Energy Grant Substation TECO Paul G. Bell, Jr. Energy Plant

Dry Floodproofing Mitigation Measures 

Although the substation was not damaged during Tropical Storm Allison in 2001, most of the TMC 

facilities lost electrical power because their basements flooded and critical electrical equipment was 

damaged. Because of the significant damage from Tropical Storm Allison and the critical nature of 

the TMC facilities, CenterPoint Energy worked with TMC management to mandate raising electrical 

equipment above the 0.2-percent-annual-chance probability BFE in all TMC buildings and installing 

disconnect switches that allow CenterPoint Energy a means to disconnect any single TMC institution 

from the electrical grid, thereby preventing a system-wide failure. 
As part of the system upgrades after Tropical Storm Allison, a flood vulnerability assessment was 

performed and the following flood mitigation measures were implemented: 

Floodwall. A floodwall surrounding the CenterPoint site was constructed in 2003 (see Figure 3-119) 

with a 30-foot-wide floodgate installed at the southwest corner and northeast corner of the site (see 

Figure 3-120). The floodgates were designed to retain 6 feet of water against the gate with 2 feet of 

additional height for site security. The top of the floodwall is at an elevation of 51 feet and is at least 

8 feet above the surrounding grade for security reasons. The 0.2-pecent-annual-chance-event flood 

elevation is 46.7 feet and therefore, the wall provides 4.3 feet of freeboard for the 0.2-pecent-annualchance event.

Figure 3-119: Exterior substation floodwall with water height shown (left) and interior wall surface (right)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-121

FLOOD-RELATED OBSERVATIONS

Figure 3-120: Substation floodgate
Sump pit and pump. The site also has a sump pit at the southwest corner to evacuate rainwater inside 

the facility and water that gets through the floodwall (see Figure 3-121). The sump pump system was 

designed to remove 3 inches of rainfall an hour from the substation. The sump pump is connected 

to a supervisory control and data acquisition (SCADA) system that indicates its operating status.

Figure 3-121: Substation sump pit and pumps

Performance during Harvey

The substation was only minimally impacted by Hurricane Harvey. Electrical service was never 

disrupted even though water surrounded the facility up to approximately 2 to 3 feet above grade 

on the outside of the floodwall. The sump pumps for removing stormwater reportedly stopped 

working causing water to accumulate to a depth of 6 inches at the southwest corner of the site. The 

SCADA system indicated the pumps had stopped running and a maintenance crew was dispatched 

to manually reactivate the pumps.

Summary of MAT Observations 

+ The CenterPoint Energy Grant Substation is located in Zone AE, adjacent to the floodway, 

with a BFE of 43.0 feet. Buildings located in Zone AE should follow the flood provisions of 

model codes and standards such as the IBC and ASCE 24.

+ Damage to the TMC from Tropical Storm Allison resulted in the need for a flood 

vulnerability assessment and subsequent installation of dry floodproofing mitigation measures 

at the substation. 

+ The dry floodproofing components and mitigation activities performed at the substation 

provided a comprehensive flood barrier, with minimal openings or penetrations, that 

performed as designed during Hurricane Harvey. The substation did not lose its ability to 

distribute power during Hurricane Harvey. 

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FLOOD-RELATED OBSERVATIONS
3.2.10.6 Thermal Energy Corporation (TECO) Paul G. Bell, Jr. Energy Plant

The TECO Paul G. Bell, Jr. Energy Plant is located at 1615 Braeswood 

Boulevard on the north bank of Brays Bayou adjacent to the floodway. 

The facility is in Zone AE, with a BFE of 43.0 feet (see Figure 3-118).

The TECO Paul G. Bell, Jr. Energy Plant is the largest combined heat 

and power chilled water district energy plant in North America. TECO 

produces steam, chilled water, and electricity. TECO has the ability 

to produce 100 percent of its electricity requirements on the energy plant site. The plant delivers 

its products through underground pipes to most of TMC’s member institution buildings. The 

institutions use the energy for air conditioning, space heating, dehumidification, sterilization, 

kitchen and laundry processes, and domestic hot water use. 

The MAT noted that most institutions have backup electric power generators and fuel supplies in 

case they lose externally supplied power, but the majority of the TMC institutions do not have any 

way to produce steam and chilled water themselves, making the services that TECO provides critical 

for continued operations. 

Dry Floodproofing Mitigation Measures 

TECO reported that there was approximately 3 inches of water across the site during Tropical 

Storm Allison in 2001. Although the plant was not damaged during Tropical Storm Allison, most of 

TMC’s facilities lost services because their basements flooded and critical electrical and mechanical 

equipment was damaged. 

Because of the significant damage resulting from Tropical Storm Allison and the critical nature of 

the TMC facilities, TECO undertook the following flood mitigation measures to fortify their supply 

of the necessary steam, chilled water, and electricity. 

Floodwall and floodgates. TECO constructed a floodwall surrounding its site (see Figure 3-122). 

The top of the floodwall is designed to be at the 0.2-percent-annual-chance probability flood 

elevation plus 2 feet of freeboard. TECO also installed floodgates at openings in the floodwall 

to compartmentalize the plant site (see Figure 3-123). After construction of the floodwall and 

installation of the floodgates, joints in the floodwall and the floodgates were independently tested 

to verify that water would not seep through them.

Figure 3-122: TECO floodwall adjacent to Brays Bayou (left image) and along Pressler Street (behind ivy in right image)

TECO BELL 

ENERGY PLANT

FIRM = Zone AE

BFE = 43.0 feet

(see Figure 3-119)

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-123

FLOOD-RELATED OBSERVATIONS
Figure 3-123: Floodgates in floodwall at TECO Energy Plant

Sump pit and pump. TECO constructed sump pits and sump pumps, including the addition of a 

redundant pump (see Figure 3-124).

Figure 3-124: Sump pits and pumps inside TECO floodwall

Preparedness and redundancies. TECO management also implemented very robust emergency 

preparedness policies and procedures with multiple redundancies built into the systems. For 

example, redundant electric supplies were installed. To further strengthen its floodproofing, TECO 

installed restraining devices to secure manholes and underground vault covers (see Figure 3-125).

3-124 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
Figure 3-125: Vault flood cover restraining device (left) and barrels used as manhole cover restraining devices (right)

Performance during Harvey

TECO was minimally impacted by Hurricane Harvey. The plant did not lose any services or its ability 

to provide steam, chilled water, or electricity to TMC customers. TECO personnel implemented 

emergency preparedness procedures well in advance of the storm and were prepared to ride out 

the storm. TECO had 40 staff on site for 51⁄2 days to manage the operations during the event. The 

facility was surrounded by approximately 1 to 4 feet of water in the adjacent streets, with higher water 

depths along the floodwall adjacent to the Bayou. The water did not rise high enough to threaten 

the top of the floodwall surrounding the site. The floodwall and floodgates have approximately 5 

feet of freeboard along Brays Bayou (see Figure 3-126) and there were no reported problems with 

water intrusion into the site through the floodwall or floodgates.

Figure 3-126: Brays Bayou adjacent to TECO Energy Plant floodwall during Hurricane Harvey

PHOTO COURTESY TECO; USED WITH PERMISSION

HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 3-125

FLOOD-RELATED OBSERVATIONS
Summary of MAT Observations 

+ The TECO Paul G. Bell, Jr. Energy Plant is located in Zone AE, adjacent to the floodway, with 

a BFE of 43.0 feet. Buildings located in Zone AE should follow the flood provisions of model 

codes and standards such as the IBC and ASCE 24.

+ TECO’s numerous physical and operational mitigation measures performed well during and 

immediately after Hurricane Harvey. 

+ The dry floodproofing components and mitigation activities performed at the Paul G. Bell, Jr. 

Energy Plant provided a comprehensive flood barrier, with minimal openings or penetrations, 

that performed as designed during Hurricane Harvey. The energy plant did not lose its ability 

to distribute steam and chilled water and to generate electricity during Hurricane Harvey. 

3-126 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

FLOOD-RELATED OBSERVATIONS
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-1

4Wind-Related Observations

The MAT evaluated building systems to determine the 

effectiveness of the various design and construction practices

 and ascertain the effect of code adoption and enforcement on 

reducing wind damage.

Although most of the damage from Hurricane Harvey was caused by flooding, Hurricane Harvey 

generated near design wind speeds that produced pressures that approximated design pressures 

derived from various editions of ASCE 7 (depending on a building’s proximity to the track of 

the storm and building and site characteristics) near where it first made landfall. The MAT was 

deployed to Aransas, Nueces, Refugio, and San Patricio Counties to assess wind performance issues 

of residential and non-residential buildings. 

The MAT primarily examined the wind pressure performance of the MWFRSs and building 

envelopes. The MAT documented the effects of wind-borne debris on building envelopes and rain 

infiltration at building envelope breaches. The MAT also examined the performance of groundand rooftop-mounted solar panel arrays. 

Within the greater Rockport, TX, area, winds from Hurricane Harvey caused extensive damage 

to roof coverings and rooftop equipment, which resulted in rain damage of interior finishes, 
4-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

furnishings, and equipment. Wind-related building damage was primarily attributable to using 

improper materials in hurricane-prone regions; design deficiencies; poor installation of wall 

coverings, windows, and doors and failure to follow guidelines for installations in high-wind zones; 

and inadequate attachment of roof coverings and roof-mounted equipment. MWFRS damage was 

observed mainly at older buildings; the observed building envelope damage for more recently 

constructed residential and non-residential buildings was less severe, but was significant. The MAT 

observed one ground-mounted solar array and two rooftop-mounted solar arrays, each with varying 

degrees of damage.

MAT observations. Evaluating buildings to observe performance of residential and non-residential 

buildings, as well as solar panel arrays, was one of the MAT’s main goals. In Aransas, Nueces, 

Refugio, and San Patricio Counties, the MAT primarily examined the wind pressure performance 

of MWFRS and building envelopes, and the effects of wind-borne debris on building envelopes, and 

rain infiltration at building envelopes. 

Chapter organization. The MAT observations of wind-impacted buildings are divided into three 

main sections: Residential Buildings (Section 4.1), Non-Residential Buildings (Section 4.2), and 

Wind Performance of Solar Panel Systems (Section 4.3). 

4.1 Residential Buildings

The Hurricane Harvey MAT visited numerous residential buildings (single family homes and 

apartment buildings) in Aransas, Nueces, Refugio, and San Patricio Counties. The MAT assessed 

the performance of the MWFRSs as well as building envelope components of buildings with varying 

ages and governing building codes.

Texas does not have an adopted building code at the State level but rather allows and encourages 

counties and municipalities to adopt the latest version of the IRC and ASCE 7. At the time of 

Hurricane Harvey, the latest versions were IRC 2015 and ASCE 7-16. Many cities in the areas affected 

by Hurricane Harvey had adopted the 2009, 2012, and 2015 IRC and ASCE 7-05. Prior to these 

adoptions, most of the coastal cities had adopted IRC 2000 and ASCE 7-98. The Texas Department 

of Insurance (TDI), which is the administrator of coastal windstorm insurance, adopted IRC 2006 

in July 2007. 

General Observations

The MAT observed that roof systems of residential buildings were particularly vulnerable to the 

high winds of Hurricane Harvey. Positive wind pressures under roof eaves, large overhangs, and 

roof surfaces caused significant damage to many homes. The MAT also observed broken windows 

and garage doors.

TDI has required tie-downs and wind clips since the first printing of the requirements to obtain 

insurance from the Texas Windstorm Insurance Association, described in the Texas Windstorm 

Insurance Association Building Code for Windstorm Resistant Construction, developed by the TDI. Such 

connections include top plate-to-foundation connections with bolts or stud-to-bottom plate clips 

with stud-to-top plate clips at every other stud. Wind clips from top plates to trusses or ceiling joists 

are also required, with the associated rafter allowed to be shear-nailed to the joist. On many of the 

older homes, the MAT observed that either poor installation or intermittent spacing of these devices 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-3

WIND-RELATED OBSERVATIONS

intended to prevent wind uplift, which led to significant failures. Section 4.1 includes a discussion 

of wind-related observations for residential buildings. Specifically, the section discusses structural 

systems, non-load-bearing walls, wall coverings, roof coverings, roof ventilation, soffits, fascia, doors, 

windows, shutters, garage doors, and damage produced by wind-borne debris impacts. 

4.1.1 Structural Systems / Main Wind Force Resisting Systems

The primary determinant for retaining the structural integrity of a building is the proper design 

and installation of the Main Wind Force Resisting System (MWFRS). The MAT observed successes 

and failures of the MWFRS in the residential buildings that were visited. This section explains the 

MWFRS, with examples from the rebuilding that was occurring in the area affected by Hurricane 

Harvey, and discusses the importance of connectors and sheathing in transferring loads. A 

discussion of MAT observations, both successes and failures, 

of these structural systems follows. 

According to the design load standard referenced in 2009 

IRC and ASCE 7-05, the MWFRS is an assemblage of 

structural elements that provides structural support and 

stability. The MWFRS can be thought of as the portion of 

a building’s structural frame that collects dead loads, wind 

loads, and other live loads from the building envelope 

and transfers these loads to the ground via the building’s 

foundation, whether a slab-on-grade or elevated pier system. 

Technical Fact Sheet 4.1, “Load Paths,” in FEMA P-499 (2010b) illustrates the concept of load paths 

and highlights important connections in a wind uplift load path. Elements of the building envelope 

that do not qualify as part of the MWFRS are identified as C&C, which includes siding, windows, 

doors, and roof-covering materials.

Although some of the residential structures the MAT surveyed after Hurricane Harvey were 

not in municipal jurisdictions and had no building code inspection requirement, many were in 

jurisdictions that had adopted the 2009, 2012, and 2015 IRC. Wind-related building failures ranged 

from roof and wall structure failure to loss of siding and damage to openings. Wall and roof failures 

are considered structural failures of the MWFRS.

Connectors and sheathing are critical elements of the MWFRS and are discussed below.

Connectors. Structures in coastal high wind zones should have robust MWFRS connections to 

adequately transfer loads from the roof structure to the wall structure and into the foundation’s 

system.

Figures 4-1 and 4-2 show a two-story apartment building under construction that is well connected 

by wall and roof connectors and structural sheathing.

The MAT also observed MWFRS connections using all-threaded tie rods extending from the 

foundation or elevated support structure with continuous connections to the top floor top plate. 

The system in Figure 4-3 uses floor-to-floor couplings, heavy nuts, and square washers. This system 

was observed in existing and new construction.

CONNECTORS

Additional information on 

connectors can be found in 

Technical Fact Sheet 4.3, “Use 

of Connectors and Brackets,” 

in FEMA P-499 (2010b).
4-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-1: 

Apartment building under 

construction (Rockport)

Figure 4-2: 

Clips connecting stud to 

bottom plate and anchorbolted bottom plate to slab 

(red arrow) (Rockport)

Sheathing. In addition to robust connectors, another vital part of the MWFRS is the sheathing—

both roof and wall sheathing. Roof sheathing transfers roof loads to the rafters and trusses. Wall 

sheathing in a shear wall transfers all of the lateral loads to the wall system, which transfers the loads 

to the foundation or pier and beam system. To perform as intended, sheathing must be rated for its 

purpose and installed properly with fasteners that are installed according to the building code and 

manufacturer’s recommendations. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-5

WIND-RELATED OBSERVATIONS

Figure 4-3: 

An example of all-threaded 

MWFRS connection system 

(Rockport)

The green wall in Figure 4-1 is an example of rated structural sheathing that is properly installed 

and incorporates a water-resistive barrier. Figure 4-4 is an example of sheathing material that was 

attached improperly, making it potentially vulnerable to failure. Nails that miss their intended target 

are often referred to as “shiners.”

Figure 4-4: 

Sheathing nails that missed 

the bottom plate (shiners) 

are shown with red arrows 

(Rockport)
4-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

MAT Observations

Figure 4-5 shows an older home in Rockport that appears to have been built in accordance with the 

1997 TDI Texas Windstorm Insurance Association Building Code for Windstorm Resistant Construction. It 

has wood panel siding, let-in corner wall bracing, straps between the floors, and clips at every other 

stud to the top plate. Figure 4-6 (same house in Figure 4-5) shows wind clips attached from the top 

plates to the ceiling joists. The rafters are missing and may have been toe-nailed to the top plate or 

nailed to the sides of the ceiling joists.

Figure 4-5: 

Older home with roof failure 

due to poor connection of 

the rafters to the joists (120 

mph, Exposure B) (Rockport)

Figure 4-6: 

Another view of the older 

home with roof failure in 

Figure 4-5 (Rockport)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-7

WIND-RELATED OBSERVATIONS

The Rockport home shown in Figure 4-7 is a post-2009 construction on the Intracoastal Waterway 

that experienced design-level winds. Most of the MWFRS remained intact during Hurricane Harvey 

as a result of good connections, but the structure was significantly damaged when a large, open, 

covered front porch suffered major wind uplift. Figures 4-8 and 4-9 illustrate the type and quantity 

of structural wind-resistant connections that kept most of the MWFRS together.

Although the MWFRS did not fail, the connections and support for the large overhangs were not 

sufficiently robust to resist both internal and external wind pressures produced by the 130 mph winds 

at this location. Furthermore, debris impacts caused significant C&C failures. Damage included loss 

of window eyebrow roofs, wind-borne debris missile impacts (green dotted arrows in Figure 4-7), 

damage to the metal roofing, broken hurricane glazing, and extensive water inundation. 

Figure 4-7:

Intracoastal Waterway home 

that experienced a designlevel wind event (130 mph, 

Exposure C) (Rockport)

Figure 4-8: 

Wind-resistant connections 

(red arrows) (same building 

as Figure 4-7) (Rockport)
4-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-9: 

Second floor wind-resistant 

connections (red arrows) 

(same building as Figure 

4-7) (Rockport)

4.1.2 Exterior Wall Coverings

Section 4.1.2 covers exterior wall coverings (also known as cladding or siding), including vinyl siding 

(Section 4.1.2.1), fiber-cement lap siding (Section 4.1.2.2), brick veneer (Section 4.1.2.3), and other 

cladding types (panels of wood and hardboard) (Section 4.1.2.4).

4.1.2.1 Vinyl Siding

The most important factors for vinyl siding performance during a high-wind event are the selection 

of siding that is appropriate for the designated wind speed at that location and the use of proper 

application techniques and installation details. Proper application techniques and installation 

details include using the right accessories, such as starter strips, receivers, and utility trim; selecting 

and placing nails; and locking successive panel courses to each other. Siding intended for higher 

wind speeds (greater than 90 mph basic wind speed based on ASCE 7-05) usually has a double-layer 

nail hem that strengthens the vinyl at the point where the nail attaches, thus resisting tearing or 

pull-through of the nail head.

MAT Observations

Although vinyl siding was the predominant and most vulnerable siding observed by the 2008 

Hurricane Ike MAT, the Hurricane Harvey MAT observed significantly fewer newer structures 

clad in vinyl siding. Many of the structures had re-claddings over foam board and original siding 

materials (see Figure 4-10). In a vinyl-sided home in Holiday Beach (Figure 4-11), all of the openings 

were properly protected, but the home lost virtually all of its vinyl cladding. The MAT determined 

that the vinyl siding was not rated for high-wind applications.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-9

WIND-RELATED OBSERVATIONS

Figure 4-10: Older home with vinyl siding (Rockport)

Figure 4-11: 

Home that lost vinyl siding 

(red arrows) and soffits (blue 

dashed arrow) (120 mph, 

Exposure C) (Holiday Beach)
4-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

4.1.2.2 Fiber-Cement Siding

Fiber-cement siding was introduced to the public in the 1950s. The original product was reinforced 

with asbestos. Because of safety concerns regarding asbestos, the industry changed the reinforcing 

product to cellulose in the mid-1980s, and the product was re-introduced in the 1990s. 

According to area building officials and architects, the allowable method of installing fiber-cement 

siding is to nail the top edge of the siding, locating the nail 3⁄4 inch to 1 inch from the top edge prior 

to installing the next piece of lap siding—a method referred to as “blind nailing.” The lower edge 

of the next piece of siding is required to be caulked to prevent wind and water from being blown 

between the lapped edges.

International Code Council Requirements

According to the 2009 IRC, Section R703.10.2, fiber-cement “lap siding shall be lapped a minimum 

of 11⁄4 inches ... and courses may be installed with the fastener heads exposed or concealed ...” 

Unless otherwise stated in the code, installation recommendations relate only to the basic wind 

speeds in the area. However, in high-wind zones, published ratings and International Code Council 

evaluation reports for the application of fiber-cement lap siding require that the siding be facenailed through both layers of siding at the lap joint, as shown in Figure 4-12. The spacing of the 

nails (16 inches or 24 inches) and permitted material exposure depend on the thickness and width 

of the siding boards and wind zone.

Figure 4-12: Installation guidance for fiber-cement siding 

SOURCE: FEMA, 2010b (TECHNICAL FACT SHEET 5.3) 

MAT Observations

Fiber-cement siding failure was common throughout the area that the MAT investigated. Examples 

are shown in Figures 4-13 and 4-14.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-11

WIND-RELATED OBSERVATIONS

Figure 4-13: 

Fiber-cement siding damage 

to a residence (130 mph, 

Exposure C) (Copano Village)

Figure 4-14: 

Fiber-cement siding ripped 

from walls (red arrows) 

(130 mph, Exposure C) 

(Port Aransas)
4-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

The MAT observed improper installations and failed installations of fiber-cement siding. Figure 

4-15 shows a nail that was placed too close to the edge. Figure 4-16 shows fiber-cement siding with 

no caulking, and Figure 4-17 shows failed caulking.

Figure 4-15: 

Fastener installed in fibercement siding 1⁄2 inch from 

edge, which led to failure of 

the plank attachment 

(Port Aransas)

Figure 4-16: 

Failed fiber-cement siding 

without caulking (red arrows) 

(130 mph, Exposure C) 

(Rockport)

Figure 4-17: 

Failed caulking (red arrows) 

(Port Aransas)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-13

WIND-RELATED OBSERVATIONS

4.1.2.3 Brick Veneer

The Hurricane Harvey seaward and inland zones experienced at or near ASCE 7-05 and TDI 

hurricane design wind speeds. Numerous brick veneer failures throughout the Hurricane Harveydamaged areas were observed. The observed performance was reflective of these higher wind 

speeds, but more importantly, showed the lack of adherence to good installation practices. Common 

failure modes include tie (anchor) fastener pull-out due to failure of masons to embed ties into the 

mortar, poor bonding between ties and mortar and mortar of poor quality, and tie corrosion.

Figure 4-18 shows a common problem with brick veneer installation. The misalignment of the tie 

reduces the embedment and promotes veneer failure by tie fastener pull-out. In contrast, Figure 

4-19 provides an example of proper brick installation, which includes:

+ Proper alignment with the mortar joint and bent at a 90-degree angle at the nail head; this 

90-degree bend minimizes tie flexing when ties are loaded in tension or compression (lefthand illustration of Figure 4-19)

+ Embedment in the joint such that mortar completely encapsulates the tie

+ Ties embedded at a minimum of 11⁄2 inches into the bed joint, with a minimum mortar cover 

of 5⁄8 inch to the outside face of the wall as shown 

Figure 4-18: 

Common problem with brick 

veneer installation: sloped 

installation of corrugated 

brick ties offer no resistance 

to horizontal wall movement 

produced by wind pressures

SOURCE: FEMA, 2010b (TECHNICAL 

FACT SHEET 5.4)

Figure 4-19: Example of proper brick installation

SOURCE: FEMA, 2010b (TECHNICAL FACT SHEET 5.4)
4-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-20 shows tie spacing for high-wind zones.

Wind Speed (mph)

(3-Second Peak Gust) Wind Pressure (psf)

Maximum Vertical Spacing for Ties (inches)

16-inch stud spacing 24-inch stud spacing

 90 –19.5 24a,b 16a

100 -24.1 24a,b 16a

110 -29.1 201⁄2b 131⁄2

120 -34.7 17 NAC

130 -40.7 15 NAC

140 -47.2 13 NAC

150 -54.2 11 NAC

a. Maximum spacing allowed by ACI 530-08.

b. In locales that have adopted the 2006 IBC/IRC, the maximum vertical spacing allowed by ACI 530-05 is 18 inches.

c. 24-inch stud spacing exceeds the maximum horizontal tie spacing of ACI 530-08 prescribed for wind speeds over 110 mph.

Notes:

1. The tie spacing is based on wind loads derived from Method 1 of ASCE 7-05, for the corner area of buildings up to 30 feet high, located 

in Exposure B with an importance factor (I) of 1.0 and no topographic influence. For other heights, exposures, or importance factors, 

engineered designs are recommended.

2. Spacing is for 21⁄2 inches long 8d common (0.131 inches diameter) ring-shank fasteners embedded 2 inches into framing. Fastener 

strength is for wall framing with a Specific Gravity G=0.055 with moisture content less than 19 percent and the following adjustment 

factors, Ct=0.8; and CD, CM, Ceg, and Ctn=1.0. Factored withdrawal strength W’=65.6#.

3. The brick veneer tie spacing table is based on fastener loads only and does not take into account the adequacy of wall framing, 

sheathing, and other building elements to resist wind pressures and control deflections from a high-wind event. Prior to repairing 

damaged brick veneer, the adequacy of wall framing, wall sheathing, and connections should be verified by an engineer.

ACI = American Concrete Institute 

ASCE = American Society of Civil Engineers

IBC = International Building Code

IRC = International Residential Code

mph = miles per hour

psf = pounds per square foot

Figure 4-20: Brick veneer tie spacing

SOURCE (MODIFIED FROM): FEMA, 2010b (TECHNICAL FACT SHEET 5.4)

MAT Observations

Numerous brick veneer failures throughout the Hurricane Harvey-damaged areas were observed. 

Many of the brick veneer structures observed by the MAT to have suffered damage from Harvey 

were older residential structures and apartments, but some newer mid-rise condominiums also 

suffered significant masonry cladding failures. The common issues observed by the MAT included 

brick ties that were randomly spaced, with the horizontal spacing ranging from 32 inches to 16 

inches on center and the vertical spacing ranging from 32 inches to 24 inches; see Figure 4-20 for 

proper spacing. Many of the corrugated ties that were observed were rusted and broken, were not 

embedded into the masonry, or had minimal embedment.

Figures 4-21 and 4-22 illustrate a residential brick veneer installation that failed. The damaged brick 

had been cleared prior to the MAT investigation. The installation shown had rusted and broken 

ties, as well as horizontal tie spacing of 32 inches; the vertical spacing of 24 inches is consistent with 

basic wind speed installations.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-15

WIND-RELATED OBSERVATIONS

Figure 4-21: Residence brick veneer failure (120 mph, Exposure B) (Rockport)

Figure 4-22: 

Residence with failed brick 

veneer installation (see also 

Figure 4-23) (Rockport) 
4-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-23 shows a 10-inch double-wythe wing-wall of an apartment building in Port Aransas. Brick 

ties were randomly installed between each wythe, and the corrugated ties connecting each wythe to 

the end brick stack course were attached at 32 inches on center and the corrugated ties were only 

observed in one wythe.

Figure 4-23: Double-wythe brick wing-wall that lost its brick stacked course (130 mph, Exposure B) (Port Aransas)

The Sea Gull Condominiums, a 12-story brick veneered structure in Port Aransas, and the Princess 

Condominiums, a 9-story brick veneered structure south of Port Aransas, experienced brick veneer 

failures. Both structures are in the narrowing portion of Mustang Island between the Gulf and the 

Intracoastal Waterway. Given the height of both buildings and the narrowness of the land mass 

between both bodies of water, as well as Applied Research Associates data, the MAT believes that 

both buildings experienced 140 mph winds with an Exposure D.

The Sea Gull Condominiums are shown in Figures 4-24 and 4-25. The floor-to-floor distance in this 

building is 8 feet; steel brick shelves are located at every other floor, making the supported masonry 

wall height 16 feet. The original brick ties were adjustable “eye and pintle” anchors, but very few 

pintles remained when the MAT observed the building, as shown in Figure 4-25. Since a few of the 

pintles remained, the MAT assumed that all pintles were originally installed. These anchors were 

installed 24 inches on center horizontally and 16 inches on center vertically. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-17

WIND-RELATED OBSERVATIONS

The light blotches on the brick walls shown in Figure 

4-25 are indicative of a wall repair. As shown in this 

portion of the failed wall, the repair appears to have 

been performed using helical stitching anchors that 

were mechanically drilled through the veneer into the 

backup material, which was either CMU or concrete 

columns and beams. The stitching anchors were 

installed through brick joints into the backup material 

at approximately 24 inches on center horizontally and 

16 inches on center vertically.

HELICAL TIES

Helical ties are normally constructed 

of Type 304 or Type 316 stainless 

steel. They are installed with a rotary 

hammer with a special installation 

head and countersunk up to 1⁄2 inch to 

allow repair to be patched with mortar 

or caulk.

Figure 4-24: 

Sea Gull Condominiums 

(140 mph, Exposure D)

(Port Aransas)

DRONE IMAGE
4-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-25: Wall detail of Sea Gull Condominiums (Port Aransas) 

DRONE IMAGE

The reasons for the failure of the original and retrofit anchors in the Sea Gull Condominiums 

structure can only be surmised as being the result of oscillations due to high wind pressures, 

thermal expansion, and/or a poor repair. The Brick Industry Association’s Technical Note 28, Brick 

Veneer/Wood Stud Walls (2012), requires that brick veneer wall heights and anchorage in high wind 

zones be rationally designed for the wind pressures in the wind zone and thermal expansion. The 

repair was likely necessitated by poor spacing of the original eyes and pintles and may have been 

poorly installed. The MAT observed horizontal expansion joints between the top of the brick wall 

and the bottom of each shelf angle that were 16 feet apart (see red dashed arrows in Figure 4-26). 

No vertical expansion joint was observed besides the natural joint that occurs in the inside corner of 

the short wall (shown by a yellow double arrow in Figure 4-26).
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-19

WIND-RELATED OBSERVATIONS

Figure 4-26: Sea Gull Condominiums (140 mph, Exposure D) (Port Aransas)

DRONE IMAGE

The Aransas Princess Condominiums are near the Sea Gull Condominiums and sustained 

similar damage, as shown in Figures 4-27 and 4-28. The stitches observed at Aransas Princess 

Condominiums appeared to be approximately 8 inches on vertical centers and approximately 16 

inches on horizontal centers, so they may have been original to the installation. The MAT observed 

vertical expansion controls, illustrated by green dotted arrows in Figures 4-27 and 4-28.

The failures in both the Sea Gull Condominiums and the Aransas Princess Condominiums occurred 

at the top of the buildings, where wind pressures are highest, and on the southwest faces, where the 

building walls are the hottest.

Figure 4-27: 

Aransas Princess 

Condominiums (140 mph, 

Exposure D) (Port Aransas)

DRONE IMAGE
4-20 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-28: Aransas Princess Condominiums (140 mph, Exposure D) (Port Aransas)

DRONE IMAGE

4.1.2.4 Other Cladding Types

Most other types of cladding, which performed poorly due to rot and decay, are relegated to 1980s 

and 1990s vintage homes.

MAT Observations

Many of the older homes had been re-sided, such as the ones shown in Figures 4-29 and 4-30, or 

were destroyed by Hurricane Harvey and removed prior to the MAT investigation. 

Figure 4-29: 

Older residence with original 

hardboard lap siding (red 

arrow) that had been 

re-sided with blue foam 

insulation vinyl siding 

(130 mph, Exposure C) 

(Key Allegro)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-21

WIND-RELATED OBSERVATIONS

Figure 4-30: 

Older residence previously 

sided with hardboard 

vertical siding (red arrows) 

that had been re-sided with 

foam board and vinyl siding 

(yellow double arrows) (120 

mph wind, Exposure B) 

(Rockport)

4.1.3 Roof Coverings

Damage to roof coverings is one of the leading causes of building performance problems during 

hurricanes. A damaged roof covering allows rainwater to enter the building, which can cause major 

damage to the interior finishes and contents. Such damage can be reduced if building owners 

address damaged roof coverings quickly. In the case of Hurricane Harvey, the historic rainfall—

in terms of intensity and duration—made it difficult for contractors and homeowners to respond 

rapidly to limit the effects of rainwater infiltration.

The MAT observed a variety of roof coverings, including asphalt shingles, architectural standing 

seam metal panels, and various types of cementitious and clay tiles. The type of damage variability 

observed after Hurricane Harvey is consistent with damage observed by MATs after Hurricane 

Charley (FEMA 488), Hurricane Ivan (FEMA 489), Hurricane Katrina (FEMA 549), and Hurricane 

Ike (FEMA P-757). Although roof damage noted in these reports is variable, a commonality shared 

among them is that roofing on hip-roofed residences generally performs better than gabled roofs. 

Data collected by various research teams after Hurricane Harvey supports this finding: over 1,000 

roofs were analyzed and the results showed that hip roofs overall had less severe damage than gable 

roofs (Fulcrum Community, 2018). An example of this is shown in Figure 4-31.
4-22 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

4.1.3.1 Asphalt Shingles

Asphalt shingles are available with Class D, G, H, 

and F labels (see text box). Class D is intended 

for the interior regions of the United States with 

normal ASCE 7 design wind speeds. Classes G, H, 

and F are intended for installation in high wind 

zones as designated by ASCE 7 for the United 

States and by TDI in Texas. Figure 4-32 shows the 

15 coastal and near-coastal counties designated 

by TDI as Catastrophe Areas (refer to Section 

2.2 for additional explanation). According to the 

TDI wind ratings, Class H shingles are required 

seaward of the Intracoastal Canal, and G and F 

would be approved in Inland I and Inland II 

areas.

Figure 4-31: 

Neighborhood showing 

varying examples of gable 

roof (yellow dotted circles) 

and hip roof (red circles) 

performance (120 mph, 

Exposure B) (Rockport)

DRONE IMAGE

ASPHALT SHINGLE CLASS RATINGS

Testing and labeling are prescribed in 

ASTM D 7158-05.* The following classes of 

shingles are specified in this standard:**

Class D: Suitable for use up to 90 

(115) mph

Class G: Suitable for use up to 120 

(150) mph

Class H: Suitable up to 150 (190) mph with 

a six-nail installation

Class F: Shingles with this classification 

are tested in accordance with the old test 

method prescribed in ASTM D 3161.

* Wind speeds cited are design wind speeds in IBC/IRC/

ASCE 7 (based on Exposure C and a maximum mean 

roof height of 60 feet).

** Wind speeds shown in parentheses are from ASTM D 

7158-17.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-23

WIND-RELATED OBSERVATIONS

Figure 4-32: TDI-designated Catastrophe Areas, 2006

ADAPTED FROM: TDI, 2018

MAT Observations

Most of the residences the MAT observed had asphalt shingle roof coverings. The home shown in 

Figure 4-33 is in the Port Aransas area, seaward of the Intracoastal Waterway, and was being reroofed with Class F shingles when the MAT visited it. The 2006 IRC indicates that ASTM D-3161 

Class F is appropriate for sites in all cases where special fastening is required. Section R905.2.6 

indicates that asphalt shingles shall be installed per the manufacturer’s installation instructions. A 

recommended best practice is to use six fasteners per shingle, rather than the typical four, where 

the basic wind speed is greater than 90 mph (ASCE 7-05 wind speed).
4-24 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-33: 

Home being reroofed with 

Class F shingles (see red 

arrows) (Port Aransas)

As previously mentioned, hip roofs tend to perform well when subjected to high winds. The home 

shown in Figure 4-34 is in Port Aransas and lost areas of shingles due to poor adhesion of the 

leading edge of the shingles. Failure along eaves commonly occurs because of incorrect application 

of the starter course and inadequate hand-dabbing of asphaltic roof cement, as recommended in 

Technical Fact Sheet 7.3, “Asphalt Shingle Roofing for High-Wind Regions,” in FEMA P-499 (2010b), 

as illustrated in Figure 4-35.

Figure 4-34: 

Home that lost shingles 

due to poor adhesion of 

the leading edges of the 

shingles (red arrows) 

(Port Aransas)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-25

WIND-RELATED OBSERVATIONS

Figure 4-35: Asphalt shingle roofing for high-wind regions

SOURCE: FEMA, 2010b (TECHNICAL FACT SHEET 7.3)

Hip, gable, and hip rafter ridges are particularly vulnerable to blow-off because winds increase 

over and around corners and edges. Figure 4-36 shows a Fulton home with generally good shingle 

performance apart from damage to the ridge vent and the loss of some eave and hip-ridge shingles 

due to loss of adhesion along the sealing strip.
4-26 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-36: 

Home with damaged 

ridge, hip-ridges, and eave 

shingles (red arrows) due to 

poor adhesion of the shingle 

tabs (Fulton)

4.1.3.2 Architectural Standing Seam Metal Roofing

The two basic types of metal roofing are (1) common corrugated roofing that is surface-screwed to 

the substrate and (2) architectural standing seam metal roofing that is installed with a hidden clip 

system that is screwed to the substrate and to which the roofing is latched. Numerous finish colors 

and types of metals are available in architectural metal roofing.

Most of the metal roofing the MAT observed was prefinished steel. Many manufacturers offer a 20 

year warranty for weather tightness and finish. Performance of this type of roofing depends on the 

quality of the substrate and the installation.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-27

WIND-RELATED OBSERVATIONS

MAT Observations

The Copano Village home shown in Figure 4-37 shows a rake edge of the roof that appears to have 

been installed improperly because no edge nailing or edge trim was observed. Figure 4-38 shows 

another Copano Village home in which the substrate failed under the wind load, causing the metal 

roof to fail. The lack of membrane underlayment between the substrate and the roofing suggests 

that the installation may have been poor. 

Figure 4-37: 

Residence with failed rake 

edge with loss of metal 

roofing edge trim (red 

arrows) (130 mph, Exposure 

B) (Copano Village)

Figure 4-38: 

Residence with failed 

substrate (green dotted 

arrows) and no membrane 

underlayment (red arrows) 

(Copano Village)
4-28 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

The home in Cape Valero shown in Figure 4-39 suffered severe standing seam roofing damage 

when the rake edge of the roof that was installed over asphalt shingles (red double arrows) and the 

rake edge became unlatched from the rake edge trim (blue dashed arrows).

Figure 4-39: Home damaged by wind pressure (130 mph, Exposure C) (Cape Valero)

4.1.3.3 Tile Roofing Systems

Tile roofing systems include clay tile, concrete tile, fiberglass tile, and metal tiles. Installation 

methods of these types of tiles vary. Some tiles are nailed to the substrate, while others require 

nailing strips, either vertical (up the slope) or horizontal (across the slope).

MAT Observations

The Key Allegro home shown in Figure 4-40 has clay tile with horizontal nailing strips. The mode of 

failure appears to have been wind uplift that “zippered” several sections of tile. Figure 4-41 shows a 

home in Copano Village with a concrete tile roof that failed when the roof structure failed.

4.1.4 Soffits, Fascia, and Roof Ventilation

Soffits, fascia, and roof ventilation are all vulnerable to high winds, and their failure can allow water 

into attics, damaging insulation and ceilings.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-29

WIND-RELATED OBSERVATIONS

Figure 4-40: 

Home with clay tile roof 

failure (green arrows) 

(120 mph, Exposure C) 

(Key Allegro)

Figure 4-41: 

Home with concrete tile roof 

failure (red arrows) 

(120 mph, Exposure B)

(Copano Village)

4.1.4.1 Soffits and Fascia

The opening created where the roof extends beyond the plane of the wall below (called eaves on the 

downslope side of a roof and a rake for the end of a gable roof) is normally closed off with a soffit. 

The fascia is the horizontal band at the roof edge. The soffit is the surface bounded by the fascia 

and below the rafters. 

Soffit panels can be wood, hardboard, fiber cement, aluminum, or vinyl. They have aluminum or 

vinyl grilles or small openings, slots, or perforations to provide ventilation into the attic, which is 
4-30 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

particularly important in hot and humid coastal Texas. Soffit venting allows air to enter the attic 

space, circulate through the attic, and be exhausted through passive vents (ridge vents, off-ridge 

vents, or gable end vents) or mechanical vents. The loss of soffit vents can allow hurricane winds 

to drive large amounts of water through the openings and soak insulation, which can lead to mold 

growth and, in some cases, the collapse of ceilings.

Being the leading edge of the roof system, soffits and fascia are particularly vulnerable to high winds. 

Except for steeper sloped roofs, roof edges (eaves and rakes) sustain the highest uplift pressures on 

the roof system.

MAT Observations

The Copano Village home shown in Figure 4-42 is a classic representation of soffit and leading-edge 

sheathing failure due to wind pressurization from below and from within. Figure 4-43, which shows 

the same home, shows the roof overhang snapped off by the winds.

Figure 4-44 shows a soffit re-covered with vinyl soffit panels that were blown off, exposing the 

original attic vent opening. Figure 4-45 shows a soffit opening that was previously covered by a 

ventilating fiber-cement board.

Figure 4-42: 

Home in which soffit and 

roof pressurization caused 

roof failure (red arrows) 

(120 mph, Exposure C) 

(Copano Village)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-31

WIND-RELATED OBSERVATIONS

Figure 4-43: 

Roof overhang that snapped 

off (red arrows); image is 

a different view of home 

shown in Figure 4-42 

(120 mph, Exposure C) 

(Copano Village)

Figure 4-44: 

Vinyl soffit product (green 

dotted arrow) removed by 

the storm, exposing the vent 

opening (red arrows) 

(120 mph, Exposure B) 

(Cape Valero)
4-32 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-45: 

Ventilating fiber-cement 

board removed by the 

storm, exposing the attic 

(red arrows) 

(120 mph, Exposure B) 

(Holiday Beach)

4.1.4.2 Roof Ventilation

Attic ventilation is a process of supplying fresh air through soffits or gable end vents, then exhausting 

the mixed attic air through ridge vents, off-ridge vents, or mechanical ventilators. Manufactured attic 

ridge vents are vulnerable to blow-off in high winds if not installed according to the manufacturer’s 

recommendations. Guidelines require the contractor to cut the decking along both sides of the 

ridge line. Failure of the vent filter can allow blowing rain to enter the attic, and if a portion of the 

vent is lost, a 3-inch slot can open in the ridge and allow direct water intrusion into the attic.

MAT Observations

The Rockport home shown in Figure 4-46 lost a 4-foot section of its ridge vent. The Fulton home 

shown in Figure 4-47 shows a more conventional off-ridge attic vent that performed well, though the 

home lost most of its hip-ridge shingles.

Figure 4-46: 

Home with a portion of ridge 

vent removed by Hurricane 

Harvey winds (red arrows) 

(120 mph, Exposure B) 

(Rockport)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-33

WIND-RELATED OBSERVATIONS

The off-ridge attic ventilators performed well (red arrows) and hip-ridge shingles 

were blown off (green dotted arrows).

Figure 4-47: 

Home with off-ridge attic 

ventilators (120 mph, 

Exposure B) (Rockport)

4.1.5 Doors

Failure of an exterior door has two important consequences. First, the failure can cause a rapid 

increase in internal pressure, which may lead to exterior wall, roof, interior partition, ceiling, or 

structural failure. Second, wind can drive rainwater through the opening, causing damage to 

interior contents and finishes that can lead to the development of mold.

The essential elements of good high-wind door performance include product testing to ensure 

sufficient factored strength to resist design wind loads (both static and cyclic loading); suitable 

anchoring of the door frame to the building; proper flashing, sealants, tracks, and drainage to 

minimize water intrusion into wall cavities or into occupied space; and, for glazed openings, the use 

of laminated glass or shutters to protect against wind-borne debris damage.

MAT Observations

The wood-framed, light-metal-gauge double entry door in the Rockport canal residence, shown in 

Figure 4-48, failed as a result of Hurricane Harvey winds and debris that knocked the inactive door 

leaf off its hinges.
4-34 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-48: 

The inactive leaf of the door 

to this residence failed 

when wind and debris tore 

the door from its hinges 

(red arrows) 

(120 mph, Exposure C) 

(Rockport)

4.1.6 Windows and Shutters

Many of the communities along the Texas coastline affected by Hurricane Harvey had adopted the 

2009 IRC and ASCE 7-05 wind provisions, which require buildings in the most hazardous portion 

of the hurricane-prone region (wind-borne debris regions) to be equipped with impact-resistant 

glazing or shutters and the home to be designed as an enclosed structure.

TDI requires opening protection for both Seaward and Inland I Areas (see Figure 4-32 for TDIdesignated Catastrophe Areas). As required by TDI, glazing or shutters must be impact-resistant as 

prescribed by the ASTM E1886 and ASTM E1996 test standards, which require resistance to impacts 

produced by a 9-pound, wooden, 2x4 board propelled at 34 mph (50 feet per second). Though 

not a TDI standard, many other States require the same resistance for wall and roof assemblies. 

The intent of the impact resistance standard is to minimize the number of breaches in the entire 

building envelope. 

MAT Observations

At the time of the MAT visit, repairs to glazing and shutters on many homes had been started. The 

MAT observed compliant and non-compliant glazing on both new and pre-Harvey installations. The 

MAT was often unable to determine the rating of the existing double-paned windows it observed due 

to access, as well as damage to the outer pane that made the label illegible. The impact resistance of a 

window is best determined when investigating window replacements or windows in new construction 

that still have window labeling in place; see Figures 4-49 through 4-51. The inspector must locate the 

certification label affixed to the window frame to determine tested performance criteria for wind 

and impact tests. The label is issued by a certification agency such as the American Architectural 

Manufacturers Association (AAMA), Window and Door Manufacturers Association, or the National 

Accreditation and Management Institute, Inc, (NAMI).
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-35

WIND-RELATED OBSERVATIONS

Figure 4-49: 

Outside layer of glazing 

sacrificed by the impact of 

wind-blown debris 

(Key Allegro)

Figure 4-50: 

Newly installed impact-rated 

window in new construction 

to replace a window where 

all the panes were broken by 

debris impact 

(120 mph, Exposure B) 

(Estes)
4-36 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-51: 

Impact-resistant glazing in 

new construction (red circle) 

(Cape Valero)

Many of the homes the MAT observed had windows that were protected by impact-resistant shutters 

in lieu of impact-resistant glazing. TDI minimally accepts 15/32-inch plywood shutters pre-cut 

to the size of each door and window. See Figure 4-52, from FEMA P-499, Home Builder’s Guide to 

Coastal Construction (2010b), for recommended methods for plywood shutter attachment to woodframe and masonry walls. The model International Code Council codes do not mandate the use 

of 2x4 stiffeners in conjunction with the wood structural panel, as shown in the illustration. Most 

structures in the affected area of Hurricane Harvey did not incorporate the 2x4 stiffener on the 

15/32-inch plywood panel. Along with plywood shutter installations, the MAT observed many types 

of removable and operable shuttering systems, including classic fixed-in-place overhead coiling 

shutters that generally performed well; see Figures 4-53 through 4-60.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-37

WIND-RELATED OBSERVATIONS

Figure 4-52: Methods of plywood shutter attachment

SOURCE: FEMA, 2010b (TECHNICAL FACT SHEET 6.2)
4-38 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-53: 

Typical plywood shutter 

installation on house 

(Rockport)

Figure 4-54: 

Barn door sliding shutters on 

house shown by red arrow 

(Key Allegro)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-39

WIND-RELATED OBSERVATIONS

Figure 4-55: 

Classic roll-down shutter 

with missile impact (red 

arrow) (Copano Village)

Figure 4-56: 

Operable Bahama shutters 

(red arrow) (Key Allegro)
4-40 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-57: 

Bi-folding shutters (red 

arrows) on house (Rockport)

Figure 4-58: 

Sliding slatted shutter 

system (red arrow) 

(Key Allegro)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-41

WIND-RELATED OBSERVATIONS

Figure 4-59: 

Sliding plywood shutter 

frame system (red arrows) 

on house (Port Aransas)

Figure 4-60: Corrugated metal shutter system and storage system (Cape Valero)
4-42 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

4.1.7 Garage Doors

Because garage doors have a longer span and larger effective area than windows and access doors, 

garage door assemblies must resist higher forces even though they are exposed to the same basic 

wind speed. A breach increases internal pressures within the breached area of the building and 

commonly produces partial building failures in high-wind events, such as tornadoes and hurricanes.

According to the TDI’s Designated Catastrophe Area map (see Figure 4-32), Mustang Island (Port 

Aransas) is classified as Seaward with a 130 mph design wind speed (3-second gust) per 2006 IBC/

IRC as a Category C Exposure. For the 2012 IBC/IRC and later versions, the site would be classified 

as Category D Exposure (flat, unobstructed areas and water surfaces).The Ingleside, Rockport, 

Fulton, and Copano Bay communities are classified as Inland I with Exposure B and a 120 mph 

design wind speed. Unless a structure is elevated and required to have breakaway walls, the garage 

should be protected with doors meeting the required wind speed for the appropriate classification. 

However, TDI does not require garage doors to be impact rated for Inland I, unless the garage door 

includes glazing. TDI requires garage doors to be rated to meet or exceed the code required design 

pressure. Garage doors that are part of a breakaway storage area are not required to comply with 

minimum design pressure requirements specified by code. In the Seaward area, all openings must 

be impact resistant or protected by wind-borne debris panels.

MAT Observations

The MAT observed many garage doors that were not rated for high winds that failed during 

Hurricane Harvey (see examples in Figures 4-61 and 4-62) but very few hurricane-rated garage 

doors that failed. Figure 4-63 shows a partial failure that appears to have been caused by negative 

pressure. Figure 4-64 is a 150 mph-rated hurricane garage door in a new home in Cape Valero on 

Copano Bay (130 mph wind speed, Exposure C) with no damage. Figure 4-65 shows a hurricanerated garage door in a Fulton home remained closed even though it suffered two bent roller 

wheels apparently from the impact of adjacent site construction material (130 mph wind speed, 

Exposure B).

Figure 4-61: Home with wind failure of an unreinforced 

garage door (red arrow) (Cape Valero)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-43

WIND-RELATED OBSERVATIONS

Figure 4-62: 

Home with insulated 

unreinforced garage door 

with loss of the lower 

exterior panel (red arrows) 

(Estes)

Figure 4-63: 

Hurricane-rated garage 

door that was damaged 

(red arrow); cause of failure 

unknown (Cape Valero)
4-44 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-64: 

20 feet x 9 feet hurricanerated garage door that was 

not tested by debris impacts; 

red arrows show hurricane 

door stiffeners (Cape Valero)

Figure 4-65: Hurricane-rated (red arrow) garage door subjected to debris impact resulting in two bent rollers 

(green dotted arrows) (130 mph, Exposure B) (Fulton)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-45

WIND-RELATED OBSERVATIONS

4.1.8 Debris Impacts

Flying debris is a common occurrence in all high-wind events. The size of debris that can become 

wind-borne increases as wind speeds increase. In wind speeds of 120 to 140 mph, such as those 

produced by Hurricane Harvey, significant amounts of lighter debris, such as shingles, metal and 

tile roofing, and building siding, along with heavier debris, such as roof sheathing and structural 

elements, are released as flying projectiles that impact buildings. The impacts of the debris break 

windows and puncture doors, walls, and roofs. The envelope openings produced by these impacts 

allow wind to enter the structure, thereby causing internal pressurization, which, when added to the 

external pressures, can cause the building structure to fail. Furthermore, punctured and broken 

elements allow hurricane rains to enter the structure, thus damaging building contents and soaking 

building elements, which fosters mold growth. 

MAT Observations

The MAT observed debris impacts throughout the Hurricane Harvey damage area as shown in 

Figures 4-66 through 4-71.

Figure 4-66: Post-2009 home that was well anchored and clipped and even had a garage door rated for high-wind 

zones (140 mph, Exposure C) (Key Allegro)
4-46 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-67: 

Impact from 2x4 on fiber 

cement siding (red arrow) 

(120 mph, Exposure C) 

(Key Allegro)

Figure 4-68: 

Plywood debris impact on 

hardboard siding (red arrow) 

(120 mph, Exposure C) 

(Port Aransas)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-47

WIND-RELATED OBSERVATIONS

Figure 4-69: 

Small debris impacts on 

stucco walls (red arrows) 

(120 mph, Exposure C) 

(Key Allegro)

Figure 4-70: 

Multiple debris impacts 

on hardboard siding (red 

arrows) (120 mph, 

Exposure C) (Holiday Beach)
4-48 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-71: 

Large impact on fiber cement 

wall on the backside of the 

same residence as shown 

in Figure 4-66 (red arrows) 

(140 mph, Exposure C) 

(Key Allegro)

4.2 Non-Residential Buildings

Non-residential buildings include commercial, critical, and government facilities that may or may 

not be deemed critical. Critical facilities include schools, fire and police stations, nursing homes, 

and hospitals. The MAT made wind performance observations of all of these building types. 

Section 4.2 includes pertinent observations of the MWFRS (Section 4.2.1); roof systems and rooftop 

equipment (Section 4.2.2); non-load-bearing walls, wall coverings, and soffits (Section 4.2.3); doors, 

windows, and shutters (Section 4.2.4); and building operational issues (Section 4.2.5).

Unless otherwise noted, the estimated wind speed at the buildings discussed in this section was 130 

mph (gust, Exposure C, at 33 feet above grade), based on Figure 1-11. Also, unless noted otherwise, 

the buildings are located in Exposure B. 

General Observations

Roof covering and rooftop equipment damage was the most common type of damage observed for 

all building types. As expected, newer buildings typically performed better than older buildings. 

Critical facilities observed by the MAT generally did not perform significantly better than 

commercial buildings. The observed critical facilities typically did not incorporate the best practices 

provided in FEMA P-424 (schools), FEMA P-543 (critical facilities), and FEMA P-577 (hospitals).
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-49

WIND-RELATED OBSERVATIONS

FEMA P-1000, SAFER, STRONGER, SMARTER: 

A GUIDE TO IMPROVING SCHOOL NATURAL HAZARD SAFETY (2017)

This publication provides “up-to-date, authoritative information and guidance that schools can 

use to develop a comprehensive strategy for addressing natural hazards. It is intended to be used 

by administrators, facilities managers, emergency managers, emergency planning committees, 

and teachers and staff at K through 12 schools. It can also be valuable for state officials, district 

administrators, school boards, teacher union leaders, and others that play a role in providing safe 

and disaster-resistant schools for all. Parents, caregivers, and students can also use this guide to 

learn about ways to advocate for safe schools in their communities.”

Available at www.fema.gov/media-library/assets/documents/132592.

4.2.1 Main Wind Force Resisting System

Although the MAT saw MWFRS failure at some older buildings, the MAT made detailed observations 

of MWFRS failure at only two locations because it believed there would be limited opportunity to 

learn from additional observations of older failed MWFRS. 

4.2.1.1 Nursing Home in Rockport

Figure 4-72 shows a collapsed wood-framed porte cochere at an 88-bed nursing home. Part of the 

roof deck also blew off, as shown in the aerial drone image of this building in the text box titled 

“Aerial Drone” in Chapter 1. The building was not occupied at the time of the MAT observations.

Figure 4-72: Collapsed porte cochere at a nursing home
4-50 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

ADDITIONAL DAMAGE OBSERVED AT NURSING HOME IN ROCKPORT

In addition to the MWFRS collapse observed at the nursing home, a few HVAC units (also known as 

rooftop units) were blown off the roof, and several windows were broken (Figure 4-73). All or most 

of the HVAC units sat on a sheet metal curb adaptor, which sat on a curb. The unit indicated by the 

yellow double arrow in Figure 4-73 is also shown in Figure 4-74. At this unit, straps connected the 

unit, curb adaptor, and curb. The curb adaptor was also screwed to the curb. Some attention was 

given to connecting the unit to the curb. However, although there was a complete load path, the 

load path had inadequate strength to resist the wind load. The curb was not examined to determine 

the type of attachment deficiency because access to the roof was not obtained.

Figure 4-73: 

Blown-off HVAC units at a 

nursing home (see Figure 

4-74 for the unit indicated 

by the yellow double arrow)

Figure 4-74: 

View of one of the HVAC 

units indicated by a yellow 

double arrow in Figure 4-73
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-51

WIND-RELATED OBSERVATIONS

4.2.1.2 Texas Department of Transportation Maintenance Facility in Rockport

The other building with an MWFRS failure that the MAT observed was an older Texas Department 

of Transportation maintenance facility, in which much of the roof structure was blown off (Figures 

4-75 and 4-76). The steel roof deck was welded to steel joists that were supported by unreinforced 

CMU-bearing walls between CMU pilasters.

Figure 4-75:

General view of the leeward 

side of the Texas Department 

of Transportation 

maintenance facility

Figure 4-76:

Aerial view of the 

Texas Department of 

Transportation maintenance 

facility showing damage to 

buildings (Exposure B, with a 

large open patch adjacent to 

and north of the building) 
4-52 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

One large section of the roof assembly was blown approximately 120 feet, and other portions were 

blown approximately 250 feet from the building (Figure 4-76). One wind-borne roof assembly 

flattened a large light fixture (Figure 4-77).

Figure 4-77:

Wind-borne roof assembly 

debris (roof assembly is 

upside down)

All of the maintenance bay doors on the windward side of the building were blown into the building 

(Figure 4-78). Although failure of the large doors increased the internal pressure, the primary 

cause of roof structure failure was inadequate connection of the steel joists. In some locations, the 

welds between the joist and bearing plate failed (Figure 4-79). However, the typical failure mode was 

uplifting of the bearing plate because the plate’s studs were not grouted into the bond beam (Figure 

4-80).

Figure 4-81 shows the opposite side of the wall shown in Figure 4-78. The exterior windows were 

protected by storm shutters. The shutters were not labeled. At this building, shutters were not 

effective at mitigating damage because there were other significant vulnerabilities (e.g., inadequately 

attached roof joists and decking) that had not been addressed.

The MAT visually evaluated the arc spot welding of the deck to the joists. Similar to observations 

made by several previous MATs during past events, weld quality varied. Figure 4-82 shows two 

adjacent deck arc spot welds. One weld was superficial—the deck detached from the weld. The other 

weld was stronger; a portion of the deck remained attached to the weld.

At the time of the MAT visit, a portable communications tower had been deployed to the site 

to compensate for the collapsed communication tower (Figure 4-83). Post-event response is 

more difficult when vital communications towers fail, thus necessitating the deployment of a

portable tower.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-53

WIND-RELATED OBSERVATIONS

Figure 4-78:

Windward side of the 

building

Figure 4-79:

Joist bearing plate that is 

still attached to a bond beam 

that blew off
4-54 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-80: 

Bearing plate studs that 

were not grouted into the 

bearing wall and provided 

no uplift resistance. This 

condition was observed at 

many of the joists

Figure 4-81:

Although the exterior 

windows were protected 

with shutters (red arrows), 

the roof structure failure 

nullified their effectiveness

IMPORTANCE OF WIND VULNERABILITY ASSESSMENT

The Texas Department of Transportation Maintenance Facility illustrates the importance of 

performing a wind vulnerability assessment prior to implementing wind mitigation measures, such 

as installing storm shutters. If a reasonably thorough assessment is not performed before executing 

mitigation work, there is high potential that mitigating significant vulnerabilities will be overlooked. In 

addition, as shown in Figure 4-81, the implemented mitigation may not be effective.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-55

WIND-RELATED OBSERVATIONS

Figure 4-82: Deck arc spot welds

Figure 4-83:

Portable 

communications tower
4-56 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

4.2.2 Roof Systems and Rooftop Equipment

Roof systems. A variety of roof systems were observed, including built-up roofs (BURs), modified 

bitumen, single-ply membranes (adhered and mechanically attached), metal panels, asphalt shingles, 

and tile. Older roof systems generally did not perform well. Several of the newer roof systems did 

not blow off, but many were punctured by wind-borne debris (much of which was displaced rooftop 

equipment). Improved wind performance of metal edge flashings and copings in newer construction 

appeared to be a significant contributor to the reduction in the number of membrane blow-offs. 

The improved performance of the metal edge flashings and copings is likely due to IBC’s reference 

to ANSI/SPRI/FM 4435/ES-1 2017, Test Standard for Edge Systems Used with Low Slope Roofing Systems 

(ES-1 was first incorporated into the 2003 edition of the IBC).

Rooftop equipment. Common rooftop 

equipment failures included condenser 

and HVAC unit blow-off due to lack of or 

inadequate attachment to curbs, blow-off of 

HVAC unit access panels, blow-off of HVAC 

sheet metal unit enclosures (cabinets), blowoff of condensate drain lines, and blow-off 

of lightning protection systems (LPS). When 

HVAC units blow off their curbs, rain can 

freely enter the building. Wind-borne rooftop 

equipment, including access panels, sheet 

metal unit enclosures, condensate drain 

lines, and LPS can puncture and tear roof 

membranes. 

Portions of several roofs were tarped at the time of the MAT observations. It was not possible to 

determine the cause of damage in many of the tarped areas. Some of the observed roofs only 

experienced roof membrane or rooftop equipment damage, while others experienced both types of 

damage. The following subsections provide a synopsis of key observations.

ADDITIONAL GUIDANCE

USVI Recovery Advisory 2, Attachment of 

Rooftop Equipment in High-Wind Regions

(2018d), provides guidance for attaching new 

and existing rooftop equipment, preparations 

prior to hurricane landfall, and post-event 

assessment.

Developed by the MAT deployed to the U.S. 

Virgin Islands, it incorporates findings from the 

Hurricane Harvey MAT.

4.2.2.1 Regional Medical Center in Aransas Pass

Figures 4-84 through 4-93 show a regional medical center in Aransas Pass. This older facility had an 

aggregate surfaced BUR over steel deck and joists. Beginning with the 2006 edition of IBC, aggregate 

roof surfacing is not permitted in hurricane-prone regions. However, there is no provision in the 

IBC or International Existing Building Code® (IEBC®) that requires existing aggregate surfaced 

roofs to be removed. The concern with aggregate surfacing is that wind-borne aggregate has the 

potential to break unprotected glazing. Also, people arriving at a hospital during a hurricane may 

be injured by aggregate blowing off the hospital’s roof.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-57

WIND-RELATED OBSERVATIONS

Figure 4-84: General view of the regional medical center (Aransas Pass)

A large portion of the roof membrane over the emergency room area blew off (Figures 4-85 and 

4-86). In one area, the blow-off appeared to be initiated by the lifting of the top nailer to which the 

gutter was attached (Figure 4-87). In other areas, gutter uplift initiated the blow-off.

Figure 4-85:

Aerial view of the vicinity 

of the hospital (Exposure B, 

with open patches

to the northwest) 

(Aransas Pass)
4-58 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-86:

View of emergency repairs 

to the roof above the 

emergency room area

Figure 4-87:

Emergency room roof 

membrane

Figure 4-88 shows an insulation moisture relief vent. These vents were common in the late 1970s, 

but their use declined after research found them to be ineffective. The vent’s plastic cap is missing. 

Based on the fact that the top of the vent was fractured, the cap was likely dislodged by wind-borne 

debris. In this condition, rain was able to enter through the open top of the vent and migrate into 

the interior of the hospital.

There was extensive damage to rooftop equipment (Figures 4-89 through 4-91). Rain entered the 

hospital at some of the damaged equipment penetrations, and wind-borne equipment may have 

punctured the roof membrane in some locations. In some instances, displaced equipment had been 

attached, but the attachment was inadequate. In other instances, the equipment was not attached 

at all.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-59

WIND-RELATED OBSERVATIONS

Figure 4-88:

Unprotected vent opening

Figure 4-89:

Inadequate attachment of 

rooftop condenser
4-60 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

The condensers shown in Figure 4-90 were attached to 4x4 wood sleepers that simply rested on the 

roof surface. This type of equipment support (i.e., lack of anchorage) is inadequate. Portions of the 

sheet metal unit enclosure (cabinet) at one of the condensers were blown away. Wind-borne sheet 

metal unit enclosures can puncture roof membranes and break unprotected glazing.

Figure 4-90:

Inadequate attachment of 

rooftop condensers

Figure 4-91 is a view of a displaced satellite dish. Rather than being mechanically attached to the 

roof structure, the base plates of the satellite dish’s support legs simply rested on the roof surface 

and were ballasted with solid CMUs, which did not provide adequate wind resistance. In 2004, the 

Hurricane Charley MAT for Florida observed a nearly identical condition (FEMA 488, 2005b). 

Displaced satellite dishes can rupture roof membranes and cause other damage or injury. FEMA 

P-577, Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds (2007b), 

recommends that ballast not be used to anchor satellite dishes in high-wind areas. Rather, the wind 

load should be calculated for the dish, and a suitable mechanical attachment to the roof deck or 

structure should be designed.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-61

WIND-RELATED OBSERVATIONS

Figure 4-91:

Displaced satellite dish 

(yellow box) and masonry 

ballast (red dashed box)
4-62 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

At the time of the MAT observations (14 days after the storm), cleanup and drying operations were 

underway (Figure 4-92). Rain leaking from the roof did not enter all rooms. Where it had entered, 

the ceiling and gypsum wallboard had been removed.

Figure 4-93 shows one of the piles of debris that had been removed from the hospital.

Evacuation of the hospital began the day before the hurricane made landfall and was completed the 

next afternoon. As of the date of this report, the facility had not reopened. Repairing the facility 

was considered, but it was determined that it was more cost-effective to build a new facility.

Figure 4-92:

View down one of the main 

hospital corridors

Figure 4-93: 

Cabinets and other debris 

from within the hospital
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-63

WIND-RELATED OBSERVATIONS

4.2.2.2 Fisheries Laboratory in Port Aransas 

Figures 4-94 and 4-95 show a fisheries laboratory in Port Aransas. This older building had an 

aggregate surfaced BUR that appeared to be mechanically attached to lightweight insulating 

concrete over a cast-in-place concrete deck. The roof membrane lifted and peeled in two areas, as 

shown at Figure 4-94, and some rooftop ductwork was blown away (Figures 4-94 and 4-95). However, 

only a limited amount of water leaked into the building at damaged rooftop equipment. The cast-inplace roof deck functioned as a secondary membrane and prevented leakage even though the roof 

membrane blew off in two areas. The laboratory was operational at the time of the MAT observation. 

This building illustrates the value of providing a secondary membrane, as recommended in FEMA 

P-424, P-543, and P-577.

Figure 4-94:

Aerial view of the vicinity of 

the fisheries laboratory

(135 mph, Exposure D)

(Port Aransas)
4-64 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-95: 

Damaged ductwork at the 

fisheries laboratory 

4.2.2.3 Older Building with Aggregate Surfaced BUR 

The building in the foreground of Figure 4-96 is an older building with an aggregate surfaced 

BUR. Figure 4-97 shows the same building. The roof membrane remained in place, but there was 

extensive aggregate blow-off. The inset in Figure 4-96 shows the back side of an adjacent house; a 

large tree limb fell onto the roof, and a portion of the roof structure from a nearby house landed on 

the roof.

Aggregate surfaced BURs normally have a minimum of 4 pounds of aggregate per square foot 

(psf). Approximately half of the aggregate is typically embedded in the flood coat. The remaining 

aggregate is loose and therefore susceptible to blow-off. Some adhered aggregate is also sometimes 

blown off after being struck and dislodged by other wind-borne aggregate, but most of the adhered 

aggregate typically remains in place. The roof shown in Figure 4-97 was atypical. As shown in the 

figure, much of the roof surface was bare. At the bare areas, the flood coat was either too cool at the 

time of aggregate placement or too thin to effectively adhere the aggregate.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-65

WIND-RELATED OBSERVATIONS

Figure 4-96: 

Building with aggregate 

surfaced BUR (Exposure D)

Figure 4-97:

Roof of the building shown 

in Figure 4-96 showing 

extensive aggregate blow-off
4-66 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

The house adjacent to the aggregate surfaced roof had storm shutters that effectively protected the 

windows (Figure 4-98).

Figure 4-98:

The red arrow indicates 

metal storm shutters. 

The yellow double arrow 

indicates aggregate blown 

from the roof shown in 

Figures 4-96 and 4-97

4.2.2.4 Rockport-Fulton Middle School

Figures 4-99 through 4-105 show the Rockport-Fulton Middle School, which opened in 2001. It had 

widespread interior water damage that was caused by roof damage. Most or all of the roof damage 

was caused by HVAC units that blew off their curbs. The displaced equipment punctured or tore 

the mechanically attached single-ply membrane, which was over insulation over steel deck. Because 

the membrane was not adhered, once the membrane was punctured or torn by wind-borne debris, 

water was able to readily enter the roof system. With no secondary membrane over the steel deck, 

water easily leaked into the interior of the building at equipment curb openings and at membrane 

punctures and tears.

Figure 4-99:

Rockport-Fulton Middle 

School. The HVAC units from 

the roof that were damaged 

had been moved to the 

ground after the storm and 

are shown in the foreground 

(Rockport)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-67

WIND-RELATED OBSERVATIONS

Figure 4-100: 

Aerial view of the RockportFulton Middle School 

(Exposure B, with open 

patches adjacent to and west 

and south of the school)
4-68 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-101: 

Collapsed, older metal 

building system shown in the 

lower right of Figure 4-100

Figure 4-102 shows the northwest roof of the middle school. Other roof areas were similarly 

damaged. Figure 4-103 shows an HVAC unit that blew off the roof.

Figure 4-102: 

Damage to northwest roof of 

middle school
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-69

WIND-RELATED OBSERVATIONS

Figure 4-103: 

HVAC unit (red arrow) that 

blew off the roof and a 

collapsed light fixture next 

to the school (yellow double 

arrow; see Figure 4-104)

Figure 4-104: 

Collapsed light fixture. There 

was significant corrosion of 

the tube near the base plate

At the time of the MAT observations (14 days after the storm), approximately 50 people involved in 

cleanup and drying operations were on site. The entire school was shut down. Rain leaking from the 

roof did not enter all rooms. Where it had entered, the ceiling had been removed (Figure 4-105).
4-70 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-105: 

Interior view of the cafeteria

4.2.2.5 Live Oak Learning Center 

Figures 4-106 through 4-113 show the Live Oak Learning Center, which opened in 2013. The 

mechanically attached single-ply membrane remained attached, even though sections of coping 

were blown off. The first row of membrane fasteners was 2 feet 3 inches from the parapet (which was 

2 feet 8 inches high). The second row was 2 feet 3 inches from the first. Subsequent rows were 6 feet 

3 inches on center. The MAT checked the windward corners and perimeter for membrane tearing 

near the fastener rows and checked some fasteners for backout. Although membrane tearing and/or 

fastener backout may be caused by dynamic loading induced by hurricanes, the MAT surmised that 

these problems did not occur during this event in the areas that were checked.

There was interior water damage in portions of the area below the main roof. Most of the water 

entered where the roof membrane had been punctured or torn by wind-blown debris. Water also 

entered where an exhaust fan was blown away. The membrane was over insulation, which was over 

steel deck. Because it was not adhered, once the membrane was punctured or torn by wind-borne 

debris, water readily entered the roof system. With no secondary membrane over the steel deck, 

water easily leaked into the interior of the building. At the time of the MAT observations (78 days 

after the storm), the elementary school was in session.

The red lines on Figure 4-106 indicate where coping was blown off. The blown-off copings appeared 

to be a major cause of roof membrane punctures and tears. The rooftop mechanical equipment 

shown in Figure 4-106 consisted of exhaust fans and relief air hoods. In lieu of rooftop HVAC units 

used at the school shown in Figure 4-100, this school used cooling towers, which were anchored to 

their supports (Figure 4-107). Hence, this school had far fewer pieces of rooftop equipment.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-71

WIND-RELATED OBSERVATIONS

Figure 4-106:

Aerial view of the Live Oak 

Learning Center showing 

damage (Exposure B, with a 

large open patch adjacent to 

and northwest of the school) 

(Rockport)

Figure 4-107: Cooling tower damage
4-72 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-108 shows a coping that blew off a curb at either an expansion joint or a roof area divider. 

The coping at the parapets and curbs were cleated on both sides of the coping. Typically, when 

cleats are used, they only occur at the outer leg of the coping, and exposed screws are used to attach 

the inner leg. Obtaining good coping/cleat interlock is difficult when cleats are used on both legs. 

The coping did not appear to comply with ANSI/SPRI/FM 4435/ES-1.

Figure 4-108: 

Blown-off coping at a 

curb. Depending on the 

curb design, interior water 

leakage may occur where 

copings are blown off

Figure 4-109 shows the roof side of the parapet where a coping was blown off. In this area, the cleat 

nails (example shown in the red circle) were spaced at 14 inches, 8 inches, and 15 inches. Cleat 

fasteners should be placed as close as possible to the drip break line. When fasteners are located 

as shown by the red dot, cleat and coping outward rotation due to suction on the roof side of the 

parapet is minimized, thus reducing the potential for the coping to disengage from the cleat due to 

cleat deformation.

Figure 4-110 shows a portion of the main roof area with a large number of recent patches at roof 

membrane punctures/tears. The area shown in Figure 4-110 is within the blue rectangle shown in 

Figure 4-106. Roof areas south and west of the blue rectangle were not checked because of time 

limitations. After initial patching was completed, leaks were reported after subsequent rains. The 

subsequent leaks occurred at punctures/tears that were not initially patched (small tears can be 

difficult to find). Note that water that enters a roof system may travel laterally before leaking into 

the interior of the building. Hence, the location where water enters the roof system may not coincide 

with the interior leakage location, thus complicating the identification of membrane puncture and 

tear locations.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-73

WIND-RELATED OBSERVATIONS

Figure 4-109:

Cleat where a coping 

blew off

Figure 4-110: Main roof damage
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WIND-RELATED OBSERVATIONS

Figure 4-111 shows an exhaust fan that was struck by wind-borne debris. The location of the fan 

is indicated by a red arrow in Figure 4-106. The fan was attached to the curb with two screws at 

each side of the fan. The attachment of the fan to the curb and attachment of the curb to the roof 

structure were adequate to resist the impact load. For an easy-to-use attachment schedule for fans 

and other small equipment, see Table 6-1 in FEMA P-424 (2010a). For this school, the attachment 

schedule recommends three screws at each side of the fan, rather than two per side as installed at 

this fan.

Figure 4-111: 

Exhaust fan struck by windborne debris 

The exhaust fan shown in Figure 4-112 was attached with only two screws (one screw on opposite 

sides of the fan). In addition, the screw heads were not in contact with the fan. If the debris that 

struck the fan shown in Figure 4-111 had struck this fan, it would likely have been knocked off the 

curb, thus allowing rain entry into the school.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-75

WIND-RELATED OBSERVATIONS

Figure 4-112: Exhaust fan 

attached with only two 

screws (red circle shows one 

of the screws)
4-76 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-113 shows where an exhaust fan was blown off the curb. Rain was able to leak into the 

building until the opening was temporarily protected. The nearby natural gas pipe support did 

not provide uplift resistance. FEMA’s U.S. Virgin Island (USVI) Recovery Advisory 2, Attachment 

of Rooftop Equipment in High-Wind Regions (2018d), shows a support detail that provides lateral and 

uplift resistance for gas pipes, condensate drain lines, and conduits.

Figure 4-113: 

Blown off exhaust fan

4.2.2.6 Fulton Learning Center

Figure 4-114 shows the Fulton Learning Center. A large addition to this older elementary school 

opened in 2013. The addition had a mechanically attached single-ply membrane. The original 

building had an older, mechanically attached single-ply membrane. The older and new roof 

membranes remained attached, even though sections of coping were blown off in several areas 

of the addition (Figure 4-115). The newer coping did not appear to comply with ANSI/SPRI/FM 

4435/ES-1.

The older and newer roof membranes were punctured and torn by wind-borne debris. Most of the 

damage occurred at the older roof. The membrane was over insulation, which was over steel deck. 

Because the membrane was not adhered, once it was punctured or torn by wind-borne debris, water 

readily entered the roof system. With no secondary membrane over the steel deck, water easily leaked 

into the interior of the building. Water also leaked into the building where rooftop equipment blew 

off its curbs.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-77

WIND-RELATED OBSERVATIONS

Figure 4-114: Fulton Learning 

Center (Fulton)

Figure 4-115:

Area where a section of 

newer coping blew off 
4-78 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

There were several condensers on the older roof; all were supported by 4x4 wood sleepers that rested 

on the roof membrane. Because of the lack of load path, many of the condensers were displaced 

(Figure 4-116). Wind-borne rooftop equipment was a major source of wind-borne debris damage at 

the older roof.

Figure 4-116: 

Displaced condensers

4.2.2.7 Port Aransas Schools 

Figure 4-117 is an aerial view of the Port Aransas elementary, middle, and high schools. All of the 

schools experienced significant roof system damage and interior damage due to roof leakage. At 

the time of the MAT observations (77 days after the storm), the damaged buildings were shut down. 

School was in session in portable classrooms that had been moved on site.

Figure 4-118 shows the elementary and middle schools. Interior and rooftop observations were not 

made because of time limitations.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-79

WIND-RELATED OBSERVATIONS

Figure 4-117:

Aerial view of the Port 

Aransas schools showing 

roof damage (135 mph)

Figure 4-118:

Aerial view of the Port 

Aransas elementary (blue 

outline) and middle school

(yellow dotted outline) 

[DRONE IMAGE]
4-80 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-119 shows the high school. The MAT made only limited interior observations because of 

time limitations. Damage was not apparent in the first floor areas that were observed. 

Figure 4-119: 

Aerial view of the Port 

Aransas high school 

[DRONE IMAGE]

Figure 4-120 shows an area where the mechanically attached single-ply membrane was punctured 

in several areas by brick veneer that fell from the stair tower wall. The nearby modified bitumen 

membrane roof had no apparent damage. Also, there was no apparent damage to the few pieces of 

rooftop equipment on that roof area.

Figure 4-121 shows signage, brick veneer, and soffit damage. The soffit was stucco supported by metal 

framing. The main consequences of the soffit damage were the cost of repair and the potential for 

it to become wind-borne debris.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-81

WIND-RELATED OBSERVATIONS

Figure 4-120:

Brick veneer failure at a stair 

tower

Figure 4-121: 

Signage, brick veneer, and 

soffit (yellow oval) failure
4-82 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

4.2.2.8 Pharmacy

Figure 4-122 shows a pharmacy that was opened in 2014. A large portion of the single-ply membrane 

blew off, which resulted in significant roof leakage. A mobile pharmacy was set up in the parking lot 

and used until the pharmacy reopened on April 22, 2018.

Figure 4-122: 

Aerial view of a pharmacy 

with roof damage (135 mph) 

(Port Aransas)

4.2.2.9 Port Aransas Hotel

Figure 4-123 shows a hotel that had a substantial portion of its modified bitumen membrane blown 

off. Some wall louvers at packaged terminal air conditioners (PTACs) were also blown off (Figure 

4-124). A portion of the gypsum board soffit at the porte cochere was blown away; the gypsum 

board was attached directly to the wood structural framing.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-83

WIND-RELATED OBSERVATIONS

Figure 4-123: Aerial view of 

a four-story hotel with roof 

damage (Port Aransas) 

Figure 4-124: 

The red arrows indicate 

where PTAC wall louvers 

were blown away. The 

lower level windows were 

protected with metal 

shutters (yellow double 

arrow)
4-84 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

4.2.2.10 Rockport Hotels 

Figure 4-125 shows two Rockport hotels that experienced significant roof covering and interior water 

damage. The northern hotel had a modified bitumen membrane. Portions of the membrane blew 

off, unanchored condensers were displaced (Figure 4-126), and a fan cowling and HVAC unit access 

panel were blown off. Figure 4-126 shows the displaced condenser at the northern hotel. Figure 

4-127 shows the interior of the first floor of the northern hotel. At the time of the MAT observations 

(76 days after the storm), the hotel was shut down.

Figure 4-125:

Aerial view of roof covering 

damage at two hotels. The 

northern building is three 

stories and the southern 

building is two stories. 

(Exposure D) (Rockport)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-85

WIND-RELATED OBSERVATIONS

Figure 4-126: 

Displaced condenser at hotel 

(Rockport)

The condenser at this hotel had rested on the curb. The red arrows show the location of 

the condenser after Hurricane Harvey. The blue dashed arrow indicates an emergency 

repair where the roof membrane had blown off. 
4-86 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-127: First floor 

corridor of a hotel (Rockport)

4.2.2.11 Older Rockport Retail Building 

Figure 4-128 shows an older retail building that experienced roof membrane and rooftop equipment 

blow-off. A portion of the parapet was also damaged (Figure 4-129).

The roof assembly was composed of a modified bitumen membrane over gypsum poured over a 

metal deck. The membrane’s base sheet was attached to the gypsum with spreading fasteners. A 

large number of fasteners pulled out of the deck in the roof area shown in Figure 4-130. However, it 

appeared that uplift of the edge flashing nailer initiated the blow-off in this area.

Figure 4-131 shows a damaged HVAC unit. The unit was strapped to a sheet metal curb adaptor, 

which sat on a curb. The connection of the unit to the curb adaptor and the connection of the 

adaptor to the curb were stronger than the wind resistance of the unit itself. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-87

WIND-RELATED OBSERVATIONS

Figure 4-128: Aerial view of an older retail building (Exposure D) (Rockport)

Figure 4-129: 

Damaged parapet; Exterior 

Insulation and Finish System 

(EIFS) over metal framing
4-88 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-130: 

Underside of the base sheet 

(yellow oval)

Figure 4-131: 

Disintegrated HVAC unit
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-89

WIND-RELATED OBSERVATIONS

The roof damage resulted in significant interior water damage (Figure 4-132). At the time of the 

MAT observations (76 days after the storm), rain was leaking into the building. 

Figure 4-132:

Inside the building under the 

area shown at Figure 4-130

4.2.2.12 Metal Building System in Aransas Pass

Figure 4-133 shows a metal building system (formerly known as “pre-engineered metal building”) 

fire station in Aransas Pass. The only apparent damage was lifting of some rake flashing and blowoff of some downspouts. The IBC currently does not have criteria regarding wind resistance of 

gutters and downspouts. The downspouts were anchored with U shaped sheet metal brackets at 4 

feet 7 inches on center. One, or in some instances both, of the bracket legs failed at the downspouts 

that blew away. Displaced downspouts can become damaging wind-borne debris.
4-90 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-133: Metal building system fire station (Aransas Pass)

4.2.3 Non-Load-Bearing Walls, Wall Coverings, and Soffits

A variety of non-load-bearing wall, wall covering, and soffit systems were observed. Pertinent 

observations are discussed below. 

4.2.3.1 Refugio Church

Figure 4-134 shows brick veneer failure at a church in Refugio, where the estimated wind speed 

was a little more than 120 mph per Figure 1-11. Although this site is far inland, the brick ties were 

significantly corroded. Section 4.1.2.3 offers examples and discussion of brick veneer failure for 

residential buildings.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-91

WIND-RELATED OBSERVATIONS

Figure 4-134: Brick veneer failure (Refugio)

4.2.3.2 Rockport Hotel

Figure 4-135 shows a Rockport hotel that was approximately 1 year old at the time of the hurricane. 

A substantial portion of the roof membrane blew off, which resulted in extensive interior water 

damage. The hotel was reportedly occupied during the hurricane. 
4-92 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-135:

Aerial view of a newer hotel 

(Rockport)

Figure 4-136 shows failure of an exterior wall, including the parapet on the side wall portion of the 

hotel. The exterior wall framing detached from its supports at the roof and floor diaphragm levels. 

The other exterior walls, including framing that extended above the roof line to form the parapet, 

did not exhibit this failure. Most of the studs were not gravity load bearing, but some stud packs in 

the wall appeared to be load bearing. Lack of access precluded a comprehensive evaluation of the 

wall failure.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-93

WIND-RELATED OBSERVATIONS

Figure 4-136:

End wall failure at hotel 

(Rockport)

Figure 4-137 shows soffit failure at the porte cochere. The soffit had an EIFS over metal framing. The 

main consequences of this damage were the cost of repair and the potential for the soffit material to 

become wind-borne debris.

Figure 4-138 shows some of the ramifications of the roof and end wall damage. The two large debris 

boxes are full of ceiling, wall covering, and other water-damaged debris from the hotel.
4-94 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-137:

Soffit failure at the porte 

cochere

Figure 4-138:

Debris from the interior of 

the hotel
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-95

WIND-RELATED OBSERVATIONS

4.2.3.3 Metal Building System at Rockport High School

Figure 4-139 shows an older metal building system at the Rockport high school. The high school is 

near the middle school shown in Figure 4-100. This large high school was constructed over many 

years using a variety of structural and building envelope materials. Much of the school experienced 

building envelope damage, and one of the gymnasiums collapsed (Figures 4-100 and 4-101. At the 

gymnasium shown in Figure 4-139, a precast non-load-bearing wall panel collapsed, and several 

metal roof and wall panels were blown away.

Figure 4-139:

High school gymnasium 

damage (Rockport)
4-96 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

The precast wall panels sat on the foundation, and weld plates were cast into the wall panel. The 

plates were welded to the frames to provide lateral resistance (Figure 4-140). However, the welds 

were insufficient to resist the wind load.

Figure 4-140:

Precast panel connection to 

the steel frame

Figure 4-141 shows the windward end wall. The girts supporting the wall panels were pushed inward. 

The girts likely failed because the metal stands supporting condensers were blown against the wall. 

Figure 4-141: 

End wall failure
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-97

WIND-RELATED OBSERVATIONS

Figure 4-142 shows a collapsed light fixture pole (standard) at the athletic field.

Figure 4-142:

Collapsed light fixture pole 

(high school buildings are in 

the background)

4.2.3.4 Civic Center in Aransas Pass 

Figure 4-143 is a view of the porte cochere at the civic center in Aransas Pass, which opened in 

2008. Most of the soffit was constructed of metal panels attached to metal framing. In some areas, 

the panels blew away, and in others, both the metal framing and panels blew away. The main 

consequences of this damage were the cost of repair and the potential for the soffits to become 

wind-borne debris.
4-98 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-143:

Soffit damage of the porte 

cochere at the civic center 

(Aransas Pass)

4.2.4 Doors, Windows, and Shutters

The MAT did not observe personnel doors that were damaged by wind pressure or wind-borne 

debris. For the doors that were observed, the MAT did not determine whether wind-driven rain 

entered the building between the door and frame. The only large doors (i.e., sectional or rolling 

doors) that were observed are the ones shown in Figure 4-78. Those older doors were from an era 

when large doors typically had limited wind resistance. The MAT observed storm shutters of various 

types, as shown at Figures 4-81, 4-98, and 4-124.

Storm shutters were also observed at two hospitals in Corpus Christi. They were major glazing 

mitigation projects. At both facilities, accordion shutters were installed at glazed entry doors, and 

permanently mounted wind-borne debris-resistant screens were installed at windows (Figure 4-144). 

With permanently mounted screens, deployment and demobilization time and costs associated 

with most other types of shutters are eliminated. The accordion shutters and screens had labels 

indicating that they had been tested. However, the labels did not indicate the level of the test missile 

(i.e., D or E as specified in ASTM E1996). At one of the hospitals, screens had blown off during 

previous storms.

The roof of one of the hospitals had been at least partially mitigated, wherein a previous aggregate 

surfaced BUR was replaced with a modified bitumen roof system. Attention had also been given 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-99

WIND-RELATED OBSERVATIONS

to anchorage of some of the rooftop equipment. However, the hospital shown in Figure 4-145 still 

had an old aggregate surface BUR. With the modest wind speeds at this site and the presence of a 

relatively tall parapet, the aggregate probably did not blow off. However, it would have been prudent 

to replace the aggregate surfaced roof in conjunction with the glazing mitigation project. Several 

sections of coping blew off the parapet of the aggregate surfaced roof.

Figure 4-144:

Permanently mounted 

screens at a hospital 

(Corpus Christi)

Figure 4-145:

Sections of coping blew off 

at various locations along the 

parapet
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WIND-RELATED OBSERVATIONS

4.2.5 Building Operations

Building damage inflicted by Hurricane Harvey had significant impacts on the operations of many 

non-residential buildings, including critical facilities, as summarized below.

+ One regional hospital was taken out of service.

+ Several nursing homes in the greater Rockport area, and as far inland as Refugio (where the 

estimated wind speed was 105 mph, Figure 4-146), were taken out of service.

+ All of the public schools in Rockport and Port Aransas were closed for weeks.

+ Several hotels in the greater Rockport area and Port Aransas were taken out of service. The 

damaged hotels were not available to residents who had to vacate their houses/apartments 

because of damage nor were they available to workers who came into the area to provide 

emergency response and recovery services.

+ Damaged retail buildings resulted in loss of local services and jobs.

Figure 4-146:

Although located far inland, 

this nursing home was shut 

down as a result of building 

envelope damage and 

subsequent water infiltration 

(Refugio)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-101

WIND-RELATED OBSERVATIONS

4.3 Wind Performance of Solar Panel Systems

This section discusses observations of ground- and rooftop-mounted solar panels, also known as 

photovoltaic (PV) panels. 

Ground-Mounted Solar Array

The MAT observed one ground-mounted array (Figure 4-147). The panels were attached with 

T-bolted compression panel clips to extruded aluminum rails. Fifteen panels were blown away, and 

one was damaged by wind-borne debris. For further information on ground-mounted PV arrays, 

refer to the MAT report, FEMA P 2021, Hurricanes Irma and Maria in the U.S. Virgin Islands (2018i).

Figure 4-147:

Ground-mounted array
4-102 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Rooftop-Mounted Solar Arrays

Two rooftop-mounted solar arrays were observed. Figures 4-148 and 4-149 show an array that had 

four rows of panels, with eight panels per row. The entire middle row blew away.

Figure 4-148:

Aerial view of the vicinity 

of a rooftop solar array 

(Exposure D)

Figure 4-149: 

The yellow arrow indicates 

the row of missing solar 

panels
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 4-103

WIND-RELATED OBSERVATIONS

The panels were attached with T-bolted compression panel clips to extruded aluminum rails, which 

were attached with clip angles to the structure (Figure 4-150). The panels, bolts, clips, and rails were 

similar to a large number of arrays that were observed in the U.S. Virgin Islands after Hurricanes 

Irma and Maria in 2017.

Figure 4-150:

Damage to a rooftopmounted solar array
4-104 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

WIND-RELATED OBSERVATIONS

Figure 4-151 shows another rooftop solar array. Asphalt shingles and roof sheathing were blown off 

this house. At the time of the MAT’s observation, the house had been reroofed, but the solar panels 

had not been reinstalled. This house illustrates the importance of conducting a wind vulnerability 

assessment of the roof assembly and mitigating significant vulnerabilities before installing

solar panels.

Figure 4-151:

Aerial view of a damaged 

rooftop solar array

For further information on rooftop solar panels, refer to FEMA’s USVI Recovery Advisory 5, Rooftop 

Solar Panel Attachment: Design, Installation and Maintenance (2018l). 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-1

5Conclusions and 

Recommendations

The conclusions and recommendations are intended to help 

reduce future damage and impacts from flood and wind events 

such as Hurricane Harvey.

The conclusions and recommendations presented in this report are based on the MAT’s observations 

in the areas studied; evaluations of relevant codes, standards, and regulations; and meetings with 

local officials, facility representatives, design professionals, and contractors. 

The recommendations are intended to assist the State of Texas, communities, businesses, and 

individuals in the reconstruction process, and to help reduce future damage and impacts from 

flood and wind events such as Hurricane Harvey. The recommendations will also help FEMA assess 

the adequacy of building codes and standards as they relate to dry floodproofing and floodplain 

management requirements and determine whether changes are needed, or additional guidance 

related to reducing hurricane damage is required. 
5-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Section 5.1 is a summary of the conclusions and recommendations based on the MAT’s observations. 

Section 5.2 discusses general conclusions and recommendations. Section 5.3 discusses conclusions 

and recommendations related to building codes, standards, and regulations. Section 5.4 includes 

flood-related building performance conclusions and recommendations. Section 5.5 includes windrelated building performance conclusions and recommendations. Section 5.6 provides conclusions 

and recommendations on FEMA technical publications and guidance. Section 5.7 provides a 

summary of the conclusions and recommendations in a tabular format.

5.1 Summary of Conclusions and Recommendations

The recommendations are presented as guidance to the State of Texas and those who are involved 

with the design, construction, and maintenance of the built environment in the State. The entities 

involved in the reconstruction and mitigation efforts should consider these recommendations in 

conjunction with their existing priorities and resources when determining how they can or will be 

implemented. 

Overall, in areas where recent codes were adopted and enforced, newer construction sustained much 

less damage than older construction, so the requirements incorporated under the TDI Windstorm 

Inspection Program, as well as floodplain management regulations and building code requirements, 

appear to be effective at improving building performance. Flood-related building damage was 

primarily attributable to non-elevated or low elevation 

buildings (legal non- conforming), dry floodproofing 

failures, the use of non-flood damage-resistant 

materials below the BFE, the lack or failure of sewer 

backflow prevention devices, and widespread flooding 

outside the SFHA. Wind-related building damage was 

primarily attributable to using improper materials in 

hurricane-prone regions; design deficiencies; poor 

installation or failure to follow installation guidelines 

for wall coverings, windows, and doors in high-wind 

zones; and inadequate attachment of roof coverings 

and roof-mounted equipment.

The MAT’s conclusions and recommendations are prioritized within each subsection by those that 

may be most important for the State, community, or interested party to implement. Specifically, 

recommendations of note from each section include:

Recommendation TX-1a (Section 5.2). Continue providing training to Windstorm Inspection 

Program inspectors and building code enforcement staff, placing emphasis on changes reflected 

in the latest adopted edition of the building code.

Recommendation TX-3a (Section 5.3). TDI should adopt the 2018 IBC and IRC as the model 

codes for its Windstorm Inspection Program.

Recommendation TX-5a (Section 5.4). Communities and building owners should consider 

elevating new and Substantially Improved/Substantially Damaged buildings above the NFIP 

elevation requirements to protect them from flooding.

LEGAL NON-CONFORMING 

CONSTRUCTION

Legal non-conforming construction 

is a structure that complied with 

floodplain management requirements 

when permitted, but BFEs or flood 

zones have since changed.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-3

CONCLUSIONS AND RECOMMENDATIONS

Recommendation TX-14a (Section 5.5). Building owners and/or facility managers should 

ensure roof-mounted equipment is adequately anchored.

Recommendation TX-23a (Section 5.6). FEMA should complete Guidelines for Wind Vulnerability 

Assessments for Critical Facilities.

5.2 General Conclusions and Recommendations

Conclusion TX-1

Building codes and floodplain management requirements were inconsistently enforced. 

Inconsistencies in code compliance and enforcement were observed throughout sites the MAT 

visited. Although there was evidence of good practices in some communities, the most common and 

routine inconsistencies observed included, among other things, improper load paths, not requiring 

products that are on the approved and tested list (e.g., the TDI Product Evaluation Index), and a 

lack of flood openings in enclosures below the lowest floor of buildings in the SFHA. 

Recommendation TX-1a. Continue providing training to Windstorm Inspection Program 

inspectors and building code enforcement staff, placing emphasis on changes reflected in 

the latest adopted edition of the building code. Communities that have adopted building 

codes and the TDI should work with the Texas State Collaborative, the International Code 

Council, and FEMA to provide building officials, plan examiners, and inspectors with training 

materials on the model building codes to ensure they are up to date on current wind provisions 

in the model building codes and standards and associated local amendments. The training 

should emphasize discrepancies observed between building code requirements and completed 

construction following Hurricane Harvey. For example, in newer/ongoing construction, the 

MAT observed the load path from the foundation to the top plate was generally sufficient, 

but there were concerns with the design and execution of load paths in the roof framing. TDI 

should consider providing additional training for Windstorm Inspection Program inspectors to 

more effectively review plans and enforce proper load path connections to meet roof framing 

requirements. Both Windstorm Inspection Program inspectors and building code enforcement 

staff should inspect the building’s structural integrity and identify any deficiencies in the design 

and construction process. 

Recommendation TX-1b. The Texas Water Development Board and other stakeholders should 

develop/modify training on the flood provisions in model building codes and/or floodplain 

management ordinances. The Texas Water Development Board, which is the designated 

Texas NFIP State Coordinating Agency, in conjunction with FEMA and the Texas Floodplain 

Management Association, should develop training related to flood damage-resistance provisions 

in the model building codes and include content on a model code-coordinated floodplain 

management ordinance. Based on observations following Harvey, the training materials should 

emphasize the use of flood damage-resistant materials and flood openings in enclosures 

below the BFE. The target audience for the training materials should be builders, developers, 

floodplain administrators, building officials, and building inspectors.
5-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Conclusion TX-2 

Some high-occupancy and critical facility building owners have a limited awareness of hurricane 

hazard risks and vulnerabilities. The quality of planning and preparedness for Hurricane Harvey 

at the non-residential buildings visited by the MAT, particularly some schools, nursing homes, 

and medical centers along the coast, varied greatly. These variations may have been due to the 

information sources used to identify risks and vulnerabilities to wind and flood events, as well as 

local government recommendations about whether to close the facilities during the event. Many 

building managers and owners may not have been aware of the higher risks to their buildings from 

such severe hurricane events.

Recommendation TX-2. Facility and building owners should perform vulnerability 

assessments. Prior to hurricane season, facility and building owners should consider having a 

vulnerability assessment conducted by a team of knowledgeable professionals to help determine 

available options to mitigate hazards and risks for buildings, critical facilities and key assets, 

and other structures that may be damaged by a flood or wind event. Owners should identify 

vulnerabilities and include mitigation measures in short- and long-term facility maintenance 

and capital improvement programs to realistically address the vulnerabilities over time, 

where possible. Facility owners and operators should work with key internal staff and design 

professionals to analyze their facilities, key systems and components, operational assumptions, 

and operations plans to determine a path forward for developing project priorities and funding 

capital improvements that maximize facility and operational resiliency. FEMA P-424, Design 

Guide for Improving School Safety in Earthquakes, Floods, and High Winds (2010a); FEMA P-1000, 

Safer, Stronger, Smarter: A Guide to Improving School Natural Hazard Safety (2017); FEMA P-543, 

Design Guide for Improving Critical Facility Safety from Flooding and High Winds (2007a); and FEMA 

P-577, Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds: Providing 

Protection to People and Buildings (2007b) are building-use-specific guidance documents that 

include multi-hazard vulnerability assessment checklists for schools, critical facilities, and 

hospitals, respectively.

5.3 Building Codes, Standards, and Regulations

Conclusion TX-3

The TDI Texas Windstorm Inspection Program requirements are based on compliance with the 

2006 IBC and IRC, which are outdated. Based on observations in Texas and other areas the 2017 

Hurricane MAT visited, buildings that had been designed or mitigated to resist high-wind loads in 

accordance with modern building codes performed substantially better than buildings constructed 

to earlier codes. In addition, the IBC and IRC have been through four code cycles since 2006, 

including incorporating two revisions to ASCE 7. 

Recommendation TX-3a. TDI should adopt the 2018 IBC and IRC as the model codes for its 

Windstorm Inspection Program. These codes and referenced standards include up-to-date 

design and construction provisions and create consistency across industry standards. When TDI 

adopts the model code and standards, minimum criteria should be kept intact or exceeded. 

Upon adopting any new requirements, TDI and communities should provide training to local 

design professionals, contractors, and inspectors on the requirements of the latest adopted codes.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-5

CONCLUSIONS AND RECOMMENDATIONS

Recommendation TX-3b. TDI should consider developing a more stringent high-wind retrofit 

program. In addition to adopting the 2018 IBC and IRC and referenced standards, TDI should 

consider developing a residential wind retrofit program that complies with or exceeds its current 

requirements to address wind vulnerabilities of existing residential buildings, as well as model 

building code requirements for existing residential buildings. TDI should consider using FEMA 

P-804, Wind Retrofit Guide for Residential Buildings (2010d), which was developed in conjunction 

with the Insurance Institute for Business and Home Safety FORTIFIED for Existing HomesTM 

Program. Note that any wind retrofit projects of one- and two-family residential buildings 

funded under the FEMA Hazard Mitigation Assistance (HMA) program must be completed in 

conformance with FEMA P-804. Individual insurance companies should provide discounts as an 

incentive for homeowners to invest in retrofit projects. 

Conclusion TX-4

Portions of local floodplain management ordinances and building codes in communities visited 

by the MAT conflict with some of the requirements in model ordinances and building codes. The 

MAT identified inconsistencies while reviewing local floodplain management ordinances and flood 

provisions in locally adopted building codes. 

Recommendation TX-4a. Harris County should review and update its floodplain management 

regulations. In the Regulations of Harris County for Floodplain Management, add a 

definition for “Substantial Damage,” ensure proper use of the term “lowest floor” (rather than 

“habitable floor”), require non-residential buildings to be elevated or dry floodproofed as 

high as residential buildings (18 inches above the BFE), and use “market value” in Substantial 

Improvement/Substantial Damage (rather than “value of structure”). 

Recommendation TX-4b. The City of Houston should review and update its floodplain 

management ordinance and guidance. Chapter 19 of the Code of Ordinances for the City 

of Houston contains the City’s floodplain ordinance. The City should consider more clearly 

specifying the height of dry floodproofing when owners of non-residential buildings elect this 

option (at least the BFE plus 1 foot). The City produces companion guidelines for Chapter 

19 that should be revised to update references to out-of-date editions for a number of FEMA 

technical bulletins (Chapter 19 references the 1993 version of Technical Bulletin 1 instead of the 

2008 version). 

Recommendation TX-4c. The City of Bellaire should review and update its flood damage 

prevention ordinance and guidance. Article II-A of Chapter 9 in the City of Bellaire’s Code 

of Ordinances addresses flood damage prevention. The City also enforces building codes that 

contain requirements for buildings in flood hazard areas. Review and update the definition 

of “lowest floor” to refer to the non-elevation requirements of Article II-A instead of NFIP 

regulations, and require non-residential buildings to be elevated or dry floodproofed as high as 

residential buildings (at least the BFE plus 1 foot). Correct the description of how lowest floors 

are determined and eliminate the implication that basements (areas below grade on all sides) 

are allowed. In addition, work with FEMA to revise the City’s guidance that explains which costs 

must be included in Substantial Improvement/Substantial Damage interpretations (a sample 

packet for this purpose is included in Appendix D of FEMA P-758, Substantial Improvement/

Substantial Damage Desk Reference [2010c]). 
5-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Recommendation TX-4d. The City of Port Aransas should review and update its flood damage 

prevention ordinance. Chapter 8 of the City of Port Aransas’ Code of Ordinances addresses 

flood damage prevention. The City should ensure that any temporary, post-hurricane regulatory 

relief does not have the effect of waiving floodplain management requirements related to repair 

of buildings that incur Substantial Damage. Review and update the definition of “lowest floor” 

to refer to the non-elevation requirements of Chapter 8 rather than NFIP regulations. 

Recommendation TX-4e. All Texas communities should consider reviewing and updating 

their local floodplain management ordinances. The Texas Water Development Board, in 

conjunction with FEMA, should consider reviewing previously adopted floodplain management 

ordinances for consistency with NFIP requirements and model building codes. The Texas Water 

Development Board should utilize FEMA’s model floodplain ordinance to help them develop 

a model ordinance that seamlessly integrates with the I-Codes. The model ordinance can be 

utilized by all Texas communities when updating their ordinance. 

5.4 Flood-Related Building Performance

Conclusion TX-5 

Many non-elevated or low-elevation buildings sustained flood damage. Forty percent of flooddamaged buildings were located outside of the 0.2-percent-annual-chance probability floodplain. 

Buildings elevated above the Hurricane Harvey flood level on strong foundations sustained little or 

no flood damage. 

Recommendation TX-5a. Communities and building owners should consider elevating new 

and Substantially Improved/Substantially Damaged buildings above the NFIP elevation 

requirements to protect them from flooding. Communities should consider requiring new 

buildings, those determined to have incurred Substantial Damage, and those that will undergo 

Substantial Improvement to be elevated in accordance with the I-Codes and ASCE 24, which 

exceed the NFIP elevation requirements. In some communities, Hurricane Harvey inundation 

levels rose higher than the BFE; therefore, communities should consider adopting elevation 

requirements that exceed ASCE 24 (i.e., more than the ASCE 24 minimum freeboard of 1 foot). 

Recommendation TX-5b. Communities should incorporate the best available flood hazard 

data wherever they are available. For example, Nueces and Aransas Counties, TX, have 

preliminary FIRMs available that should be compared to effective FIRMs to require new 

buildings, Substantial Improvements, Substantially Damaged buildings, and reconstructed 

buildings to be elevated relative to the higher BFE. While a preliminary FIRM is not regulatory 

until adopted, using the latest flood hazard information is a best practice. 

Recommendation TX-5c. Communities should consider future conditions in zoning, building 

code, and floodplain management requirements. While the model building codes and 

standards limit new construction in High-Risk Flood Hazard Areas, including areas prone to 

erosion and high-velocity flow areas, the DFE requirements (which exceed the minimum NFIP 

requirements) do not provide the same level of protection in all geographic areas. For example, 

1 foot of additional elevation above the BFE on the FIRM may be equivalent to the 0.5-percentannual-chance probability flood in one area and the 0.2-percent-annual-chance probability 

flood in another. As specified in ASCE 24, reasons for adopting higher flood elevations include 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-7

CONCLUSIONS AND RECOMMENDATIONS

anticipated future conditions (including predicted upland development, subsidence, or sea 

level rise), accommodating the flood of record, and compensating for uncertainties inherent in 

determining flood frequencies and flood elevations for other flood events. Communities should 

evaluate all of these factors, especially the future conditions, and consider adopting DFEs that 

best reflect the anticipated flood conditions over the life of the building.

Conclusion TX-6 

Dry floodproofing measures often failed under less than design flood conditions. Following 

Tropical Storm Allison in June 2001, several buildings throughout the Houston area were dry 

floodproofed (with and without FEMA grant funding). The MAT visited approximately 20 dry 

floodproofed sites following Hurricane Harvey and identified several lessons learned from dry 

floodproofing failures under less than design flood conditions. The MAT also identified best 

practices from successfully implemented dry floodproofing measures. 

Recommendation TX-6a. Local floodplain administrators, design professionals, and building 

owners should follow the guidance in FEMA’s Texas Recovery Advisory 1 (2018g) and Florida 

Recovery Advisory 1 (2018f). Texas Recovery Advisory 1, Dry Floodproofing: Planning and 

Design Considerations (2018g), and Florida Recovery Advisory 1, Dry Floodproofing: Operational 

Considerations (2018f) have guidance related to dry floodproofing methods and procedures 

based on MAT observations made during and after Hurricanes Irma and Harvey. The MAT 

observations illustrate that designing and implementing dry floodproofing for buildings is 

complicated. Therefore, guidance based on recent events should be incorporated into the 

design and implementation of new and existing dry floodproofing. Specific considerations from 

the recovery advisories include:

+ Conduct a thorough vulnerability assessment, including a survey of all potential water entry 

points, as part of the design process.

+ Incorporate freeboard into the DFE based on the building use. 

+ Treat flood barriers like firewall assemblies—label them and minimize modifications and 

penetrations.

+ Evaluate utility components and penetrations through walls and floors as potential water 

entry points. 

+ Install check valves in floor drain systems and require ejector systems with check valves/

backflow preventers for stormwater and sanitary sewers. 

+ Provide waterstops at the seals in foundation walls and floor slabs where those spaces are 

intended to remain dry and are located below the DFE. 

Recommendation TX-6b. Local floodplain administrators, design professionals, and building 

owners should ensure sump pumps, with a floor drain system to collect seepage, are included 

as part of all dry floodproofing systems. To satisfy the performance expectations for dry 

floodproofed buildings when NFIP compliance is required, NFIP Technical Bulletin 3, NonResidential Floodproofing—Requirements and Certification (1993) and ASCE 24 require sump pumps 

to remove seepage; emergency power should be provided to run the pumps as well. Most dry 

floodproofed buildings visited did not have sump pumps, which contributed to failure or heavy 

damage, so incorporating them should be emphasized.
5-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Conclusion TX-7 

Dry floodproofed buildings that were considered substantially impermeable sustained damage 

that resulted in significant loss of function while repairs were completed. In some cases, redundant 

mitigation measures within dry floodproofed buildings, such as compartmentalizing critical 

functions or elevating utility systems, helped reduce the loss of function. In particular, the use of 

flood damage-resistant materials on the interior of dry floodproofed portions of buildings reduced 

damage as well as loss of function. 

Recommendation TX-7. Flood damage-resistant materials should be used below the 

DFE inside dry floodproofed buildings when possible. Local floodplain administrators, 

design professionals, and building owners should consider encouraging the use of flood 

damage-resistant materials below the DFE inside dry floodproofed buildings. Using flood 

damage-resistant materials is considered a best practice and helps minimize damage and time 

needed to remove and replace interior finishes. 

Conclusion TX-8 

Dry floodproofed buildings where building managers had instilled a culture of preparedness 

sustained less damage than other dry floodproofed buildings. The scope and detail of operations, 

maintenance, and testing plans was an indicator of dry floodproofing system performance. 

Recommendation TX-8a. Facility managers should develop an emergency operations plan 

(EOP) for severe weather. An EOP that outlines how to prepare the building when severe 

weather events are expected should be developed by facility managers. Each dry floodproofed 

facility should have an EOP with action items or an implementation checklist based on a 

timeline keyed to official severe weather warnings and watches. ASCE 24 Chapter 6 contains 

requirements for and discussion of EOPs.

Recommendation TX-8b. Facility managers should routinely re-evaluate dry floodproofing 

designs and plans as required by codes and standards. After each deployment of a dry 

floodproofing system, including training exercises, the overall design of dry floodproofing 

systems and EOPs for severe weather should be revisited to resolve any deficiencies identified 

while systems were being tested, installed, or subjected to floodwater. ASCE 24 Chapter 6 

requires periodic practice of installing shields as well as testing of sump pumps and other 

drainage measures.

Recommendation TX-8c. Facility managers should take reasonable measures to instill a 

culture of preparedness. Facility managers should conduct annual training exercises during 

which dry floodproofing measures are installed, taking note of the time to install each portion 

of the system and the total time to install the entire dry floodproofing system. The commentary 

in ASCE 24 indicates persons responsible for installing or implementing the measures must 

be familiar with the procedures and equipment. Therefore, training exercises should include 

building maintenance and engineering staff along with other building staff that may be 

needed to install dry floodproofing systems with little warning time. Maintenance of dry 

floodproofing system components should be conducted annually, as well as during training 

exercises and following deployment for a flood event. To ensure system functionality, periodic 

maintenance should include checking gaskets and seals, installation hardware and fasteners, 

and the condition of building elements to which dry floodproofing components will be attached. 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-9

CONCLUSIONS AND RECOMMENDATIONS

Consider creating a video recording of manual dry floodproofing installations, especially the 

complex steps, so the video can be referenced later if untrained staff are required to assist.

Conclusion TX-9 

Non-flood damage-resistant materials were used below the BFE in elevated buildings and had 

to be replaced. The MAT observed several instances of non-flood damage-resistant materials 

being removed from garages and crawlspaces below newer elevated buildings (new construction 

since floodplain management requirements were adopted). While the total flood insurance claims 

for these buildings were typically about $10,000 to $15,000, compared to $120,000 to $150,000 

for adjacent non-elevated buildings, even those lower claims and relatively minor damage would 

likely have been avoided, or at least considerably reduced, if the appropriate flood damage-resistant 

materials had been used as required by local floodplain management regulations. 

Recommendation TX-9. Local floodplain administrators must enforce, and design 

professionals and builders must comply with, the requirement to use flood damage-resistant 

materials below an elevated building’s DFE. When communities issue permits for new 

construction, Substantial Improvement, and repair of Substantially Damaged buildings, the 

NFIP requires all building materials below the BFE to be flood damage-resistant, regardless 

of the expected or historical flood duration. Model building codes and ASCE 24 require flood 

damage-resistant materials to be used below the lowest floor. Refer to NFIP Technical Bulletin 

2, Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood Hazard Areas 

in accordance with the National Flood Insurance Program (2008b), for the classification of specific 

materials. 

Conclusion TX-10 

Damage to buildings not designed and constructed to current building code requirements was 

noticeably greater than damage to NFIP-compliant buildings. Buildings that incorporated the 

best available flood hazard data along with requirements from consensus-based building codes and 

standards promulgated by the International Code Council and the ASCE sustained less damage 

than those that did not. Although buildings both inside and outside of the SFHA were flooded, 

those within the SFHA that sustained the most damage were designed and built before communities 

joined the NFIP and began regulating development in SFHAs. In Houston, the average NFIP flood 

insurance claim for pre-FIRM buildings (pre-1980) was double that of post-FIRM buildings. Some 

of the pre-FIRM buildings also flooded in 2015, 2016, and other significant rainfall events. 

Recommendation TX-10a. When and where possible, FEMA should consider updating the 

NFIP standards to be at least equivalent to the consensus-based codes. The model building 

codes require freeboard above the BFE. FEMA should update the minimum NFIP requirements 

to include freeboard, or at least require freeboard as a minimum criterion to participate in 

the NFIP’s CRS, described in Section 2.1.1.4. While the consensus-based codes are periodically 

updated (currently every 3 years), the NFIP building requirements have not significantly 

changed in the 50 years of the program. 
5-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Recommendation TX-10b. FEMA and communities should re-evaluate the criteria for 

Substantial Improvement/Substantial Damage. In light of the number of “Existing”1 and 

legal non-conforming (see text box in Section 5.1) buildings that were inundated, FEMA and 

communities should re-evaluate the criteria for Substantial Improvement/Substantial Damage. 

Under the CRS program, communities earn points for higher regulatory standards when 

counting improvements cumulatively or having a Substantial Improvement threshold lower 

than 50 percent. The purpose of Substantial Improvement/Substantial Damage is to reduce the 

number of non-conforming buildings that are exposed to flood damage. Communities should 

consider adopting a threshold lower than 50 percent and consider developing requirements 

specific to repetitively flooded properties. FEMA should require having a Substantial 

Improvement threshold lower than 50 percent and/or using the Severe Repetitive Loss 

definition to trigger Substantial Damage (regardless of the 50 percent threshold) as a minimum 

criterion to participate in the NFIP’s CRS.

Conclusion TX-11

The State and communities did not receive (or did not receive in a timely manner) data on 

buildings that appeared to have incurred Substantial Damage. When buildings appeared to have 

incurred Substantial Damage, the State and communities either did not receive requested data 

submitted by NFIP claims adjusters, or did not receive the information in a timely manner.

Recommendation TX-11. FEMA should develop an effective and timely means to deliver the 

Adjuster Preliminary Damage Assessment data. When NFIP claims adjusters identify claims 

that, based on available data, appear to have incurred Substantial Damage, the adjusters submit 

data using FEMA Form 086-0-020, Adjuster Preliminary Damage Assessment (2018a). The form 

indicates FEMA and communities can use the data to identify potentially Substantially Damaged 

buildings. FEMA P-758, Substantial Improvement/Substantial Damage Desk Reference (2010c) (Section 

7.4.1), describes using the data for screening purposes only, especially after flood events that 

damage large numbers of buildings. FEMA should develop an effective and timely means to 

deliver data submitted by NFIP claims adjusters to States and communities.

Conclusion TX-12 

The MAT observed widespread flood damage both within and outside the regulatory floodplain.

In the City of Houston, approximately 48,850 buildings located in the SFHA were damaged and 

approximately 35,000 buildings located in the 0.2-percent-annual-chance floodplain were damaged. 

Another 70,000 buildings situated outside the 0.2-percent-annual-chance floodplain were damaged. 

Hundreds of these properties, including those outside the SFHA, have received repetitive claim 

payments from the NFIP. In some cases, historical flood insurance claims in specific areas indicated 

a flood risk that was not reflected on the FIRM (i.e., there were repetitive claims for properties 

outside the SFHA).

Recommendation TX-12a. FEMA should make NFIP policy information, especially data 

related to historical claims, available to help supplement flood hazard data on the FIRM. The 

number of active policies and historical claim information should be made public at a street 

1 The NFIP uses the term “Existing” as follows: Existing Construction is a structure built before the community had adopted a Flood Insurance 

Rate Map (FIRM).
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-11

CONCLUSIONS AND RECOMMENDATIONS

or community level and updated periodically to show historical trends versus one-time events. 

Generally, the public relies on FIRMs to identify risk, yet in many areas in Houston, claims are 

a better measure of risk and would supplement the FIRM. Property owners, including those 

outside the SFHA who are not required to carry flood insurance but are eligible for preferred 

risk policies, should have access to historical claims to supplement their flood insurance 

coverage decision-making process. FEMA should perform a study to help determine acceptable 

methods for making claims information more readily available without compromising privacy 

information. The analysis should include alternatives with advantages and disadvantages, along 

with a recommended path forward. 

Recommendation TX-12b. Owners of buildings located near but outside the SFHA should 

consider implementing flood risk reduction measures. Aside from critical facilities (e.g., 

fire and police stations, hospitals), most model building code and floodplain management 

requirements do not apply to buildings near but outside the SFHA. Building owners, especially 

those located immediately adjacent to the SFHA where flooding has occurred, should evaluate 

their flood hazard when constructing or renovating their building and consider implementing 

flood risk reduction measures (e.g., elevating, wet floodproofing, dry floodproofing).

Conclusion TX-13 

Contractors and designers have insufficient guidance on elevated slab projects. The MAT observed 

several ongoing residential elevated slab projects. The single-family buildings were typically being 

elevated on segmented concrete piles using a variety of methods to reinforce the slab and establish 

a load path between the slab and the columns. While each site and slab was unique, there were 

inconsistencies in existing slab reinforcement, and the design standard or method being applied 

to evaluate the slabs and determine whether each slab had sufficient capacity to support itself once 

elevated was unclear.

Recommendation TX-13. Continue ongoing research on the performance of elevated slab 

foundations and develop related outreach material. The University of Texas at Arlington has an 

ongoing research project related to the performance of elevated slab foundations. The purpose 

of the research is to support structural engineers in evaluating existing slab foundations, 

estimating the amount of strengthening required to meet the loading requirements, and 

providing suggested methods for strengthening slabs. Although FEMA P-312, Homeowner’s 

Guide to Retrofitting: Six Ways to Protect Your Home From Flooding (2014), and other guidance exists 

related to elevated slab projects, this research will provide engineers with technical data to 

support their evaluations and designs based on testing representative concrete slabs that are 

typically constructed to be continuously supported by the ground. Considering the number of 

existing slab foundations and the potential for numerous elevated slab projects, the State of 

Texas may want to consider supplementing the ongoing research with FEMA Hazard Mitigation 

Grant Program funds or other funding to support this type of research. Outreach materials 

related to this research should be developed and distributed to elevation contractors and design 

professionals to consider and incorporate into elevated slab projects.
5-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

5.5 Wind-Related Building Performance 

Conclusion TX-14 

Roof-mounted equipment lacked adequate attachments. Inadequate attachment of roof-mounted 

equipment was responsible for much of the wind damage to non-residential buildings incurred 

during Hurricane Harvey. 

Recommendation TX-14a. Building owners and/or facility managers should ensure roofmounted equipment is adequately anchored. Building owners should perform a vulnerability 

assessment and place more emphasis on anchoring roof-mounted equipment throughout the 

State, especially in the hurricane-prone regions. FEMA P-424, Design Guide for Improving School 

Safety in Earthquakes, Floods, and High Winds (2010a); FEMA P-543, Design Guide for Improving 

Critical Facility Safety from Flooding and High Winds (2007a); FEMA P-577, Design Guide for Improving 

Hospital Safety in Earthquakes, Floods, and High Winds: Providing Protection to People and Buildings

(2007b); and USVI Recovery Advisory 2, Attachment of Rooftop Equipment in High-Wind Regions

(2018d), contain building-use-specific guidance for performing vulnerability assessments. 

Securing items on the roof should be a continued area of emphasis throughout the life of the 

building, including when roof-mounted equipment is replaced. In addition, owners should 

ensure equipment tie-downs lead to a proper load path so as not to cause more extensive 

damage to the roof. If the equipment cannot be adequately mounted on the roof, then the 

equipment should be moved elsewhere on the site instead of the roof.

Recommendation TX-14b. FEMA should ensure that securing roof-mounted equipment is 

incorporated into eligible Public Assistance Hazard Mitigation Proposals. Appendix J of the 

FEMA Public Assistance Program and Policy Guide (PAPPG; 2018j) lists securing roof-mounted 

equipment via a continuous load path using tie-downs, straps, or other anchoring systems to 

resist expected wind forces as a cost-effective hazard mitigation measure. All eligible facilities 

with damage caused by inadequately attached equipment should incorporate securing roofmounted equipment as a hazard mitigation measure under the Public Assistance grant when 

technically feasible and cost-effective.

Conclusion TX-15

Windows (glazed openings) on most existing buildings are vulnerable to damage and failure 

from wind pressures and wind-borne debris. The MAT observed that buildings of all types with 

unprotected glazing on exterior walls were vulnerable to failure from wind pressures and windborne debris. When these glazed openings fail, the buildings are exposed to additional internal 

wind pressures, and the building interior also becomes exposed to the wind and rain associated 

with the event. These failures were observed in all building types visited, including residential and 

non-residential.

Recommendation TX-15a. Building owners should consider protecting the glazed openings on 

their existing buildings. Owners of existing buildings should consider protecting glazed window 

systems and doors with rated opening protection systems (i.e., storm shutters) or retrofitting the 

building with impact-resistant glazing. When those options are cost prohibitive, homeowners 

should consider constructing and maintaining plywood panels that are cut and sized to cover 

each window or glass door at the home (per the wood panel design criteria for opening 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-13

CONCLUSIONS AND RECOMMENDATIONS

protection set forth in the IRC). FEMA USVI Recovery Advisory 4, Design, Installation, and Retrofit 

of Doors, Windows, and Shutters (2018e), provides guidance on the installation and protection 

of windows and doors. When evaluating opening protection systems, building owners should 

consider passive versus active alternatives, along with their capacity to maintain and implement 

the mitigation measure.

Recommendation TX-15b. FEMA should ensure that opening protection is incorporated into 

eligible Public Assistance Hazard Mitigation Proposals. Appendix J of the FEMA PAPPG lists 

replacing doors, door frames, hinges, and hardware with wind-resistant units; strengthening 

windows; replacing glass with impact-resistant material; and installing shutters on windows as 

cost-effective hazard mitigation measures. All eligible facilities with glazing damage should 

incorporate glazing protection as a hazard mitigation measure under the Public Assistance 

grant when technically feasible and cost-effective.

Conclusion TX-16

The loss of wall coverings on residential buildings was widespread and, in some cases, served as 

an initiation point for progressive damage. The MAT observed evidence of inadequate resistance 

to wind pressures for certain wall coverings of residential buildings. The lack of face nailing on 

fiber cement siding in areas visited throughout Aransas and Nueces Counties led to extensive loss of 

wall covering on residential buildings. The loss of vinyl siding in newer construction was commonly 

due to not selecting siding appropriate for the designated wind speed; improper fasteners and/or 

improper fastener spacing were also a common factor. 

Recommendation TX-16a. Design professionals should specify, and contractors should use, 

face nails on fiber cement siding. Unless the product has been tested and the manufacturer’s 

installation instructions do not require face nails based on the wind hazard at the building 

location, design professionals should specify, and contractors should use, face nails instead of 

blind nails for fiber cement siding in all three zones of the TDI-designated Catastrophe Area. 

Refer to Technical Fact Sheet 5.3, “Siding Installation in High-Wind Regions” in FEMA P-499 

(2010b). In addition, contractors should consider sealing the free siding edge with a continuous 

bead of sealant as a best practice. At a minimum the manufacturer’s installation requirements 

for fastener type, size, and spacing should be followed (requirements vary based on the wind 

hazard for the building location). 

Recommendation TX-16b. Windstorm inspectors and local building officials should 

enforce the use of approved materials in high-wind regions and ensure they are installed 

in accordance with the manufacturer’s requirements. The TDI maintains a list of products 

that comply with the adopted standards for the Windstorm Inspection Program. The MAT 

observed that improper materials were used in new construction that sustained damage. Design 

professionals, contractors, construction material suppliers, and inspectors should only use/allow 

products that are on the approved and tested list and ensure they are installed in accordance 

with industry and manufacturers’ recommendations for high-wind zone installations. For 

example, high-wind siding should be used instead of standard siding in areas with a design wind 

speed greater than 110 mph per ASCE 7-05, or 139 mph per ASCE 7-10/16. 
5-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Conclusion TX-17

Asphalt shingle roof damage was observed throughout high-wind regions. The MAT observed 

many wind performance problems with asphalt shingles, including shingles that had been recently 

installed. Asphalt shingles rated less than that required by TDI were observed in new construction, 

as well as on project sites that were being re-roofed following Hurricane Harvey.

Recommendation TX-17. Contractors should use and inspectors should enforce the use of 

asphalt roof shingles rated for high-wind regions and follow special installation methods to 

increase wind resistance. Texas Recovery Advisory 2, Asphalt Shingle Roofing for High-Wind Regions 

(2018c), provides guidance on installing asphalt roof shingles that will enhance wind resistance 

in high-wind regions. When asphalt shingles are used, the TDI should require shingles based 

on wind resistance determined by test method ASTM D 7158, which calls for Class G shingles in 

Inland Zone I (basic wind speed 120 mph) and Inland Zone II (basic wind speed 110 mph), and 

Class H shingles in the Seaward Zone (basic wind speed 130 mph).

Conclusion TX-18 

Many soffits lacked adequate wind resistance, typically because the wrong material was used for 

the region or it was improperly installed. The MAT observed widespread loss of soffits in residential 

and non-residential construction, generally due to improper materials, lack of fasteners, and/or 

inadequate framing, and wind-driven rain infiltrated some areas where soffits were displaced or 

lost. The loss of soffit vents can allow hurricane winds to drive large amounts of water through the 

openings and soak insulation, which can lead to mold growth and, in some cases, the collapse of 

ceilings.

Recommendation TX-18. Designers, contractors, and inspectors should place more emphasis 

on proper soffit installation in high-wind regions. Wind-driven rain should be limited from 

entering building envelopes and damaging building interiors through proper soffit installation. 

Florida Recovery Advisory 2, Soffit Installation in Florida (2018m), provides soffit installation 

guidance. 

Conclusion TX-19

Brick veneer failures were common. The MAT observed numerous brick veneer failures throughout 

the Hurricane Harvey-damaged areas, including several mid-rise condominiums. The common 

issues observed were randomly spaced brick ties and corrosion or minimal embedment of many 

corrugated ties. 

Recommendation TX-19. Design professionals and contractors should improve installation 

of brick veneer in high-wind regions. Model codes prior to 1995 permitted brick veneer in 

any location, with no wind speed restrictions. Current building requirements and referenced 

standards, including TMS 402/602, Building Code Requirements for Masonry Structures (2016) 

(formerly the ACI 530), provide design and construction guidance for the installation of 

brick veneer. Technical Fact Sheet 5.4, “Attachment of Brick Veneer in High-Wind Regions” in 

FEMA P-499 (2010b), provides additional guidance on properly attaching brick veneer in highwind regions. Design professionals and contractors should place more emphasis on proper 

construction of brick veneer wall systems to limit potential damage.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-15

CONCLUSIONS AND RECOMMENDATIONS

Conclusion TX-20

The performance of high-wind-rated sectional and rolling doors was noticeably better than those 

that were not designed for use in high-wind regions. The MAT observed many non-rated sectional 

doors that failed during Hurricane Harvey. On the other hand, very few hurricane-rated sectional 

doors failed. 

Recommendation TX-20. Building owners in the hurricane-prone regions should have 

sectional and rolling doors evaluated and replace existing doors that lack adequate resistance. 

Sectional and rolling doors should be installed and reinforced in accordance with industry 

and manufacturer’s recommendations for hurricane-prone region installations to prevent 

catastrophic door failure and building pressurization. While most non-rated sectional and 

rolling doors observed by the MAT appeared to pre-date TDI Windstorm Inspection Program 

requirements, building owners, designers, and contractors should ensure any new doors are on 

the approved product evaluation list. 

Conclusion TX-21

The improved wind performance of metal edge flashings and copings in new construction 

contributed to the reduced number of roof membrane blow-offs. The improved performance is 

likely due to the IBC’s reference to the American National Standards Institute/Single Ply Roofing 

Industry/FM Approvals (ANSI/SPRI/FM) 4435/ES-1 2017, Test Standard for Edge Systems Used with 

Low Slope Roofing Systems (ES-1 was first incorporated into the 2003 edition of the IBC). 

Recommendation TX-21. Building owners with single-ply roof membranes should ensure their 

metal edge systems are properly installed. Metal edge flashing and coping on roofs with singleply roof membranes should be installed in accordance with ANSI/SPRI/FM 4435/ES-1 2017 and 

manufacturer’s recommendations for hurricane-prone region installations should be followed to 

prevent roof cover loss. 

Conclusion TX-22 

Current testing standards may need to further consider debris impact. In multiple locations, the 

MAT observed broken laminated glass that remained in the frame, but allowed water infiltration; 

the leakage may have been related to flashing deficiencies, glass breakage, or both. The MAT also 

observed one instance where a window subframe blew out of the main window frame because windborne debris impacted a jack stud; the stud was pushed inward, which caused the main window 

frame to twist. While the products observed were tested for the region in which they were installed, 

the damage indicates the performance measures in current testing requirements may need to be reevaluated and adjusted, especially with respect to limiting infiltration of wind-driven rain. 

Recommendation TX-22a. FEMA should work with industry partners to evaluate whether 

ASTM testing requirements for debris impacts and wind pressures should be adjusted. 

Using damage observations made after Hurricane Harvey, the FEMA Building Science Branch 

should collaborate with industry partners and identify trends in damages (e.g., interior finishes 

subject to water intrusion/wind driven rain) that are potentially a result of inadequate testing 

requirements. For example, ASTM E1886, the standard for glazing protection systems impacted 
5-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

by missiles and exposed to cyclic pressure differentials, does not consider water leakage after 

debris impact, nor does it consider debris impact to the framing around the opening. The 

current testing standard evaluates missile impacts to the window, but the framing around the 

glazing is not impacted during testing. 

Recommendation TX-22b. Industry groups and/or academia should study debris generation 

and strikes to protective systems during hurricanes to determine whether the wind speed 

triggers for the ASCE 7 wind-borne debris region are appropriate. Industry groups and/or 

academia should study debris generation and associated debris strikes to protective systems from 

the 2017 hurricane, as well as for future storms, to determine whether the current wind speed 

triggers for the wind-borne debris region as defined in ASCE 7 are appropriate. Data collected 

and analyzed during the study can be used to make recommendations on ASCE 7-required 

protection of windows and glazed doors. 

5.6 FEMA Technical Publications and Guidance

Conclusion TX-23 

Select FEMA Building Science technical guidance publications are becoming increasingly 

incongruent with current building codes and do not include lessons learned from recent MATs. 

The Building Science Branch at FEMA HQ develops and maintains over 200 publications and 

resources that provide technical guidance on how to assess risk; identify vulnerabilities; better 

understand the NFIP and the regulatory environment with respect to building codes and standards; 

and describe best practices and mitigation measures that can be taken to reduce vulnerabilities 

to flood, wind, and seismic hazards. Some of the FEMA Building Science technical guidance 

publications do not reflect advanced requirements in current building codes nor do they include 

new lessons learned from recent MAT reports.

The 2017 hurricane season brought landfalling hurricanes on the island territories and the 

continental United States. There were many valuable and important damage observations and 

lessons learned from this and other events, and the observed damage might have been avoided if the 

guidance from these documents had been incorporated at different building locations. However, 

while the approaches and theories in these publications are still accurate, many of the building 

codes have been updated in the last 8 to 10 years and may impact the current approaches outlined 

in these documents. 

Recommendation TX-23a. FEMA should complete Guidelines for Wind Vulnerability Assessments 

for Critical Facilities. FEMA’s Building Science Branch has been developing guidance to assess 

wind vulnerabilities of critical facilities. FEMA should include lessons learned from the 2017 

hurricane season in finishing this publication, which would greatly benefit many stakeholders in 

the U.S.

Recommendation TX-23b. FEMA should update select FEMA Building Science publications 

that affect coastal construction. The FEMA Building Science Branch should consider updating 

or producing a supplement for its key hurricane technical guidance publications to include 

lessons learned from the 2017 hurricane season and reflect updates to building codes since the 
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-17

CONCLUSIONS AND RECOMMENDATIONS

publications’ latest releases. These publications might include, but are not necessarily limited to, 

the following:

+ FEMA P-55, Coastal Construction Manual (2011)

+ FEMA P-499, Home Builder’s Guide to Coastal Construction (2010b)

+ FEMA P-762, Local Officials Guide for Coastal Construction (2009b)

+ FEMA P-804, Wind Retrofit Guide for Residential Buildings (2010d)

Recommendation TX-23c. FEMA should update the FEMA Risk Management Series guidance 

publications for natural hazards. The FEMA Building Science Branch, working with other 

FEMA and DHS entities, should consider updating or producing a supplement to select technical 

documents from the FEMA Natural Hazard Risk Management Series to include lessons learned 

from the 2017 hurricane season and reflect updates to building codes since the publications’ 

latest releases. These publications might include, but are not limited to, the following:

+ FEMA P-424, Design Guide for Improving School Safety in Earthquakes, Floods, and High Winds 

(2010a)

+ FEMA 543, Design Guide for Improving Critical Facility Safety from Flooding and High Winds

(2007a)

+ FEMA 577, Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds: 

Providing Protection to People and Buildings (2007b)

Conclusion TX-24 

Post-Tropical Storm Allison Public Assistance Hazard Mitigation Proposals did not require 

post-construction certification to a specific requirement or standard. The MAT observed dry 

floodproofing failures at several sites where the dry floodproofing measure had been installed using 

Public Assistance funding. The Public Assistance Mitigation Proposal for these measures did not 

reference or require compliance with NFIP Technical Bulletin 3, Non-Residential Floodproofing—

Requirements and Certification (1993) or ASCE 24-98. 

Recommendation TX-24a. FEMA should make the requirements for projects developed 

under the FEMA Public Assistance and the Hazard Mitigation Assistance programs consistent 

between the programs. The FEMA PAPPG allows buildings to be dry or wet floodproofed as a 

hazard mitigation measure without specific requirements (unless the measure triggers a code 

requirement), whereas the FEMA HMA guidance requires mitigation grant recipients to design 

all dry floodproofing projects in accordance with ASCE 24. When applicable, FEMA should 

incorporate consensus standards (ASCE 24), testing standards (ANSI, ASTM, etc.), or other best 

practice guidance when identifying cost-effective mitigation measures in the PAPPG. 

Recommendation TX-24b. Hazard Mitigation Proposals for dry floodproofing under the 

Public Assistance program should be required to reference ASCE 24. All Public Assistance 

Hazard Mitigation Proposals that include dry floodproofing as a mitigation measure should 

require design and construction to be completed in accordance with ASCE 24. In addition, 
5-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

dry floodproofing design and construction should incorporate guidance from Texas Recovery 

Advisory 1, Dry Floodproofing: Planning and Design Considerations (2018g), and Florida Recovery 

Advisory 1, Dry Floodproofing: Operational Considerations (2018f).

Conclusion TX-25

Future dry floodproofing design and construction can benefit from observed failures and 

successes. The MAT visited about 20 dry floodproofed sites following Hurricane Harvey and 

observed several lessons learned from dry floodproofing failures under less than design flood 

conditions, as well as best practices from successes. For example, dry floodproofed facilities that had 

undergone a comprehensive flood vulnerability assessment prior to the design and construction of 

the floodproofing measures and had a thorough EOP that was regularly exercised were much less 

likely to have flood damage.

Recommendation TX-25a. FEMA should update dry floodproofing guidance. Based on the 

varying performance of dry floodproofing measures observed, FEMA should revise existing 

dry floodproofing guidance to include data and observations from recent events. In particular, 

NFIP Technical Bulletin 3, Non-Residential Floodproofing—Requirements and Certification (1993), 

should be updated to improve guidance on planning, design and construction, and emergency 

operations, as well as maintenance planning requirements. Specific points of emphasis include:

+ For new construction, recommend using ACI 350, Code Requirements for Environmental 

Engineering Concrete Structures (2006) for designing concrete that will be constructed below 

the required dry floodproofing elevation (ACI 350 concrete design reduces the crack width 

in concrete and increases the fineness of the concrete matrix to reduce concrete permeability 

rates).

+ For both new construction and retrofits to existing structures, include information on the use 

of products certified by the National Flood Barrier Testing and Certification Program and 

the applicability of the ANSI 2510 standard for flood barrier products (ANSI 2510 establishes 

performance standards for perimeter barriers, opening barriers, backflow valves, and flood 

abatement pumps).

+ Consider limiting the amount of allowable building envelope that is not permanently 

substantially impermeable. Generally, passive dry floodproofing measures were more effective 

than active measures at reducing flood damage. However, the number of active measures and 

time required to implement them was typically a better indicator of performance; buildings 

with fewer active dry floodproofing measures performed better than those with more. As 

a result, the extent of temporary protective measures, whether passive or active, would be 

limited to the length of the perimeter required for egress (pedestrian and vehicular in the 

case of parking structures and loading docks).

FEMA should also consider updating FEMA P-936, Floodproofing for Non-Residential Buildings 

(2013), with relevant lessons learned from the 2017 hurricane season.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-19

CONCLUSIONS AND RECOMMENDATIONS

Recommendation TX-25b. FEMA should evaluate existing dry floodproofing guidance 

and post-flood investigations to develop a recommendation for inclusion in ASCE 24. 

FEMA should review recommendations, fact sheets, and recovery advisories related to dry 

floodproofing included in other MAT reports to develop a comprehensive recommendation for 

dry floodproofing design, limitations, testing, and maintenance and operations requirements for 

consideration by the ASCE 24 committee charged with revising Chapter 6, “Dry Floodproofing 

and Wet Floodproofing.” 

Conclusion TX-26 

Many communities have difficulty implementing the Substantial Improvement/Substantial 

Damage requirements, especially after major disasters. Several thousand flood-damaged buildings 

in SFHAs flooded by Hurricane Harvey were designed and built before communities joined the 

NFIP and began regulating development in SFHAs. Enforcing the NFIP requirements to bring 

Substantially Improved and Substantially Damaged buildings into compliance continues to be 

one of the more difficult challenges for floodplain administrators and building officials. Updated 

guidance on administering the Substantial Improvement/Substantial Damage requirements in 

forms accessible by local officials, design professionals, builders, and property owners is needed. 

When flood-damaged buildings are insured by the NFIP, local officials must determine whether 

a building was Substantially Damaged in order for policyholders to qualify for Increased Cost of 

Compliance.

Recommendation TX-26a. FEMA should update FEMA P-758; at the same time, FEMA 213 

should be updated to be consistent with FEMA P-758. FEMA P-758, Substantial Improvement/

Substantial Damage Desk Reference (2010c) should be updated. Updates should include lessons 

learned, and recommended guidance and clarifications since it was published in 2010. At the 

same time, FEMA 213, Answers to Questions about Substantially Improved/Substantially Damaged 

Buildings (2018b) should be updated to be consistent with FEMA P-758. Outreach material 

should be developed as part of the publication updates.

Recommendation TX-26b. FEMA should consider expanding existing training materials 

related to Substantial Improvement/Substantial Damage. FEMA should consider developing a 

webinar format training for distribution to NFIP State Coordinators and other entities related 

to Substantial Improvement/Substantial Damage. The materials should incorporate lessons 

learned after Hurricane Harvey and other recent flood events and should include a unit that 

focuses on the local official’s role in helping insured property owners satisfy requirements to 

qualify for Increased Cost of Compliance claims and in issuing permits for mitigation measures 

eligible for use of those claim payments.
5-20 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

5.7 Summary of Conclusions and Recommendations

Table 5-1 is a matrix listing the conclusions and recommendations cross-referenced to the sections 

of the report that describe the supporting observations. The recommendations provided in the 

table have also been cross-referenced to Recovery Support Functions (RSFs) supported by FEMA 

through the National Disaster Recovery Framework (NDRF). FEMA developed the RSFs with the 

objective of facilitating the identification, coordination, and delivery of Federal assistance needed 

to supplement recovery resources and efforts by local, State, tribal, and territorial governments, 

as well as private and nonprofit sectors. The MAT has identified RSFs for the recommendations 

provided in this report to assist Texas with accelerating the process of recovery, redevelopment, and 

revitalization.

NATIONAL DISASTER RECOVERY FRAMEWORK AND RECOVERY SUPPORT FUNCTIONS

FEMA developed the National Disaster 

Recovery Framework (NDRF) to create a 

common platform and forum by which the whole 

community builds, sustains, and coordinates 

delivery of recovery capabilities. FEMA guidance 

states: 

Resilient and sustainable recovery 

encompasses more than the restoration of 

a community’s physical structures to predisaster conditions. The primary value of 

the NDRF is its emphasis on preparing for 

recovery in advance of disaster. The ability 

of a community to accelerate the recovery 

process begins with its efforts in pre-disaster 

preparedness, including coordinating with 

whole community partners, mitigating risks, 

incorporating continuity planning, identifying 

resources, and developing capacity to 

effectively manage the recovery process, 

and through collaborative and inclusive 

planning processes. Collaboration across the 

whole community provides an opportunity 

to integrate mitigation, resilience, and 

sustainability into the community’s short- and 

long-term recovery goals. 

The Recovery Support Functions compose 

the coordinating structure for key functional 

areas of assistance in the NDRF. Their purpose 

is to support local governments by facilitating 

problem solving; improving access to resources; 

and fostering coordination among State and 

Federal agencies, nongovernmental partners, 

and stakeholders. 

The list of Recovery Support Functions and 

the leading coordinating agencies is presented 

below (and available on line at www.fema.gov/

recovery-support-functions): 

•	 Community Planning and Capacity Building 

(CPCB) Recovery Support Function (U.S. 

Department of Homeland Security/FEMA) 

•	 Economic Recovery Support Function (U.S. 

Department of Commerce) 

•	 Health and Social Services Recovery Support 

Function (U.S. Department of Health and 

Human Services) 

•	 Housing Recovery Support Function 

(U.S. Department of Housing and Urban 

Development)

•	 Infrastructure Systems Recovery Support 

Function (U.S. Army Corps of Engineers)

•	 Natural and Cultural Resources Recovery 

Support Function (U.S. Department of the 

Interior)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-21

CONCLUSIONS AND RECOMMENDATIONS

Table 5-1: Summary of Conclusions and Recommendations 

Observations Conclusions Recommendations

Recovery 

Support 

Function

Chapter 4 

(Section 4.1) TX-1

Building codes and 

floodplain management 

requirements were 

inconsistently enforced.

TX-1a. Continue providing training to Windstorm 

Inspection Program inspectors and building code 

enforcement staff, placing emphasis on changes 

reflected in the latest adopted edition of the building 

code.

CPCB, 

Housing

Chapter 3 

(Section 3.1)

TX-1b. The Texas Water Development Board and 

other stakeholders should develop/modify training on 

the flood provisions in model building codes and/or 

floodplain management ordinances.

CPCB

Chapters 3 

and 4

TX-2

Some high-occupancy 

and critical facility 

building owners have 

a limited awareness of 

hurricane hazard risks and 

vulnerabilities.

TX-2. Facility and building owners should perform 

vulnerability assessments. CPCB, Health 

and Social 

Services, 

Housing

Chapter 4 

(Section 4.1)

TX-3

The TDI Texas Windstorm 

Inspection Program 

requirements are based 

on compliance with the 

2006 IBC and IRC, which 

are outdated.

TX-3a. TDI should adopt the 2018 IBC and IRC as the 

model codes for its Windstorm Inspection Program.

CPCB, 

Housing

TX-3b. TDI should consider developing a more 

stringent high-wind retrofit program.

Chapter 2 

(Section 

2.1.3)

TX-4

Portions of local 

floodplain management 

ordinances and building 

codes in communities 

visited by the MAT 

conflict with some of the 

requirements in model 

ordinances and building 

codes.

TX-4a. Harris County should review and update its 

floodplain management regulations.

CPCB

TX-4b. The City of Houston should review and 

update its floodplain management ordinance and 

guidance.

TX-4c. The City of Bellaire should review and update 

its flood damage prevention ordinance and guidance.

TX-4d. The City of Port Aransas should review and 

update its flood damage prevention ordinance.

General 

MAT Field 

Observation

TX-4e. All Texas communities should consider 

reviewing and updating their local floodplain 

management ordinances.

Chapter 3 

(Section 3.1)

TX-5 

Many non-elevated or 

low-elevation buildings 

sustained flood damage.

TX-5a. Communities and building owners should 

consider elevating new and Substantially Improved/

Substantially Damaged buildings above the NFIP 

elevation requirements to protect them from flooding.

CPCB, 

Housing

Chapter 3

TX-5b. Communities should incorporate the best 

available flood hazard data wherever they are 

available.

TX-5c. Communities should consider future 

conditions in zoning, building code, and floodplain 

management requirements.
5-22 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Table 5-1: Summary of Conclusions and Recommendations (continued)

Observations Conclusions Recommendations

Recovery 

Support 

Function

Chapter 3 

(Section 

3.2)

TX-6

Dry floodproofing 

measures often failed 

under less than design 

flood conditions.

TX-6a. Local floodplain administrators, design 

professionals, and building owners should follow 

the guidance in FEMA’s Texas Recovery Advisory 1 

(2018g) and Florida Recovery Advisory 1 (2018f). CPCB, 

TX-6b. Infrastructure Local floodplain administrators, design 

professionals, and building owners should ensure 

sump pumps, with a floor drain system to collect 

seepage, are included as part of all dry floodproofing 

systems.

TX-7

Dry floodproofed buildings 

that were considered 

substantially impermeable 

sustained damage that 

resulted in significant loss 

of function while repairs 

were completed.

TX-7. Flood damage-resistant materials should be 

used below the DFE inside dry floodproofed buildings 

when possible.

CPCB, 

Infrastructure

TX-8 

Dry floodproofed buildings 

where building managers 

had instilled a culture of 

preparedness sustained 

less damage than 

other dry floodproofed 

buildings.

TX-8a. Facility managers should develop an 

emergency operations plan (EOP) for severe weather.

CPCB, 

Infrastructure

TX-8b. Facility managers should routinely re-evaluate 

dry floodproofing designs and plans as required by 

codes and standards.

TX-8c. Facility managers should take reasonable 

measures to instill a culture of preparedness.

Chapter 3 

(Section 3.1)

TX-9

Non-flood damageresistant materials were 

used below the BFE in 

elevated buildings and 

had to be replaced.

TX-9. Local floodplain administrators must enforce, 

and design professionals and builders must comply 

with, the requirement to use flood damage-resistant 

materials below an elevated building’s DFE. CPCB

Chapter 3

TX-10

Damage to buildings not 

designed and constructed 

to current building 

code requirements 

was noticeably greater 

than damage to NFIPcompliant buildings.

TX-10a. When and where possible, FEMA should 

consider updating the NFIP standards to be at least 

equivalent to the consensus-based codes.

CPCB, 

Housing

TX-10b. FEMA and communities should re-evaluate 

the criteria for Substantial Improvement/Substantial 

Damage. CPCB

General 

MAT Field 

Observation

TX-11 

The State and 

communities did not 

receive (or did not receive 

in a timely manner) 

data on buildings that 

appeared to have incurred 

Substantial Damage.

TX-11. FEMA should develop an effective and timely 

means to deliver the Adjuster Preliminary Damage 

Assessment data.

CPCB
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-23

CONCLUSIONS AND RECOMMENDATIONS

Observations Conclusions Recommendations

Recovery 

Support 

Function

Chapter 3

TX-12 

The MAT observed 

widespread flood damage 

both within and outside 

the regulatory floodplain.

TX-12a. FEMA should make NFIP policy information, 

especially data related to historical claims, available 

to help supplement flood hazard data on the FIRM.

CPCB

TX-12b. Owners of buildings located near but outside 

the SFHA should consider implementing flood risk 

reduction measures.

CPCB, 

Housing

Chapter 3 

(Section 3.1)

TX-13 

Contractors and 

designers have insufficient 

guidance on elevated slab 

projects.

TX-13. Continue ongoing research on the 

performance of elevated slab foundations and 

develop related outreach material. CPCB

Chapter 4 

(Section 

4.2)

TX-14

Roof-mounted equipment 

lacked adequate 

attachments.

TX-14a. Building owners and/or facility managers 

should ensure roof-mounted equipment is adequately 

anchored.

CPCB, Health 

and Social 

Services, 

Housing

TX-14b. FEMA should ensure that securing roofmounted equipment is incorporated into eligible 

Public Assistance Hazard Mitigation Proposals.

Chapter 4

TX-15

Windows (glazed 

openings) on most 

existing buildings are 

vulnerable to damage 

and failure from wind 

pressures and wind-borne 

debris.

TX-15a. Building owners should consider protecting 

the glazed openings on their existing buildings.

CPCB, Health 

and Social 

Services, 

Housing

TX-15b. FEMA should ensure that opening protection 

is incorporated into eligible Public Assistance Hazard 

Mitigation Proposals.

Chapter 4 

(Section 4.1)

TX-16

The loss of wall coverings 

on residential buildings 

was widespread and, 

in some cases, served 

as an initiation point for 

progressive damage.

TX-16a. Design professionals should specify, and 

contractors should use, face nails on fiber cement 

siding.

CPCB, 

Housing

TX-16b. Windstorm inspectors and local building 

officials should enforce the use of approved materials 

in high-wind regions and ensure they are installed in 

accordance with the manufacturer’s requirements.

CPCB

TX-17

Asphalt shingle roof 

damage was observed 

throughout high-wind 

regions.

TX-17. Contractors should use and inspectors should 

enforce the use of asphalt roof shingles rated for 

high-wind regions and follow special installation 

methods to increase wind resistance.

CPCB

Chapter 4

TX-18 

Many soffits lacked 

adequate wind resistance, 

typically because the 

wrong material was used 

for the region or it was 

improperly installed.

TX-18. Designers, contractors, and inspectors should 

place more emphasis on proper soffit installation in 

high-wind regions.

CPCB

Table 5-1: Summary of Conclusions and Recommendations (continued)
5-24 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

CONCLUSIONS AND RECOMMENDATIONS

Observations Conclusions Recommendations

Recovery 

Support 

Function

Chapter 4 

(Section 4.1)

TX-19

Brick veneer failures were 

common.

TX-19. Design professionals and contractors should 

improve installation of brick veneer in high-wind 

regions. CPCB

TX-20 

The performance of 

high-wind-rated sectional 

and rolling doors was 

noticeably better than 

those that were not 

designed for use in highwind regions.

TX-20. Building owners in the hurricane-prone 

regions should have sectional and rolling doors 

evaluated and replace existing doors that lack 

adequate resistance. CPCB

Chapter 4 

(Section 

4.2)

TX-21

The improved wind 

performance of 

metal edge flashings 

and copings in new 

construction contributed 

to the reduced number of 

roof membrane blow-offs.

TX-21. Building owners with single-ply roof 

membranes should ensure their metal edge systems 

are properly installed.

CPCB

Chapter 4

TX-22 

Current testing standards 

may need to further 

consider debris impact.

TX-22a. FEMA should work with industry partners 

to evaluate whether ASTM testing requirements 

for debris impacts and wind pressures should be 

adjusted. CPCB, 

TX-22b. Industry groups and/or academia should Housing study debris generation and strikes to protective 

systems during hurricanes to determine whether 

the wind speed triggers for the ASCE 7 wind-borne 

debris region are appropriate.

General 

MAT Field 

Observation

TX-23

Select FEMA Building 

Science technical 

guidance publications are 

becoming increasingly 

incongruent with current 

building codes and do not 

include lessons learned 

from recent MATs.

TX-23a. FEMA should complete Guidelines for Wind 

Vulnerability Assessments for Critical Facilities.

CPCB, Health 

and Social 

Services

TX-23b. FEMA should update select FEMA Building 

Science publications that affect coastal construction.

CPCB, 

Housing

TX-23c. FEMA should update the FEMA Risk 

Management Series guidance publications for natural 

hazards.

CPCB, Health 

and Social 

Services

Table 5-1: Summary of Conclusions and Recommendations (continued)
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT 5-25

CONCLUSIONS AND RECOMMENDATIONS

Observations Conclusions Recommendations

Recovery 

Support 

Function

Chapter 3 

(Section 

3.2)

TX-24 

Post-Tropical Storm 

Allison Public Assistance 

Hazard Mitigation 

Proposals did not require 

post-construction 

certification to a specific 

requirement or standard.

TX-24a. FEMA should make the requirements 

for projects developed under the FEMA Public 

Assistance and the Hazard Mitigation Assistance 

programs consistent between the programs.

CPCB, Health 

and Social 

Services

TX-24b. Hazard Mitigation Proposals for dry 

floodproofing under the Public Assistance program 

should be required to reference ASCE 24.

CPCB, Health 

and Social 

Services, 

Infrastructure

TX-25 

Future dry floodproofing 

design and construction 

can benefit from observed 

failures and successes.

TX-25a. FEMA should update dry floodproofing 

guidance.

CPCB, 

Infrastructure

TX-25b. FEMA should evaluate existing dry 

floodproofing guidance and post-flood investigations 

to develop a recommendation for inclusion in 

ASCE 24.

General 

MAT Field 

Observation

TX-26

Many communities have 

difficulty implementing the 

Substantial Improvement/

Substantial Damage 

requirements, especially 

after major disasters.

TX-26a. FEMA should update FEMA P-758; at the 

same time, FEMA 213 should be updated to be 

consistent with FEMA P-758.

CPCB TX-26b. FEMA should consider expanding existing 

training materials related to Substantial Improvement/

Substantial Damage.

Table 5-1: Summary of Conclusions and Recommendations (concluded)

ASCE = American Society of Civil Engineers

BFE = base flood elevation 

CPCB = Community Planning and Capacity Building 

DFE = design flood elevation 

EOP = emergency operations plan 

FEMA = Federal Emergency Management Agency

FIRM = Flood Insurance Rate Map

IBC = International Building Code

IRC = International Residential Code

MAT = Mitigation Assessment Team 

NFIP = National Flood Insurance Program 

SFHA = Special Flood Hazard Area

TDI = Texas Department of Insurance
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT A-1

AAppendix A: 

Acknowledgments

The Federal Emergency Management Agency (FEMA) would like to acknowledge the contributions 

of the following persons to the Mitigation Assessment Team study of the areas affected by Hurricane 

Harvey in Texas: 

David Alamia, MPA CEM

Harris County Office of Emergency 

Management

Scott Aldridge

CDM Smith

Courtney Alters

Riverview Reality Partners

Robert Azimi

FM Approvals 

Randy Behm, PE, CFM

U.S. Army Corps of Engineers

Chad Berginnis, CFM

Association of State Floodplain Managers 

Matthew Berkheiser, DrPh, CIH, CSP

The University of Texas MD Anderson 

Cancer Center

Jason Berrio

Thermal Energy Corporation (TECO)

Bill Blanton, CFM

FEMA Headquarters

John Bourdeau, Jr., CFM, PMP

FEMA Region VI

Dana Bres, PE

U.S. Department of Housing and Urban 

Development

Adam Briones

Harris County Sheriff’s Office

Lindsay Brugger, AIA

American Institute of Architects

Jose Campos

Hicks Ventures

Abel Carrillo

Port Aransas Building Official 

Paul Carter

Harris County Engineering Department 

Facilities & Property Maintenance
A-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE HARVEY IN TEXAS

ACKNOWLEDGMENTS

Bill Coulbourne, PE, F.SEI, F.ASCE

AECOM

Paul Croas

Harris County Sheriff’s Office

Richard Driscoll

Floodbreak

FEMA Modeling Working Group

Gina Filippone, CFM

AECOM

Jacob Frazell, PMP, CFM, LEED GA

Harris County Engineering Department 

Facilities & Property Maintenance

Fanny Frederick

The University of Texas MD Anderson 

Cancer Center

Jose Garcia, PE, CEM

Thermal Energy Corporation (TECO)

Rose Grant

State Farm 

Zane Gifford

Riverview Reality Partners

Ram Goonie, CEM

Thermal Energy Corporation (TECO)

Bert Gumeringer

Texas Children’s Hospital

Carlos Gutierrez, PE, MLSE

CSF Consulting LP

Lisa Hargrove

Houstonfirst

Leslie Chapman-Henderson

Federal Alliance for Safe Homes, Inc.

Micah Hennings

Harris County Engineering Department 

Facilities & Property Maintenance

Andrew Hoyns

Hicks Ventures

Greg Hudgins

The University of Texas MD Anderson 

Cancer Center

John Ingargiola, EI, CFM, CBO

FEMA Headquarters 

Insurance Institute for Business & Home 

Safety

International Code Council

Samantha Krautwurst, PE

AECOM 

Edward Laatsch, PE

FEMA Headquarters

Donald Leifheit Jr., CFM

FEMA Region VI 

Marc Levitan, PhD

National Institute of Standards and 

Technology

Tom Little, CFM, CGP

Smartvent 

Rachel Minnery, FAIA

American Institute of Architects

James Mitchell

Texas Children’s Hospital

Judith Mitrani-Reiser, PhD

National Institute of Standards and 

Technology

Karen Mooney, MBA, ACC

The University of Texas MD Anderson 

Cancer Center

Rock Morille, MBA, BSME

Baylor College of Medicine

Devina Patel

The University of Texas MD Anderson 

Cancer Center

Tim Peglow, PE, CCE, SASHE

The University of Texas MD Anderson 

Cancer Center
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT A-3

ACKNOWLEDGMENTS

John “Bud” Plisich

FEMA Region IV

Carol Porter, DNP, RN, FAAN

The University of Texas MD Anderson 

Cancer Center

James Power

The University of Texas MD Anderson 

Cancer Center

Oscar Rangel

The University of Texas MD Anderson 

Cancer Center

James Reddington

City of Houston

Michael Rimoldi, MPA, CBO, CFM

Federal Alliance for Safe Homes, Inc.

David B. Roueche, PhD

Auburn University

Bob Roy

Center Point Energy

Lance Rumfield

Center Point Energy

Elex Sanchez

Texas Children’s Hospital

Sheldon Schroeder, AIA

Freeman Schroeder Architects

Rodney Smalligan

The University of Texas MD Anderson 

Cancer Center

Michael Staley

Harris Heath Ben Taub Hospital

Benny Stansbury

Harris Heath Ben Taub Hospital

Steve Suter

The University of Texas MD Anderson 

Cancer Center

Biv Taylor, PE

Houston Energy Corridor Facilities Manager

Steve Thompson, PE

TX Department of Insurance

Amanda Torres

Rockport Community Planner 

Raymond Tirado

Four Leaf Towers

Bruce Turner, PE, CPE

Thermal Energy Corporation (TECO)

Roksan Okan-Vick, FAIA

Houstonfirst

Peter Vickery, PhD, PE, F.SEI, F.ASCE

Applied Research Associates

Larry Voice

FEMA Region VI

Ronald C. Wanhanen, PE

FEMA Region VI

Chad Wleczyk

Center Point Energy
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT B-1

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(formerly the ACI 530).

USACE (U.S. Army Corps of Engineers). 1995. Flood Proofing Regulations. EP 1165-2-314. 

http://www.publications.usace.army.mil/Portals/76/Publications/EngineerPamphlets/

EP_1165-2-314.pdf.
HURRICANE HARVEY IN TEXAS MITIGATION ASSESSMENT TEAM REPORT C-1

CAppendix C: 

Recovery Advisories

FEMA has prepared new Recovery Advisories (RAs) that present guidance to engineers, architects, 

homeowners, and local officials on mitigation measures that can be taken to minimize building 

damage in a hurricane event. Two advisories are referenced in this appendix:

FL-RA1: Dry Floodproofing: Planning and Design Considerations

FL-RA2: Asphalt Shingle Roofing for High-Wind Regions

These advisories are online at https://www.fema.gov/media-library/assets/documents/158123
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 1 of 14

Dry Floodproofing: 

Planning and Design 

Considerations

HURRICANE HARVEY IN TEXAS Recovery Advisory 1, April 2018

Purpose and Intended Audience

The purpose of this Recovery Advisory is to provide 

guidance on the design of dry floodproofing 

measures to reduce flood damage and limit 

interruption of building services. This advisory 

incorporates observations made by the Federal 

Emergency Management Agency (FEMA) Mitigation 

Assessment Teams (MATs) in Texas and Florida 

after Hurricanes Harvey and Irma. It describes best 

design practices and successful implementation of 

dry floodproofing, as well as lessons learned from 

failures. The information in this advisory is directed 

toward existing and new non-residential facilities.

This guidance, along with other FEMA publications 

related to dry floodproofing, should be used 

by building owners and design professionals 

examining ways to reduce future risk. It will also 

be useful to communities and building owners 

preparing designs and proposals for FEMA 

Section 404 Hazard Mitigation grants and hazard 

mitigation elements included in recovery funding 

available through FEMA Section 406 Public 

Assistance. To improve resiliency in future flooding 

events, lessons learned and best practices from 

the MATs can be incorporated into retrofits when 

dry floodproofing measures are applied to existing 

buildings and when designing dry floodproofing 

systems for new buildings. 

The audience for this advisory includes building 

owners, operators, and managers; architects; 

engineers; building officials; contractors; and local 

government officials responsible for public building 

planning, design, and maintenance.

Key Issues

The key issues identified by the MATs during field 

visits in Texas and Florida are shown in Table 1. 

A number of these key issues are discussed in 

detail in other FEMA publications (see the list of 

references and resources in this advisory) and not 

Dry Floodproofing

Dry floodproofing is a combination of measures 

that result in a structure, including its attendant 

utilities and equipment, being watertight, with 

all elements substantially impermeable to 

the entrance of floodwater and with structural 

components having the capacity to resist flood 

loads (ASCE 24; ASCE 2014).

The image below shows an example of dry 

floodproofing where a passive opening protection 

deployed to protect a below-grade loading dock 

was threatened by rising floodwaters.

Photograph courtesy of Andrew Hoyns, Hicks Ventures

FEMA Public Assistance Program Funding for 

Dry Floodproofing Projects

In addition to funding for repair and recovery 

projects, FEMA Public Assistance (PA) Program 

funding may be available for cost-effective hazard 

mitigation measures that increase resilience, such 

as dry floodproofing projects. For more information, 

refer to Chapter 2 Section VII.C., “Hazard 

Mitigation” of FEMA’s Public Assistance Program 

and Policy Guide (2018).

in this advisory. This advisory focuses on key issues 

to help fill information gaps or supplement guidance in 

other FEMA publications.
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 2 of 14

Table 1: Key Issues Identified by MATs

Key Topic Areas

Discussed in this 

Advisory?

Additional FEMA Sources 

of Information 

Backup power Yes

FEMA P-1019 

FEMA P-348 (Chapter 5)

Iowa Floods of 2016 RA5

Building penetration elevations relative 

to base/design flood elevations Yes FEMA P-936 (Sections 2.6.3, 3.4, 3.9, and 3.10)

FEMA P-259 (Chapter 5D)

Flood barrier penetrations and 

seepage control Yes FEMA P-312 (Chapters 7 and 8)

FEMA P-936 (Section 3.4.3)

Issues with sewer system and 

stormwater systems (ejector pumps 

with back-flow preventers)

Yes

FEMA 259 (Sections 5D.10 and 5W.12)

FEMA P-348 (Section 5.3)

FEMA P-936 (Sections 2.2 and 3.7)

Rainfall behind the flood barrier Yes FEMA P-312 (Section 3.4.2; Chapters 7 and 8)

FEMA P-936 (Sections 2.2.8 and 3.7)

Seepage disposal Yes FEMA P-936 (Sections 2.2.7 and 3.7)

Use of flood damage-resistant 

materials Yes

FEMA TB 2

FEMA P-936 (Sections 3.2 and 3.9)

See also *

Use of redundant systems and 

compartmentalization/layered 

protection

Yes FEMA P-348 (Chapter 5)

Design flood elevation requirements No Hurricane Sandy RA5 

Iowa Floods of 2016 RA1

Hydrostatic forces and buoyancy No Hurricane Sandy RA2 

FEMA P-936 (Section 2.2)

Performance of critical building 

systems No

Hurricane Sandy RA2, RA4, and RA6

Iowa Floods of 2016 RA3

FEMA P-348 (Chapter 5)

FEMA P-936 (Section 2.6.3)

Note: Complete titles and URLs for each publication are presented at the end of this advisory 

RA = Recovery Advisory; TB = Technical Bulletin

*Refer also to Floodproof Commercial Construction: Working for Coastal Communities (Oak Ridge National Laboratory 2011)

This Recovery Advisory Addresses 

" Observations of dry floodproofing system failures

" Flood vulnerability assessments

" Planning and pre-design considerations

" Design considerations

A companion advisory, titled Dry Floodproofing: Operational Considerations (Hurricane Irma in Florida, 

FL-RA1, 2018) describes deployment considerations (deployment, operations, maintenance, testing) for 

dry floodproofing.
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 3 of 14

Observations of Dry Floodproofing System Failures 

Hurricanes Harvey and Irma caused numerous failures in dry floodproofing systems used to protect nonresidential buildings, which led to extensive damage to mechanical, electrical, and plumbing system 

components, as well as building and interior finishes, and occasionally structural components. Based on the 

observations of FEMA’s MATs deployed after the hurricanes, the performance of dry floodproofing measures 

was highly variable, ranging from effective to completely ineffective. Observed failures at dry floodproofed 

buildings included overtopping of flood walls or barriers, failure of the opening protections, structural failure 

of flood barriers, failure to identify lowest point of floodwater entry, seepage issues, and sanitary sewer and 

stormwater system issues. 

As a result of these failures, critical building systems located in basements and first floors were damaged 

and rendered inoperable. Even where opening protection succeeded in holding back most of the floodwater, 

seepage through the flood barrier and water entry through penetrations resulted in significant damage to 

interior finishes and building systems. In addition to failures, there were numerous observations of “near 

misses” where dry floodproofing measures and human intervention prevented widespread flood damage. If 

flood levels had been only slightly higher or if building managers had not taken action before the onset of 

flooding, many observed successes would have become failures. This section describes the types of failure 

modes the MATs observed after Hurricanes Harvey and Irma.

Key Terminology

Flood Barrier: The physical barrier, composed of 

opening protection, floor slab, and wall system, 

that separates floodwater from the dry floodproofed 

portion of the building.

Opening Protection: A cover, shield, or door that 

covers a window, doorway, loading dock access, or 

other opening in a building wall or floor. Sometimes 

called “closure device.”

Floodwall: A constructed barrier of flood damageresistant materials to keep water away from or out 

of a specific area. Floodwalls surround a building 

and are typically offset from the exterior walls of 

the building; some floodwalls can be integrated into 

the building envelope. Floodwalls are considered a 

component of the overall flood barrier. 

Flood Entry Point: Any opening, joint, gap, crack, 

low point, or other location through or over which 

floodwater can enter the dry floodproofed area.

Overtopping 

Floodwalls and opening protection were overtopped 

in locations where the water surface elevation (WSE) 

exceeded that of the top of the flood barrier. 

Failure of Opening Protection 

Opening protection failed either because it was not 

properly sealed against its frame or because hydrostatic 

or hydrodynamic forces exceeded the structural capacity 

of the barrier. Figure 1 shows a submarine door that 

failed at its midpoint due to hydrostatic forces. 

Structural Failure of Flood Barrier 

Flood barriers failed in locations where the hydrostatic 

forces exceeded the capacity of the wall system. 

Other failures occurred in areas where abandoned 

building openings were infilled with materials, 

typically unreinforced masonry, that could not resist 

hydrostatic forces.

Figure 1: Structural failure of a submarine door from 

hydrostatic forces; the door failed along a weld in the door 

panel adjacent to a stiffener (red circle)

Photograph courtesy of Carlos Gutierrez, CSF Consulting
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 4 of 14

Failure to Identify and Protect Lowest Point 

of Entry 

Buildings were flooded when dry floodproofing 

measures were incomplete and did not adequately 

protect the lowest point of entry from floodwater. 

Figure 2 shows a building where the low point in 

the flood barrier was not identified or protected, 

allowing floodwater to overtop the low point in the 

flood barrier. 

Failure to Maintain Structural Integrity of the 

Flood Barrier 

Basements and other below-grade areas were 

flooded due to large openings being cut through 

the foundation walls during construction or 

capital improvement projects. These openings 

were sealed without re-establishing structural 

integrity or impermeability. Sealing these openings 

without making them substantially impermeable 

and not re-establishing an adequate structural 

load path left a weakness in the flood barrier, 

making it vulnerable to floodwater entry and flood 

damage when exposed to hydrostatic forces. 

Figure 3 shows a 6-foot by 6-foot opening cut 

into a foundation wall to provide access for a 

construction project. After construction was 

completed, the opening was filled in with timber 

framing and gypsum wall board. During Hurricane 

Harvey, the timber-framed infill wall failed and 

allowed floodwater to fill the building.

Figure 2: Building where floodwater overtopped the unidentified 

and unprotected low point in the flood barrier; overtopping 

location is obscured by the tree on the left-hand side of the 

image

Seepage Issues

The MAT observed several types of seepage 

issues, described below.

Substantially Impermeable

According to the U.S. Army Corps of Engineers 

(USACE), a wall is considered substantially 

impermeable if it limits water accumulation to 

4 inches in a 24-hour period (USACE 1995). In 

addition, sump pumps are required to control 

any seepage, and flood damage-resistant 

materials must be used in all areas where 

seepage is likely to occur. This standard is 

the minimum requirement; it is possible to 

achieve lower seepage rates, which is strongly 

encouraged by FEMA, particularly in new 

construction.

Figure 3: Floodwater entered the building through a large opening 

cut into a foundation wall; opening is located approximately 12 

feet above the floor
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 5 of 14

Failure to remove seepage through flood barriers. Numerous 

buildings experienced damage to interior finishes as a result of 

water seeping through the flood barrier. Buildings that were not 

equipped to remove the seepage had several near misses as 

water came within inches of critical building systems. In addition 

to damaging building finishes, water leaking into buildings 

required basements to be evacuated, caused failures in pump 

control panels for sump pumps and potable water supply 

pumps, and damaged elevator systems. Figure 4 shows an 

example of water seepage at a submarine door.

Unsealed penetrations through flood barriers. The MAT 

observed instances of improperly sealed or unsealed 

penetrations in flood barriers, such as for utilities, failing and 

allowing floodwater to enter buildings. Even buildings with 

extensive and redundant dry floodproofing systems were flooded 

because of penetrations for utilities passing through the flood 

barrier not being properly waterproofed and sealed. Figure 

5 shows an example of unsealed penetrations that allowed 

floodwater to enter and flood a subgrade tunnel. Floodwater 

eventually filled the tunnel to the ceiling, causing 2 inches of 

water to leak into the basement of a connected building.

Another significant source of water infiltration was conduits from 

utility vaults or electrical pull boxes outside of the flood barrier 

that penetrated the flood barrier to interior spaces. Water 

from inside the vault or pull box was able to flow inside the 

conduit, often entering the building inside the electrical room or 

control room.

Figure 4: Water seepage at a submarine door 

Photograph courtesy of Facilities and Property 

Maintenance, Harris County Engineering Department

Figure 5: Unsealed conduit 

and utility penetrations 

through the flood barrier 

(yellow circles, left) allowed 

subgrade tunnel to fill with 

water (yellow arrow, right); 

the penetrations (shown 

on left image) are on the 

other side of the door at the 

end of the tunnel (shown 

on right image). The utility 

penetrations were sealed 

after the flooding, prior to the 

MAT visit) 

Photograph on the right courtesy 

of Facilities and Property 

Maintenance, Harris County 

Engineering Department
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 6 of 14

Failure to waterproof joints in the building 

envelope. The MAT observed numerous instances 

where significant water seepage originated from 

unsealed joints in the building envelope. Most 

water seepage through unsealed joints occurred 

where the concrete foundation wall stopped, 

typically 6 inches above surrounding grade, but 

significantly below the base flood elevation (BFE), 

design flood elevation (DFE), and WSE. Figure 6 

shows an unsealed joint between the concrete 

foundation wall and the reinforced masonry wall 

with granite facade; if the joint is left unsealed, 

water can seep into the building. Another 

common area for water seepage was unsealed 

joints between the concrete foundation slab and 

foundation wall. 

Sanitary Sewer or Stormwater System Flows 

Failures associated with backflow from sanitary 

sewers and stormwater conveyance systems 

resulted in significant damage to building finishes 

and critical building systems throughout the areas 

affected by the hurricanes. While most of the 

buildings had some type of check valve or backflow 

preventer, the system configuration, pressure rating of the piping, age of the piping, and the building function 

all contributed to backflow issues. At one location, the issues were the result of occupants remaining in 

buildings and using its sanitary systems even after the check valves had been closed as a result of the main 

lines becoming surcharged by water pressure generated by floodwater. For buildings that did not have ejector 

pumps as part of the sanitary system, sewer water originating from within the building could not overcome the 

pressure in municipal lines and backflowed into the interior space. 

Other damage occurred when there were no check valves installed on floor drains connected to stormwater 

drainage networks. When stormwater overwhelmed other components in the drainage network, water was 

able to backflow though floor drains and fill dry floodproofed areas from within the building.

Figure 6: Unsealed joint (red arrow) between concrete foundation 

wall and a reinforced masonry wall with granite facing panel

Flood Vulnerability Assessments

Unless flood provisions were incorporated into their design, 

existing buildings are vulnerable to flooding if they are 

located in or near areas subject to flooding. Numerous 

buildings sustained flood damage as a result of building 

owners or managers not fully understanding the flood hazard 

for the building and/or failure to identify and protect all 

potential sources of water entry. Flooding can cause damage 

ranging from minor inconvenience to complete closure of 

and significant damage to the building. To reduce the likelihood of such damage in future events, building 

owners and managers should consider performing a flood vulnerability assessment to identify equipment 

and systems vulnerable to flooding and take actions to reduce their vulnerability to flooding. The information 

obtained during the flood vulnerability assessment, combined with building function and staff or tenant 

capabilities to deploy dry floodproofing measures, should be used to design the dry floodproofing measures. 

Prior to performing a flood vulnerability assessment, the floodwater source with corresponding 10-percent-, 

2-percent-, 1-percent-, and 0.2-percent-annual-chance (10-, 50-, 100-, and 500-year) WSE and the enforced 

DFE should be identified for the building. The assessment should determine if the code minimum should 

Vulnerability Assessments 

Additional guidance on conducting flood 

vulnerability assessments is outlined in 

Appendix C of FEMA P-936, Floodproofing 

Non-Residential Structures. 
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 7 of 14

be applied or whether a higher freeboard is cost 

effective and should be incorporated into the DFE. 

Assessments should account for the fact that 

once a floodproofing barrier is overtopped, a dry 

floodproofed building is impossible to keep dry and 

could negate all floodproofing efforts.

Vulnerability assessments should be conducted 

by a team of architects and engineers working 

closely with building managers, operators, and 

maintenance staff. It is highly recommended 

that a surveyor be incorporated into the team to 

identify the grades adjacent to the building and the 

elevations of all pertinent openings and entrances 

into the building, the first floor and subgrade 

floors, any utility penetrations into the building, 

and all critical building systems. The vulnerability 

assessment should identify the following: 

" Locations and elevations of building entrances, such as personnel and overhead doors

" Locations and elevations of openings, such as windows, vents, and louvers

" Locations and elevations of utility (electrical, potable water, sanitary sewer, stormwater, chill water, steam, 

etc.) conduits entering or exiting the building

" Locations and elevations of any unsealed construction joints where water can enter 

" The components of the sanitary sewer and stormwater systems, i.e., whether there is an ejector pump 

system or a gravity system, if there is a backflow preventer on the discharge piping, if the system is 

connected to backup power, and the location of the pump control panel. Additionally, it would be beneficial 

to determine the maximum surcharge level in the municipal system.

" Locations and elevations of the backup power systems, taking note of the building systems connected to 

backup power, size and location of fuel tank, and location of exhaust ductwork

" Locations and elevations of critical building systems, i.e., building electrical components, steam and chill 

water, electrical control panels, fire pumps, etc. 

In addition to determining flood entry points, the 

team should consider the effects of water entry. 

Specifically, if the flood barrier is penetrated, what 

areas of the building or building systems would 

be exposed to floodwater. Clarifying the path 

floodwater will take upon entering the building will 

identify optimal locations for installing drains to 

collect water seepage or submarine doors to form 

a redundant barrier. The use of flood damageresistant materials in these areas, and below 

the DFE, will help minimize damage and reduce 

downtime after the floodwater recedes. 

Figure 7 is an illustration of an existing building 

with examples of the types of openings and 

penetrations that should be identified during a flood 

vulnerability assessment.

Freeboard

Freeboard is a factor if safety, usually feet above 

a flood level, used to compensate for unknown 

factors that can contribute to flood heights greater 

than calculated heights. Providing freeboard in 

excess of code minimums is often a cost-effective 

means of limiting future damage. FEMA National 

Flood Insurance Program (NFIP) regulations require 

a minimum of 1 foot of freeboard. The American 

Society of Civil Engineers (ASCE) 24-14, Standard 

for Flood Resistant Design and Construction, and 

Hurricane Sandy Recovery Advisory 5 provide 

additional guidance and considerations related to 

flood risk and determining how much freeboard to 

incorporate into a design.

National Flood Barrier Testing and Certification 

Program

This program, a partnership among the Association 

of State Floodplain Managers, U.S. Army Corps 

of Engineers, and FM Approvals, currently tests 

and certifies four types of products to meet 

ANSI/FM 2510: temporary (perimeter) barriers, 

closure devices (opening protection), backwater 

valves, and mitigation (flood abatement) pumps. 

Testing and certification standards are currently 

being developed for semi-permanent barriers and 

sealants. A list of certified products can be found 

at www.nationalfloodbarrier.org. 
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 8 of 14

DFE

BFE

CMU 

building

wall

Cast-in-place concrete 

foundation wall and slab

1

Building entrance

Windows

Access ramp to loading dock

Electric service equipment room

Building central plant equipment room

Construction joint

Water service

Sewer line

Utility power

Ventilation grill

Sump pit with sump pump

Stormwater drain

Component

1

2

3

4

5

6

7

8

9

10

11

12

Waste line

Floor drain

Access tunnel to adjacent building

Submarine door

Backup generator with fuel tank

Fuel line

13

14

15

16

2

8

1

4

7

5

9

11

13

12

14

18

10 15

16 17

6

3

17

18

Figure 7: Example of an existing building with multiple openings and penetrations below the BFE and DFE; blue numbered circles 

indicate a small sample of the types of openings and penetrations that should be identified during a flood vulnerability assessment 

and protected by the flood barrier

Planning and Pre-Design Considerations

After the flood vulnerability assessment and prior to design, each identified opening should be evaluated 

to determine the appropriate method of opening protection. Opening protection systems should come from 

a reputable manufacturer and be compliant with a testing standard such as ANSI/FM 2510 that includes, 

among other requirements, performance standards for hydrostatic test strength, impact and wear resistance, 

system leakage (seepage), environmental corrosion, abrasion resistance, and tear and puncture resistance. 

If the system is not tested in accordance with ANSI/FM 2510, opening protection systems should, at a 

minimum, have a demonstrated ability to resist hydrostatic forces associated with the DFE. Homemade 

barriers should not be used. After the components of the flood barrier have been installed, it is highly 

recommended that they be tested to ensure water tightness. 

Key considerations. The pre-design process for flood protection systems should be comprehensive, ensuring 

that all opening protection components for the entire building can be installed based on the implementation 

timeframe used in the building’s emergency operations plan (for more information, refer to the companion 

FL-RA1, Dry Floodproofing: Operational Considerations). Key considerations should include, but not necessarily 

be limited to:

" The timing and rate of anticipated floodwater rise, availability of staff and equipment to install the opening 

protection, building occupancy classification, daily use of the openings, and maintenance requirements. 
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 9 of 14

" The amount of traffic, whether vehicular or pedestrian. Traffic may affect the selection of opening 

protection systems, since gaskets on shields or doors may need to be protected against damage during 

day-to-day use. 

" The type of gasket—inflatable or compression—should be considered when selecting opening protection 

systems. Inflatable gaskets tend to be composed of thinner material and are generally more susceptible 

to cracking under prolonged exposure to weather and sunlight. 

Active versus passive protection. The rate of floodwater rise 

and anticipated amount of advance warning are often the most 

important considerations in determining whether to use active 

(requiring human intervention) or passive (automatic) opening 

protection (see text box). 

Openings at elevations that can flood during frequent flood events 

(e.g., 10-percent-annual-chance [10-year] flood events or strong 

downpour) may require passive opening protection (see Figure 8). 

Another important consideration is the presence of 24/7 on-site 

support staff—owners of buildings without continuous support 

staff should also consider passive opening protection since there 

may not be enough time for a contractor crew to arrive and install 

active opening protection systems. On the other hand, passive 

opening protection measures require regular maintenance, as their 

components are exposed to the elements. 

If active protection is selected, designers need to determine if 

the opening protection will be permanently attached (using hinges 

or rails) or detached (such as bolted-on shields or flood logs). It 

is recommended that brackets or stanchions for active opening 

protection systems be incorporated into the design of the exterior 

of the building to reduce installation time. The lack of availability of 

equipment or staff to move flood protection measures into place 

in a timely manner can render the flood protection ineffective and 

leave the building vulnerable.

Active and Passive Opening 

Protection 

Active: A dry floodproofing opening 

protection system that requires 

human intervention to install the 

physical barrier. These systems 

are effective only if there is enough 

warning time to mobilize the labor 

and equipment necessary to 

implement them and then safely 

evacuate.

Passive: A dry floodproofing 

opening protection system 

that does not require human 

intervention to deploy the physical 

barrier.

Automatic/Passive Barrier

Automatic/passive barrier

Floodwater

side

Floodwater side

Dry floodproofed side

Dry floodproofed side

Note: Figure mirrored for clarity

Figure 8: Example 

of passive opening 

protection installed to 

protect openings in the 

floodwall constructed 

around an existing 

building to establish 

a flood barrier with 

minimal openings 

below the DFE
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 10 of 14

Design Considerations

A successful dry floodproofing systems design 

should start with a flood vulnerability assessment 

and should consider building use, maintenance 

considerations, and operational requirements 

before, during, and after an event (refer to previous 

sections of this advisory). The design should 

take a comprehensive approach that addresses 

all possible points of water entry and allows the 

building to maintain flood protection effectiveness 

for the life of the building. 

Dry floodproofing design is discussed in detail in 

FEMA P-936, Floodproofing Non-Residential Structures (2013), and Section 6 of the American Society of Civil 

Engineers (ASCE) 24, Standard for Flood Resistant Design and Construction (2014). Design considerations 

are discussed in Chapter 2 of FEMA P-936. Specific dry floodproofing details are addressed in Chapter 3; the 

introduction of Chapter 3 provides readers with a list of building retrofitting recommendations. 

NFIP Floodproofing Certificate. The requirements of the NFIP Floodproofing Certificate are described in 

FEMA P-936 and should be understood before starting design. The NFIP Floodproofing Certificate requires 

compliance with ASCE 24 and is both a design and construction certification. Professional engineers and 

architects should read the Floodproofing Certificate in its entirety and the applicable sections of ASCE 24, 

FEMA P-936, and Technical Bulletin 3, Non-Residential Floodproofing (FEMA 1993), prior to signing it. 

Improving reliability of floodproofing measures. Based on the performance of dry floodproofing retrofit 

mitigation measures observed by the MATs after Hurricanes Harvey and Irma in Texas and Florida, additional 

attention must be paid to specific items to improve the reliability of floodproofing measures. The MATs 

recommend that the measures described in Table 2 be considered to help avoid the types of system failures 

observed.

Dry Floodproofing New Facilities

Installing dry floodproofing in new construction 

involves considerations and techniques that 

are similar to those used when installing dry 

floodproofing in existing buildings. However, with 

new construction the floors and wall systems 

can be designed and constructed to resist the 

hydrostatic and buoyant forces without costly 

retrofits.

Combining Flood Risk Reduction Measures

For new buildings, the design height of dry 

floodproofing can be reduced by using fill 

material to raise the building site. The image on 

the right shows where the designer elevated the 

building on fill, thereby reducing the height of the 

dry floodproofing system for the building. 

Reducing the height of dry floodproofing 

measures allows more flexibility in the design, 

reduces flood loads, reduces the potential for 

leakage, and can minimize any loss of function. 

The image on the right shows a dry floodproofed 

building that was constructed on approximately 

3 feet of fill. The building incorporated 1.5 feet 

of freeboard into floodproofing design, and the 

flood level during Hurricane Harvey used up 1.0 

of the 1.5 feet.

Photograph courtesy of Kati Southern
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 11 of 14

Table 2. Dry Floodproofing Design Considerations

Item Description

Backflow preventers Install backflow prevention valves for any piping in the building below the flood 

protection elevation or that connects to other piping networks that extend below the 

flood protection elevation. Backflow prevention systems can be either passive or 

active.

Building system 

locations

Locate building systems (e.g., mechanical, electrical, and plumbing components; 

communication systems; potable water supply pumps; fire suppression equipment) 

above the DFE. Consider relocating critical building systems above the flood 

protection elevation. If relocating is not possible, consider installing redundant 

protection systems and protecting these systems to a higher-severity flood event 

than the rest of the dry floodproofed area.

Design forces Flood load calculations should address both lateral hydrostatic and vertical 

buoyancy forces, as well as velocity, debris impact, and wave forces, if applicable. 

Wall and floor systems may need to be modified or sections completely 

reconstructed to resist flood loads or to ensure that water cannot penetrate the wall 

or floor. Additional reinforcement may be required in some areas, and connections 

between floors and walls may need to be improved to resist lateral and uplift loads. 

In some instances, this modification may require constructing a new wall around the 

existing exterior wall to achieve the desired strength or waterproofness.

Design of a 

substantially 

impermeable system

Design and construction criteria for dry floodproofing require both walls and floors to 

be “substantially impermeable.” Some things to consider for wall systems are: 

• Deciding whether to build a new floodwall or modify the building envelope.

• Sealing existing construction joints and injecting cracks in concrete walls.

• For new construction:

• The construction joint in and between the foundation slab and walls should

contain a waterstop.

• Design concrete walls below the flood protection elevation in accordance with

American Concrete Institute (ACI) 350, Code Requirements for Environmental

Engineering Concrete Structures, instead of ACI 318, Building Code Requirements

for Structural Concrete. ACI 350 has additional requirements that minimize the

possibility of water seeping through a concrete slab or wall.

• Use a concrete admixture that will limit the porosity of the concrete or a

silica admixture.

Refer to FEMA P-936 (2013) for additional information.

Ejector system Incorporate ejector systems to prevent the accumulation or backflow of sanitary 

(wastewater) or stormwater into protected buildings.

• Install ejector systems for stormwater with back-flow prevention

• Drain fixtures below the maximum surcharge level into a sump, and pump effluent

out to a municipal line

• Design and size pipelines for the maximum anticipated surcharge pressure

conditions associated with ejector pumps

For buildings that must be occupied when municipal lines are surcharged, collect 

sanitary sewage from all fixtures below the surcharge level (not just those below the 

level of the sanitary sewer lateral) into a sanitary sewage sump equipped with an 

ejector pump and check valve. Ensure the ejector pump has adequate capacity to 

discharge with anticipated sewage flow rates against the maximum anticipated head 

of the surcharged lines. 
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 12 of 14

Table 2. Dry Floodproofing Design Considerations (concluded)

Item Description

Flood barrier 

penetrations

Do not penetrate the flood barrier unless no other options exist and do so only when 

absolutely required. All penetrations below the DFE should be sealed to resist flood 

forces and render the flood barrier substantially impermeable. For chill water lines 

and steam lines, consider removing a small section of insulation and casing around 

the insulation, since some of those materials can prevent a watertight seal from 

being made.

Flood damage-resistant 

materials

Consider wet floodproofing behind dry floodproofed barriers. In the event of seepage 

through walls or shield systems, the incorporation of flood damage-resistant 

materials will reduce the amount of damage to the building. The MATs found that 

damaged drywall behind the flood barrier still had to be replaced in numerous dry 

floodproofed buildings, which resulted in sections of the building being unusable 

while repairs were made.

Labeling of the flood 

barrier

The location of the flood barrier and DFE should be indicated on the building 

drawings, similar to how fire walls are labeled. Additionally, the walls and slabs 

that create a dry floodproofed area should be labeled with “Flood Barrier: No 

Penetrations Below This Level” with a demarcation of the DFE. 

Peer review Perform a peer review on plans and specifications for dry floodproofed systems to 

help ensure that failure points have been properly identified and addressed. 

Pump control panel 

locations

Relocate pump control panels above the DFE and away from perimeter walls. The 

MAT observed buildings where water seeping through cracks in the perimeter wall 

entered pump control panels, resulting in their malfunction. 

Sealing inside flood 

barrier penetrations

Seal the inside of electrical conduits, as the interior of electrical conduits can 

convey water even if the wall penetration is properly waterproofed.

Seepage Regardless of the type of dry floodproofing incorporated into the system, the 

approach should plan for seepage. All dry floodproofing systems required to 

comply with ASCE 24 or the NFIP must have a sump pump system sufficient to 

adequately drain seepage in the dry floodproofed area. It is recommended that the 

sump pumps be connected to a standby power source. Redundancy in the system 

should be considered and leak detection alarms incorporated into the design. 

Internal drainage systems should have a discharge point above the flood protection 

elevation.

Standby power Provide standby power for critical building systems, which includes sump pump 

systems, building mechanical systems, and electrical systems. Standby power 

systems should be sized to meet the start-up power loading requirements of 

equipment. Design should consider the possible loss of power for extended times 

when critical building systems may need to function for days or weeks until power is 

restored. Fuel sources and how to replenish supplies should be considered, as well 

as how many redundant generators should be installed. 

Stormwater Rainfall behind the flood barrier should be considered. Sump pumps should be 

sized to handle the additional water, and the use of redundant or additional pumps 

should be considered when designing systems that remove rainfall from behind 

the flood barrier. When designing for rainfall events behind the flood barrier, the 

design rainfall should be consistent with the design level of protection, so protection 

for a 0.2-percent-annual-chance (500-year) flood event should accommodate a 

0.2-percent-annual-chance (500-year) rainstorm or rainfall of record.

System redundancy Consider providing redundancy in the overall flood protection system, 

compartmentalization, or a series of gates or shields. This redundancy is especially 

important in tunnels and below-grade areas, where the potential for a single point 

of failure can be reduced by such measures. Over the years, MATs have observed 

many single points of failure that have resulted in excessive damage that could have 

been reduced had redundant systems been in place. 
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 13 of 14

References and Resources 

References

ASCE (American Society of Civil Engineers). 2016. Minimum Design Loads of Buildings and Other Structures.

ASCE Standard ASCE 7-16.

ASCE. 2014. Standard for Flood Resistant Design and Construction. ASCE Standard ASCE 24-14.

FEMA (Federal Emergency Management Agency). 1993. Non-Residential Floodproofing - Requirements and 

Certification. Technical Bulletin 3-93. https://www.fema.gov/media-library/assets/documents/3473.

FEMA. 2012. Engineering Principles and Practices of Retrofitting Floodprone Residential Structures, Third 

Edition. FEMA P-259. https://www.fema.gov/media-library/assets/documents/3001. 

FEMA. 2013. Floodproofing Non-Residential Structures. FEMA P-936. https://www.fema.gov/media-library/

assets/documents/34270. 

FEMA. 2014. Homeowner’s Guide to Retrofitting, 3rd Edition. FEMA P-312. https://www.fema.gov/medialibrary/assets/documents/480. 

FEMA. 2017. Protecting Building Utility Systems from Flood Damage. FEMA P-348. https://www.fema.gov/

media-library/assets/documents/3729. 

FEMA. 2018. Public Assistance Program and Policy Guide (PAPPG). FP 104-009-2. January 2018 (V.3). https://

www.fema.gov/media-library/assets/documents/111781.

American National Standards Institute and FM Approvals. 2014. Approval Standard for Flood Abatement 

Equipment. ANSI/FM 2510. http://www.fmapprovals.com/products-we-certify/products-we-certify/floodmitigation-products.

Oak Ridge National Laboratory. 2011. Floodproof Construction: Working for Coastal Communities. Southeast 

Region Research Initiative (SERRI) Report 80024-01. Part of SERRI Project: Floodproof Commercial 

Construction and Fortified Residential Construction for Neighborhood-scale Mixed-use Buildings. 

https://static1.squarespace.com/static/54500d67e4b0fe2b86e37264/t/549343a1e4b0d5186e34f

6e6/1418937249160/SERRI+Report+80024-01_Floodproof+Construction+%28Sept+2011%29.pdf]. 

USACE (U.S. Army Corps of Engineers). 1995. Flood Proofing Regulations. EP 1165-2-314. http://www.

publications.usace.army.mil/Portals/76/Publications/EngineerPamphlets/EP_1165-2-314.pdf. 

Resources

Risk Management Series publications listed below are available at https://www.fema.gov/security-riskmanagement-series-publications.

" FEMA. 2007. Design Guide for Improving Critical Facility Safety from Flooding and High Winds. FEMA P-543.

" FEMA. 2007. Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds. FEMA 

P-577.

" FEMA. 2010. Design Guide for Improving School Safety in Earthquakes, Floods, and High Winds. FEMA 

P-424.

Technical Bulletins listed below are available at https://www.fema.gov/media-library/collections/4.

" FEMA. 1993. Non-Residential Floodproofing - Requirements and Certification. Technical Bulletin 3-93.

" FEMA. 1993. Wet Floodproofing Requirements. Technical Bulletin 7-93.
Dry Floodproofing Planning and Design Considerations TX-RA1 / April 2018 Page 14 of 14

" FEMA. 2008. Flood Damage-Resistant Materials Requirements. Technical Bulletin 2. 

Recovery Advisories for Hurricane Sandy listed below are available at https://www.fema.gov/media-library/

assets/documents/30966.

" FEMA. 2013. Reducing Flood Effects in Critical Facilities. Hurricane Sandy RA2.

" FEMA. 2013. Reducing Interruptions to Mid- and High-Rise Buildings During Floods. Hurricane Sandy RA4.

" FEMA. 2013. Designing for Flood Levels Above the BFE After Hurricane Sandy. Hurricane Sandy RA5.

Recovery Advisories from the 2016 Fall Flooding in Iowa listed below are available at https://www.fema.gov/

media-library/assets/documents/130555. 

" FEMA. 2017. Flood Protection for Critical and Essential Facilities. 2016 Fall Flooding in Iowa RA3.

" FEMA. 2017. Flood Protection and Elevation of Building Utilities. 2016 Fall Flooding in Iowa RA4. 

" FEMA. 2017. Flood Protection for Backup and Emergency Power Fuel Systems. 2016 Fall Flooding in 

Iowa RA5.

To order publications, contact the FEMA 

Distribution Center:

Call: 1-800-480-2520

(Monday–Friday, 8 a.m.–5 p.m., EST)

Fax: 240-699-0525

Email: FEMA-PublicationsWarehouse@fema.dhs.gov

Additional FEMA documents can be 

found in the FEMA Library at 

https://www.fema.gov/media-library/

resources.

Please scan this QR code 

to visit the FEMA Building 

Science Web page.

For more information, see the FEMA Building Science 

Frequently Asked Questions Web site at http://www.fema.

gov/frequently-asked-questions-building-science.

If you have any additional questions on FEMA Building 

Science Publications, contact the helpline at FEMABuildingsciencehelp@fema.dhs.gov or 866-927-2104.

You may also sign up for the FEMA Building Science email 

subscription, which is updated with publication releases 

and FEMA Building Science activities. Subscribe at https://

service.govdelivery.com/accounts/USDHSFEMA/subscriber/

new?topic_id=USDHSFEMA_193.

Visit the Building Science Branch of the Risk Management 

Directorate at FEMA’s Federal Insurance and Mitigation 

Administration at https://www.fema.gov/building-science.
Asphalt Shingle Roofing for High-Wind Regions Hurricane Harvey in Texas-RA2 / April 2018 Page 1 of 4

Asphalt Shingle Roofing for 

High-Wind Regions 

HURRICANE HARVEY IN TEXAS Recovery Advisory 2, April 2018

Purpose and Intended Audience

The purpose of this Recovery Advisory is to recommend practices for 

installing asphalt roof shingles that will enhance wind resistance in high-wind 

regions. For the purpose of this advisory, a high-wind region is considered to 

be an area where the basic (design) wind speed for Risk Category II buildings 

(as defined in American Society of Civil Engineers [ASCE] 7, Minimum Design 

Loads and Associated Criteria for Buildings and Other Structures) is greater 

than 115 miles per hour. The primary audience for this advisory includes 

contractors and design professionals, but the practices presented here may 

also be helpful for homeowners and other building owners.

Key Issues 

" Various types of asphalt shingle wind performance problems are discussed and shown in FEMA P-55, 

Coastal Construction Manual: Principles and Practices of Planning, Siting, Designing, Constructing, and 

Maintaining Residential Buildings in Coastal Areas, 4th Edition (2011). 

" The FEMA Hurricane Harvey Mitigation Assessment Team (MAT) observed many asphalt shingle wind 

performance problems, similar to those shown in FEMA P-55. 

" The damaged shingle roof coverings included shingles that had recently been installed.

" In instances where the MAT made detailed observations, the installations did not incorporate the best 

practices described in Technical Fact Sheet No. 7.3 in FEMA P-499, Home Builder’s Guide to Coastal 

Construction (2010).

This Recovery Advisory Addresses

" Construction Guidance

" Fastener Guidelines

" Weathering and Durability

" Wind-Resistance Ratings

Key Actions for Achieving Good Wind Performance

" Use special installation methods described in this advisory for asphalt roof shingles used in highwind regions.

" Use wind-resistance ratings to choose among shingles, but do not rely on ratings for performance. 

" Consult the local building code for specific installation requirements. Requirements may vary locally. 

" Always use underlayment (see Technical Fact Sheet No. 7.2 in FEMA P-499 [2010] for installation 

techniques in coastal areas).

" Pay close attention to roof-to-wall flashing and use enhanced flashing techniques (see Technical Fact 

Sheet No. 5.2 in FEMA P-499). 

This Recovery Advisory 

supersedes Technical 

Fact Sheet No. 7.3 in 

FEMA P-499. The primary 

change is the inclusion 

of ASTM D7158, which 

was published after FEMA 

P-499 was published.
Asphalt Shingle Roofing for High-Wind Regions Hurricane Harvey in Texas-RA2 / April 2018 Page 2 of 4

Construction Guidance

1. Follow shingle installation procedures for enhanced wind resistance, including the asphalt roof cement 

and nailing guidance shown in Figure 1. 

2. Consider shingle characteristics and physical properties (Tables 1 and 2). Note that higher pull-through 

resistance may need to be specified. 

3. Ensure that the fastening equipment and method results in properly driven roofing nails for maximum 

blow-off resistance (Figure 2).

Figure 1: Enhanced shingle securement

Source: modified from FEMA P-499, 2010

Table 1. Shingle Types and Characteristics 

Shingle Type Product Standard Characteristics

FiberglassReinforced ASTM D3462

Considerable variation in fastener pullthrough resistance offered by different 

products. 

Styrene-ButadieneStyrene (SBS) 

Modified Bitumen

A standard does not exist for this 

product. It is recommended that SBS 

modified bitumen shingles meet the 

physical properties specified in ASTM 

D3462.

Because of the flexibility imparted by 

the SBS polymers, this type of shingle is 

less likely to tear if the tabs are lifted in 

a windstorm.
Asphalt Shingle Roofing for High-Wind Regions Hurricane Harvey in Texas-RA2 / April 2018 Page 3 of 4

Table 2. Shingle Physical Properties 

Properties Design Wind Speed1 > 115 to 150 mph Design Wind Speed1 > 150 mph

Fastener Pull- Minimum Recommended: 25 lb at 73 2 Minimum Recommended: 30 lb Through Resistance degrees Fahrenheit (°F)

1 Design wind speed is an ultimate speed (as defined in ASCE 7), based on 3-second peak gust at 33 feet above grade in Exposure C (as defined 

in ASCE 7).

2 ASTM D3462 specifies a minimum fastener pull-through resistance of 20 lb at 73°F for single-layer specimens. If a higher resistance is desired, 

it must be specified. 

Figure 2: Examples of properly and improperly driven roofing nails 

Fastener Guidelines

" Use roofing nails that extend through the underside of the roof sheathing, or a minimum of 3/4 inch 

into planking.

" Use roofing nails instead of staples.

" Use stainless steel nails for buildings within 3,000 feet of saltwater.

Weathering and Durability

Hail Resistance

Durability ratings are relative and are not standardized Many high-wind regions also experience among manufacturers. However, a shingle with a longer hail storms. Underwriter’s Laboratories (UL) warranty (e.g., 30-year instead of 20-year) should Standard 2218 is used to evaluate the impact provide greater durability. resistance of coverings. Products passing this 

Modified bitumen shingles generally offer improved tear- test are classified as Class 1, 2, 3, or 4. Class 

off resistance of tabs. 4 has the highest impact resistance.

Wind-Resistance Ratings

It is recommended that shingle wind resistance be determined by test method ASTM D7158. Shingles that 

have been evaluated in accordance with D7158 have a Class D (115 mph), G (150 mph), or H (190 mph) 

ultimate wind speed rating. Select shingles that have a class rating equal to or greater than the basic wind 

speed specified in the building code. If the building is sited in Exposure D, is more than 60 feet tall, or is 

sited on an abrupt change in topography (such as an isolated hill, ridge, or escarpment), consult the shingle 

manufacturer. (Note: for definitions of Exposure D and abrupt change in topography, refer to ASCE 7.)

References 

ASCE (American Society of Civil Engineers). 2016. Minimum Design Loads and Associated Criteria for Buildings 

and Other Structures. ASCE 7. 

FEMA (Federal Emergency Management Agency). 2010. Home Builder’s Guide to Coastal Construction. FEMA 

P-499. http://www.fema.gov/library/viewRecord.do?fromSearch=fromsearch&id=2138. 

FEMA. 2011. Coastal Construction Manual: Principles and Practices of Planning, Siting, Designing, Constructing, 

and Maintaining Residential Buildings in Coastal Areas, 4th Edition. FEMA P-55. https://www.fema.gov/

media-library/assets/documents/3293.
Asphalt Shingle Roofing for High-Wind Regions Hurricane Harvey in Texas-RA2 / April 2018 Page 4 of 4

For more information, see the FEMA Building Science 

Frequently Asked Questions Web site at https://www.fema.

gov/frequently-asked-questions-building-science.

If you have any additional questions on FEMA Building 

Science Publications, contact the helpline at 

FEMA-Buildingsciencehelp@fema.dhs.gov or 866-927-2104.

You may also sign up for the FEMA Building Science email 

subscription, which is updated with publication releases and 

FEMA Building Science activities.

Subscribe at https://service.govdelivery.com/accounts/

USDHSFEMA/subscriber/new?topic_id=USDHSFEMA_193.

Visit the Building Science Branch of the Risk Management 

Directorate at FEMA’s Federal Insurance and Mitigation 

Administration at https://www.fema.gov/building-science.

To order publications, contact the FEMA 

Distribution Center:

Call: 1-800-480-2520

(Monday–Friday, 8 a.m.–5 p.m., EST)

Fax: 240-699-0525

E-mail: FEMA-PublicationsWarehouse@fema.dhs.gov

Additional FEMA documents can be 

found in the FEMA Library at 

https://www.fema.gov/media-library/

resources.

Please scan this QR code 

to visit the FEMA Building 

Science Web page.