Mitigation Assessment Team Report

Hurricane Isaac 

in Louisiana

Building Performance Observations, 

Recommendations, and Technical Guidance

FEMA P-938 / March 2013
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 warrantee, 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.

Washington, D.C. International Code Council. ICC logo image reproduced with permission. All rights reserved. www.ICCSAFE.org
MITIGATION ASSESSMENT TEAM REPORT

Hurricane Isaac

in Louisiana

Building Performance Observations, 

Recommendations, and Technical Guidance

FEMA P-938 / March 2013
Members of the Mitigation Assessment Team

Chapter Leaders and Authors

Executive Summary 

Jennifer Sparenberg 

Chapter 1

Lauren Seelbach 

Chapter 2

Rebecca Quinn

Erin Ashley

Chapter 3

Manuel Perotin 

Erin Ashley

Chapter 4

Manuel Perotin

Chapter 5

John Squerciati

Manuel Perotin 

Chapter 6

Jennifer Sparenberg

All 

Appendix A

Jennifer Sparenberg 

Appendix B 

Jennifer Sparenberg 

Appendix C 

Jennifer Sparenberg 

Appendix D 

Adam Reeder 

Appendix E 

Amit Mahadevia

Omar Kapur

Lauren Seelbach

Team Members

Team Leader

Thomas C. Pickering, P.E., FEMA Region VI

Team Manager 

Erin Ashley, PhD, LEED AP, URS Group Inc.

Team Members

Daniel Bass, R.A., CFM, FEMA HQ

John Ingargiola, EI, CBO, CFM, FEMA HQ

Christopher P. Jones, P.E.

David Low, P.E., DK Low & Associates, LLC

Glenn Overcash, P.E., URS Group Inc.

Manuel Perotin, P.E., CFM, Atkins Global

Adam Reeder, P.E., CFM, Atkins Global

Lauren Seelbach, EIT, CFM, URS Group Inc.

John Squerciati, P.E., CFM, Dewberry

Jonathan Westcott, P.E., FEMA HQ

Brian Willsey, FEMA HQ

Internal Support

Technical Editors:

Susan Patton

Ivy Porpotage

Amy Siegel

Graphic Artists:

Lee-Ann Lyons

Billy Ruppert
I The Braithwaite Auditorium 

was rebuilt after it was 

damaged by Hurricane 

Katrina. The facility 

was built based on 

the preliminary Flood 

Insurance Rate Map base 

flood elevation (VE 21) and 

sustained minimal damage 

during Hurricane Isaac.

In response to Hurricane Isaac, the Federal Emergency 

Management Agency (FEMA) deployed a Mitigation 

Assessment Team (MAT) to assess damage from the 

hurricane and provide observations, conclusions, and 

recommendations on the performance of buildings and 

other structures affected by wind and flood forces. The 

MAT included representatives from FEMA Headquarters 

and other Federal agencies, local government officials, 

academia, and experts from the design and construction 

industry. The conclusions and recommendations of this 

report are intended to provide decision makers with 

information and technical guidance that can be used to 

reduce future hurricane damage.
Photographs that appear across the top of the first page of each chapter (from left to right): 

Cellular tower equipment on elevated platform near Port Sulphur Community Center. The damage 

to this Mandeville, LA, elevated Zone V residence was limited to the loss of stairs. Residential 

building in Madisonville, LA, under construction with a partially enclosed ground-level area. NASA 

satellite image taken on August 28, 2012 as Hurricane Isaac approached the Louisiana coastline. 

Residential building in Mandeville, LA with electric meter installed adjacent to side entrance. 

Exterior damage to the garage of a non-elevated residence in Plaquemines Parish, LA.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT i

Executive Summary

Hurricane Isaac made landfall twice along the coast of 

Louisiana: first on August 28, 2012, at the mouth of the 

Mississippi River in the southeastern portion of the State 

and again the next day near Port Fourchon, LA.

Hurricane Isaac was the ninth named storm during the 2012 hurricane season and the third to 

make landfall on the continental United States. It was significant not only for its impact on the 

Louisiana coast, but also because it made landfall almost exactly 7 years after Hurricane Katrina 

and affected many of the same locations.

When Hurricane Isaac first made landfall in Louisiana, it was a Category 1 hurricane with sustained 

winds of 80 miles per hour and a broad wind field encompassing nearly 200 miles. The broad wind 

field produced a storm surge higher than usually associated with a Category 1 storm. After the 

initial landfall, the eye of the hurricane moved westward along the coast, making a second landfall 

on August 29 west of Port Fourchon, LA. The storm then turned to the north and weakened; it was 

downgraded to a tropical storm by 1 p.m. on August 29 and then further downgraded to a tropical 

depression on August 30 at 3 p.m. 
ii MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EXECUTIVE SUMMARY

Despite weakening upon landfall, Isaac’s slow movement resulted in prolonged exposure to storm 

conditions for affected areas. Isaac produced more than 19 inches of rain in New Orleans and more 

than 12 inches in areas around the Gulf Coast. The peak storm surge was reported as 12 to 14 feet 

in the Braithwaite community. 

Damage caused by Hurricane Isaac resulted primarily from flooding in areas not protected by the 

Federal levee system, the 2012 greater New Orleans area 100-year Hurricane and Storm Damage 

Risk Reduction System, including but not limited to Slidell, Mandeville, Madisonville, LaPlace, 

and Lafitte. The storm surge pushed floodwater over a non-Federal levee in Plaquemines Parish, 

flooding a large area on the East Bank of the Mississippi River. Hurricane Isaac damaged nearly 

59,000 homes in southeast Louisiana. In addition to housing damage, power loss contributed to the 

widespread impact of the storm and affected nearly 43 percent of the State’s energy users.

Total economic losses from Hurricane Isaac are estimated to be in excess of $2 billion, with insured 

losses on land estimated at between $500 million and $1.5 billion by the claims forecasting company 

EQECAT (Sanburn 2012, Vanacore 2012). Losses of offshore assets are estimated at over $1 billion. 

Mitigation Assessment Team

In response to a request for technical support from the Federal Emergency Management (FEMA) 

Joint Field Office in Baton Rouge, LA, FEMA’s Mitigation Division deployed a Mitigation Assessment 

Team (MAT) composed of national and regional experts to affected areas in Louisiana on October 

8, 2012.

The MAT was charged with evaluating damage from Hurricane Isaac, especially for buildings 

constructed or reconstructed after Hurricane Katrina, assessing the performance of Emergency 

Operations Centers and other critical facilities affected by the storm, evaluating the performance 

of electrical distribution and communication facilities, and investigating possible claims of wind 

damage in newly constructed buildings. 

Assessment Observations

In general, Hurricane Isaac was below a design level wind event, with flood elevations that did 

not exceed the effective base flood elevation (BFE) in areas visited by the MAT (excluding areas 

in LaPlace and along the East Bank of the Mississippi River in Plaquemines Parish). The key 

recommendations of this MAT report, which are based on the team’s observations while in the field, 

are summarized in the following section. 

Recommendations

The recommendations presented in this report are made based on the MAT’s field observations. 

They are directed toward designers, contractors, building officials, and coastal populations and 

recommend disaster-resistant practices for hurricane-prone regions.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT iii

EXECUTIVE SUMMARY

Residential Construction

+ Elevation. Build to the preliminary Flood Insurance Rate Maps or the best available data (i.e., 

Hurricane Katrina Advisory Base Flood Elevations). Incorporate freeboard requirements in 

accordance with the American Society of Civil Engineers Flood Resistant Design and Construction

(ASCE 24) in addition to best available map data. 

+ Slab-on-grade elevation projects. For slab-on-grade elevation projects, obtain necessary 

information regarding the structural properties of the slab prior to design. In design, properly 

detail and design connections and load paths to resist flotation, impact loads, and uplift. 

+ Stairs for building access. Construct stairs used for access to elevated buildings with adequate 

connections to the structure and at the base. To improve performance, integrate partial 

openings in the risers. If this is not possible, construct stairs such that there are landings with 

supports that can resist flood forces, and construct risers parallel to wave action where possible. 

+ Enclosed areas. Enclosed areas below the BFE should be constructed of flood damage-resistant 

materials and should have walls designed to break away under flood loads. 

+ Utilities and electrical service components. Elevate all electrical service components to or 

above the BFE, and ensure that they are accessible. If this is not possible, elevate the electrical 

panel. Attach overhead service drop lines to the side of the residence rather than the roof if 

allowable by code. 

+ Fire separation and flood damage-resistant materials. For elevated buildings on open 

foundations with enclosed parking underneath, introduce fire separation on the exposed 

underside of the building. Fire separation should meet the guidelines of the 2012 International 

Residential Code Table R302.6 for habitable rooms above a garage, which requires not less than 

5/8-inch Type X gypsum board or equivalent. Considerations should be made to ensure that 

this material is also flood damage resistant. 

+ Raised floor system covering. Proper fastener selection and attachment methods are 

recommended to reduce damage to raised floor system exterior covering on the underside of 

elevated buildings. Use materials that can withstand the wind loads expected on the structure. 

Nonresidential Construction and Infrastructure

+ Siting of critical facilities, community centers, and schools. Site new and replacement 

community centers, critical facilities, and schools outside the 500-year floodplain where possible; 

where not possible, elevate the critical facilities and all utility equipment above the 500-year 

elevation or the best available BFE information. 

+ Infrastructure. Where possible, site electrical substations, pump stations, and cellular towers 

outside the 500-year floodplain; where not possible, elevate facilities and electrical equipment 

above the 500-year elevation.
Outreach and National Flood Insurance Program Reform 

+ Outreach efforts. Continue ongoing statewide efforts focused on educating the public on 

new flood insurance program provisions contained in the Biggert-Waters Act (EDEN 2012). 

Place continued emphasis on the implications elevation has on an individual’s long-term flood 

insurance premiums. 

Best Practices 

+ Mitigation Reconstruction Program. Buildings constructed under the program were not 

damaged. Increase awareness of the pilot program, especially when older, non-compliant 

buildings are being considered for elevation projects.

Codes and Regulations

+ State statutes that predate adoption of Act 12 should be evaluated to identify and resolve 

contradictions that could complicate enforcement and interpretation, and an explicit statement 

that buildings in flood hazard areas are also subject to local regulations should be included. 

Act 12 provides the authority for adoption of the Louisiana State Uniform Construction Code 

(LSUCC). 

+ National Flood Insurance Program (NFIP) communities should review local administrative and 

enforcement regulations to ensure their enforcement of the LSUCC provisions applicable in 

flood hazard areas are consistent with the NFIP.

+ A clear statement that work on existing dwellings in flood hazard areas is subject to the flood 

requirements of the LSUCC would eliminate misinterpretation.

+ The State should establish a freeboard requirement in areas with defined subsidence rates.

+ Opportunities to improve the reach of training courses should be pursued, and floodplain 

management courses offered by the State and others should be considered for continuing 

education credits for code officials. 

+ Communities should evaluate the benefits of adopting requirements for additional freeboard in 

excess of what is required in the LSUCC.

+ Local floodplain management regulations should be reviewed to resolve inconsistencies with the 

minimum requirements of the NFIP.

+ Communities that have enforcement agreements with other governmental entities or with 

certified third parties should review those agreements to include local floodplain management 

requirements that are not already in the LSUCC.

+ The State should distribute notices of the availability of FEMA’s revised publication on 

manufactured homes to manufactured home installers and local officials.

iv MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EXECUTIVE SUMMARY
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT v

Contents

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

Mitigation Assessment Team....................................................................................................................ii

Assessment Observations .........................................................................................................................ii

Recommendations....................................................................................................................................ii

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

1.1 Hurricane Isaac – The Event.................................................................................................... 1-2

1.1.1 Timeline ........................................................................................................................ 1-3

1.1.2 Damage and Economic Loss........................................................................................ 1-3

1.2 Historic Hurricanes ..................................................................................................................1-4

1.3 Riverine and Coastal Flooding.................................................................................................1-5

1.3.1 Storm Surge .................................................................................................................. 1-5

1.3.2 High Water Marks ........................................................................................................ 1-6

1.4 FEMA Mitigation Assessment Team ........................................................................................1-6
Chapter 2. Regulations, Codes, and Standards........................................................................................2-1

2.1 National Flood Insurance Program......................................................................................... 2-2

2.1.1 General Performance Requirements for Buildings.................................................... 2-3

2.1.2 Minimum Requirements for Buildings in Zone A ..................................................... 2-4

2.1.3 Minimum Requirements for Buildings in Zone V ..................................................... 2-5

2.1.4 NFIP Community Rating System................................................................................. 2-6

2.2 Louisiana and Regulation of Construction ............................................................................ 2-7

2.2.1 Louisiana State Uniform Construction Code Council ............................................. 2-7

2.2.2 Louisiana Statutory Provisions ................................................................................... 2-8

2.2.3 Local Enforcement of the LSUCC and Floodplain Management Regulations ....... 2-9

2.2.4 Post-Katrina Mitigation Grant to Build Code Enforcement Capacity .....................2-10

2.2.5 Flood Provisions of the Louisiana State Uniform Construction Code ...................2-10

2.2.6 Manufactured Homes ................................................................................................2-12

2.3 Local Floodplain Management Regulations and Building Codes ...................................... 2-13

2.3.1 Jefferson Parish, LA.....................................................................................................2-13

2.3.2 LaPlace, LA (unincorporated St. John the Baptist Parish) ......................................2-16

2.3.3 Madisonville, LA..........................................................................................................2-17

2.3.4 Mandeville, LA.............................................................................................................2-18

2.3.5 Plaquemines Parish, LA ..............................................................................................2-19

2.3.6 Slidell, LA.................................................................................................................... 2-20

Chapter 3. Residential Construction........................................................................................................ 3-1

3.1 Residential Flood Damage........................................................................................................3-2

3.2 Residential Wind Damage ........................................................................................................3-5

3.3 Foundation Performance..........................................................................................................3-7

3.4 Utilities..................................................................................................................................... 3-11

3.5 Stairs ........................................................................................................................................ 3-14

3.6 Enclosed Areas ........................................................................................................................3-15

3.7 Underside of Elevated Buildings............................................................................................ 3-17

vi MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

TABLE OF CONTENTS
3.8 Fire-Resistant Materials........................................................................................................... 3-18

Chapter 4. Nonresidential Construction and Infrastructure .................................................................... 4-1

4.1 Community Centers..................................................................................................................4-1

4.2 Critical Facilities........................................................................................................................4-5

4.3 Infrastructure............................................................................................................................4-9

Chapter 5. Evaluation of Elevation Projects............................................................................................. 5-1

Chapter 6. Conclusions and Recommendations...................................................................................... 6-1

6.1 Residential Construction..........................................................................................................6-2

6.1.1 Elevating to the Preliminary FIRM ............................................................................. 6-2

6.1.2 Slab-on-Grade Elevation Projects................................................................................ 6-2

6.1.3 Stairs for Building Access............................................................................................. 6-3

6.1.4 Utilities and Electrical Service Components ..............................................................6-4

6.1.5 Enclosed Areas..............................................................................................................6-5

6.1.6 Fire Separation in Elevated Homes.............................................................................6-5

6.1.7 Building Envelope ........................................................................................................6-6

6.2 Nonresidential Construction and Infrastructure ...................................................................6-6

6.2.1 Community Centers, Critical Facilities, and Schools................................................. 6-7

6.2.2 Infrastructure ...............................................................................................................6-8

6.3 Outreach and NFIP Reform.....................................................................................................6-8

6.4 Best Practices.............................................................................................................................6-9

6.5 Codes and Regulations........................................................................................................... 6-10

6.5.1 Louisiana Revised Statutes and Building Codes ...................................................... 6-10

6.5.1.1 Existing Statutes.......................................................................................... 6-10

6.5.1.2 LSUCC and Administrative Provisions...................................................... 6-11

6.5.1.3 Existing Buildings....................................................................................... 6-12

6.5.1.4 Flood Protection in Subsidence Areas....................................................... 6-12

6.5.2 Code Officials and Continuing Education ............................................................... 6-13

6.5.3 Local Floodplain Management Regulations and Codes.......................................... 6-13

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT vii

TABLE OF CONTENTS
6.5.3.1 Additional Elevation (Freeboard) ............................................................. 6-13

6.5.3.2 Consistency with the NFIP ..........................................................................6-14

6.5.3.3 Agreements for Enforcement......................................................................6-14

6.5.3.4 Manufactured Homes................................................................................. 6-15

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

Appendix B. Bibliography and Additional FEMA Resources ....................................................................B-1

Appendix C. Acronyms.............................................................................................................................C-1

Appendix D. Hurricane Isaac Recovery Advisories................................................................................. D-1

Appendix E. High Water Marks................................................................................................................E-1

List of Figures

Figure 1-1: Hurricane Isaac’s path through southeastern Louisiana ............................................. 1-2

Figure 1-2: Storm tracks of Hurricanes Isaac and Katrina .............................................................. 1-5

Figure 3-1: Wave and surge damage to a residential building. The house is located in Zone 

V along Lake Pontchartrain’s western shoreline (Saint John the Baptist Parish, 

LA).................................................................................................................................... 3-3

Figure 3-2: Damage was observed in most at-grade slab foundation residences, while 

minimal damage was observed in adjacent elevated properties (Barataria, LA). ...... 3-3

Figure 3-3: Typical flood depth of at-grade slab foundation residences; inset illustrates 

flood depth of 31 inches above the at-grade slab foundation (Slidell, LA).................3-4

Figure 3-4: The damage to some elevated Zone V residences was limited to the loss of 

stairs (Mandeville, LA)....................................................................................................3-4

Figure 3-5: Minimal damage was observed in most elevated residences. The USGS HWM 

near this location was 9.74 feet, compared to an effective BFE of Zone A14 

(EL12), Katrina ABFE of Zone AE (EL13), and preliminary FIRM of Zone VE 

(EL16) (Orleans Parish, LA). .........................................................................................3-5

viii MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

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Figure 3-6: Loss of standard vinyl siding to recently elevated residential building; use and/

or damage of high-wind siding was not observed by the MAT (Plaquemines 

Parish, LA). ......................................................................................................................3-6

Figure 3-7: Roof soffit and fascia damage to Exposure C residential building 

(Plaquemines Parish, LA). ..............................................................................................3-6

Figure 3-8: Pilot Mitigation Reconstruction Program project; no observed wind damage 

(Mandeville, LA). ............................................................................................................ 3-7

Figure 3-9: Neighboring residential buildings; the elevated residence had no observed 

damage, while the non-elevated home had significant interior damage caused 

by more than 2 feet of flooding (red arrow indicates flood depth) 

(Slidell, LA)......................................................................................................................3-8

Figure 3-10: House elevated as part of the HMGP Pilot Mitigation Reconstruction Program 

(Mandeville, LA). ............................................................................................................3-8

Figure 3-11: Slab-on-grade elevation with structural cracks due to differential lifting 

(Slidell, LA)...................................................................................................................... 3-9

Figure 3-12: Slab-on-grade elevation in progress (Slidell, LA). ........................................................ 3-9

Figure 3-13: Elevated slab with insufficient steel cover (Slidell, LA). ............................................. 3-10

Figure 3-14: Structurally insufficient connection to pier. This house had a total of 7 such 

connections out of 17 piers supporting the structure (Mandeville, LA). .................. 3-11

Figure 3-15: Typical inundation damage to electric meter; note meter is temporarily 

reattached to pile with new bracing and strapping until permanently repaired 

(Jefferson Parish, LA). .................................................................................................. 3-12

Figure 3-16: Residential building with electric meter installed adjacent to side entrance 

(Mandeville, LA). .......................................................................................................... 3-13

Figure 3-17: Electric meter attached to foundation pier (Plaquemines Parish, LA). .................... 3-13

Figure 3-18: Post-Katrina residential reconstruction with service drop attached to the side 

of house (Slidell, LA). ....................................................................................................3-14

Figure 3-19: Curved and split stair configurations for elevated residential buildings 

(Mandeville, LA). ...........................................................................................................3-14

Figure 3-20: Front and side view of stair damage to elevated waterfront residential building 

due to closed riser, inadequate foot anchoring, and insufficient connection 

with the building frame (Mandeville, LA). ................................................................. 3-15

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT ix

TABLE OF CONTENTS
Figure 3-21: Residential building under construction with a partially enclosed area—front 

closed/rear open with effective BFE of A13 (EL12), Katrina ABFE of Zone AE 

(EL13), and preliminary FIRM of Zone VE (EL14) (Madisonville, LA)................... 3-16

Figure 3-22: Example of above-grade enclosure below elevated residence (Plaquemines 

Parish, LA). .................................................................................................................... 3-16

Figure 3-23: Enclosed area that was not finished with flood-resistant materials, nor did it 

have flood openings (Plaquemines Parish, LA). ..........................................................3-17

Figure 3-24: Loss of the sheathing from the underside of an elevated building due to wind 

gusts (reported to exceed 80 mph) that exceeded the capacity of the vinyl 

siding (Plaquemines Parish, LA).................................................................................. 3-18

Figure 3-25: Elevated house with combustible materials and vehicle parking below elevated 

space (Mandeville, LA). ................................................................................................ 3-19

Figure 3-26: Elevated house with open space to interior of the home that would allow fire 

to spread (Mandeville, LA)........................................................................................... 3-19

Figure 4-1: The Braithwaite Auditorium was rebuilt to the preliminary BFE following 

damage caused by Hurricane Katrina (Braithwaite Park [East Bank] – 

Plaquemines Parish, LA)................................................................................................. 4-2

Figure 4-2: HWM visible on glass at entrance to elevators below lowest floor of Braithwaite 

Auditorium (Braithwaite Park [East Bank] – Plaquemines Parish, LA)...................... 4-2

Figure 4-3: The Braithwaite Auditorium has an elevated generator for emergency power 

(Braithwaite Park [East Bank] – Plaquemines Parish, LA). ......................................... 4-3

Figure 4-4: No damage was observed in the auditorium (Braithwaite Park [East Bank] – 

Plaquemines Parish, LA)................................................................................................. 4-3

Figure 4-5: Residences in the Braithwaite Park subdivision were inundated with more 

than 8 feet of water; the auditorium (red arrow) is at the north end of the 

subdivision (Braithwaite Park [East Bank] – Plaquemines Parish, LA).......................4-4

Figure 4-6: The Braithwaite Auditorium generator transfer switch and other electrical 

components were built at grade and damaged by floodwaters (Braithwaite 

Park [East Bank] – Plaquemines Parish, LA). ...............................................................4-5

Figure 4-7: Recently constructed Port Sulphur Community Center; no damage was 

observed or reported for the elevated facility (Port Sulphur [West Bank] – 

Plaquemines Parish, LA).................................................................................................4-5

Figure 4-8: Woodlawn Fire Station (Woodlawn [East Bank] – Plaquemines Parish, LA). ............4-6

x MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

TABLE OF CONTENTS
Figure 4-9: Post-Hurricane Isaac aerial of Woodlawn Fire Station (Woodlawn [East Bank] 

– Plaquemines Parish, LA)..............................................................................................4-6

Figure 4-10: The recently completed Parish Learning Center was constructed 

approximately 10 feet above grade (Port Sulphur [West Bank] – Plaquemines 

Parish, LA). ...................................................................................................................... 4-7

Figure 4-11: South Plaquemines High School under construction; the preliminary BFE at 

this site is Zone VE (EL 15) (Boothville [West Bank] – Plaquemines Parish, LA).....4-8

Figure 4-12: The Phoenix Pre-K–12 School under construction; the preliminary BFE at this 

site is Zone AE (EL 17) (Phoenix [East Bank] – Plaquemines Parish, LA)................. 4-9

Figure 4-13: Electrical repairs being completed after substation equipment was inundated 

by floodwaters (Braithwaite [East Bank] – Plaquemines Parish, LA)........................ 4-10

Figure 4-14: Substation equipment elevated several feet above grade (Belle Chase [West 

Bank] – Plaquemines Parish, LA)................................................................................. 4-10

Figure 4-15: A berm was constructed around the perimeter of this substation to protect it 

after Hurricane Katrina (Belle Chase [West Bank] – Plaquemines Parish, LA). ..... 4-11

Figure 4-16: Flood inundation depths were 4 to 5 feet above grade at the substation 

protected by the berm that was overtopped (Belle Chase [West Bank] – 

Plaquemines Parish, LA)............................................................................................... 4-11

Figure 4-17: The protective berm (red arrow) was overtopped, resulting in damage to 

the substation; note cellular tower (yellow arrow) northwest of the substation 

(Belle Chase [West Bank] – Plaquemines Parish, LA)................................................ 4-12

Figure 4-18: Cellular tower equipment on elevated platform near Port Sulphur Community 

Center (Port Sulphur [West Bank] – Plaquemines Parish, LA). ................................ 4-12

Figure 4-19: Post-Hurricane Isaac aerial of the pump station south of Braithwaite Park 

(Braithwaite Park [East Bank] – Plaquemines Parish, LA). ....................................... 4-13

Figure 4-20: Elevated stormwater pump station south of Braithwaite Park reconstructed 

after Hurricane Katrina with FEMA Public Assistance funds (Braithwaite [East 

Bank] – Plaquemines Parish, LA)..................................................................................4-14

Figure 4-21: The control panels and generator at this pump station were elevated as part 

of a mitigation measure with FEMA Public Assistance funds; insets illustrate 

connections between equipment and platform (Slidell, LA). .....................................4-14

Figure 5-1: Comparison of elevated versus at-grade constructions (Plaquemines Parish, LA)..... 5-2

Figure 5-2: Post-Hurricane Isaac aerial of the residences in Figure 5-1 (Plaquemines 

Parish, LA). ...................................................................................................................... 5-3

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT xi

TABLE OF CONTENTS
Figure 5-3: Roof cover loss at non-elevated residential building (Plaquemines Parish, LA).........5-4

Figure 5-4: Interior damage to the garage of the non-elevated residence (Plaquemines 

Parish, LA). ......................................................................................................................5-4

Figure 5-5: Exterior damage to the garage of the non-elevated residence (Plaquemines 

Parish, LA). ......................................................................................................................5-5

Figure 5-6: Interior damage to the non-elevated residence (Plaquemines Parish, LA). ............... 5-5

Figure 5-7: Interior damage to the non-elevated residence (Plaquemines Parish, LA). ...............5-6

Figure 5-8: Exterior damage (wood siding) to the elevated house (Plaquemines Parish, LA).....5-6

Figure 5-9: Single-family residence post-Katrina (Mandeville, LA)................................................ 5-7

Figure 5-10: Single-family residence elevated post-Katrina (Mandeville, LA). ................................ 5-7

Figure 5-11: A nonresidential building on Lakeshore Drive in Mandeville post-Hurricane 

Katrina (Mandeville, LA)................................................................................................5-8

Figure 5-12: Entrance to nonresidential building on Lakeshore Drive in Mandeville postHurricane Katrina (Mandeville, LA).............................................................................5-8

Figure 5-13: Interior damage from Hurricane Katrina to nonresidential building on 

Lakeshore Drive (Mandeville, LA)................................................................................. 5-9

Figure 5-14: The same nonresidential building along Lakeshore Drive in Mandeville 

elevated post-Hurricane Katrina (Mandeville, LA). ..................................................... 5-9

Figure 5-15: Post-Hurricane Isaac aerial of elevated residence along Highway 39 

(Plaquemines Parish, LA). ............................................................................................ 5-10

Figure 5-16: Elevated house built in 2009 on Highway 39 had approximately 2 feet of water 

infiltrate the first floor; inset: yellow line illustrates observed HWM on door 

(Plaquemines Parish, LA). .............................................................................................5-11

Figure 5-17: Debris pile near at-grade residence (Plaquemines Parish, LA).................................. 5-12

Figure 5-18: 2008 aerial of the Frenier Fishing Village (St. John the Baptist Parish, LA). ........... 5-13

Figure 5-19: Surge damage to lakefront residential structure (Structure B in Figure 5-18) 

(St. John the Baptist Parish, LA). ................................................................................. 5-13

Figure 5-20: Elevated residence with no observed damage (Structure E in Figure 5-18) (St. 

John the Baptist Parish, LA). .........................................................................................5-14

xii MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

TABLE OF CONTENTS
Figure 5-21: Remains of residential building that was approximately 2 to 3 feet above grade 

(Structure D in Figure 5-18) (St. John the Baptist Parish, LA)...................................5-14

Figure 5-22: Debris pile of waterfront single-family residence along the west bank of Lake 

Pontchartrain (Structure D in Figure 5-18) (St. John the Baptist Parish, LA)..........5-14

Figure 5-23: Residential building elevated approximately 3 to 4 feet above grade that lost 

stairs and received other damage below the lowest floor (Structure C in Figure 

5-18) (St. John the Baptist Parish, LA)......................................................................... 5-15

Figure 5-24: Nonresidential structure with damage to the screen surrounding the area 

under the lowest floor (Structure A in Figure 5-18) (St. John the Baptist 

Parish, LA). .................................................................................................................... 5-15

Figure 5-25: Residence built about 2000 with minimal damage to partially enclosed areas 

below the lowest floor (Structure F in Figure 5-18) (St. John the Baptist 

Parish, LA). .................................................................................................................... 5-16

Figure 6-1: Residential stairs with partially open risers to reduce potential flood damage 

(Mandeville, LA). ............................................................................................................6-4

List of Tables

Table 1-1: Housing Damage in Louisiana ....................................................................................... 1-4

Table 1-2: Comparison of Hurricanes Katrina and Isaac in Louisiana......................................... 1-5

Table 2-1: NFIP/CRS Data for Communities Visited by the MAT................................................2-13

Table 2-2: Jefferson Parish Elevation Comparison: Floodplain Management Regulations 

vs. LSUCC........................................................................................................................2-15

Table 2-3: St. John the Baptist Parish Elevation Comparison: Floodplain Management 

Regulations vs. LSUCC...................................................................................................2-16

Table 2-4: Madisonville Elevation Comparison: Floodplain Management Regulations vs. 

LSUCC.............................................................................................................................2-17

Table 2-5: Mandeville Freeboard Comparison: Floodplain Management Regulations vs. 

LSUCC.............................................................................................................................2-19

Table 2-6: Plaquemines Parish Freeboard Comparison: Floodplain Management 

Regulations vs. LSUCC.................................................................................................. 2-20

Table 2-7: Slidell Freeboard Comparison: Floodplain Management Regulations vs. LSUCC....2-21

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT xiii

TABLE OF CONTENTS
Table 5-1: Estimated Isaac Damages at Adjacent Properties Along Highway 23 (West Bank) ....5-6

Table 5-2: Estimated Katrina versus Isaac (pre- versus post-elevation) Damages at 

Lakeshore Drive Property ...............................................................................................5-8

Table 5-3: Estimated Isaac Damages at Lakeshore Drive Nonresidential Property...................... 5-9

Table 5-4: Estimated Isaac Damages at Adjacent Properties Along Highway 39 (East Bank) ... 5-12

Table 5-5: Estimated Isaac Damages at Adjacent Properties in Frenier Fishing Village ............ 5-16

xiv MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

TABLE OF CONTENTS
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 1-1

1Introduction

On October 8, 2012, the Department of Homeland Security’s 

Federal Emergency Management Agency (FEMA) Region VI 

Joint Field Office (JFO), in conjunction with the Mitigation 

Division of FEMA, deployed a Mitigation Assessment Team 

(MAT) to Louisiana to assess damage caused by Hurricane Isaac 

and document the successes of Post-Katrina reconstruction. 

This report presents the MAT’s observations, conclusions, and 

recommendations as a result of those field investigations.

This chapter includes an introduction, a discussion of the event, historical information, and a 

description of the MAT process. Chapter 2 discusses the floodplain management regulations and 

the building codes and standards that affect construction in Louisiana. Chapter 3 contains a basic 

assessment and characterization of the observed flood and wind effects on residential construction. 

Chapter 4 details the performance of nonresidential structures and infrastructure. Chapter 5 

presents an evaluation of elevation projects the MAT assessed. Chapter 6 presents the conclusions 

and recommendations, which are intended to help guide the reconstruction of hurricane-resistant 
1-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

INTRODUCTION

communities in Louisiana and other hurricane-prone regions affected by future hurricanes. In 

addition, the following appendices are presented herein:

Appendix A: Acknowledgements 

Appendix B: References

Appendix C: Acronyms and Glossary of Terms

Appendix D: FEMA Recovery Advisories for Hurricane Isaac

Appendix E: High Water Marks

1.1 Hurricane Isaac – The Event

Hurricane Isaac made landfall twice along the Louisiana coast as a Category 1 hurricane. The storm’s 

first landfall was at the mouth of the Mississippi River in the southeastern portion of the State on 

August 28, 2012, at which point it moved west, making its second landfall near Port Fourchon, LA, 

the following day. The track of the storm in southeastern Louisiana is shown in Figure 1-1. 

Figure 1‐1: Hurricane Isaac’s path through southeastern Louisiana 

SOURCE: USGS ISAAC STORM TIDE MAPPER HTTP://WIM.USGS.GOV/ISAACSTORMTIDEMAPPER/STORMTIDEMAPPER.HTML
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 1-3

INTRODUCTION

Hurricane Isaac was the ninth named storm during the 2012 hurricane season and the third to make 

landfall on the continental United States. It was significant not only for its impact on the Louisiana 

coast but also because it made landfall almost exactly 7 years after Hurricane Katrina and affected 

many of the same locations. This provided the MAT with a unique opportunity to evaluate postKatrina mitigation measures in the New Orleans area for their performance in this storm.

1.1.1 Timeline

According to the National Hurricane Center, Hurricane Isaac originated as Tropical Depression 9, 

east of the Lesser Antilles on August 21, 2012, and was upgraded to Tropical Storm Isaac later that 

day. On August 28, the storm was upgraded to a Category 1 hurricane before making its first landfall 

over the Mississippi River Delta in extreme southeast Louisiana at 6 p.m. (Central Daylight Saving 

Time) (NOAA 2012b). Wind speeds at this time were 80 miles per hour (mph), and the wind field 

was broad, 200 miles at times. This breadth is significant because a broad wind field may produce 

higher levels of surge than a higher category storm with a smaller wind field. After the initial 

landfall in Louisiana, the eye of the hurricane moved west along the coast, making a second landfall 

on August 29 at 1:15 a.m. west of Port Fourchon, LA. The storm then turned to the north and 

weakened, though still producing large amounts of rain throughout the region. Hurricane Isaac was 

downgraded to a tropical storm by 1 p.m. on August 29 and then further downgraded to a tropical 

depression on August 30 at 3 p.m. Despite weakening upon landfall, Isaac’s slow movement resulted 

in prolonged exposure to storm conditions for affected areas. Isaac produced more than 19 inches of 

rain in New Orleans and more than 12 inches in areas around the Gulf Coast. The peak storm surge 

was estimated at 12 to 14 feet in the Braithwaite, LA, area (USACE 2012). After its initial landfall 

and movement north, the storm traveled slowly north-northwest through Louisiana and then over 

Arkansas and southern Missouri.

Once Isaac made landfall, many areas that had ordered mandatory evacuations, as well as some that 

had not, experienced extreme flooding as a result of Isaac’s storm surge and large volume of rain. 

In particular, the East Bank of the Mississippi River in Plaquemines Parish experienced high flood 

levels, and those who had ignored the mandatory evacuation orders had to be rescued from attics 

and rooftops. 

1.1.2 Damage and Economic Loss

The damage from Hurricane Isaac primarily resulted from flooding. The levees constructed in the 

greater New Orleans area after Hurricane Katrina, the 2012 greater New Orleans area 100-year 

Hurricane and Storm Damage Risk Reduction System (HSDRRS), succeeded in holding back Isaac’s 

floodwaters. However, flooding did occur in areas not protected by the Federal levee system. The 

storm surge pushed floodwaters over a non-Federal levee in Plaquemines Parish, flooding a large 

area on the East Bank of the Mississippi River from Braithwaite south, including White Ditch. This 

flooding forced many citizens in Plaquemines Parish to evacuate. To alleviate some of this flooding, 

a section of levee was removed in a low-lying area near the Braithwaite Park neighborhood. 

In addition to Plaquemines Parish, other communities in the greater New Orleans area sustained 

damage, including Slidell, Mandeville, Madisonville, LaPlace, and Lafitte, among others. Based 

on FEMA damage assessments conducted after the storm, Hurricane Isaac damaged nearly 

59,000 homes in southeast Louisiana (Associated Press 2012). This estimate includes nearly 47,000 
1-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

INTRODUCTION

owner-occupied houses and just over 12,000 rental 

units. Hurricane Isaac caused damage across 21 

parishes, with Jefferson, Orleans, and St. John 

the Baptist Parishes having the highest numbers 

of damaged properties. Table 1-1 summarizes the 

number of owner-occupied housing and rental 

units damaged by Hurricane Isaac in Louisiana.

In addition to housing damage, power loss 

contributed to the widespread impact of the storm. 

At least 903,000 residences lost power, mainly 

in the New Orleans metropolitan area. This 

represents nearly 43 percent of the State’s energy 

users (Louisiana Public Service Commission, 

media update August 31, 2012).

Total economic losses from Hurricane Isaac, as 

of September 4, 2012, are estimated by claims 

forecasting company EQECAT to be in excess of 

$2 billion, with insured losses on land estimated at 

between $500 million and $1.5 billion (Sanburn 

2012, Vanacore 2012). This includes residential 

and commercial property, onshore energy 

production, and business interruption. Losses of 

offshore assets are estimated at over $1 billion. 

1.2 Historic Hurricanes

The Louisiana coastline has experienced 59 hurricane strikes since 1851 (including Isaac), with 

Hurricane Katrina the most notable. Hurricane Katrina, which struck the U.S. coast on August 25, 

2005, ranks as one of the most destructive hurricanes in U.S. history in terms of cost (No. 1), deaths 

(No. 3), and intensity (No. 3). Hurricane Isaac affected many of the same areas as Katrina (Figure 

1-2), which provided an opportunity to study the performance of structures that were elevated after 

Hurricane Katrina.

Table 1-2 shows a comparison of Hurricanes Katrina and Isaac. All 55 of the parishes included in 

Isaac’s Federal disaster declaration (and therefore eligible for either Individual or Public Assistance) 

were also included in Katrina’s Federal disaster declaration (Table 1-2). Hurricane Isaac was a weaker 

wind event than Hurricane Katrina, with a maximum sustained wind speed of 65 mph, compared 

to Katrina’s 127 mph maximum wind speed. Isaac’s wind speeds did not equal or exceed the design 

level wind speeds for the affected areas. However, because Isaac was a slower moving storm and took 

a different path through Louisiana than Katrina, it produced higher and longer lasting storm surge 

conditions in areas not affected as severely by Katrina. Isaac’s longer duration storm surge pushed 

more water into Lake Pontchartrain and Lake Maurepas (USACE 2012). In addition, some areas, 

including Braithwaite, LaPlace, and Lafitte, experienced higher storm surges during Isaac than 

during Katrina because of the slow movement and direction of the storm (USACE 2012). 

Table 1‐1: Housing Damage in Louisiana

Parish

Housing Damage 

(number of homes)

Ascension 1,112

Assumption 562

East Baton Rouge 1,114

East Feliciana 165

Iberville 515

Jefferson 12,912

Lafourche 2,103

Livingston 2,453

Orleans 9,777

Plaquemines 2,983

St. Bernard 2,257

St. Charles 1,368

St. Helena 482

St. James 953

St. John the Baptist 6,871

St. Mary 1,127

St. Tammany 4,572

Tangipahoa 4,584

Terrebonne 1,695

Washington 1,293

West Feliciana 54

TOTAL 58,952
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 1-5

INTRODUCTION

Figure 1‐2: 

Storm tracks of Hurricanes 

Isaac and Katrina

Table 1‐2: Comparison of Hurricanes Katrina and Isaac in Louisiana

Storm Feature Katrina1 Isaac

Category at Landfall 3 1

Minimum Pressure at Landfall (millibars) 920 925

Maximum Sustained Wind Speed (mph) 127 65

Peak Storm Surge 10 to 20 feet above 

normal tide levels

10 to 15 feet above 

normal tide levels

Affected Parishes2 64 55

Number of Residential Buildings Damaged 283,838 59,000 (estimated)

Cost $108 billion $2 billion

mph = miles per hour

1 Source: FEMA 549, Hurricane Katrina in the Gulf Coast Mitigation Assessment Team Report, July 2006 (FEMA 2006a)

2 Includes parishes receiving Individual Assistance and/or Public Assistance (source: Katrina, http://www.fema.gov/disaster/1603/

designated-areas; Isaac, http://www.fema.gov/disaster/4080/designated-areas)

1.3 Riverine and Coastal Flooding

The areas affected by Hurricane Isaac were primarily low-lying regions that are susceptible to 

flooding. Although the storm was only rated a Category 1 on the Saffir-Simpson scale, far lower than 

Hurricane Katrina, some areas still experienced significant flooding. Storm surge was exacerbated 

by intense and prolonged rainfall, affecting the coastline and traveling up the Mississippi River. 

These factors combined to produce higher flooding than Hurricane Katrina in some areas.

1.3.1 Storm Surge

The implementation of the HSDRRS system after Hurricane Katrina played a key role in protecting 

low-lying areas from storm surge in Hurricane Isaac. However, some areas experienced flood levels 
1-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

INTRODUCTION

greater than those experienced during Hurricane Katrina. According to the U.S. Army Corps of 

Engineers (USACE), surge elevations generally ranged from 5 to 7 feet on the West Bank of the 

Mississippi River near Ama, LA, and from 12 to 14 feet on the East Bank of the Mississippi River 

near Braithwaite, LA. During Hurricane Isaac, southeastern Louisiana experienced sustained 

tropical-storm-force winds for as long as 45 hours from August 28 through August 30. These strong 

winds generated offshore waves of 5 to 15 feet. This storm surge, combined with the heavy rainfall, 

produced high water marks (HWMs) that, in some locations, exceeded levels for Hurricane Katrina. 

1.3.2 High Water Marks 

HWM data for Hurricane Isaac was provided to the MAT by the U.S. Geological Survey (USGS). 

Appendix E provides more detail of HWM data compared to the effective base flood elevation (BFE), 

the post-Katrina Advisory Base Flood Elevation (ABFE), and the preliminary BFE (as applicable) in 

the areas affected by Hurricane Isaac. 

1.4 FEMA Mitigation Assessment Team

In response to a request for technical support from the FEMA JFO in Baton Rouge, LA, FEMA’s 

Mitigation Division deployed a MAT composed of national and regional experts to affected areas in 

Louisiana on October 8, 2012. The MAT was charged with evaluating damage from Hurricane Isaac 

as well as post-Hurricane Katrina construction and reconstruction efforts, assessing the performance 

of critical facilities affected by the storm, evaluating the performance of electrical distribution and 

communication facilities, and investigating claims of wind damage in newer buildings.

Hurricane Isaac was below a design level wind event, which enabled the team to examine building 

elements that failed when they would not have been expected to fail. In addition, the MAT deployment 

provided a unique opportunity to visit a location that was previously studied by a MAT (Hurricane 

Katrina MAT) and to evaluate building performance of structures built since Hurricane Katrina.

Preliminary field investigations to assess damage in New Orleans and the surrounding areas were 

conducted between October 1 and October 4, 2012. These investigations involved identifying 

damaged areas for further observation. The data collected in the preliminary field investigations 

determined the area of focus for the full MAT. The full complement of MAT experts was deployed 

from October 8 through October 12 and conducted ground observations in Jefferson Parish, Orleans 

Parish, Plaquemines Parish, and St. Tammany Parish, observing sites in the City of New Orleans, as 

well as in the nearby communities of LaPlace, Port Sulphur, Mandeville, and Slidell. The team also 

visited affected rural areas in Plaquemines Parish. 

Damage was observed to single- and multi-family buildings, manufactured housing, commercial 

properties, communications towers, and electrical substations. In addition, critical and essential 

facilities, such as fire stations, were evaluated to document building performance as well as loss of 

function from Hurricane Isaac. The MAT’s observations are presented in this report. Photographs 

and figures are included to illustrate building performance in the wind field and surge areas 

produced by Hurricane Isaac. The conclusions and recommendations of the MAT as presented in 

this report are intended to assist in minimizing damage from future hurricanes.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-1

2Regulations, Codes, and 

Standards

A combination of local floodplain management regulations 

and building codes determine the requirements that govern 

construction in flood-prone regions.

The floodplain management regulations of 

the National Flood Insurance Program (NFIP) 

and the flood provisions of the family of codes 

developed and maintained by the International 

Code Council, Inc. (ICC) are related. Since 

1998, FEMA has participated in the code 

development process for the International 

Code Series (I-Codes). Every 3 years, the family 

of codes is modified through a formal, public 

consensus process. 

THE I-CODES AND THE NFIP

FEMA prepared excerpts of the flood provi‐

sions of the 2009 and 2012 I‐Codes, a checklist 

that compares the requirements of the NFIP 

to the flood provisions of the 2009 edition of 

the I‐Codes and ASCE 24-05 (a standard ref‐

erenced by the I-Codes), and Highlights of 

ASCE 24 (FEMA 2010c). These resources are 

accessible online at http://www.fema.gov/

building-science/building-code-resources.
2-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

The flood provisions in the 2009 and 2012 I-Codes are consistent with NFIP requirements for 

buildings and structures. Consequently, communities can rely on the I-Codes to fulfill some of the 

requirements they must meet to participate in the NFIP. 

Unless constrained by State requirements, communities that enforce building codes with NFIPconsistent provisions have two primary tools to regulate development in flood hazard areas: 

(1) building codes that govern the design and construction of buildings and structures, and 

(2) either Appendix G of the International Building Code (IBC) or local floodplain management 

regulations. These tools are designed to work together to result in buildings, structures, and all other 

development, that are resistant to flood loads and flood damage. 

This chapter begins with an overview of the NFIP and a summary of the program’s minimum 

requirements for buildings and structures in Special Flood Hazard Areas (SFHAs). It then offers 

an overview of the Louisiana State Uniform Construction Code Council, highlights of the statutory 

provisions that are, in effect, State amendments to the I-Codes, and notes on local enforcement 

of the code and floodplain management regulations. The flood provisions of the Louisiana State 

Uniform Construction Code (LSUCC) are summarized, along with requirements for manufactured 

home installation. 

The chapter concludes with a section that summarizes community-specific elements of floodplain 

management regulations and building codes for Plaquemine Parish and the Cities of Mandeville and 

Slidell, which were among the jurisdictions visited by the FEMA MAT. 

2.1 National Flood Insurance Program

The authorizing legislation for the NFIP is the National Flood Insurance Act of 1968, as amended 

(42 U.S. Code 4001 et seq.). In that act, the U.S. Congress expressly 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.”

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 within flood hazard areas, 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 pre-date 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 indicate that buildings that meet 

the minimum requirements experience 80 percent less flood damage than buildings that pre-date 

the NFIP. Ample evidence suggests that buildings designed to higher standards that exceed the 

minimum requirements are even less likely to sustain damage.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-3

 REGULATIONS, CODES, AND STANDARDS

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 that are estimated to be subject to 

flooding under certain conditions.

+ Floodplain management criteria, which 

establish the minimum requirements for communities to adopt and apply to development 

within 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 floodrelated damage to buildings and contents. 

Performance requirements of the NFIP for 

development in SFHAs are set forth in Federal 

regulations at Title 44 of the Code of Federal 

Regulations (CFR) Parts 59 and 60. The 

requirements apply to all types of development 

proposed in SFHAs. The NFIP broadly defines the 

term “development,” and the requirements apply 

to new development as well as existing buildings 

and structures in SFHAs.

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 long-term objective 

of building disaster-resistant communities.

2.1.1 General Performance 

Requirements for Buildings

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:

HIGHER STANDARDS

FEMA encourages States and commu‐

nities to adopt “higher standards” that 

provide a greater degree of protection 

than the NFIP minimum requirements. 

The most common higher standard that 

affects buildings is freeboard, a require‐

ment to elevate buildings above the BFE. 

However, some States do not permit lo‐

cal amendments to building codes, which 

prevent communities from requiring free‐

board and other higher standards.

DEVELOPMENT

Development means any manmade 

change to improved or unimproved real 

estate, including, but not limited to, build‐

ings or other structures, mining, dredging, 

filling, grading, paving, excavation or drill‐

ing operations, or storage of equipment or 

materials (44 CFR 59.1).

SUBSTANTIAL DAMAGE AND 

SUBSTANTIAL IMPROVEMENT

Substantial Damage is damage of any 

origin for which the cost to restore a dam‐

aged building to its pre-damage condition 

equals or exceeds 50 percent of the build‐

ing’s market value before the damage 

occurred.

Substantial Improvement is any recon‐

struction, rehabilitation, addition, or other 

improvement of a building, the cost of 

which equals or exceeds 50 percent of the 

building’s pre-improvement market val‐

ue. When repairs and improvements are 

made simultaneously, all costs are totaled 

and used in the determination.
2-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

+ Buildings shall 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 shall be resistant to flood damage.

+ Buildings shall be constructed by methods and practices that minimize flood damage.

+ Buildings shall be constructed with electrical, heating, ventilation, plumbing, and airconditioning equipment and other service facilities that are designed and/or located so as 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 2.1.2, and 

requirements for coastal high hazard areas that are designated Zone V (including VE and V1–30) 

are summarized in Section 2.1.3.

2.1.2 Minimum Requirements for Buildings in Zone A

In addition to the general requirements summarized in Section 2.1.1, 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 crawlspaces.

Building Elevation and Foundations (Zone A)

In Zone A, where FEMA designates BFEs, the NFIP 

requirements specify that the lowest floors of new 

and substantially improved buildings, including 

basements, are required to 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 stemwalls, columns, piers, pilings, or slabs 

on earthen fill. Nonresidential 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 are to be used if available. If 

no data are 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. 

LOWEST FLOOR

Lowest Floor means the lowest floor of 

the lowest enclosed area (including base‐

ment). An unfinished or flood-resistant 

enclosure, usable solely for parking of ve‐

hicles, building access, or storage in an 

area other than a basement area is not 

considered a building’s lowest floor; pro‐

vided that such enclosure is not built so as 

to render the structure in violation of the 

applicable non-elevation design require‐

ments of Section 60.3 (44 CFR 59.1).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-5

 REGULATIONS, CODES, AND STANDARDS

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 Flood Insurance Rate Map (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 vehicle parking, building access, or storage. 

The walls of enclosures 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 meet either a prescriptive requirement (1 square inch of net open area 

for every square foot of enclosed area) or a performance expectation (certified by a registered design 

professional). The following installation specifications apply to all flood openings: (1) a minimum 

of two openings for each enclosure, (2) the bottom of openings 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, permit the automatic entry and exit of floodwaters. See NFIP Technical Bulletin 1, Openings in 

Foundation Walls and Walls of Enclosures (FEMA 2008e).

2.1.3 Minimum Requirements for Buildings in Zone V 

In addition to the general requirements summarized in Section 2.1.1, 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 floors of new and substantially improved 

buildings are required to be at or above the BFE. Open foundations are required, including pilings 

and columns. 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. 

Obstructions and Enclosures Below Elevated Buildings (Zone V)

The NFIP requirements specify that the area under elevated buildings must be free of obstructions 

that could interfere with the free passage of floodwater and debris underneath the buildings. The 

NFIP requirements specify that areas below the lowest floors may be enclosed; however, the use of 

enclosures is restricted to vehicle parking, building access, or storage. 
2-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

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 that extend above grade, 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. See NFIP Technical 

Bulletin 5, Free-of-Obstruction Requirements (FEMA 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. See NFIP Technical Bulletin 9, Design and Construction Guidance 

for Breakaway Walls Below Elevated Coastal Buildings (FEMA 2008a). 

The NFIP regulations specify a design safe-loading resistance for breakaway walls 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). 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.

2.1.4 NFIP Community Rating System

The NFIP’s Community Rating System (CRS) is a voluntary incentive program that recognizes 

community floodplain management activities that exceed NFIP requirements. The CRS provides 

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.1

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 that, therefore, receive the largest possible discount. NFIP flood insurance 

premium rates are discounted in increments 

of 5 percent; i.e., a Class 1 community receives a 

45 percent premium discount, while a Class 9 

community receives a 5 percent discount (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. 

1 http://www.fema.gov/national-flood-insurance-program/community-rating-system.

COMMUNITY RATING SYSTEM

As of February 2013, 42 communities in 

Louisiana participate in the CRS. 

Nationwide, more than 21,500 communi‐

ties participate in the NFIP, of which more 

than 1,200 also participate in the CRS.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-7

 REGULATIONS, CODES, AND STANDARDS

2.2 Louisiana and Regulation of Construction 

Shortly after Hurricane Katrina devastated much of coastal Louisiana, the State Legislature convened 

the 2005 First Extraordinary Session. A significant outcome was passage of Act 12, a statute to 

“provide for a state uniform construction code to govern new construction, reconstruction, additions 

to homes previously built to the International Residential Code, extensive alterations, and repair of 

buildings and other structures and the installation of mechanical devices and equipment therein.”2

The public policy of Louisiana is to maintain reasonable standards of construction in buildings and 

other structures in the State consistent with the public health, safety, and welfare of its citizens. The 

State uniform construction code establishes uniform performance standards that provide reasonable 

safeguards for health, safety, welfare, comfort, and security, balanced with affordability. The code 

encourages the use of construction materials of the greatest durability, lowers long-term costs, and 

provides greater storm resistance. 

As of early 2013, the LSUCC is based on the 2009 I-Codes. The Louisiana code includes identified 

parts of the 2009 editions of the IBC, International Existing Building Code (IEBC), International 

Residential Code for One- and Two-Family Dwellings (IRC), International Mechanical Code (IMC), 

International Fuel Gas Code (IFGC), the Louisiana One- and Two-Family Supplement to the 2006 

IMC, and 2010 the National Electrical Code (NEC). State amendments to the codes identify parts 

that are not adopted. The Louisiana Plumbing Code was developed by the State Department of 

Health and Hospitals.

2.2.1 Louisiana State Uniform Construction Code Council 

Act 12 authorized the Louisiana State Uniform Construction Code Council, consisting of 19 

members appointed by the Governor. Members have various professional backgrounds, including 

construction, engineering, architecture, insurance, and local government. The primary functions of 

the Council are:

+ To review and adopt the State uniform 

construction code, which is based on the 

I-Codes. The adoption process involves review 

committees that make recommendations 

and technical committees that evaluate the 

recommendations. The Council then acts on 

the recommendations and sends the resulting 

code and amendments to the legislature. 

+ To provide training and education to code officials. The Council establishes the requirements 

and process for the certification and continuing education of code enforcement officers, code 

enforcement inspectors, third-party providers, and building officials.

+ To accept all requests for amendments of the code (except the plumbing code). The Council 

determines whether amendments to the codes are justified. When the Council finds justification 

2 http://lsuccc.dps.louisiana.gov/index.html.

NEXT EDITION OF THE LSUCC

Codes based on the 2012 I-Codes are 

expected to be adopted after the spring 

2013 legislative session and will be effec‐

tive January 1, 2014. 
2-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

for an amendment, it may adopt it after finding that the modification improves public health, 

safety, and welfare. 

2.2.2 Louisiana Statutory Provisions 

Louisiana statutes impose some limitations and requirements that are, in effect, State amendments 

to the I-Codes. The more significant provisions are described here.

Powers of parish governing authorities (Revised Statute [R.S.] 33:1236). Parishes are permitted 

to pass zoning ordinances, subdivision regulations, building codes, health regulations, and 

other applications and extensions of the normal police power to provide standards and effective 

enforcement provisions for the prudent use and occupancy of flood-prone and mudslide areas. 

Specifically, parishes may use such authorities to qualify for the NFIP.

Public contracts, works and improvements (R.S. 38:84). Parishes and municipalities are authorized 

to comply with the Federal flood insurance act by adoption of ordinances, rules, and regulations, 

including zoning and land use regulations, as necessary. NFIP participation is mandated “before 

construction of any project for local flood protection, or any project for hurricane or storm damage 

reduction which involves or receives federal assistance.” 

State buildings (R.S. 40:1722 and 40:1724). New 

construction, alteration, addition, or renovation 

of all State buildings must comply with the 

building code. Plans and specifications shall 

be approved by State authorities. The provision 

explicitly states that State-owned buildings shall 

not be subject to local permitting, review, or 

oversight, but shall be required to comply with 

the flood zone requirements of the NFIP.

State Uniform Construction Code; “Act 12” 

enacted by the 2005 First Extraordinary Session (R.S. 40:1730.21–40). 

+ Requires all municipalities and parishes to enforce only the construction codes provided in the 

statute (no local amendments). 

+ Specifies enforcement of the code shall not conflict with R.S. 51:912.21 et seq. for the installation 

of manufactured homes. 

+ Requires homeowners of “new residential construction” to provide lenders with copies of 

certificates of occupancy, and requires lenders to file such copies in parish conveyance records.

+ Requires parishes and municipalities to appoint certified building officials or, by agreement, 

contract with other governmental entities or private, certified third parties to issue permits and 

enforce the code.

LOUISIANA COMMUNITIES THAT 

PARTICIPATE IN THE NFIP

The Community Status Book for Louisiana, 

maintained by FEMA, indicates 312 commu‐

nities participate in the NFIP, while 23 towns 

and villages that are identified as flood-prone

elect not to participate (www.fema.gov/cis/

LA.html, accessed February 26, 2013).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-9

 REGULATIONS, CODES, AND STANDARDS

+ Adopts codes from the I-Codes (IBC, IEBC, 

IRC, IMC, IFGC); specifically, the code 

“shall be updated prior to the second regular 

legislative session after the release of the latest 

edition of the appropriate code.”

+ Does not adopt Chapter 1 of any codes but 

permits adoption of IBC appendices.

+ For the IRC, limits enforcement “only for 

new construction, reconstruction, additions 

to homes previously built to the IRC, and 

extensive alterations” and defines those terms. 

Permits local enforcement of IRC Appendix J, Existing Buildings. 

+ Explicitly states that the code shall not apply to the construction or improvement of specifically 

listed industrial facilities that are “inside the restricted access area.” The LSUCC and the fire 

code apply to any buildings, even if inside restricted access areas, if the buildings are accessible 

by the public.

+ Defines “farm structure” and “residential accessory structure,” and describes “private outdoor 

recreational structures” (such as hunting or fishing camps). The effect is that those structures 

are excluded from the code, except “for residential construction, the standards published by the 

Federal Emergency Management Agency for the National Flood Insurance Program shall apply.” 

LSUCC AND WIND SPEEDS

The Louisiana State Uniform Construction 

Code Council adopted an emergency rule 

to require the use of wind speeds in the 

2012 IRC for any permit issued on or after 

January 1, 2013. Since adoption in 2005 of 

the first State code based on the I-Codes, 

the statute has required use of the 2003 

IRC wind speeds for dwellings. 

2.2.3 Local Enforcement of the LSUCC and Floodplain Management Regulations 

All local jurisdictions are required to enforce the 

LSUCC, and local amendments are not permitted. 

The statutes are explicit that parishes and 

municipalities may adopt regulations to qualify 

for the NFIP, and the statute that establishes the 

building code explicitly references “standards” 

published by FEMA for the NFIP. Therefore, 

the Council does not oppose communities that 

adopt, as part of the local floodplain management 

regulations, “higher standards” that affect the 

design and construction of buildings in SFHAs, 

especially when those higher standards are adopted 

by communities that participate in the NFIP CRS. 

To date, the Council is unaware of situations where 

conflicts between the code requirements and 

local regulations have created problems. Should a 

problem arise, it would first be addressed by the 

local appeals board. Decisions of local appeals 

boards may be brought before the Council. 

HIGHER STANDARDS ADOPTED BY 

CRS COMMUNITIES

As of May 2012, 42 of Louisiana’s more 

than 300 NFIP communities also par‐

ticipate in the CRS, reducing NFIP flood 

insurance premiums by 5 to 20 percent. 

Communities receive credit for higher 

standards that affect buildings:

•	 17 receive credit for freeboard

•	 5 receive credit for foundation limits

•	 7 receive credit for cumulative substan‐

tial improvement

•	 2 receive credit for lower substantial im‐

provement threshold

•	 1 receives credit for enclosure limits 
2-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

2.2.4 Post-Katrina Mitigation Grant to Build Code Enforcement Capacity 

In 2005, very few local officials were certified as building professionals. With FEMA’s encouragement, 

in early 2007, the Governor’s Office of Homeland Security and Emergency Preparedness obtained 

a $10.5 million Federal hazard mitigation grant to help build State and local capacity to enforce 

building codes. The program, jointly administered by the Department of Public Safety and the 

Louisiana State Uniform Construction Code Council, supports training, education, the purchase of 

hardware and software for code implementation, and direct salary for regional code offices that work 

across a number of parishes.3 

2.2.5 Flood Provisions of the Louisiana State Uniform Construction Code 

The LSUCC that was in effect when Hurricane Isaac came onshore is based on the 2009 edition of 

the I-Codes. The flood provisions of the LSUCC are the same as the flood provisions of the I-Codes. 

According to FEMA, the flood provisions of the 2009 and 2012 I-Codes are consistent with the NFIP 

requirements for buildings and structures, and communities can rely on the I-Codes to fulfill some 

of the requirements for participation in the NFIP.4

The IBC achieves consistency with NFIP regulations in large measure through reference to 

American Society of Civil Engineers (ASCE) 24, Flood Resistant Design and Construction, while the 

IRC’s consistency is based on the code’s prescriptive provisions. 

LSUCC, Building Code. The scope of the building code includes all buildings and structures except 

one- and two-family homes (covered by the residential code) and other buildings that are explicitly 

identified in the statute as not subject to the code (see Section 2.2.2). The code does not include any 

administrative provisions (Chapter 1 of the IBC). 

The LSUCC references ASCE 7, Minimum Design Loads for Buildings and Other Structures, for loads that 

must be accounted for in building design, including wind loads, snow loads, seismic loads, and flood 

loads. Flood loads include hydrostatic loads, hydrodynamic loads, wave loads, and debris impact loads. 

The LSUCC includes flood provisions in several chapters, but most are in Section IBC 1612, Flood 

Loads, in Chapter 16, Structural Design, which references ASCE 24 for specific design and other 

requirements applicable in flood hazard areas:

+ Section 1612.1 – General requirement that buildings, including buildings that are undergoing 

Substantial Improvement or repair of Substantial Damage, be designed and constructed to resist 

the effects of flood hazards and flood loads.

+ Section 1612.2 – Definitions of terms used in the flood provisions of the code.

+ Section 1612.3 – Flood hazard areas established by the adoption of flood hazard maps, which 

are, at a minimum, maps prepared by FEMA; requirements that apply if design flood elevations 

(DFEs)/BFEs are not included in the adopted map; and requirements for determining impacts 

in riverine flood hazard areas if DFEs/BFEs are specified but floodways are not delineated. 

3 http://lsuccc.dps.louisiana.gov/grant.html.

4 FEMA prepared excerpts of the flood provisions of the I-Codes: http://www.fema.gov/building-science/building-code-resources.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-11

 REGULATIONS, CODES, AND STANDARDS

+ Section 1612.4 – Requirement to design and construct buildings and structures in flood hazard 

areas in accordance with ASCE 7 (loads) and ASCE 24 (all other requirements). Technical flood 

requirements are part of the IBC by reference to ASCE 24.

+ Section 1612.5 – Documentation that must be prepared and sealed by registered design 

professionals.

Chapter 34 of the LSUCC includes requirements that apply to work on existing buildings. The NFIP 

requires local jurisdictions to evaluate work proposed for existing buildings, especially buildings that 

predate a community’s participation in the NFIP. If the work on an existing building is determined to 

constitute Substantial Improvement or repair of Substantial Damage, the building must be brought 

into compliance with the requirements for new buildings in flood hazard areas. Chapter 34 includes 

provisions applicable to existing buildings in flood hazard areas. Separate sections contain flood 

requirements for additions, alterations, repairs, change of occupancy, and improvement of historic 

structures. 

ASCE 24, Flood Resistant Design and Construction. ASCE 24 addresses topics pertinent to designing 

buildings in all flood hazard areas, including floodways, coastal high hazard areas, and other high-risk 

flood hazard areas such as alluvial fans, flash flood areas, mudslide areas, erosion-prone areas, and 

high-velocity areas. It covers the following topics: (1) scope, definitions, structure classification, basic 

requirements applicable in all flood hazard areas; (2) requirements for Zone A areas not identified 

as high-risk areas; (3) requirements for high-risk areas; (4) requirements for Zone V and Coastal A 

Zones; (5) materials; (6) dry floodproofing and wet floodproofing; (7) utilities; (8) building access; 

and (9) miscellaneous construction. 

In some respects, ASCE 24 and the codes that reference ASCE 24 exceed or are more specific than 

the NFIP minimum requirements. ASCE 24-05 requirements are summarized in Highlights of ASCE 

24, Flood Resistant Design and Construction (FEMA 2010c).5

LSUCC, Residential Code. The residential code of the LSUCC is applicable to one- and two-family 

dwellings and most townhomes. The code does not include any administrative provisions (Chapter 1 

of the IBC). Flood provisions are included throughout the code, but most are in Section R322, which 

is specific to flood hazards. 

+ R322.1 includes requirements that apply in all flood hazard areas. The section includes the 

general performance statement that all buildings are designed, connected, and anchored to 

resist flotation, collapse, or permanent lateral movement due to structural loads and stresses 

from flooding equal to the design flood. This section also establishes the DFE, defines the lowest 

floor, specifies protection of equipment, specifies requirements for water supply and sanitary 

sewage systems, requires use of flood damage-resistant materials, and requires submission of asbuilt elevation documentation. 

+ R322.2 includes requirements for flood hazard areas other than coastal high hazard areas (Zone 

A). The section specifies that if the area subject to waves between 11⁄2 and 3 feet is delineated, 

the area shall be designated a Coastal A Zone. Elevation requirements are specified, requiring 

the lowest floor to be at or above the DFE. If a Coastal A Zone is designated, the lowest floor 

5 http://www.fema.gov/library/viewRecord.do?id=3515.
2-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

is required to be at least 1 foot above the BFE. Limitations on enclosures below the DFE are 

specified and, unless designed in accordance with the code requirements for foundations, 

masonry wall height limits are specified as a function of wall reinforcement and wall thickness.

+ R322.3 includes requirements for coastal high hazard areas (Zone V). The section requires 

buildings to be landward of the reach of mean high tide and specifies that alteration of sand 

dunes and mangrove stands are not permitted unless engineering analyses demonstrate no 

increase in the potential for flood damage. Elevation requirements specify that the bottom 

of the lowest horizontal structural member, as a function of orientation with respect to the 

direction of wave approach, must be at or above the DFE. Limitations on enclosures and walls 

below the DFE are also specified, and scour and erosion must be considered in the design 

of foundations. The section also specifies that documentation of the design and methods of 

construction are to be prepared and sealed by a registered design professional. 

The LSUCC Residential Code and ASCE 24. The residential code requires homes proposed to 

be located in floodways (where floodwaters tend to be deeper and flow faster) to be designed in 

accordance with ASCE 24. This requirement is intended to account for flood loads associated with 

flood depth and velocity in the foundation design instead of relying on the prescriptive requirements 

of the residential code. In addition, ASCE 24 is permitted as an alternative to the requirements in 

coastal high hazard areas (Zone V). 

LSUCC, Existing Building Code. The scope of the existing building code includes repairs, 

alterations, additions, changes in occupancy, and relocated buildings. The code does not include 

any administrative provisions (Chapter 1 of the IBC). For work covered by this code, if the work 

constitutes Substantial Improvement (including repair of Substantial Damage), the proposed 

work and the existing building are to be brought into compliance with the flood-resistant design 

requirements for new construction. Certain historic buildings in flood hazard areas are not required 

to be brought into compliance if they retain their historic designation. 

2.2.6 Manufactured Homes 

Requirements for installation of new and used manufactured homes are specified in R.S. 51:912.21 

through 31. Manufactured home installers are required to be licensed, and educational requirements 

are specified. The installation standards require compliance with manufacturer’s installation 

instructions (or the State standards, if the original instructions are not available). Specific 

requirements are listed for steel piers, manufactured load-bearing supports, and concrete products. 

The following provisions are pertinent for installation in flood hazard areas:

+ Compliance with “Manufactured Home Installation in Flood Hazard Areas, published by the Federal 

Emergency Management Agency”6 is explicitly required for installation in flood-prone areas.

+ Piers over 36 inches tall and corner supports over 24 inches in height are specified in detail, with 

concrete blocks used for the piers (without specifically saying they are permitted in SFHAs). 

+ All piers over 52 inches in height must be designed by an architect or engineer.

6 Although not explicit in the statutory citation, this refers to FEMA 85, which was published in 1985 and superseded by FEMA P-85, 

Protecting Manufactured Homes from Floods and Other Hazards (2009c).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-13

 REGULATIONS, CODES, AND STANDARDS

The statute for the LSUCC specifically states that the building code does not apply to the installation 

of manufactured homes (R.S. 33:4775).

2.3 Local Floodplain Management Regulations and Building Codes 

The MAT reviewed the floodplain management regulations and local regulations that pertain to 

enforcement of the building code adopted by Plaquemines Parish and the Cities of Mandeville and 

Slidell. This section shows the more significant observations based on the reviews.

Each community has adopted floodplain management regulations that contain provisions required 

for participation in the NFIP, including provisions that apply to buildings and structures within 

the scope of the LSUCC. Because the statute explicitly states that the LSUCC does not apply to 

several types of buildings, the State deems it important that communities retain complete floodplain 

management regulations that include all requirements, including those for buildings and structures. 

Any conflicts between the building code and local regulations are resolved by the building official 

and local floodplain administrator, typically with the more restrictive provision prevailing (e.g., 

locally adopted freeboard). This is considered appropriate because of the explicit statutory provision 

that references the standards of the NFIP (R.S. 40:1730.30). Appeals of those decisions may be made 

to local appeals boards; subsequent appeals can be made to the Council. Table 2-1 summarizes NFIP 

and CRS data for communities that the MAT visited.

Table 2-1: NFIP/CRS Data for Communities Visited by the MAT

Community Name (CID)

NFIP Entry 

Date

Current 

Effective FIRM CRS Entry Date

Effective Date 

of Current 

CRS Class

Current 

CRS Class

Jefferson Parish (225199) 10/1/1971 3/23/1995 10/1/1992 5/1/2010 6

LaPlace (part of St. John 

the Baptist Parish, 220164) 7/16/1980 11/4/2010 10/1/1994 5/1/2010 8

Madisonville (220201) 12/2/1980 3/16/1983 Not in CRS Not in CRS Not in CRS

Mandeville (220202) 9/28/1979 5/16/2012 10/1/1992 10/1/2008 7

Plaquemines Parish 

(220139) 5/1/1985 9/30/1993 Not in CRS Not in CRS Not in CRS

Slidell (220204) 12/16/1980 4/21/1999 10/1/1992 10/1/2008 8

NFIP = National Flood Insurance Program

FIRM = Flood Insurance Rate Map

CRS = Community Rating System

SOURCE: NFIP COMMUNITY STATUS BOOK, HTTP://WWW.FEMA.GOV/CIS/LA.HTML; COMMUNITY RATING SYSTEM (CRS) COMMUNITIES 

AND THEIR CLASSES, HTTP://WWW.FEMA.GOV/LIBRARY/VIEWRECORD.DO?ID=3629

2.3.1 Jefferson Parish, LA

Jefferson Parish enforces both the LSUCC and floodplain management regulations (Zone A and 

Zone V) in the unincorporated areas of the parish. The floodplain management regulations contain 

the minimum requirements to conform to the NFIP requirements in 44 CFR Parts 59 and 60, but 

may have incomplete specifications for certain higher standards:
2-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

1) Floodplain Management Regulations:

a. Require minimum NFIP elevation (see Table 2-2). 

b. Define but does not use “area of future conditions flood hazard” and “freeboard.”

c. Define “cumulative Substantial Damage” to be flood-related damage on two separate 

occasions, rolling 10-year period, for which the cost of repairing equals, on average, 25 

percent of the market value of the structure before damage occurred. Specific provision 

at Sec. 14-5.5 simply “recognizes and accepts” the definition. There is no change to the 

definition “Substantial Damage,” and thus no requirement to treat buildings that sustain 

“cumulative Substantial Damage” as Substantially Damaged.

d. In definition of “lowest floor,” references the “nonelevation design requirement of Section 

60.3” rather than of the parish’s regulation (i.e., enclosures).

e. Use “first floor elevation” (not defined) where NFIP regulations use “lowest floor”; uses 

“livable areas.” 

f. Define “repetitive loss” but does not include such structures in the definition for 

“Substantial Damage”; does not clearly require repetitive loss structures to comply with any 

requirement other than elevation (see Sec. 14-5.1 General standards). 

g. Define “severe repetitive loss,” but uses the term only under the parish’s responsibility to 

review construction to ensure compliance with “first floor elevation” requirements; does not 

clearly require compliance (see Sec. 14-4.3(e) and Sec. 14-5.1 General standards).

h. Define “residential structure” to exclude “trailers, hotels, motels, and motor lodges,” thus 

permitting buildings with those occupancies to be dry floodproofed.

i. Require expansion of any existing use in coastal high hazard areas to be in accordance with 

the requirements. 

j. Limit placement of new manufactured homes in floodways and coastal high hazard areas to 

existing parks or subdivisions. 

k. Use but does not define “floodproofed” (it is described in certification requirements in Sec. 

14-5.1(8)(c)). 

l. Adopt the “Preliminary Flood Insurance Study for Jefferson Parish” and the “Preliminary 

DFIRMs [digital Flood Insurance Rate Maps] for the East Bank of the Mississippi and 

ABFEs dated April 12, 2006, and revisions thereto,” in addition to the “previous March 23, 

1995 Official Flood Maps.” Several other paragraphs describe maps; also see Sec. 14-5.6, 

Higher regulatory standards for specific designated areas.

2) Building Code:

a. Adopts provisions for administration and enforcement of the LSUCC; specifically adopts 

the LSUCC, as amended (but identifies the 2006 editions of the I-Codes); and specifically 

adopts Part I-Administrative of the 2006 editions of the I-Codes. 

b. Does not adopt IBC Appendix G.

c. Sec. 8-2-101.5.1 clearly establishes that every existing building must comply with the 

requirements for new construction “in its entirety” when repair, renovation, addition, or 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-15

 REGULATIONS, CODES, AND STANDARDS

other improvement equals or exceeds 50 percent of market value. Specifies that “When 

a building is substantially damaged due to any origin, other than flooding, the building 

or structure shall meet the technical codes and requirements of this chapter for new 

construction.” When damage is due to flooding, an exception requires “only the base flood 

elevation requirements for new construction shall be fully met.” Omits compliance with all 

other flood requirements (e.g., foundation type, utilities, flood damage-resistant materials) 

and appears to not require full compliance with the rest of the code. Sec. 8-2.101.5.1.1 

provides that except for regulations pertaining to floodplain management, the code official 

shall determine the extent of compliance.

d. Sec. 8-2-101.6 specifies that the code shall not be mandatory for existing buildings 

identified and classified as historic buildings, which may have the effect of superseding the 

requirements of IEBC.

e. Does not retain the IBC inspections in flood hazard areas.

f. Sec. 8-3-111.1.4, Slab foundation: (a) for residential use, requires the top of slab to be at or 

above BFE shown on the FIRM; (b) for nonresidential use, requires the same or, if below 

the BFE, permits floodproofing; and (c) in Zone V, requires construction to “conform 

to the FEMA regulations” and to be certified that “the structure is securely attached to 

adequately anchored pilings or columns.”

g. Sec. 8-3-111.1.5, Piers or chain wall foundations, requires the “lowest portion of the 

structural members of the lowest floor (excluding the pilings, columns, or piers)” to be at 

or above the BFE established by FEMA and requires certification (without zone specified 

and without reference to same basis for establishing SFHAs as specified in the floodplain 

management regulations), that “the structure is securely attached to adequately anchored 

pilings, columns or piers.”

h. Has parish-specific requirements related to soils, requirements for footings and foundation 

walls, and detailed specifications for piles.

Table 2-2: Jefferson Parish Elevation Comparison: Floodplain Management Regulations vs. LSUCC

Lowest Floor: Zone 

A, Residential

Lowest Floor/Floodproofing: 

Zone A, Nonresidential

Bottom of LHSM of the 

Lowest Floor: Zone V

Floodplain Management 

Regulations

At or above the 

BFE At or above the BFE At or above the BFE

LSUCC

IRC: to or above 

the BFE (BFE 

+ 1 foot where 

Coastal A Zone is 

delineated)

IBC: BFE + 1 foot 

(Category II)

IBC: BFE + 1 foot 

for lowest floor/dry 

floodproofing (Categories 

II and III)

IBC: BFE + 2 feet for lowest 

floor/dry floodproofing 

(Category IV)

IRC: 

•	 At/above BFE if LHSM is 

parallel

•	 At/above BFE + 1 foot if 

LHSM is perpendicular

IBC: same as IRC, except 

additional freeboard for 

Categories III and IV

LHSM = lowest horizontal structural member

BFE = base flood elevation

LSUCC = Louisiana State Uniform Construction Code

IRC = International Residential Code

IBC = International Building Code
2-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

2.3.2 LaPlace, LA (unincorporated St. John the Baptist Parish)

LaPlace is part of the unincorporated St. John the Baptist Parish, and development in LaPlace is 

subject to the requirements of the parish. The parish enforces both the LSUCC and floodplain 

management regulations (Zone A and Zone V) in the unincorporated areas of the parish. The 

floodplain management regulations appear to conform to the NFIP requirements in 44 CFR Parts 

59 and 60:

1) Floodplain Management Regulations: 

a. Require minimum NFIP elevation (see Table 2-3). 

b. Have nonstandard definition of “elevated building”; the term is not used. 

c. Reference NFIP regulations rather than restating requirements (see definition 

“Lowest Floor,” appointment of Floodplain Administrator, and provisions for floodway 

encroachments.

2) Building Code: Adopts the Louisiana State Uniform Construction Code

a. Has no technical amendments to the building codes.

b. Does not adopt IBC Appendix G.

c. Adopts IBC provision that authorizes the code official to grant modifications if “special 

circumstance makes the strict letter of this article impractical and the modification does 

not lessen health, accessibility, life and fire safety requirements.” 

d. Specifies content of applications and plans, including specific information for construction 

in flood hazard areas. 

e. Includes “floodplain inspection” upon placement of the lowest floor and prior to further 

vertical construction, and submission of elevation documentation.

f. Requires businesses engaged in moving buildings to obtain a license from the parish 

engineer. 

Table 2-3: St. John the Baptist Parish Elevation Comparison: Floodplain Management Regulations vs. LSUCC

Lowest Floor: Zone 

A, Residential

Lowest Floor/

Floodproofing: Zone 

A, Nonresidential

Bottom of LHSM of the 

Lowest Floor: Zone V

Floodplain Management 

Regulations At or above the BFE At or above the BFE At or above the BFE

LSUCC

IRC: to or above the 

BFE (BFE + 1 foot 

where Coastal A 

Zone is delineated)

IBC: BFE + 1 foot 

(Category II)

IBC: BFE + 1 foot for lowest 

floor/dry floodproofing 

(Categories II and III)

IBC: BFE + 2 feet for lowest 

floor/dry floodproofing 

(Category IV)

IRC: 

•	 At/above BFE if LHSM is parallel

•	 At/above BFE + 1 foot if LHSM is 

perpendicular

IBC: same as IRC, except additional 

freeboard for Categories III and IV

LHSM = lowest horizontal structural member

BFE = base flood elevation

LSUCC = Louisiana State Uniform Construction Code

IRC = International Residential Code

IBC = International Building Code
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-17

 REGULATIONS, CODES, AND STANDARDS

2.3.3 Madisonville, LA

The Town of Madisonville enforces both the LSUCC and floodplain management regulations (Zone 

A and Zone V). The Town’s Web page makes available only the floodplain management regulations, 

and no other regulations. The floodplain management regulations do not fully conform to the NFIP 

requirements in 44 CFR Parts 59 and 60. The following are the most significant differences:

1) Floodplain Management Regulations:

a. Require minimum NFIP elevation (see Table 2-4). 

b. Define but do not use “habitable floor” with a qualification that “a floor used for storage 

purposes only is not a ‘habitable floor.’”

c. Do not define “historic structure”; the Substantial Improvement exception does not use the 

term.

d. Do not define or use “Substantial Damage.”

e. Do not include additions in the definition of Substantial Improvement.

f. Specify the Floodplain Administrator by name.

g. Have no provisions for manufactured homes in Zone V.

2) Building Code: not available online.

Table 2-4: Madisonville Elevation Comparison: Floodplain Management Regulations vs. LSUCC

Lowest Floor: Zone 

A, Residential

Lowest Floor/

Floodproofing: Zone 

A, Nonresidential

Bottom of LHSM of the 

Lowest Floor: Zone V

Floodplain Management 

Regulations At or above the BFE At or above the BFE At or above the BFE

LSUCC

IRC: to or above the 

BFE (BFE + 1 foot 

where Coastal A Zone 

is delineated)

IBC: BFE + 1 foot 

(Category II)

IBC: BFE + 1 foot 

for lowest floor/

dry floodproofing 

(Categories II and III)

IBC: BFE + 2 feet 

for lowest floor/

dry floodproofing 

(Category IV)

IRC: 

•	 At/above BFE if 

LHSM is parallel

•	 At/above BFE + 

1 foot if LHSM is 

perpendicular

IBC: same as IRC, 

except additional 

freeboard for 

Categories III and IV

LHSM = lowest horizontal structural member

BFE = base flood elevation

LSUCC = Louisiana State Uniform Construction Code

IRC = International Residential Code

IBC = International Building Code
2-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

2.3.4 Mandeville, LA

The City of Mandeville enforces both the LSUCC and floodplain management regulations (Zone A 

and Zone V). The floodplain management regulations do not fully conform to the NFIP requirements 

in 44 CFR Parts 59 and 60. The following are the most significant differences:

1) Floodplain Management Regulations: 

a. Do not define or use “Substantial Damage”

b. Do not include additions in the definition of Substantial Improvement ; specify costs “shall 

be cumulative, beginning from the date that the first alteration commenced”)

c. Have no provisions for manufactured homes in Zone V

d. Specify elevation requirements:

i. Freeboard of +12 inches in Zone A, residential only

ii. No freeboard for nonresidential structures

iii. No freeboard for Zone V

iv. No freeboard for Zones AO/AH

e. Prohibit manufactured homes in Zone A and Zone V but specify elevation and other 

requirements for manufactured homes in Zone A (and apparently the requirements 

apply to new installations, replacements, and Substantial Improvements). Require certain 

manufactured homes to meet full elevation requirements. 

2) Building Code: 

a. Adopts the code mandated by the Louisiana State Uniform Construction Code Council, 

without specifying which codes or editions (and retains references to Southern Building 

Code Congress International [SBCCI]). 

b. Does not adopt IBC Appendix G.

c. Specifies content of applications and plans, and requires submission of flood elevation 

certificate in flood hazard areas; also requires certificates “before authorization for the 

provision of permanent electrical service will be issued.”

d. Adopts a “grading supplement” (references SBCCI Standard Excavation and Grading 

Code), which specifies the finished floor elevation of attached and detached garages and 

accessory structures when fill is placed, and requires, among other things:

i. The finished floor elevation of the living area of all habitable dwelling units shall not 

be less than 12 inches above the crown of a paved street, where the crown or center 

line of the street is elevation plus 11 feet or higher.

ii. Where the crown of the street is below elevation 11 feet (above datum), the top of the 

finished floor of the living area of all habitable dwelling units shall be not less than 

elevation plus 12 feet or current applicable FEMA requirements.

e. Makes no technical amendments to the building codes. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-19

 REGULATIONS, CODES, AND STANDARDS

3) The State accepts higher standards adopted in local floodplain management regulations 

as prevailing over the LSUCC. The parish adopts a freeboard requirement for residential 

buildings that exceeds the elevation requirements of the LSUCC (Table 2-5). 

Table 2-5: Mandeville Freeboard Comparison: Floodplain Management Regulations vs. LSUCC

Lowest Floor: Zone 

A, Residential

Lowest Floor/

Floodproofing: Zone 

A, Nonresidential

Bottom of LHSM of the 

Lowest Floor: Zone V

Floodplain Management 

Regulations BFE + 12 inches To the BFE To the BFE

LSUCC

IRC: to or above the 

BFE (BFE + 1 foot 

where Coastal A Zone 

is delineated)

IBC: BFE + 1 foot 

(Category II)

IBC: BFE + 1 foot 

for lowest floor/

dry floodproofing 

(Categories II and III)

IBC: BFE + 2 feet 

for lowest floor/

dry floodproofing 

(Category IV)

IRC: 

•	 At/above BFE if 

LHSM is parallel

•	 At/above BFE + 

1 foot if LHSM is 

perpendicular

IBC: same as IRC, 

except additional 

freeboard for 

Categories III and IV

LHSM = lowest horizontal structural member

BFE = base flood elevation

LSUCC = Louisiana State Uniform Construction Code

IRC = International Residential Code

IBC = International Building Code

2.3.5 Plaquemines Parish, LA

Plaquemines Parish enforces both the LSUCC and floodplain management regulations (Zone A 

and Zone V) in the unincorporated areas of the parish. The floodplain management regulations do 

not fully conform to the NFIP requirements in 44 CFR Parts 59 and 60. The following are the most 

significant differences: 

1) Floodplain Management Regulations: 

a. Permit detached “accessory structures not used or designed for human habitation” below 

the BFE, provided they are “limited to accessory uses permitted in conjunction with 

residences by the zoning ordinances.” 

b. Requirements for manufactured homes in Zone V point to the requirements for Zone A 

(thus not specifying elevation of the bottom of the lowest horizontal structural member). 

c. Essentially require elevation of residential structures on fill by stating that the use of other 

methods will be approved if the use of fill is demonstrated to be impractical based on lot 

size and similar factors, while also requiring permit applications to include information 

“necessary to determine the extent to which any proposed fill or other landscape alteration 

will result in displacement of flood waters.”

d. Do not permit placement of manufactured homes and recreational vehicles in floodways 

except in existing parks and subdivisions. Manufactured home units used for offices, 
2-20 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

REGULATIONS, CODES, AND STANDARDS

storage, or other nonresidential purpose are required to meet the same requirements as 

those used for residences.

e. Require subdivisions for residential use to either (1) provide building sites with an average 

elevation at or above the BFE, or (2) be subject to deed restrictions requiring elevation 

of structures to or above the BFE. Proposals for nonresidential structures are treated the 

same, except the deed restriction requires elevation or floodproofing. 

2) Building Code: 

a. Adopts the Louisiana State Uniform Construction Code as it may from time to time be 

amended and promulgated by the State and all applicable standards and appendices 

referenced in that code, including Appendix J (Existing Buildings) to the residential 

building code. Also adopts the administrative chapters “of the various building codes.” The 

parish does not adopt IBC Appendix G.

b. No technical amendments to the building codes. 

c. Does not adopt freeboard requirements that exceed the elevation requirements of the 

LSUCC (Table 2-6). 

Table 2-6: Plaquemines Parish Freeboard Comparison: Floodplain Management Regulations vs. LSUCC

Lowest Floor: Zone 

A, Residential

Lowest Floor/

Floodproofing: Zone 

A, Nonresidential

Bottom of LHSM of the 

Lowest Floor: Zone V

Floodplain Management 

Regulations To or above the BFE To or above the BFE To or above the BFE

LSUCC

IRC: to or above the 

BFE (BFE + 1 foot 

where Coastal A Zone is 

delineated)

IBC: BFE + 1 foot 

(Category II)

IBC: BFE + 1 foot 

for lowest floor/dry 

floodproofing (Categories 

II and III)

IBC: BFE + 2 feet 

for lowest floor/dry 

floodproofing (Category IV)

IRC: 

•	 At/above BFE if LHSM is 

parallel

•	 At/above BFE + 1 foot if 

LHSM is perpendicular

IBC: same as IRC, except 

additional freeboard for 

Categories III and IV

LHSM = lowest horizontal structural member

BFE = base flood elevation

LSUCC = Louisiana State Uniform Construction Code

IRC = International Residential Code

IBC = International Building Code

2.3.6 Slidell, LA

The City of Slidell enforces both the LSUCC and floodplain management regulations (Zone A only). 

The floodplain management regulations do not fully conform to the NFIP requirements in 44 CFR 

Parts 59 and 60. The following are the more significant differences:

1) Floodplain Management Regulations: 

a. Use but do not define “lowest floor.”

b. Do not define “Substantial Damage.”
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 2-21

 REGULATIONS, CODES, AND STANDARDS

c. Require survey of the “bottom of the lowest structural member of the lowest floor” (even 

though only Zone A).

d. “Adopt” 1 foot of freeboard “in the adoption of ABFEs,” but freeboard is not addressed 

in the requirements that specify elevations for buildings. How this requirement is 

administered and whether it results in buildings having their lowest floors elevated (or 

floodproofed, for nonresidential buildings) to the ABFE plus 1 foot is unclear.

e. Include specifications and limitations for fill; specifically identifies use of “enclosed 

retaining wall or other method not requiring the use of fill (such as pilings or pier 

construction)” if necessary.

2) Building Code: 

a. Adopts the 2000 editions of IBC, IRC, IMC, and IFGC “and any subsequent amendments 

and revisions.” Does not adopt IBC Appendix G.

b. When private drainage facilities are proposed, the plans shall show the areas subject to 

inundation at flood stage and the “recommended floor elevation of residences to ensure 

safety in flood conditions and conformance with federal flood insurance regulations.”

c. No technical amendments to the building codes. 

3) The State accepts higher standards adopted in local floodplain management regulations as 

prevailing over the LSUCC. The city’s regulations refer to the ABFE and require an additional 

foot of elevation, which may exceed the elevation requirements of the LSUCC (Table 2-7). 

Table 2-7: Slidell Freeboard Comparison: Floodplain Management Regulations vs. LSUCC

Lowest Floor: Zone A, Residential Lowest Floor/Floodproofing: 

Zone A, Nonresidential

Floodplain Management 

Regulations ABFE + 1 foot ABFE + 1 foot

LSUCC

IRC: to or above the BFE (BFE + 1 foot 

where Coastal A Zone is delineated)

IBC: BFE + 1 foot (Category II)

IBC: 

•	 BFE + 1 foot for lowest floor/dry 

floodproofing (Categories II and III)

•	 BFE + 2 feet for lowest floor/dry 

floodproofing (Category IV)

ABFE = Advisory Base Flood Elevation

LSUCC = Louisiana State Uniform Construction Code

BFE = base flood elevation

IRC = International Residential Code

IBC = International Building Code

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-1

3Residential Construction

During field investigations, one focus of the MAT was on the 

performance of residential buildings, particularly those repaired 

or reconstructed after Hurricane Katrina.

Assessing the structural and building envelope performance of residential buildings was one of 

the MAT’s primary goals. In particular, buildings reconstructed after Hurricane Katrina that had 

experienced design flood conditions were of interest. The MAT used location-specific information 

that they gathered prior to and during the field investigations to identify which buildings were 

constructed post-Katrina. This prior knowledge of the hazard conditions that the buildings were 

exposed to during Hurricane Isaac was beneficial in the assessments. 

Damage documented within this chapter was observed in the field or made available through 

information gathered from other public sources (local building departments, Substantial Damage 

inspection records, elevation certificates, etc.). Statements made herein are not intended to 

represent final judgments as to the cause of damage to individual buildings; the MAT recognizes 

that further investigation by others may refine or alter judgments made in this report. Nevertheless, 

general damage patterns and trends the MAT observed are the basis for the recommendations in 

this report for improving residential design and construction.
3-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

3.1 Residential Flood Damage

Isaac’s flood elevations did not exceed effective BFEs in most of the areas visited by the MAT. 

Consequently, severe flood damage to one- and two-family residential buildings was not common 

throughout the study area. Damage to residential buildings was primarily a result of inundation 

by storm surge. The exceptions to these observations were in LaPlace, a community along Lake 

Pontchartrain, and in several areas along the East Bank of the Mississippi River in Plaquemines 

Parish. In these areas, flood levels did exceed the effective BFEs, and the MAT observed evidence of 

damage caused by waves, velocity flow, and flood-borne debris. 

Most traditional one- and two-family residential buildings in the affected area were built on shallow 

foundations, such as slabs, stem walls, crawlspaces, or piers. In newly constructed buildings, pile 

or column foundations were more common. Masonry pier foundations were the most common 

foundations in areas designated Zone V and in Zone A near the shoreline, followed by timber pile 

foundations. When properly designed and constructed, all of these foundations were effective 

during Hurricane Isaac where waves and surge remained below the floor system. In areas that 

experienced damage, including LaPlace, Slidell, Mandeville, Orleans Parish, and Jefferson Parish, 

the damage was caused by slow rising water. Flood depths in residential buildings ranged from 2 to 

4 feet above slab foundations. Typical damage to these buildings included interior finish; flooring; 

heating, ventilation, and air conditioning (HVAC); and contents damage. Very few homes on 

elevated foundations (piles/piers) in these areas visited by the MAT experienced flooding above 

the floor system; those that did experienced similar damage as homes on slab foundations. The one 

exception was buildings not properly anchored to piers that were displaced from their foundation.

The most extreme inundation was observed in Braithwaite along the East Bank in Plaquemines 

Parish, where floodwaters reached 8 to 10 feet above floor systems. In some areas along the East 

Bank, the MAT observed severe building damage in areas where levees were overtopped by rapidly 

rising, fast-moving water. This caused many buildings to be washed off their foundations.

At the Frenier Fishing Village, located east of LaPlace along the western shoreline of Lake 

Pontchartrain, some buildings were destroyed when surge and waves exceeded the floor elevation 

(see Figure 3-1). Age (ranged from 5 years to more than 30 years old) and elevation of construction 

were the primary damage indicators in this small community, with the older, non-elevated, preFIRM residences being destroyed and newer, elevated homes having less damage.

Most other areas visited by the MAT experienced damage caused by slow-rising water, where few 

indications of erosion and scour damage to foundations were observed. Typical flood damage in 

these areas is shown in Figures 3-2 through 3-4.

New construction and post-Katrina elevation projects consistently had minimal, if any, damage 

compared to adjacent non-elevated properties (see Figure 3-5). No flood damage was observed for 

the residential buildings the MAT visited that were constructed under the FEMA Hazard Mitigation 

Grant Program (HMGP) Pilot Mitigation Reconstruction Program. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-3

RESIDENTIAL CONSTRUCTION

Figure 3‐1: 

Wave and surge damage to 

a residential building. The 

house is located in Zone V 

along Lake Pontchartrain’s 

western shoreline (Saint 

John the Baptist Parish, LA). 

Figure 3‐2: Damage was observed in most at-grade slab foundation residences, while minimal damage was observed in 

adjacent elevated properties (Barataria, LA). 
3-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

Figure 3‐3: Typical flood depth of at-grade slab foundation residences; inset illustrates flood depth of 31 inches above 

the at-grade slab foundation (Slidell, LA).

Figure 3‐4: 

The damage to some elevated Zone V residences was limited to 

the loss of stairs (Mandeville, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-5

RESIDENTIAL CONSTRUCTION

Figure 3‐5: 

Minimal damage was 

observed in most elevated 

residences. The USGS HWM 

near this location was 

9.74 feet, compared to an 

effective BFE of Zone A14 

(EL12), Katrina ABFE of Zone 

AE (EL13), and preliminary 

FIRM of Zone VE (EL16) 

(Orleans Parish, LA). 

3.2 Residential Wind Damage

Wind damage to one- and two-family residential buildings was minor. The most common damage 

observed was to exterior finishes (vinyl siding, soffit material, fascia, etc.) and included minor roof 

cover loss. Age of construction was a major contributing factor to the extent of wind damage. As 

expected, the building envelopes on older houses did not perform as well as those on new houses. 

The one exception to this observation was the widespread loss of underside paneling in relatively 

new elevated coastal construction (see Section 3.7). Typical residential wind damage is shown in 

Figures 3-6 and 3-7. 

As anticipated, new residential buildings 

constructed under the FEMA Pilot Mitigation 

Reconstruction Program had no observed wind 

damage (see Figure 3-8); however, the number 

of properties built under this program was 

surprisingly low. In some cases, typically because 

of structural concerns, local communities were 

unable to complete a traditional elevation project 

because the structure would not be compliant with 

minimum standards of the 2003 I-Codes or other 

local codes and ordinances (because structural 

integrity may be questionable, the structure 

cannot be retrofitted to withstand current design 

wind speeds, etc.). 

PILOT MITIGATION 

RECONSTRUCTION PROGRAM

Under the Pilot Mitigation Reconstruction 

Program, eligible Applicants can receive 

Federal mitigation funds to demolish an 

existing structure and construct an improved, elevated structure on the same 

site. This may include pre-existing structures that were Substantially Damaged or 

destroyed as a result of a declared event.
3-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

Figure 3‐6: Loss of standard vinyl siding to recently elevated 

residential building; use and/or damage of high-wind siding 

was not observed by the MAT (Plaquemines Parish, LA). 

Figure 3‐7: 

Roof soffit and fascia 

damage to Exposure 

C residential building 

(Plaquemines Parish, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-7

RESIDENTIAL CONSTRUCTION

Figure 3‐8: 

Pilot Mitigation 

Reconstruction Program 

project; no observed wind 

damage (Mandeville, LA).

3.3 Foundation Performance

The MAT observed a wide range of foundations in residential buildings. Foundation types included 

closed-style foundations like slab-on-grade, crawlspace on perimeter foundation walls, and 

backfilled stem walls, and open-style foundations like piers and piles. The MAT also observed several 

homes that were originally constructed with slab-on-grade foundations that had been elevated 

with their slabs intact. In those homes, the elevated slabs were typically supported on masonry or 

concrete piers. 

Most non-elevated single-family or duplex residential buildings observed were constructed using 

a concrete slab-on-grade or masonry crawlspace foundation. Many of these buildings were preFIRM and experienced significant flood damage from inundation and the resulting hydrostatic 

and hydrodynamic forces. Side-by-side comparisons of non-elevated and elevated buildings in 

Slidell and Mandeville are shown in Figures 3-9 and 3-10. The elevated house had no observed 

damage, while the non-elevated house had interior finish, flooring, HVAC, plumbing, electrical, 

and contents damage caused by over 2 feet of flooding. The MAT consistently observed that the 

non-elevated houses experienced far greater flood damage than houses constructed on elevated 

foundations built to the ABFE or the preliminary FIRM developed after Hurricane Katrina. Flood 

depths in non-elevated houses in St. Tammany Parish were observed to be from 2 to 4 feet. However, 

in some locations of Plaquemines Parish, flood depths reached the rooftops of non-elevated homes. 

The deeper the flooding, the more damage the inundation caused; thus, the greatest damage was 

observed in Plaquemines Parish, especially along the East Bank of the Mississippi River.

Elevated foundations for existing single-family residential buildings were typically concrete or 

masonry piers supporting elevated slabs. Many of the home elevation projects were completed 

after Hurricane Katrina using FEMA Hazard Mitigation funds. Some elevated foundation projects 

involved detaching the home from its slab-on-grade foundation, elevating the walls, roof, and other 
3-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

portions of the structure, and constructing a new elevated wood-framed first floor, while leaving 

the existing slab-on-grade in place. A few of the elevated houses the MAT observed were entirely 

new structures constructed on piers or piles as part of the Pilot Mitigation Reconstruction Program. 

Many elevated foundations were raised an entire story to comply with local freeboard requirements 

as well as to accommodate vehicle parking or storage underneath the building. Local building 

officials informed the MAT that they preferred reconstruction over other elevation techniques 

because it eliminated the uncertainty in the structural capacity of the existing slab and structure 

and allowed new housing to be constructed to current prescriptive codes and standards.

Figure 3‐9: Neighboring residential buildings; the elevated residence had no observed damage, while the non-elevated 

home had significant interior damage caused by more than 2 feet of flooding (red arrow indicates flood depth) 

(Slidell, LA). 

Figure 3‐10: 

House elevated as part of 

the HMGP Pilot Mitigation 

Reconstruction Program 

(Mandeville, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-9

RESIDENTIAL CONSTRUCTION

Elevated Slab Concerns

The MAT observed many residential buildings where the existing slab had been elevated in place. 

The process to elevate a structure with a slab-on-grade foundation begins with excavating around 

the existing foundation to allow a network of lifting beams to be placed underneath the existing 

slab. Once the beams are in place, the home is lifted on the network of beams using hydraulic jacks. 

As with traditional elevation projects, there is a risk for cracking due to differential lifting, as shown 

in Figure 3-11. The elevated home is then supported on temporary timber cribbing or shoring until 

the permanent elevated foundation is completed. Figure 3-12 shows a home supported on timber 

cribbing. Permanent elevated foundations typically consist of reinforced concrete or masonry piers. 

Once the permanent foundations are in place and have been connected with the slab, the cribbing 

and other temporary supports are removed.

Figure 3‐11: 

Slab-on-grade elevation 

with structural cracks due to 

differential lifting 

(Slidell, LA).

Figure 3‐12: 

Slab-on-grade elevation in 

progress (Slidell, LA). 
3-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

The MAT observed several slab-on-grade elevations with the following features:

+ Vertical supports consisting of square masonry or concrete piers or 3-inch pipe columns 

that supported the elevated slabs. Pier and column spacing varied greatly. Most spans were 

approximately 6 feet; some exceeded 12 feet. In some cases the permanent supporting 

foundations were constructed using mini-piers. These mini-piers consisted of concrete blocks 

connected to one another with a series of threaded steel dowel rods, cable, or other material 

running through a hole in the center of each block. 

+ A decorative perimeter wall finish was placed around the base of the elevated houses to provide 

an attractive covering for the uneven appearance of the raised grade slab. 

Local building officials who the MAT interviewed in both Slidell and Mandeville on October 8 and 9, 

2012, expressed concerns about slab-on-grade foundation elevation projects. Although neither of 

the building officials had documented any foundation failures, one official had received numerous 

reports of buildings in the community with structural cracks associated with this technique, and 

both expressed concerns about the lack of data provided by owners’ representatives on the existing 

slab (i.e., concrete thickness, steel reinforcement) and the pier-to-slab connections. 

The MAT’s field observations of completed and ongoing slab elevation projects confirmed the 

observations of local building officials and revealed the following concerns:

+ Insufficient slab reinforcement/thickness: Elevated concrete slabs were often found to be of 

minimal thickness with limited wire mesh steel reinforcement and/or insufficient concrete cover 

of the wire mesh, as shown in Figure 3-13. This was also observed in ongoing residential building 

slab elevation projects with attached garages. 

Figure 3‐13: 

Elevated slab with 

insufficient steel cover 

(Slidell, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-11

RESIDENTIAL CONSTRUCTION

+ Lack of pier-to-slab connections: Different types of elevated foundation-to-floor framing 

connections were observed, including bolted connections for pile foundations and grouted 

connections for pier foundations. However, elevated slabs were often observed to have no visible 

connection to their piers. Where connections were observed, they appeared to be structurally 

insufficient, as shown in Figure 3-14.

Figure 3‐14: 

Structurally insufficient 

connection to pier. This 

house had a total of 7 such 

connections out of 17 piers 

supporting the structure 

(Mandeville, LA). 

3.4 Utilities

The most prevalent damage to elevated residential buildings observed by the MAT was flood damage 

to electrical service components (see Figure 3-15). The NEC and local utility company requirements 

control where electrical service components can be located. The NEC requirements primarily focus 

on safe clearances around energized lines and safe working space; utility company requirements 

incorporate access requirements based on local conditions so they can control, maintain, and repair 

the equipment. Utility companies commonly require the center of electrical meters to be placed 4 to 

6 feet above the finished grade to allow access for recording electrical usage as well as disconnecting 

or removing the electrical meters if they need to discontinue electric service to a home. Utility 

repairs to individual residences are typically some of the last repairs to be made, which impedes 

recovery and extends power outages, especially if the equipment is beyond repair and needs to be 

replaced.

When allowed by the local utility company, placing all electrical equipment above the flood level 

prevents floodwater from damaging it. The MAT observed several residences where components 

were elevated and accessible by stairs, walkways, or decks. These elevated structures typically 

supported condensers and other mechanical equipment (e.g., generators). When the equipment 

was properly elevated above potential flood levels, the damage to it was minimal. 
3-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

Figure 3‐15: Typical inundation damage to electric meter; note 

meter is temporarily reattached to pile with new bracing and 

strapping until permanently repaired (Jefferson Parish, LA). 

Proper elevation of equipment involves installing it above design flood levels and maintaining access 

for utility workers and first responders. Figure 3-16 shows an example of elevated electrical service 

components. 

When conditions or local utility company requirements limit elevation of electrical meters and they 

must be situated below design flood levels, it is critical not to attach utilities to breakaway walls 

or other building components not designed to resist flood loads. Figure 3-17 shows an example 

of a home where the utilities are attached to foundation piers. See the Minimizing Flood Damage to 

Electrical Service Components Recovery Advisory in Appendix D for more details on recommended 

practices for utility placement.

A service drop is an overhead electrical line running from a utility pole to a home. Traditionally, the 

lines enter residential buildings through a weatherhead that penetrates the roof (see Figure 3-18). 

The MAT observed service drops along rooftops and along the sides of the houses. At times, vertical 

clearance requirements constrain the service drop location to rooftops, but in most circumstances 

there is some flexibility in where the connection is installed. When the service drop was attached 

to the roof, the MAT observed some instances where a utility pole collapsed or wind-borne debris 

struck it, causing the weatherhead to shift in a way that tore the roof and allowed water to penetrate. 

This was less likely when the service drop was installed on the side of the house. Overhead clearance 

requirements or the locations of the utility pole and the electrical meter may dictate whether a 

weatherhead is attached to the roof or the side of the house. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-13

RESIDENTIAL CONSTRUCTION

Figure 3‐16: 

Residential building with 

electric meter installed 

adjacent to side entrance 

(Mandeville, LA).

Figure 3‐17: 

Electric meter attached to 

foundation pier (Plaquemines 

Parish, LA). 
3-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

Figure 3‐18: 

Post-Katrina residential 

reconstruction with 

service drop attached to 

the side of house 

(Slidell, LA).

3.5 Stairs 

The MAT observed a variety of exterior stairway configurations on elevated residential buildings 

in St. Tammany and Plaquemines Parishes. Stairway materials ranged from wood to masonry and 

wrought iron. In many neighborhoods, exterior stairs on residential buildings were curved or 

segmented in multiple directions as shown in Figure 3-19. This is often done for aesthetic reasons, 

to reduce the visual impact of the elevation on the structure.

Figure 3‐19: Curved and split stair configurations for elevated residential buildings (Mandeville, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-15

RESIDENTIAL CONSTRUCTION

The MAT observed damage to these exterior stairways, most frequently along Lakeshore Drive in 

Mandeville, as shown in Figure 3-20. Many of the homes with stairway damage had long runs of 

wooden stairs with solid risers oriented perpendicular to the direction of the flow of floodwater and 

no intermediate landings. Stairs of this type suffered the most severe damage or complete loss.

Figure 3‐20: Front and side view of stair damage to elevated waterfront residential building due to closed riser, 

inadequate foot anchoring, and insufficient connection with the building frame (Mandeville, LA). 

3.6 Enclosed Areas

The NFIP defines an enclosure as the portion of an elevated building below the lowest elevated floor 

that is either partially or fully enclosed by rigid walls. This area is to be used solely for parking, 

storage, and building access. The lowest floor is defined as the lowest floor of the lowest enclosed area 

(including the basement). The area within an enclosure is not considered the lowest floor provided 

that it is built in compliance with the applicable non-elevation design requirements of 44 CFR §60.3.

The MAT observed a variety of enclosed areas below elevated buildings, including several partially 

enclosed areas (see Figure 3-21), some fully enclosed areas, and a small number of above-grade 

enclosed areas (see Figure 3-22).

All enclosures below the BFE must be made of flood damage-resistant materials; in Zone A they must 

also have openings that allow floodwater levels inside and outside to rise simultaneously to equalize 

the hydrostatic pressure. Often, homeowners finish these areas as additional living space, which is 

in violation of the NFIP. The MAT observed damage to enclosures that were not constructed with 

flood damage-resistant materials (see Figure 3-23).
3-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

Figure 3‐21: Residential building under construction 

with a partially enclosed area—front closed/rear open 

with effective BFE of A13 (EL12), Katrina ABFE of Zone 

AE (EL13), and preliminary FIRM of Zone VE (EL14) 

(Madisonville, LA).

Figure 3‐22: Example of above-grade enclosure below 

elevated residence (Plaquemines Parish, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-17

RESIDENTIAL CONSTRUCTION

Figure 3‐23: 

Enclosed area that was 

not finished with floodresistant materials, nor 

did it have flood openings 

(Plaquemines Parish, LA). 

For enclosures below elevated homes in Zone V, rigid walls are not permitted. Enclosures in these 

areas must use breakaway wall construction, which is designed to fail under flood-loading conditions. 

Areas used for building access, storage, and vehicle parking in Zone V are required to be open or 

enclosed with lattice or breakaway walls. In addition, the MAT observed above-grade enclosures at 

a few sites. The primary issue with above-grade enclosures is that they may not be intended to fail 

under flood-loading conditions and, thus, may cause additional loading to foundation elements or 

cause damage to spread upward. The ramps into these above-grade enclosures can also become 

flood-borne debris and potentially impact the foundation and/or surrounding buildings. Any 

damage to enclosures below the lowest floor must not result in damage to the foundation, the utility 

connections, or the elevated portion of the building. For homeowners in Zone V, having breakaway 

enclosure walls below an elevated building will result in somewhat higher flood insurance premiums 

than having a completely open foundation. 

3.7 Underside of Elevated Buildings

The MAT observed hurricane wind damage to paneling and sheathing on the underside of several 

elevated homes in Plaquemines Parish. Paneling torn completely away became a source of windborne debris with the potential to damage neighboring buildings, and the loss of this layer of 

protection allowed water infiltration. Figure 3-24 shows an example of a residential building that 

experienced a loss of sheathing underneath the elevated first floor. 
3-18 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

RESIDENTIAL CONSTRUCTION

Figure 3‐24: 

Loss of the sheathing from 

the underside of an elevated 

building due to wind gusts 

(reported to exceed 80 

mph) that exceeded the 

capacity of the vinyl siding 

(Plaquemines Parish, LA).

Although the wind loads underneath a building are significantly less than those on the roof system, 

the potential loads imposed on the sheathing system should be calculated to determine the fastener 

size and spacing required to adequately attach the material. The MAT team observed that, in many 

instances, vinyl paneling material used to cover the underside of elevated buildings frequently tore 

at the connection point or failed because fasteners pulled out. Less damage was observed at elevated 

buildings where the covering material was wood that was properly fastened to the framing above. 

The use of wood or more rigid materials may not eliminate all damage during high-wind events, but 

it will minimize the damage. See the Minimizing Wind and Water Intrusion by Covering the Underside of 

Elevated Buildings Recovery Advisory in Appendix D for more details on recommended practices.

3.8 Fire‐Resistant Materials

The MAT observed several elevated structures with combustible materials or vehicles stored under 

the elevated portion of the home. In many cases, the underside of the elevated structure did not 

have a fire-resistant floor assembly. The residential structures observed by the MAT often had 

plywood sheathing or a wood finish material over standard wood floor joists or the lowest horizontal 

structural member, as seen in Figure 3-25. Using standard exterior grade plywood sheathing alone 

or wood finish material, such as wainscoting, is dangerous if the area underneath the elevated 

building requires a fire-resistant floor system. If the area underneath an elevated building is used 

for parking or storing even small quantities of fuel or other potentially combustible materials, most 

building codes require partitioning these areas from living spaces. For structures with elevated 

concrete slabs, the MAT observed several instances of conduits, plumbing, or other penetrations 

through the concrete slab without a compliant fire stop system, solid fire blocking, or a fire barrier. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 3-19

RESIDENTIAL CONSTRUCTION

Figure 3‐25: 

Elevated house with combustible materials 

and vehicle parking below elevated space 

(Mandeville, LA).

Such conduits, as shown in Figure 3-26, would allow fire beneath the slab to enter the structure. 

The elevated structure should be constructed in accordance with the IRC or IBC. The 2012 IRC 

Table R302.6 requires not less than 5/8-inch Type X gypsum board or equivalent for habitable 

rooms above a garage. See the Minimizing Wind and Water Intrusion by Covering the Underside of Elevated 

Buildings Recovery Advisory in Appendix D for more detail on fire-resistant assemblies in elevated 

structures.

Figure 3‐26: 

Elevated house with open 

space to interior of the home 

that would allow fire to 

spread (Mandeville, LA). 

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-1

4Nonresidential Construction 

and Infrastructure

During a disaster, communities rely heavily on certain 

services, including emergency responders, power, water 

and communication networks, and shelters.

Similar to the method used for assessing residential construction, the MAT focused on infrastructure 

and nonresidential buildings that were repaired or reconstructed after Hurricane Katrina that 

experienced flood conditions during Isaac. Based on the data gathered and damage assessment 

reports available prior to field investigations, the MAT observed three types of nonresidential 

construction: community centers, critical facilities, and infrastructure. Very few low-rise office and 

light commercial buildings experienced flood damage in areas visited by the MAT.

4.1 Community Centers

The Braithwaite Auditorium is a large reinforced masonry and concrete frame building constructed 

on an elevated concrete foundation system with a concrete slab underneath. The auditorium was 
4-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

rebuilt in 2011 as a result of damage caused by Hurricane Katrina. The elevation of the facility was 

based on the 2009 preliminary FIRM BFE (Zone VE [EL21]) rather than the Hurricane Katrina 

ABFE (Zone AE [EL 18]), with the lowest horizontal structural member more than 19 feet above 

grade (see Figure 4-1). This placed the structure above the flood levels of Hurricane Isaac, which 

were approximately 11 feet above grade (see Figure 4-2). However, not all utilities and associated 

Figure 4‐1: 

The Braithwaite Auditorium 

was rebuilt to the 

preliminary BFE following 

damage caused by Hurricane 

Katrina (Braithwaite Park 

[East Bank] – Plaquemines 

Parish, LA).

Figure 4‐2: 

HWM visible on glass at 

entrance to elevators below 

lowest floor of Braithwaite 

Auditorium (Braithwaite Park 

[East Bank] – Plaquemines 

Parish, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-3

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

equipment were elevated to the same height as the structure. The building has an elevator for 

handicap access as well as a generator for emergency power (see Figure 4-3); the automatic transfer 

switch and other electrical service components for this equipment were both damaged by Hurricane 

Isaac. No damage was observed inside the auditorium (see Figure 4-4). 

Figure 4‐3: 

The Braithwaite Auditorium 

has an elevated generator 

for emergency power 

(Braithwaite Park [East 

Bank] – Plaquemines 

Parish, LA).

Figure 4‐4: 

No damage was observed in 

the auditorium (Braithwaite 

Park [East Bank] – 

Plaquemines Parish, LA).
4-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

The auditorium building was elevated much higher than any of the homes in the nearby 

neighborhood. In fact, the auditorium’s lowest floor was higher than some rooftops in this 

neighborhood. As a result, the new auditorium suffered minimal damage compared to surrounding 

residential buildings, which were inundated with 8 to 10 feet of water (see Figure 4-5). The primary 

damage the MAT observed at the auditorium was to the electrical equipment. Although the facility 

was used shortly after the storm, the generator transfer switch and other electrical components 

below the lowest floor were in need of repair (see Figure 4-6).

As part of Hurricane Katrina recovery, the Port Sulphur Community Center was constructed in 2010 

with FEMA Public Assistance funding (see Figure 4-7). Plaquemines Parish consolidated 10 existing 

facilities into four community centers with similar construction to the Braithwaite Auditorium. 

These new centers were built to preliminary FIRM BFE (Zone VE [EL13]) rather than the Hurricane 

Katrina ABFE (Zone AE [EL 10]). No damage was observed by or reported to the MAT for the Port 

Sulphur Community Center; there was no flooding in this area.

Figure 4‐5: Residences in the Braithwaite Park subdivision were inundated with more than 8 feet of water; the 

auditorium (red arrow) is at the north end of the subdivision (Braithwaite Park [East Bank] – Plaquemines Parish, LA).

AERIAL COURTESY OF NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA); GENERATED FROM HURRICANE ISAAC 

RESPONSE IMAGERY VIEWER AT HTTP://STORMS.NGS.NOAA.GOV/STORMS/ISAAC/.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-5

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐6: 

The Braithwaite Auditorium generator 

transfer switch and other electrical 

components were built at grade and 

damaged by floodwaters (Braithwaite Park 

[East Bank] – Plaquemines Parish, LA). 

Figure 4‐7: 

Recently constructed Port 

Sulphur Community Center; 

no damage was observed 

or reported for the elevated 

facility (Port Sulphur [West 

Bank] – Plaquemines 

Parish, LA). 

4.2 Critical Facilities

The MAT observed the Woodlawn Fire Station in Plaquemines Parish (Figure 4-8). The Woodlawn 

Fire Station was built on the site of an abandoned high school. The fire station bay is a pre-engineered 

metal building with a metal roof and walls and brick façade. The fire station has four apparatus 

bays but housed 10 emergency vehicles prior to the hurricane. Firefighters serving the Woodlawn 

Fire Station said that the site of the station was selected because “it has never been flooded before.” 

Although the MAT did not observe visible structural damage, the station did receive flooding of 

approximately 8 feet. 
4-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐8: 

Woodlawn Fire Station 

(Woodlawn [East Bank] – 

Plaquemines Parish, LA).

According to a representative of the fire department, nine pieces of equipment (fire engines, 

command vehicles, etc.) and all of the fire department gear (hoses, safety equipment, clothing, 

tools, etc.) were significantly damaged and, therefore, were not available for response and recovery 

operations. One fire truck was undamaged because a firefighter drove the truck to the top of a 

levee prior to inundation. Figure 4-9 shows a post-storm inundation aerial for reference. The fire 

department did not have a formal continuity of operations or contingency plan in place in the 

event of a hurricane, but had onsite portable generators that allowed the fire station to serve as a 

community shelter for the duration of the rescue operations.

Figure 4‐9: Post-Hurricane Isaac aerial of Woodlawn Fire Station (Woodlawn [East Bank] – Plaquemines Parish, LA). 

AERIAL COURTESY OF NOAA; GENERATED FROM HURRICANE ISAAC RESPONSE IMAGERY VIEWER AT HTTP://STORMS.NGS.NOAA.GOV/

STORMS/ISAAC/.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-7

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

The MAT observed several Plaquemines Parish schools that were under construction. To comply 

with flood elevation requirements, the new schools were being constructed more than 10 feet above 

grade (see Figures 4-10 through 4-12). The MAT verified that, based on the flood elevations in the 

area, these schools would not have been inundated during Hurricane Isaac.

Figure 4‐10: 

The recently completed 

Parish Learning Center 

was constructed 

approximately 10 feet 

above grade (Port 

Sulphur [West Bank] – 

Plaquemines Parish, LA). 
4-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐11: 

South Plaquemines High 

School under construction; 

the preliminary BFE at 

this site is Zone VE (EL 15) 

(Boothville [West Bank] – 

Plaquemines Parish, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-9

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐12: 

The Phoenix Pre-K–12

School under construction; 

the preliminary BFE at this 

site is Zone AE (EL 17) 

(Phoenix [East Bank] – 

Plaquemines Parish, LA). 

4.3 Infrastructure

The MAT visited three substations in Plaquemines Parish, as well as various pump stations and 

cellular towers, throughout areas impacted by Hurricane Isaac. The three substations were 

inundated by floodwater, and the damage forced the utility companies to de-energize them. In two 

of the three substations, utility companies used temporary trailer-mounted substations to energize 

downstream electrical distribution lines while repairs were made (see Figure 4-13).

In two of the substations, most electrical equipment was placed at or near grade, and the placement 

offered little protection from floods. In the third substation, some flood protection was evident. In 

that substation, several pieces of electrical equipment were elevated on steel frames, some several 

feet above grade (Figure 4-14). Also, a protective berm was constructed around the perimeter of that 
4-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

substation. The berm was reportedly constructed after the substation flooded during Hurricane 

Katrina. During Hurricane Isaac, the berm was overtopped and the substation was inundated (see 

Figures 4-15 through 4-17).

Figure 4‐13: 

Electrical repairs being 

completed after substation 

equipment was inundated 

by floodwaters (Braithwaite 

[East Bank] – Plaquemines 

Parish, LA).

Figure 4‐14: 

Substation equipment 

elevated several feet above 

grade (Belle Chase [West 

Bank] – Plaquemines 

Parish, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-11

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐15: 

A berm was constructed 

around the perimeter of 

this substation to protect 

it after Hurricane Katrina 

(Belle Chase [West Bank] – 

Plaquemines Parish, LA). 

Figure 4‐16: 

Flood inundation depths 

were 4 to 5 feet above 

grade at the substation 

protected by the berm that 

was overtopped (Belle Chase 

[West Bank] – Plaquemines 

Parish, LA). 
4-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐17: The protective berm (red arrow) was overtopped, resulting in damage to the substation; note cellular tower 

(yellow arrow) northwest of the substation (Belle Chase [West Bank] – Plaquemines Parish, LA). 

AERIAL COURTESY OF NOAA; GENERATED FROM HURRICANE ISAAC RESPONSE IMAGERY VIEWER AT HTTP://STORMS.NGS.NOAA.GOV/

STORMS/ISAAC/.

The MAT observed several cellular towers with equipment elevated on platforms (see Figure 4-18). 

The MAT did not observe flood damage to the cellular tower equipment.

Figure 4‐18: 

Cellular tower equipment on 

elevated platform near Port 

Sulphur Community Center 

(Port Sulphur [West Bank] – 

Plaquemines Parish, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 4-13

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

The MAT visited stormwater pumping stations in Slidell and Plaquemines Parish. Both were located 

in SFHAs, and both were repaired and mitigated after Hurricane Katrina under FEMA’s Public 

Assistance Program. The elevation projects included installing new equipment and foundations, 

relocating control panels, and installing a generator with fuel tank and transfer switch for emergency 

power generation (see Figures 4-19 through 4-21). The MAT did not observe damage at either pump 

station, and both remained operational during the storm.

Figure 4‐19: Post-Hurricane Isaac aerial of the pump station south of Braithwaite Park (Braithwaite Park [East Bank] – 

Plaquemines Parish, LA). 

AERIAL COURTESY OF NOAA; GENERATED FROM HURRICANE ISAAC RESPONSE IMAGERY VIEWER AT HTTP://STORMS.NGS.NOAA.GOV/

STORMS/ISAAC/.
4-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

NONRESIDENTIAL CONSTRUCTION AND INFRASTRUCTURE

Figure 4‐20: 

Elevated stormwater pump 

station south of Braithwaite 

Park reconstructed after 

Hurricane Katrina with FEMA 

Public Assistance funds 

(Braithwaite [East Bank] – 

Plaquemines Parish, LA). 

Figure 4‐21: The control panels and generator at this pump station were elevated as part of a mitigation measure with 

FEMA Public Assistance funds; insets illustrate connections between equipment and platform (Slidell, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-1

5Evaluation of Elevation 

Projects

Hurricane Isaac’s landfall and impact in Louisiana afforded 

the MAT the unique opportunity to observe the performance of 

mitigation measures put in place as a result of Hurricane Katrina.

One of the primary objectives of the Hurricane Isaac MAT was to evaluate the performance of 

buildings constructed or elevated after Hurricane Katrina. To assess the performance of mitigation 

projects, this chapter compares damage to buildings located adjacent to one another as well as 

pre- versus post-Katrina construction of the same building. The chapter also examines buildings 

that were originally built to a higher elevation 

than surrounding structures. Sites were randomly 

selected based on communities visited while 

the MAT conducted field investigations and the 

availability of data to complete the comparisons. 

The damage summaries are based on observations 

made by the MAT as well as data collected from 

other sources (Substantial Damage determinations, 

A depth-damage function is a mathematical relationship between the depth of 

floodwater above or below the first floor of 

a building and the amount of damage that 

can be attributed to that water.
5-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

interviews with building officials, community damage summary reports, etc.). Estimated damage in 

this section is based on depth-damage functions used to estimate building, contents, and loss-of-function 

based on flood depths at each structure. Although the assessments of buildings are as accurate as 

possible based on MAT observations, statements made herein are not intended to represent final 

judgments as to the severity of damage to individual buildings. 

The two adjacent properties (see Figures 5-1 and 5-2) along Highway 23 in Plaquemines Parish 

were in the inundation area during Hurricane Isaac and located within the SFHA (effective FIRM 

– Zone A13 [EL5] 05/01/1985; Katrina ABFE – Zone AE [EL10]; Post-Katrina Preliminary FIRM – 

Zone VE [EL16]). The slab-on-grade house was built about 2004/2005 and was severely damaged 

during Hurricane Isaac. Winds caused roof cover loss, and approximately 5 feet of flood inundation 

damaged interior and exterior finishes (see Figures 5-3 through 5-7). The elevated wood-frame 

house was built on masonry piers about 2007 and received minor damage during Hurricane Isaac. 

Most of the damage to the elevated house was limited to the exterior finishes, including roof cover 

loss, and was caused by wind (see Figure 5-8); water did not reach the first floor. Estimated damages 

based on depth-damage functions are included in Table 5-1.

Figure 5-1:

Comparison of elevated 

versus at-grade 

constructions (Plaquemines 

Parish, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-3

EVALUATION OF ELEVATION PROJECTS

Figure 5-2: Post-Hurricane Isaac aerial of the residences in Figure 5-1 (Plaquemines Parish, LA).

SOURCE: NOAA; GENERATED FROM HURRICANE ISAAC RESPONSE IMAGERY VIEWER AT HTTP://STORMS.NGS.NOAA.GOV/

STORMS/ISAAC/
5-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

Figure 5-3:

Roof cover loss at nonelevated residential building 

(Plaquemines Parish, LA).

Figure 5-4:

Interior damage to the 

garage of the non-elevated 

residence (Plaquemines 

Parish, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-5

EVALUATION OF ELEVATION PROJECTS

Figure 5-5:

Exterior damage to the 

garage of the non-elevated 

residence (Plaquemines 

Parish, LA).

Figure 5-6:

Interior damage to the 

non-elevated residence 

(Plaquemines Parish, LA).
5-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

Figure 5-7:

Interior damage to the 

non-elevated residence 

(Plaquemines Parish, LA).

Figure 5-8:

Exterior damage (wood 

siding) to the elevated house 

(Plaquemines Parish, LA).

Table 5-1: Estimated Isaac Damages at Adjacent Properties Along Highway 23 (West Bank)

Description Flood Depth Above Lowest Floor (feet) Estimated Damages*

Slab-on-Grade 5 $148,243

Elevated <0 $4,000

* Assumes 1,600-square-foot residence with building construction cost of $100 per square foot. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-7

EVALUATION OF ELEVATION PROJECTS

The single-family residence on Lakeshore Drive in Mandeville was a slab-on-grade property during 

Hurricane Katrina (see Figure 5-9) and had 3 to 4 feet of flooding in 2005. The property is in the 

SFHA (effective FIRM – VE [EL12] 05/16/2012; Katrina ABFE – Zone VE [EL15]) after Hurricane 

Katrina (see Figure 5-10). The building was not inundated during Hurricane Isaac. See Table 5-2 for 

a comparison of estimated damages.

Figure 5-9:

Single-family residence 

post-Katrina 

(Mandeville, LA).

Figure 5-10:

Single-family residence 

elevated post-Katrina 

(Mandeville, LA).
5-8 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

Table 5-2: Estimated Katrina versus Isaac (pre- versus post-elevation) Damages at Lakeshore Drive Property 

Description Flood Depth Above Lowest Floor (feet) Estimated Damages*

Slab-on-Grade 5 $162,643

Elevated <0 No observed damage

* Assumes 2,000-square-foot residence with building construction cost of $100 per square foot. 

A nonresidential building along Lakeshore Drive in Mandeville was floodproofed 2 to 3 feet above 

ground level prior to Hurricane Katrina but experienced flooding of 7 feet that overtopped the 

floodproofed elevation by 4 feet (see Figures 5-11 through 5-13). After being Substantially Damaged 

by Hurricane Katrina, the building was reconstructed on an open foundation (see Figure 5-14). The 

building was not inundated during Hurricane Isaac. See Table 5-3 for a comparison of estimated 

damages. The property is located within the SFHA (effective FIRM – Zone VE [EL12] 05/16/2012; 

Katrina ABFE – Zone VE [EL15]).

Figure 5-11:

A nonresidential building 

on Lakeshore Drive in 

Mandeville post-Hurricane 

Katrina (Mandeville, LA).

Figure 5-12:

Entrance to nonresidential 

building on Lakeshore Drive 

in Mandeville post-Hurricane 

Katrina (Mandeville, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-9

EVALUATION OF ELEVATION PROJECTS

Table 5-3: Estimated Isaac Damages at Lakeshore Drive Nonresidential Property

Description Flood Depth Above Lowest Floor (feet) Estimated Damages*

Slab-on-Grade 4 $172,587

Elevated <0 No observed damage

* Assumes 1,800-square-foot building with building construction cost of $120 per square foot. 

Figure 5-13:

Interior damage from 

Hurricane Katrina to 

nonresidential building 

on Lakeshore Drive 

(Mandeville, LA).

Figure 5-14:

The same nonresidential 

building along Lakeshore 

Drive in Mandeville elevated 

post-Hurricane Katrina 

(Mandeville, LA).
5-10 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

In one of the areas with the deepest inundation from Hurricane Isaac, the MAT visited an elevated 

property that almost avoided flood damage. This residence along Highway 39 was built in 2009 and 

is located within the SFHA (effective FIRM – Zone A6 [EL3] 05/01/1985; Katrina ABFE – Zone 

AE [EL18]; Post-Katrina Preliminary FIRM – AE [EL17]). Although the house was inundated with 

2 feet of water, the damage was much less compared to older homes nearby that were built at grade 

(see Figures 5-15 through 5-17). Estimated damages based on depth-damage functions are shown in 

Table 5-4.

Figure 5-15: Post-Hurricane Isaac aerial of elevated residence along Highway 39 (Plaquemines Parish, LA).

SOURCE: NOAA; GENERATED FROM HURRICANE ISAAC RESPONSE IMAGERY VIEWER AT HTTP://STORMS.NGS.NOAA.GOV/

STORMS/ISAAC/
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-11

EVALUATION OF ELEVATION PROJECTS

Figure 5-16: Elevated house built in 2009 on Highway 39 had approximately 2 feet of water infiltrate the first floor; 

inset: yellow line illustrates observed HWM on door (Plaquemines Parish, LA).
5-12 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

Figure 5-17:

Debris pile near at-grade 

residence (Plaquemines 

Parish, LA).

Table 5-4: Estimated Isaac Damages at Adjacent Properties Along Highway 39 (East Bank) 

* Assumes 1,600-square-foot residence with building construction cost of $100 per square foot. 

The MAT visited the Frenier Fishing Village, a small community along the west bank of Lake 

Pontchartrain, with estimated building ages ranging from less than 5 years to more than 30 years 

old. The entire community is located in the Coastal High Hazard Area (effective FIRM – Zone 

VE [EL16] 11/04/2010; Katrina ABFE – N/A; Historic FIRM – Zone V16 [EL16]) and consists of 

about a dozen residential and nonresidential buildings. All buildings were constructed on an open 

foundation; however, the first floor elevations vary from approximately 1 to 12 feet above grade. As 

a result, the magnitude of flood damage from Isaac varied from collapse/failure to no damage (see 

Figures 5-18 through 5-25). See Table 5-5 for a comparison of estimated damage.

Description Flood Depth Above Lowest Floor (feet) Estimated Damages*

Slab-on-Grade 8 $244,389

Elevated 2 $61,969
5-13

Figure 5-18: 2008 aerial of the Frenier Fishing Village (St. John the Baptist Parish, LA). 

AERIAL COURTESY OF LOUISIANA LA COASTAL WETLANDS PLANNING, PROTECTION AND RESTORATION ACT AND THE USGS NATIONAL 

WETLANDS RESEARCH CENTER; GENERATED FROM HTTP://LACOAST.GOV/NEW/PUBS/MAP_DATA/2008DOQQ/DEFAULT.ASPX.

Figure 5-19: 

Surge damage to lakefront 

residential structure 

(Structure B in Figure 5-18) 

(St. John the Baptist 

Parish, LA).

HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT

EVALUATION OF ELEVATION PROJECTS
5-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

Figure 5-20:

Elevated residence with no 

observed damage (Structure 

E in Figure 5-18) (St. John 

the Baptist Parish, LA).

Figure 5-21:

Remains of residential 

building that was 

approximately 2 to 3 feet 

above grade (Structure D in 

Figure 5-18) (St. John the 

Baptist Parish, LA).

Figure 5-22:

Debris pile of waterfront 

single-family residence 

along the west bank of Lake 

Pontchartrain (Structure D 

in Figure 5-18) (St. John the 

Baptist Parish, LA).
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 5-15

EVALUATION OF ELEVATION PROJECTS

Figure 5-23:

Residential building elevated 

approximately 3 to 4 feet 

above grade that lost stairs 

and received other damage 

below the lowest floor 

(Structure C in Figure 5-18)

(St. John the Baptist 

Parish, LA).

Figure 5-24:

Nonresidential structure 

with damage to the screen 

surrounding the area under 

the lowest floor (Structure A 

in Figure 5-18) (St. John the 

Baptist Parish, LA).
5-16 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

EVALUATION OF ELEVATION PROJECTS

Figure 5-25:

Residence built about 2000 

with minimal damage to 

partially enclosed areas 

below the lowest floor 

(Structure F in Figure 5-18) 

(St. John the Baptist 

Parish, LA).

Table 5-5: Estimated Isaac Damages at Adjacent Properties in Frenier Fishing Village

Description Flood Depth Above Lowest Floor (feet) Estimated Damages*

1 to 2 Feet Above Lowest Horizontal 

Structural Member (Structure D) 2 Destroyed

1 Foot Above Lowest Horizontal 

Structural Member (Structure B) 0-1 Substantially damaged

Elevated and New Construction 

(Structures A, C, E, & F) < 0 $3,000

* Assumes 1,500-square-foot residence with building construction cost of $100 per square foot. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-1

6Conclusions and 

Recommendations

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 State 

and local officials and other interested parties. They are intended 

to assist the State of Louisiana, communities, businesses, and 

individuals in the reconstruction process and to help reduce future 

damage and impacts from flood and design level wind events similar 

to Hurricane Isaac.

Section 6.1 discusses conclusions and recommendations related to residential buildings. Section 6.2 

includes conclusions and recommendations related to critical facilities and infrastructure. Section 

6.3 discusses outreach and NFIP reform, Section 6.4 discusses best practices, and Section 6.5 

discusses conclusions and recommendations related to building codes and floodplain management 

regulations.
6-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

CONCLUSIONS AND RECOMMENDATIONS

6.1 Residential Construction

Louisiana State Emergency Officials estimate 59,000 residences were damaged by Hurricane Isaac. 

Flood depths reached as high as the rooftops of structures on foundations at or slightly above grade, 

but structures elevated to the BFE were largely undamaged.

Generally, the post-Katrina mitigated structures were not tested during Isaac. Because Hurricane 

Isaac’s flood elevations did not exceed effective BFEs in areas visited by the MAT, excluding areas 

in LaPlace and along the East Bank of the Mississippi River in Plaquemines Parish, observations of 

severe flood damage to one- and two-family residential buildings were rare. Elevated residences that 

were either new construction or post-Katrina elevation projects had minimal or no flood damage 

compared to adjacent non-elevated structures. 

6.1.1 Elevating to the Preliminary FIRM

Conclusion

Buildings elevated to the best available elevation data, including preliminary FIRMs, are far 

less likely to suffer damage in a flood. The MAT observed this in side-by-side comparisons of 

neighboring buildings in St. Tammany and Plaquemines Parishes. In these cases, one of the buildings 

was elevated and the other was not. When the area was flooded, the elevated building suffered 

little or no damage, while the non-elevated building was severely damaged. Most Louisiana parishes 

affected by Hurricane Isaac had not adopted the preliminary FIRMs. However, many communities 

adopted the ABFEs after Hurricane Katrina, which often represented the best available information 

for that community. Although this information may not be as current as the preliminary FIRMs 

in some areas, buildings elevated to these ABFEs suffered less damage than those not elevated. In 

addition, based on discussions with local building officials and the MAT review of local ordinances 

(Section 2.3), the MAT determined that some communities affected had adopted some form of 

freeboard requirement to elevate buildings above the regulatory BFEs. 

Recommendation 

Residential buildings should be built to the preliminary FIRM or best available elevation data, 

such as ABFEs. In addition, the adoption of freeboard requirements is beneficial. To facilitate this, 

NFIP communities in Louisiana should either adopt the preliminary FIRMs that were developed 

after Hurricane Katrina or require the use of the Hurricane Katrina ABFEs in determining 

structure elevation. Further, the communities should consider adopting freeboard requirements in 

accordance with ASCE 24-05. If the flood risk data indicate the structure is located within a flood 

zone subject to wave action, then the building should be elevated on an open foundation. 

6.1.2 Slab-on-Grade Elevation Projects

Conclusions

Considering information regarding the slab’s structural properties may minimize the potential for 

structural cracking during elevation. Properties that should be considered include slab thickness, 

steel reinforcement, and concrete cover of the steel reinforcement. Insufficient slab thickness, 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-3

CONCLUSIONS AND RECOMMENDATIONS

steel reinforcement, or concrete cover of the steel reinforcement can result in bending, shear, or 

deflection failure of the elevated slab when exposed to design live and dead loads. This is illustrated 

in Section 3.3 for elevations observed in Slidell and Mandeville, where the slab thickness and steel 

reinforcement cover appeared to be deficient. 

A lack of connections between the substructure and the superstructure increases the risk of 

failure during a design level flood or hurricane. Elevated slabs with no or minimal connections 

to their piers may not be able to withstand significant lateral or uplift forces from design flood and 

wind events. The MAT observed homes both elevated and in the process of being elevated that did 

not have sufficient connections between the foundation piers and the slab. Although the MAT did 

not observe failure of these connections, Hurricane Isaac was not a design level flood or wind event 

in most of the locations visited. 

Recommendations

Gather information regarding the slab’s reinforcement and structural properties during the 

design phase. Before beginning an elevation project for a home with a slab-on-grade foundation, 

the slab should be assessed to determine whether, once elevated, it can function as a structural 

element without the risk of failure when the structural system is exposed to design live and dead 

loads. In most cases, this will require drilling holes to measure slab thickness before excavation and 

thoroughly evaluating the slab after excavation. Slabs that are not adequate to support design loads 

without bending, shear, or deflection failure should be removed and replaced or reinforced. 

FEMA-funded elevation projects should include details of the new foundation’s capability to resist 

lateral forces from flood and wind loads as well as undermining by erosion or localized scour.

Shallow foundations in areas visited by the MAT were most vulnerable to undermining. Piles and 

piers are susceptible to failure when improperly sized and/or spaced.

Properly detail and design the connections and load path between the substructure and 

superstructure. These connections must be able to withstand the significant lateral and uplift 

forces present in a design flood or wind event.

6.1.3 Stairs for Building Access

Conclusion

The design and location of stairways providing access to elevated buildings affects how they 

perform in a flood. More specifically, stairs with closed risers that are perpendicular to the flood 

source incur greater flood loads. The MAT observed several instances where long runs of exterior 

stairs with no intermediate landings and closed risers that were oriented perpendicular to the 

direction of flood flow experienced significant damage. This often resulted in complete loss of 

building access as shown in Section 3.5. 

Recommendation

Design staircases to provide a reasonable means of safe and convenient access to the building.

Stairways leading from ground level to elevated structures are vulnerable to flood forces and 

frequently separate from the point of attachment. Proper materials and connections are essential 
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CONCLUSIONS AND RECOMMENDATIONS

for adequate performance. For residential buildings, stairs should be constructed with partially 

open risers in accordance with building code requirements and should be oriented perpendicular 

to the direction of flood flow to reduce flood damage, as shown in Figure 6-1. Constructing these 

stairs with open risers will reduce the forces incurred by the stair structure and thus reduce the 

likelihood that they will fail during a flood. If constructing stairs with open risers is not possible, 

construct stairs such that there are intermediate landings with supports that can resist flood forces.

Figure 6-1:

Residential stairs with 

partially open risers to 

reduce potential flood 

damage (Mandeville, LA).

6.1.4 Utilities and Electrical Service Components

Conclusions

Utilities located below the BFE are more likely to sustain damage in a flood than those that are 

elevated. The MAT observed many instances of flood damage to electrical service components, 

even among elevated residential buildings. This was because either some or all of the electrical 

service components were located below the BFE. The MAT also observed utilities that had been 

successfully elevated, and as a result sustained minimal to no damage during Hurricane Isaac. 

Elevated equipment was generally accessible by stairs, walkways, and decks. Commonly elevated 

equipment consisted of condensers and other mechanical equipment such as generators.

Overhead electric service drop lines attached to the roof may fail in hurricane conditions. Where 

the service drop was attached to the roof, the MAT observed some instances where a utility pole 

collapsed or wind-borne debris struck it, causing the weatherhead to shift in a way that tore the roof 

and allowed water to penetrate. 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-5

CONCLUSIONS AND RECOMMENDATIONS

Recommendations

Elevate electrical service components to or above the BFE. Submersion of electrical components 

during a flood causes damage that prevents power from being supplied to residences after floodwaters 

have receded. However, the NEC and local utility companies specify where electrical components 

can be installed, and the location is dictated by clearance and accessibility requirements. If elevating 

all service components is not possible, the electrical box should be elevated at the very least, as 

the replacement of that piece of equipment is the responsibility of the homeowner. In addition, 

meters and boxes below the BFE should not be attached to breakaway walls or other components not 

designed to resist flood loads. 

Overhead electric service drop lines should be attached to the side of the residence if possible.

Although service drops attached to the side of a house have the potential to allow heavy rains to 

penetrate the wall if the connection shifts, the water penetration is less problematic than for service 

drops attached through the roof.

6.1.5 Enclosed Areas

Conclusion

Above-grade enclosed areas located beneath elevated structures are likely to be damaged in a 

flood. The MAT observed a variety of enclosed areas beneath elevated structures, including 

partially enclosed areas and above-grade enclosures. According to the NFIP, all enclosures below 

the BFE must be constructed using flood damage-resistant materials. However, homeowners often 

finish these areas and use them as additional living space. Where damage was observed by the 

MAT, it occurred because flood damage-resistant materials were not used in the construction of the 

enclosed area. In addition, the failure of these above-grade enclosed areas creates debris that may 

impact surrounding structures.

Recommendation

Above-grade enclosed areas should be constructed of flood damage-resistant materials and 

should have walls designed to break away under flood loads. Solid breakaway wall panels used 

for enclosures become large flood-borne debris elements when they break away. Lattice or louvers 

should be used in the construction of these enclosed areas instead of solid breakaway walls, as 

they reduce debris and cost less to repair. If solid breakaway walls are used, they should have flood 

openings. Although not required by the NFIP or building codes, adding flood openings may delay 

the failure of the walls under flooding conditions below the BFE, reduce flood-borne debris, and 

reduce repair costs. 

6.1.6 Fire Separation in Elevated Homes

Conclusion

Fire protection of homes elevated to protect against the flood hazard should be a design 

consideration. The MAT observed elevated buildings with inadequate fire separation between 

occupied space and below-BFE parking, access, and storage areas. Many of the elevated residential 
6-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

CONCLUSIONS AND RECOMMENDATIONS

buildings observed by the MAT had plywood sheathing or wood finish materials applied over 

standard wood floor joists or the lowest horizontal structural member. Elevations of residential 

buildings with concrete slabs were also observed to be lacking fire stop systems, solid fire blocking, 

or a fire barrier at penetrations. 

Recommendation

Fire separation should be provided for elevated residential structures. For elevated buildings 

where the below-BFE space is used for parking or storage of flammable materials, fire separation is 

needed on the exposed underside of the building. Fire separation should meet the guidelines of the 

2012 IRC Table R302.6 for habitable rooms above a garage, which requires not less than 5/8-inch 

Type X gypsum board or equivalent. This material should also be flood damage resistant.

6.1.7 Building Envelope

Conclusion

Insufficient attachment and/or material selection for the underside covering of elevated floor 

systems, as well as for roof covering and siding, may contribute to failure during wind events. The 

MAT observed widespread loss of underside paneling in relatively new elevated coastal construction. 

Although the most common building envelope damage observed by the MAT was loss of roof 

covering and vinyl siding, the damage to underside coverings was not anticipated. More specifically, 

for the loss of roof covering and vinyl siding, older homes typically suffered greater wind damage, 

but the loss of underside paneling was observed in relatively new construction. 

Recommendation

Use proper fastener selection, attachment methods, and materials during construction.

Homeowners should consider mitigation measures such as upgrading the attachment of the roof 

covering to the roof deck, applying a moisture barrier/housewrap over exterior walls, and upgrading 

the attachment of vinyl siding to exterior wall sheathing. Retrofitting residential structures to 

protect against wind damage should be done in conjunction with elevation projects to provide a 

more comprehensive protection system for the structure.

6.2 Nonresidential Construction and Infrastructure

Critical facilities performed as expected. Those elevated to or above the BFE and those located 

outside the 500-year floodplain sustained little to no damage. Facilities located in areas prone to 

flooding and not mitigated sustained damage.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-7

CONCLUSIONS AND RECOMMENDATIONS

6.2.1 Community Centers, Critical Facilities, and Schools

Conclusion

Facilities were usable after the event if they had been constructed above or outside of the 500-year 

floodplain. The MAT visited several community centers constructed in Plaquemines Parish after 

Hurricane Katrina. The following are brief summaries of the observations at each.

Braithwaite Auditorium. Reconstructed post-Katrina, the auditorium was built to the preliminary 

FIRM BFE (VE21), rather than the Katrina ABFE (AE18). Hurricane Isaac’s flood depths of 11 feet 

at the auditorium were well below the structure’s lowest horizontal structural member. Damage at 

the auditorium was primarily to electrical equipment located below the building’s lowest horizontal 

structural member.

Boothville Community Center. Constructed in 2011, the community center is elevated 10 feet 

above grade. The building was undamaged by Isaac’s floodwaters, but damaged by driven rain that 

penetrated the building after strong winds damaged the wall covering.

Woodlawn Fire Station. Hurricane Isaac flooded this station, located in Plaquemines Parish, 

with 8 feet of water. The station was not flooded by previous storms, including Hurricane Katrina. 

Despite being inundated with floodwater, no visible structural damage to the station was observed. 

However, nine pieces of equipment including fire trucks, engines, and ambulances and all of the 

department’s fire gear were significantly damaged by floodwaters and unavailable for response and 

recovery efforts during Hurricane Isaac.

School Buildings. The MAT visited several schools throughout Plaquemines Parish that are under 

construction. The new schools are being constructed 10 feet above grade. The MAT verified that 

these new schools’ first floors would not have been inundated by Hurricane Isaac.

Recommendations

Construct critical facilities outside of or above the 500-year floodplain. Community centers that 

were elevated to the preliminary FIRM BFE were observed to have little or no flood damage. New 

and replacement community centers and critical facilities should be sited outside the 500-year 

floodplain, where possible; where not possible, critical facilities should be elevated to the preliminary 

FIRM BFE, rather than the Hurricane Katrina ABFE. In most instances, the preliminary FIRM 

BFEs are higher than Hurricane Katrina ABFEs and afford more protection.

Equipment and utilities for community centers and critical facilities should also be elevated to 

the preliminary FIRM BFE. If elevation of these components is not feasible for critical facilities in 

Zone A, they should be dry floodproofed to an elevation several feet above the BFE.

Consider evacuation and continuity of operations plans in design. The elevation of and 

floodproofing measures for critical and public facilities are limited to the DFE; therefore, 

communities must plan accordingly. The facilities will be protected to reduce building damage 

and functional downtime following a major flood, but communities must still develop evacuation, 

continuity of operations, and sheltering plans along with triggers to implement these plans based on 

existing forecast capabilities and estimated implementation timelines.
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CONCLUSIONS AND RECOMMENDATIONS

6.2.2 Infrastructure

Conclusion

Electrical substations located in flood hazard areas are vulnerable to significant damage 

during flood events. Because the locations of substations are heavily dictated by the routing of 

the transmission lines that supply them and by the population that they serve, placing substations 

outside of areas prone to flooding is often not possible. The MAT observed several substations 

that had sustained flood damage and as a result were not operational or relied on temporary or 

emergency equipment.

Recommendations

Where feasible, new electrical substations should be located outside of SFHAs. When new 

electrical substations are constructed in SFHAs, they should be considered Risk Structure Category 

IV per ASCE 24, and vulnerable equipment should be elevated or protected to or above the elevation 

required in ASCE 24. Elevating vulnerable equipment within the substation will reduce damage 

and reduce the amount of time the substation is offline. Such equipment includes control panels, 

high-voltage circuit breakers, switchgear, and panelboards that supply electrical loads within the 

substation. This equipment can be readily elevated if platforms or other means to access equipment 

for maintenance and repairs is provided. Some equipment, such as large power transformers, is 

difficult to elevate, but damage can be reduced if all vulnerable components like gauges, transducers, 

and controls are placed as high as possible.

For existing substations located in SFHAs, critical equipment should be relocated as high as 

practical to reduce the potential for flood damage or a minimum of 3 feet above grade. Elevated 

platforms should be provided to allow access for maintenance, service, and repairs.

6.3 Outreach and NFIP Reform

Conclusion

Outreach efforts are in place and functioning well. Currently, the State of Louisiana and 

Louisiana State University conduct outreach to communicate with residents and business owners 

about the NFIP and the upcoming reform to the NFIP enacted through the Biggert-Waters Flood 

Insurance Reform and Modernization Act of 2012. Outreach focuses on educating the public on 

the implications of property owners elevating their buildings above the BFE in relation to insurance 

premiums and protecting against flood events that exceed the BFE.

Recommendation

Outreach efforts should continue and should focus on educating the public about the following 

new provisions contained within the Biggert-Waters Act (EDEN 2012):

+ Pre-FIRM (subsidized) rates will be discontinued for all business properties, secondary 

residences, and residences that meet the definition of “severe repetitive loss property,” through a 

series of 25 percent per year increases in flood insurance premiums until the premium reflects 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-9

CONCLUSIONS AND RECOMMENDATIONS

the actuarial rate for the property. When any Pre-FIRM-rated property is sold, the new flood 

policy will reflect actuarial rates; this includes both primary residences and properties for which 

the loss of subsidy is being phased out. In addition, no extension of subsidy will be provided 

for new policies, policies that have a lapse in coverage as a result of deliberate choice of the 

policyholder, or any prospective policyholder who refuses to accept any offer for mitigation 

assistance by the Administrator. 

+ Grandfathered rates will be discontinued, with policies moving to actuarial rates over a period 

of 5 years. Each annual increase in premium over those 5 years will reflect 20 percent of the 

difference between the grandfathered and actuarial rates. The rate increase will begin with the 

first renewal following the effective date of the FIRM in which the higher risk is identified; the 

schedule of 20 percent increases will not change with a sale of the property.

6.4 Best Practices

This section presents the findings of building performance evaluations conducted separately from 

the MAT assessments but that are relevant to the focus of this report.

Conclusions

Review of post-Katrina projects highlighted best practices. FEMA’s Hazard Performance Analysis 

(HPA) Group evaluated residential structures in Barataria, Mandeville, and Slidell that had been 

elevated after Katrina using HMGP funds and were also located in areas flooded by Hurricane Isaac. 

The HPA Group evaluated 13 elevated properties along Bayou Barataria in an area not protected by 

a Federal levee. Although the storm surge for Hurricane Isaac was not as severe as that of Hurricane 

Katrina, the duration of flooding was longer. All 13 properties had been elevated, some as much as 

36 inches above the BFE, and none were flooded by Hurricane Isaac. Homes along Bayou Barataria 

that were not elevated were flooded by Hurricane Isaac’s storm surge, which varied from 18 to 24 

inches above grade (HPA 2012a).

In Mandeville, the HPA Group evaluated 14 elevated residences. All had been elevated and all were 

undamaged by Hurricane Isaac floodwaters. In examining losses avoided, the HPA Group focused 

on one home and compared the pre-mitigated floor elevation to the depth of flooding. They found 

that, had the house not been elevated, it would have been inundated with 36 inches of water (HPA 

2012b).

The HPA Group also evaluated 54 elevated properties in Slidell. Thirty-nine of the 54 homes were 

impacted by Hurricane Isaac, and it was determined that the elevation of these homes reduced the 

flood damage. Homes in this area that had not been elevated were inundated by 30 to 36 inches of 

water. The remaining 15 properties evaluated were in areas not affected by Hurricane Isaac flooding 

(HPA 2012c).

New residential buildings constructed under the FEMA HMGP Reconstruction Grant Pilot for 

Hurricanes Katrina, Rita, and Wilma had no observed damage; however, the number of properties 

built under this program was low compared to the number of elevation projects. The Reconstruction 

Grant Pilot requires that a community first evaluate the feasibility of elevating a building before 
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CONCLUSIONS AND RECOMMENDATIONS

considering reconstruction. If a community chooses not to support structural elevation, either due 

to non-compliance with existing codes or because of unaddressed vulnerabilities, then mitigation 

reconstruction may be considered as an alternative.

Recommendations

Distribute HPA reports to the public. FEMA and the State should distribute the Hazard 

Performance Analysis of Post-Katrina Mitigated Properties reports for three communities in 

Louisiana (Jefferson Parish, and Slidell and Mandeville in St. Tammany Parish) to the public to 

encourage mitigation. 

States should conduct losses avoided studies of mitigated properties after future flood events to 

evaluate project effectiveness. Such studies would compare the losses that would have been incurred 

for mitigated homes had they not been mitigated to the losses that were actually incurred. 

Local building officials should increase public awareness of the FEMA HMGP Reconstruction 

Grant Pilot for Hurricanes Katrina, Rita, and Wilma. The lack of mitigation reconstruction 

projects may be a result of numerous factors (limited awareness of the pilot program, grant process, 

financial reasons, etc.), but local officials should be encouraged to make building owners aware of 

this program, especially when older, non-compliant buildings are being considered for elevation 

projects. Communities should not support or permit elevation projects of structures that do not 

comply with all local codes and standards, not just the local floodplain management ordinance. 

6.5 Codes and Regulations

The following sections present conclusions and recommendations that are based on the MAT’s 

review of building codes and floodplain regulations in Louisiana and six of the communities visited 

by the MAT.

6.5.1 Louisiana Revised Statutes and Building Codes

6.5.1.1 Existing Statutes

Conclusions

A number of existing statutes remain unchanged and create conflicts with new statutes. The 

MAT’s review of the Louisiana Revised Statutes found that, subsequent to passage of Act 12 in 2005, 

a number of older statutory provisions remain unchanged and, thus, appear to create conflicts with 

more recent statutory provisions. For example, R.S. 33:1236(35)(b) permits parishes to adopt the 

Southern Building Code and other obsolete codes, while Act 12, in R.S. 40:1730.21–40 specifies that 

all municipalities and parishes shall enforce the codes adopted by the State, which are based on the 

I-Codes (see Chapter 2).

Another example of conflicting statutory provisions that could lead to misinterpretation is the use of 

the term “extensive alteration” (R.S. 40:1730.28), which has no direct relationship to whether work 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-11

CONCLUSIONS AND RECOMMENDATIONS

on existing buildings located in flood hazard areas is determined to be Substantial Improvement or 

Substantial Damage. 

The MAT’s review of the statutes also determined that State amendments to the model I-Codes 

exempt several buildings from the LSUCC, including farm structures, residential accessory 

structures, private recreational structures (such as hunting or fishing camps), and additions 

to dwellings that pre-date the first LSUCC. An explicit exemption applies to the construction or 

improvement of certain industrial facilities engaged in specific activities, provided the facilities are 

“inside the restricted access area” (R.S. 40:1730.29). Although R.S. 40:1730.30 specifies that the 

“standards” published by FEMA for the NFIP apply to “residential construction,” the impression is 

left that the listed exempt structures are not required to comply with local floodplain management 

regulations enforced by NFIP-participating communities. 

The State of Louisiana Hazard Mitigation Strategy, in Section Eight, identifies a number of 

refinements or corrections to Act 12:

+ Regulation of additions and improvements to existing structures

+ Refining the definition of “work area” such that extensive alterations, renovations, and repairs 

are covered, even if less than 50 percent of the total area is involved (see IRC Appendix J)

+ Resolving confusion in wording that implies that commercial properties under the NFIP are not 

covered by the LSUCC 

Recommendations

Review existing statutes to determine and resolve conflicts. The Louisiana State Uniform 

Construction Code Council should review the existing statutes to identify provisions that conflict 

with Act 12 or that appear contradictory, and should evaluate whether to act on the recommendations 

in the Louisiana State Hazard Mitigation Strategy. Based on the review, the Council should request 

“cleanup” legislation. 

In addition, misinterpretation could be avoided if the statutes include a clear statement that all 

structures that are exempt or otherwise not within the scope of the LSUCC are still subject to 

local floodplain management regulations. Communities that participate in the NFIP are required 

to regulate all development; any perceived barriers that could prevent fulfilling that requirement 

should be removed.

6.5.1.2 LSUCC and Administrative Provisions

Conclusion

LSUCC excludes Chapter 1 – Administration from the building code. As part of its adoption 

of the building code, the Council excludes IBC Chapter 1 – Administration. Many Louisiana 

communities separately adopt one or more of the administrative chapters of the I-Codes, sometimes 

with amendments, and some communities write their own administrative provisions. For example, 

Plaquemines Parish adopted the administrative chapters of each of the I-Codes included in the 

LSUCC. The City of Slidell adopted each of the codes that make up the LSUCC, thereby including 
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CONCLUSIONS AND RECOMMENDATIONS

the administrative chapters. The City of Mandeville wrote complete administrative provisions, 

although requirements similar to the administrative provisions of the I-Codes specific to flood 

hazard areas are not included.

Recommendations

Communities should review local provisions to ensure that requirements related to enforcing 

flood provisions are sufficient. Communities in Louisiana handle the administrative provisions in 

a number of ways. Communities should compare their locally adopted provisions for administration 

and enforcement of the LSUCC to the administrative provisions of Chapter 1, Scope and 

Administration, of the IBC and IRC 1 to ensure that requirements related to enforcing the flood 

provisions are sufficient. In addition, local code administrative provisions should be reviewed by the 

NFIP State Coordinating Agency and FEMA when conducting Community Assistance Visits.

6.5.1.3 Existing Buildings

Conclusion

With respect to existing buildings, the LSUCC incorporates the IEBC and the IRC. The IRC is 

scoped to cover work that can only be performed on existing dwellings (e.g., alteration, movement, 

enlargement, replacement, repair, equipment, use and occupancy, location, removal, demolition). 

Communities are permitted to adopt IRC Appendix J, Existing Dwellings. Despite this, based on 

discussion with the Louisiana State Uniform Construction Code Council’s Administrator, some code 

officials and others may not clearly understand whether and how existing dwellings are regulated, 

which may lead to different interpretations. 

Recommendation

The Council should provide a clear statement that work on existing dwellings is subject to the 

LSUCC. In particular, the NFIP and code requirement to regulate Substantial Improvement and 

restoration of Substantial Damage should be enforced.

6.5.1.4 Flood Protection in Subsidence Areas

Conclusion

The State of Louisiana Hazard Mitigation Strategy, in Section Eight, recommends that the State 

“establish a state freeboard requirement for construction in areas with significant (to be defined) 

subsidence rates, such that during the useful life of a building (e.g., as defined by FEMA BCA 

standards) no increased risk should be encountered.” Subsidence has occurred throughout the area 

affected by Hurricane Isaac, which may be a contributing factor to increased flood risk and damage.

1 http://www.fema.gov/building-science/building-code-resources
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CONCLUSIONS AND RECOMMENDATIONS

Recommendation

The State should act on the recommendation in the Louisiana Hazard Mitigation Strategy to 

establish a State freeboard requirement for construction in areas with significant (to be defined) 

subsidence rates.

6.5.2 Code Officials and Continuing Education

Conclusion

After Hurricane Katrina, FEMA awarded an HMGP grant to the State to help build State and 

local capacity to enforce building codes. The State has a continuing education requirement 

for code officials. Some funding was used for training and education, which contributed to a 

significant increase in the number of certified code officials. FEMA, the NFIP State Coordinating 

Agency (Louisiana Department of Transportation and Development), the Louisiana Floodplain 

Management Association, and the Louisiana Building Code Alliance offer or sponsor floodplain 

management training courses. The Association of State Floodplain Managers lists nearly 200 

individuals who are Certified Floodplain Managers.2

Recommendation

The State Hazard Mitigation Strategy indicates the Council may convert regional training 

seminars to an “interactive, on-line certification program.” The Council should evaluate this 

activity in the interest of increasing opportunities for code officials to learn about the code and 

obtain continuing education credits. The content of the courses should be reviewed to determine 

whether the flood provisions of the code are addressed. 

Floodplain management courses offered or sponsored by FEMA, the NFIP State Coordinating 

Agency, and the Louisiana Floodplain Management Association should be submitted to the 

Louisiana State Uniform Construction Code Council to determine whether the content, in whole 

or in part, warrants continuing education credits for code officials. The State and the Building 

Officials Association of Louisiana should notify building officials when floodplain management 

courses are offered.

6.5.3 Local Floodplain Management Regulations and Codes

6.5.3.1 Additional Elevation (Freeboard)

Conclusion

The requirements of local floodplain management regulations and the flood provisions of the 

LSUCC are enforced together. In general, any higher standard adopted in local regulations is 

deemed to prevail, especially a requirement for additional elevation (freeboard). The MAT’s review 

of local regulations for Plaquemines Parish and the cities of Mandeville and Slidell determined 

2 http://www.floods.org/Certification/certlist.asp#LA (accessed January 9, 2013)
6-14 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

CONCLUSIONS AND RECOMMENDATIONS

that those cities require some additional elevation (see Tables 2-2, 2-3, and 2-4). The building 

codes include a requirement for some additional elevation (see excerpts of the IBC and IRC3 and 

Highlights of ASCE 24 [FEMA 2010c]4). 

Recommendation

Communities should reevaluate the benefits of adopting additional elevation requirements so 

that new construction and Substantially Improved buildings are elevated higher than the minimum 

requirements of the LSUCC. This is especially important in areas where land subsidence has 

contributed to flood risk that is not reflected on FIRMs. Of particular benefit will be additional 

elevation requirements for dwellings, because the building code does not require freeboard for most 

dwellings. At a minimum, local officials should be diligent in enforcing the elevation requirements 

of the building code, which has some elevation requirements that exceed the minimum NFIP 

elevation requirements and, thus, also exceed any local floodplain requirement that is the same as 

the NFIP.

6.5.3.2 Consistency with the NFIP

Conclusion

The MAT’s review of the floodplain management regulations for Jefferson Parish, St. John the Baptist 

Parish, and Plaquemines Parish and the Cities of Madisonville, Mandeville, and Slidell identified 

one or more specific provisions that may not be fully consistent with the minimum requirements 

of the NFIP. Although the flood provisions of the LSUCC are consistent with the NFIP, because 

a number of buildings and some additions are not subject to the building code, complete local 

floodplain management regulations are necessary.

Recommendation

The NFIP State Coordinating Agency and the FEMA Regional Office should review the floodplain 

management regulations adopted by communities affected by Hurricane Isaac to verify the 

MAT’s conclusion that one or more provisions may not be fully consistent with the NFIP. Identified 

deficiencies should be corrected as soon as possible by adoption of amendments to those regulations.

6.5.3.3 Agreements for Enforcement

Conclusion

The statute provides that municipalities and parishes may enter into agreements with other 

governmental entities, or with certified third parties, to issue permits and enforce the building code 

(R.S. 40:1730.24 and 25). Because the building codes include flood provisions, those agreements 

cover buildings in flood hazard areas, but do not explicitly cover other requirements adopted by 

communities in their local floodplain management regulations. Although Plaquemines Parish and 

3 http://www.fema.gov/building-science/building-code-resources

4 http://www.fema.gov/library/viewRecord.do?id=3515
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT 6-15

CONCLUSIONS AND RECOMMENDATIONS

the Cities of Mandeville and Slidell do not have such agreements, other communities in the State 

do, especially in the more rural areas.

Recommendation

The NFIP State Coordinating Agency and the Council should encourage communities that 

have agreements with other governmental entities or agreements with certified third parties to 

review those agreements and include specific provisions related to local floodplain management 

requirements that are not already in the building code, such as an explicit requirement to conduct 

floodplain management inspections and make Substantial Damage determinations. Model 

language should be prepared to facilitate inclusion in third-party agreements. These provisions 

are also important if a community has adopted a higher standard that affects buildings (such as 

additional elevation), so that the entity responsible for permits and code enforcement is aware 

of those higher standards and can ensure that buildings and certain additions not subject to the 

building code are regulated. In addition, because local floodplain management regulations are 

adopted for participation in the NFIP, the agreements should include a specific requirement that 

the entity providing services participate in Community Assistance Visits and Community Assistance 

Contacts conducted by the NFIP State Coordinating Agency and FEMA.

6.5.3.4 Manufactured Homes

Conclusion

Statutory provisions for manufactured homes are not in the same section of law as the building code, 

but are found in R.S. 51:912.21–31. Oversight of manufactured home installers and of installation 

requirements (foundations, anchoring, and set up) was recently transferred to the Office of the 

State Fire Marshal. For installation in floodprone areas, the statute explicitly requires compliance 

with FEMA’s Manufactured Home Installation in Flood Hazard Areas (1985).

Recommendation

FEMA’s most recent revision of the guidance publication referenced in R.S. 51:912.21–31is 

FEMA P 85, Protecting Manufactured Homes from Floods and Other Hazards (2009c). The NFIP State 

Coordinating Agency should work with the Office of the State Fire Marshal to distribute notices of 

the revised document to manufactured home installers and local officials. Of particular interest 

to many manufactured home installers and local officials is the inclusion of a number of preengineered foundation solutions that are designed for a range of both wind and flood conditions. 

Hurricane Isaac in Louisiana MITIGATION ASSESSMENT TEAM REPORT A-1 

AAcknowledgments

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 Isaac: 

Jamelyn Austin-Trucks, CFM, CGM 

FEMA Region VI, Mitigation, Hazard Mitigation Assistance Branch 

Keith Bernard 

St. Genevieve Catholic Church, Slidell, LA 

Christopher Brown, CBO, CFM 

Building Official/Floodplain Manager, City of Mandeville, LA 

Blaine Clancy 

City Engineer, Department of Engineering, City of Slidell, LA 

Ken Dugas, P.E. 

Chief Engineer, Engineering and Public Works, Plaquemines Parish, LA 

Gary Ehrlich, P.E. 

Program Manager, Structural Codes & Standards, National Association of Home Builders 

George France, MCP, CBO, CFM 

Chief Building Official, Department of Building Safety, City of Slidell, LA 

Phil Hoffman 

Hoffman Custom Built Homes, LaPlace, LA 

Mark Joiner 

Administrator, Louisiana State Uniform Construction Code Council 

William LeBouef 

National Sales Manager, Esulation LLC, Slidell, LA 
A-2 MITIGATION ASSESSMENT TEAM REPORT Hurricane Isaac in Louisiana

Ackno wledgments

Michael Metcalf, CBO, CFM 

Building Official/Superintendent, Plaquemines Parish, LA 

Randy Noel 

Reve Incorporated, LaPlace, LA 

Donna O’Dell, P.E. 

Director, Department of Engineering, City of Slidell, LA 

Cindy O’Neal, CFM 

Louisiana NFIP State Coordinator 

Pat Skinner 

Disaster Recovery & Mitigation Specialist, Louisiana State University 

Mark Roberts 

ICC Regional Manager for Government Relations, International Code Council 

Joseph Williamson 

Principal, Belle Chasse Middle School, Belle Chasse, LA 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT B-1

BBibliography and Additional 

FEMA Resources

ACI (American Concrete Institute). 1989. Building Code Requirements for Masonry Structures. 

ACI-530-88/ASCE 5-88. Farmington Hills, MI.

ASCE (American Society of Civil Engineers). 2005. Flood Resistant Design and Construction, 

ASCE/SEI 24-05. Reston, VA.

ASCE. 2010. Minimum Design Loads for Buildings and Other Structures, ASCE/SEI Standard 7-10. 

Reston, VA. 

Associated Press. 2012. “Hurricane Isaac damaged 59,000 homes in Louisiana, officials estimate,” 

The Times-Picayune. September 28, 2012. http://www.nola.com/hurricane/index.

ssf/2012/09/hurricane_isaac_damaged_59000.html

ASTM (American Society for Testing and Materials). 1996. Standard Test Method for Windload 

Resistance of Rigid (Poly Vinyl Chloride) (PVC) Siding. ASTM D 5206. West Conshohocken, 

PA.

ASTM. 2008. Standard Test Method for Wind Resistance of Asphalt Shingles (Uplift Force/Uplift Resistance 

Method). ASTM D 7158. West Conshohocken, PA.

ASTM. 2009a. Standard Specification for Rigid (Poly Vinyl Chloride) (PVC) Siding. ASTM D 5206. West 

Conshohocken, PA.

ASTM. 2009b. Test Method for Wind-Resistance of Asphalt Shingles (Fan Induced Method). ASTM D 3679. 

West Conshohocken, PA.

Cooperative Institute for Meteorological Satellite Studies, Space Science Engineering Center, 

University of Wisconsin-Madison. 2012. Tropical Cyclones: A Satellite Perspective. 

http://tropic.ssec.wisc.edu/storm_archive/2012/storms/isaac/isaac.html
B-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

BIBLIOGRAPHY AND ADDITIONAL FEMA RESOURCES

EDEN (Extension Disaster Education Network). 2012. “Flood Premiums Rising Dramatically,” 

December 12, 2012. http://eden.lsu.edu/Topics/Hazards/Floods/NFIP/Pages/

FloodPremiumsRisingDramatically.aspx

FEMA (Federal Emergency Management Agency). 1985. Manufactured Home Installation in Flood 

Hazard Areas, FEMA 85. Washington, D.C., September 1985. 

FEMA. 2006a. Hurricane Katrina in the Gulf Coast: Building Performance Observations, Recommendations, 

and Technical Guidance. FEMA 549. Washington, D.C., July 2006.

FEMA. 2006b. Recommended Residential Construction for the Gulf Coast: Building on Strong and Safe 

Foundations, FEMA 550. Washington, D.C., July 2006.

FEMA. 2007a. Design Guide for Improving Critical Facility Safety from Flooding and High Winds: Providing 

Protection to People and Buildings, FEMA 543. Washington, D.C., January 2007.

FEMA. 2007b. Reducing Flood Losses Through the International Codes: Meeting the Requirements of the 

National Flood Insurance Program, FEMA 9-0372, Third Edition. Washington, D.C., December 

2007.

FEMA. 2008a. Design and Construction Guidance for Breakaway Walls Below Elevated Buildings Located 

in Coastal High Hazard Areas in accordance with the National Flood Insurance Program, NFIP 

Technical Bulletin 9, August 2008.

FEMA. 2008b. Flood Damage-Resistant Materials Requirements for Buildings in Special Flood Hazard Areas 

in accordance with the National Flood Insurance Program, NFIP Technical Bulletin 2, August 

2008.

FEMA. 2008c. Free-of-Obstruction Requirements for Buildings Located in Coastal High Hazard Areas in 

accordance with the National Flood Insurance Program, NFIP Technical Bulletin 5, August 2008.

FEMA. 2008d. Hurricane Ike in Texas and Louisiana: Building Performance Observations, 

Recommendations, and Technical Guidance, FEMA P-757. Washington, D.C., July 2009.

FEMA. 2008e. Openings in Foundation Walls and Walls of Enclosures Below Elevated Buildings in Special 

Flood Hazard Areas in accordance with the National Flood Insurance Program, NFIP Technical 

Bulletin 1, August 2008.

FEMA. 2009a. Homeowner’s Guide to Retrofitting (Second Edition), FEMA P-312. Washington, D.C., 

December 2009.

FEMA. 2009b. Local Officials Guide for Coastal Construction, FEMA P-762. Washington, D.C., February 

2009.

FEMA. 2009c. Protecting Manufactured Homes from Floods and Other Hazards, FEMA P-85. Washington, 

D.C., November 2009.

FEMA. 2010a. “Attachment of Brick Veneer in High-Wind Regions,” Technical Fact Sheet No. 

5.4, Home Builder’s Guide to Coastal Construction, Technical Fact Sheet Series, FEMA 499. 

Washington, D.C., December 2010.

FEMA. 2010b. Design Guide for Improving School Safety in Earthquakes, Floods, and High Wind, FEMA 

P-424. Washington, D.C., December 2010.

FEMA. 2010c. Highlights of ASCE 24, Flood Resistant Design and Construction. Washington, D.C., 

December 2010.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT B-3

BIBLIOGRAPHY AND ADDITIONAL FEMA RESOURCES

FEMA. 2010d. “Minimizing Water Intrusion Through Roof Vents in High-Wind Regions,” Technical 

Fact Sheet No. 7.5, Home Builder’s Guide to Coastal Construction, Technical Fact Sheet Series, 

FEMA 499. Washington, D.C., December 2010.

HPA (Hazard Performance Analysis Group). 2012a. Hazard Performance Analysis of Post-Katrina 

Mitigated Properties in Jefferson Parish Area. FEMA Hazard Analysis and Performance Group 

Report, September 2012. 

HPA. 2012b. Hazard Performance Analysis of Post-Katrina Mitigated Properties in Slidell, LA, St. Tammany 

Parish Area. FEMA Hazard Analysis and Performance Group Report, September 2012. 

HPA. 2012c. Hazard Performance Analysis of Post-Katrina Mitigated Properties in the Town of Mandeville, 

LA, St. Tammany Parish Area. FEMA Hazard Analysis and Performance Group Report, 

September 2012. 

ICC (International Code Council). 2009a. International Building Code, 2009 edition. Washington, 

D.C.

ICC. 2009b. International Residential Code, 2009 edition. Washington, D.C.

Isidore, Chris, 2012. “Isaac threatens Gulf oil production,” CNNMoney. August 27, 2012. 

http://money.cnn.com/2012/08/27/news/economy/isaac-oil-prices/index.html

Llanos, Miguel, 2012. “Mandatory evacuations outside New Orleans as Isaac nears 

hurricane strength,” NBC News (via MSN). August 27, 2012. http://usnews.nbcnews.

com/_news/2012/08/27/13501215-mandatory-evacuations-outside-new-orleans-as-isaacnears-hurricane-strength?lite

Louisiana Public Service Commission. 2012. “Hurricane Isaac Friday Update.” Media release. 

August 31, 2012. http://www.lpsc.org/_docs/_press/Press%20Release2.pdf

Louisiana State Uniform Construction Code Council. 2010. Louisiana State Uniform Construction 

Code. 

NFPA (National Fire Protection Association. 2012. Building Construction and Safety Code, NFPA 5000, 

2012 edition. Quincy, MA.

NFPA. 2011. National Electrical Code, NFPA 70, 2011 edition. 

NFIP (National Flood Insurance Program). 2012a. Flood Insurance Manual, effective October 1, 2012. 

Washington, D.C., revised October 2012. National Flood Insurance Program. 2012. 

NFIP. 2012b. The National Flood Insurance Program Community Status Book, State of Louisiana. October 

1, 2012. 

NHC (National Hurricane Center). 2011. The Deadliest, Costliest, and Most Intense United States Tropical 

Cyclones from 1851 to 2010 (and Other Frequently Requested Hurricane Facts). National Weather 

Service, National Hurricane Center. NOAA Technical Memorandum NWS NHC-6. 

http://www.nhc.noaa.gov/pdf/nws-nhc-6.pdf

NHC. 2012. Hurricanes in History. National Weather Service, National Hurricane Center. 

http://www.nhc.noaa.gov/outreach/history/

NOAA (National Oceanic and Atmospheric Administration). 2012a. Hurricane Isaac Response 

Imagery Viewer. http://storms.ngs.noaa.gov/storms/isaac/
B-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

BIBLIOGRAPHY AND ADDITIONAL FEMA RESOURCES

NOAA. 2012b. NOAA Water Level and Meteorological Data Report: Hurricane Isaac. 

http://tidesandcurrents.noaa.gov/publications/Hurricane_Isaac_2012_Water_Level_and_

Meteorological_Data_Report.pdf

NOLA Defender. 2012. “Corps closes more floodgates as Hurricane Isaac approaches,” 

NOLA Defender. http://www.noladefender.com/content corps-closes-m23ore-floodgateshurr67icane-isaac-approaches

Sanburn, Josh. 2012. “Hurricane Isaac causes billions in damage, but far less than Katrina,” 

Time Business & Money. August 31, 2012. http://business.time.com/2012/08/31/

hurricane-isaac-causes-billions-in-damage-but-far-less-than-katrina/

SBCCI (Southern Building Code Congress International). 1985. Hurricane Resistant Residential 

Construction Code.

The Times Picayune, 2012. “Hurricane Isaac’s death toll: Editorial,” The Times-Picayune. 

September 2, 2012. http://www.nola.com/opinions/index.ssf/2012/09/

hurricane_isaacs_death_toll_ed.html

USACE (U.S. Army Corps of Engineers). 2012. Hurricane Isaac with and without 2012 100-Year 

HSDRRS Evaluation. Preliminary Report, November 2012. http://www.mvn.usace.army.mil/

pao/HurrIsaacwapp.pdf

USGS (U.S. Geological Survey). 2012. Hurricane Isaac’s Path Through Louisiana. USGS Isaac Storm 

Tide Mapper: http://wim.usgs.gov/isaacstormtidemapper/stormtidemapper.html

U.S. Department of Housing and Urban Development. 2006. Manufactured Home Construction and 

Safety Standards, Title 24 Code of Federal Regulations (CFR) Part 3280. Revised as of 

April 1, 2006.

Vanacore, Andrew. 2012 “Hurricane Isaac damage could cost billions to repair,” The TimesPicayune. September 4, 2012. http://www.nola.com/hurricane/index.ssf/2012/09/

cost_of_isaac_repairs_could_be.html 

FEMA Publications and Resources

FEMA post-disaster reports available through FEMA publications: 1-800-480-2520 and at 

http://www.fema.gov/fema-mitigation-assessment-team-reports

FEMA 55, Coastal Construction Manual: Principles and Practices of Planning, Siting, Designing, 

Constructing, and Maintaining Residential Buildings in Coastal Areas. June 2000. 

http://www.fema.gov/library/viewRecord.do?id=1671 

FEMA 85, Manufactured Home Installation in Flood Hazard Areas. September 1985. 

FEMA 320, Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business. 

August 2008. http://www.fema.gov/library/viewRecord.do?id=1536

FEMA 361, Design and Construction Guidance for Community Safe Rooms. August 2008. 

http://www.fema.gov/library/viewRecord.do?id=1657 

FEMA 424, Design Guide for Improving School Safety in Earthquakes, Floods, and High Winds. 

January 2004. http://www.fema.gov/library/viewRecord.do?id=1986 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT B-5

BIBLIOGRAPHY AND ADDITIONAL FEMA RESOURCES

FEMA 431, Tornado Protection: Selecting Refuge Areas in Buildings. November 2003. http://www.fema.

gov/library/viewRecord.do?id=1563

FEMA 499, Home Builder’s Guide to Coastal Construction, Technical Fact Sheet Series, 31 sheets. 

August 2005. http://www.fema.gov/library/viewRecord.do?id=2138

FEMA 543, Design Guide for Improving Critical Facility Safety from Flooding and High Winds: Providing 

Protection to People and Buildings. January 2007. http://www.fema.gov/library/viewRecord.

do?id=2441

FEMA 549, Hurricane Katrina in the Gulf Coast: Building Performance Observations, Recommendations, 

and Technical Guidance. July 2006. http://www.fema.gov/library/viewRecord.do?id=1857

FEMA 550, Recommended Residential Construction for the Gulf Coast: Building on Strong and Safe 

Foundations. July 2006. http://www.fema.gov/library/viewRecord.do?id=1853

FEMA 577, Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds: Providing 

Protection to People and Buildings. June 2007. http://www.fema.gov/library/viewRecord.

do?id=2739

FEMA 9-0372, Reducing Flood Losses Through the International Codes: Meeting the Requirements of the 

National Flood Insurance Program. December 2007. http://www.fema.gov/library/viewRecord.

do?id=2094

FEMA P-85, Protecting Manufactured Homes from Floods and Other Hazards, November 2009. 

http://www.fema.gov/library/viewRecord.do?id=1577

FEMA P-762, Local Officials Guide to Coastal Construction. February 2009. http://www.fema.gov/

library/viewRecord.do?id=3647

NFIP Technical Bulletins

http://www.fema.gov/national-flood-insurance-program-2/nfip-technical-bulletins

FIA-TB-0: User’s Guide to Technical Bulletins

FIA-TB-1: Openings in Foundation Walls and Walls of Enclosures (updated 2008)

FIA-TB-2: Flood Damage-Resistant Materials Requirements (updated 2008)

FIA-TB-3: Non-Residential Floodproofing – Requirements and Certification

FIA-TB-4: Elevator Installation

FIA-TB-5: Free-of-Obstruction Requirements (updated 2008)

FIA-TB-6: Below-Grade Parking Requirements

FIA-TB-7: Wet Floodproofing Requirements

FIA-TB-8: Corrosion Protection of Metal Connectors in Coastal Areas

FIA-TB-9: Design and Construction Guidance for Breakaway Walls Below Elevated Coastal 

Buildings (updated 2008)
B-6 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

BIBLIOGRAPHY AND ADDITIONAL FEMA RESOURCES

FIA-TB-10: Ensuring that Structures Built on Fill In or Near Special Flood Hazard Areas are 

Reasonably Safe from Flooding

FIA-TB-11: Crawlspace Construction for Buildings Located in Special Flood Hazard Areas

NFIP Evaluation Studies

http://www.fema.gov/national-flood-insurance-program/national-flood-insuranceprogram-evaluation 

Evaluation of the National Flood Insurance Program’s Building 

Standards

http://www.fema.gov/library/viewRecord.do?id=2592 

FEMA Safe Room Web Site

http://www.fema.gov/safe-rooms
Hurricane Isaac in Louisiana MITIGATION ASSESSMENT TEAM REPORT C-1 

C

 

 

Acronyms
 

Acronym Definition 

ABFE Advisory Base Flood Elevation 

ASCE American Society of Civil Engineers 

BFE base flood elevation 

CFR Code of Federal Regulations 

CRS Community Rating System 

DFE design flood elevation 

FEMA Federal Emergency Management Agency 

FIRM Flood Insurance Rate Map 

HMGP Hazard Mitigation Grant Program 

HPA Hazard Performance Analysis (Group) 

HSDRRS Hurricane and Storm Damage Risk Reduction System 

HVAC heating, ventilation, and air conditioning 

HWM high water mark 

IBC International Building Code 

ICC International Code Council 

I-Codes International Code Series 

IEBC International Existing Building Code 

IFGC International Fuel Gas Code 
C-2 MITIGATION ASSESSMENT TEAM REPORT Hurricane Isaac in Louisiana

Acron yms

IMC International Mechanical Code 

IRC International Residential Code for One- and Two-Family Dwellings 

JFO Joint Field Office 

LHSM lowest horizontal structural member 

LSUCC Louisiana State Uniform Construction Code 

MAT Mitigation Assessment Team 

mph miles per hour 

NAVD 88 North American Vertical Datum of 1988 

NEC National Electrical Code 

NFIP National Flood Insurance Program 

NOAA National Oceanic and Atmospheric Administration 

R.S. Revised Statute 

SBCCI Southern Building Code Congress International 

SFHA Special Flood Hazard Area 

USACE U.S. Army Corps of Engineers 

USGS U.S. Geological Survey 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT D-1

DRecovery Advisories for 

Hurricane Isaac

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 have been prepared and are included in this appendix:

RA1: Minimizing Wind and Water Intrusion by Covering the Underside of Elevated Buildings

RA2: Minimizing Flood Damage to Electrical Service Components

These advisories are also available online at http://www.fema.gov/library/viewRecord.do?id=6727.

Minimizing Wind and Water Intrusion 

by Covering the Underside 

of Elevated Buildings

HURRICANE ISAAC RECOVERY ADVISORY RA1, December 2012
 

Minimizing Wind and Water Intrusion by Covering the Underside of Elevated Buildings December 2012 Page 1 of 4 

Purpose 

The purpose of this Hurricane Recovery 

Advisory is to describe practices for minimizing 

damage to the underside of elevated buildings 

(see Figure 1) resulting from high-wind events. 

The undersides of elevated coastal buildings 

are typically covered with paneling (vinyl 

or aluminum soffit sheeting) or sheathing 

(plywood) to protect the insulation and metal 

connectors used for the floor system. These 

undersides are often damaged by high winds 

during hurricanes, allowing water to be driven 

into the building. Figure 1. Loss of the covering from the underside of an elevated 

building due to high winds (Plaquemines Parish, LA, Hurricane Isaac) 

Key Issues 

•Hurricane winds can pull off paneling or sheathing from the 

underside of elevated buildings. 

• Lost paneling or sheathing can become wind-borne debris, 

which can damage property. 

• Hurricane winds can drive large amounts of water through areas 

where paneling or sheathing has been lost or where gaps have 

been created. 

• If the area underneath an elevated building is used for 

parking or storing small quantities of fuel or other potentially 

combustible materials, depending on how the space is 

categorized by the building code or local building official, 

these areas may be required to meet code requirements to 

partition these areas from living spaces. In addition, the use 

of fire-resistant-rated assemblies on the underside of elevated 

buildings are often not properly addressed. 

The information in this recovery advisory is intended to help 

minimize the loss of underside paneling or sheathing on elevated 

coastal buildings during high-wind events. Minimizing damage to 

these underside coverings will prevent damage to floor systems 

as well as water infiltration. 

Fire-Resistant-Rated Assemblies 

Many elevated buildings use the space 

underneath as a parking or storage 

area. According to building codes, 

the barrier between this space and 

the living area should be treated as a 

partition between a garage or parking 

area and a living area. Garages and 

parking areas must be separated from 

living areas with a fire-resistant floor or 

wall assembly. A variety of materials 

can be used; typically gypsum or an 

approved equivalent material is required 

to meet the guidelines for a fireresistant-rated assembly. The purpose 

of the assembly is to prevent a fire from 

a vehicle or flammable/combustible 

material from spreading too quickly into 

the living space, thereby allowing the 

occupants sufficient time to escape the 

building prior to the structure’s collapse, 

while minimizing their exposure to fire 

and smoke. Use of Space Below the Elevated Building 

Key Issues 

• Floodplain management regulations restrict the use of building space below the base flood elevation to 

vehicle parking, building access, and storage (see Figure 2). 

• Local regulations may require parking/garage areas to be separated from the living space with a fireresistant-rated floor assembly. 
Minimizing Wind and Water Intrusion by Covering the Underside of Elevated Buildings December 2012 Page 2 of 4 

Codes and Guidelines 

The building should be constructed in 

accordance with the International Residential 

Code or the International Building Code, 

depending on design requirements. 

Although these codes have slightly different 

requirements, depending on how the space 

is categorized by the building code, both may 

require a fire-resistant-rated assembly to be 

used between the parking area and living 

space. 

In addition to meeting applicable code 

requirements, the area below the elevated 

building must also meet the requirements 

of the NFIP as described in NFIP Technical 

Bulletins (TBs) TB 1, Openings in Foundation 

Walls and Walls of Enclosures; TB 5, Free-ofObstruction Requirements; and TB 9, Design 

and Construction Guidance for Breakaway Walls. 

Mitigation Guidance for Covering the Underside of an Elevated Building 

Key Issues 

• Underside paneling or sheathing assemblies for elevated structures should utilize flood-damage-resistant 

materials. 

• These assemblies may be required to meet the fire-resistance-rating criteria for a garage depending on how 

the space is categorized by the building code or local building official. 

• These assemblies should be designed to resist wind loads based on the adopted wind speed maps for the 

area where the building is located. 

Material Selection 

The materials selected for the underside of an elevated building need to meet the requirements of NFIP TB 2, 

Flood Damage-Resistant Materials Requirements, and any additional building code requirements related to 

flood protection. If required by the code in the building’s jurisdiction, designers should research the materials 

to ensure that they can be used to construct a fire-resistant-rated assembly that will also resist wind loads. 

Coastal areas are corrosive environments, and any fasteners used on the exterior of the building must be 

resistant to corrosion. Corrosion-resistant fasteners should be used for the entire floor system assembly and 

all paneling or sheathing materials. The compatibility of the fasteners with the materials must be verified. 

Ideally, corrosion-resistant fasteners should be used even in areas where the assembly is covered with 

paneling or sheathing material. 

Creating a Fire-Resistant-Rated Assembly 

FEMA post-disaster damage assessments have reported that plywood sheathing performs well in highwind conditions. However, plywood sheathing alone is insufficient if the underside of the elevated building 

requires a fire-resistant-rated floor system. Although fire-retardant-treated plywood that meets some of the 

fire-resistance requirements is available, it is not a substitute for fire-resistive gypsum, a common material in 

many fire-resistant-rated assemblies. 

Some alternative products may meet the fire-resistance requirement. The designer should contact the 

manufacturer to verify that the material will create a code-compliant assembly when used with the other 

materials in the assembly (floor system). The proposed design should be submitted to the local building 

official for approval. Building codes often require assemblies of a designated fire resistance to be 

documented by a recognized testing and listing organization/laboratory (e.g., Underwriters Laboratory). All 

structural elements, such as piles, posts, or columns, should be evaluated to determine if additional fire 

Figure 2. Space under an elevated building used as a parking area 

(St. Tammany Parish, LA, Hurricane Isaac) 
Minimizing Wind and Water Intrusion by Covering the Underside of Elevated Buildings December 2012 Page 3 of 4 

protection is needed. For instance, sprinkler systems may be required to meet building code requirements in 

some jurisdictions. 

Creating a Wind-Resistant Assembly 

Currently, no design standards provide guidance on how to calculate wind loads underneath an elevated 

building. Although the wind loads underneath the building are significantly less than those on the roof system, 

designers should try to determine the potential loads imposed on the plywood sheathing system to determine 

the appropriate fastener size and spacing to adequately attach the plywood sheathing. If a refined wind load 

analysis will not be performed, it may be appropriate to use the plywood sheathing fastening requirements for 

low-slope roof systems with the design wind speed for the area where the building is located. In many cases, 

floor joists are spaced at 16 inches, rather than a roof truss spacing of approximately 24 inches on center, 

which may adjust typical fastener spacing due to the tighter spacing of support members (joists). 

FEMA post-disaster assessments have observed that 

vinyl siding or soffit paneling material used to cover 

the underside of elevated buildings frequently fails, 

usually as a result of the vinyl tearing or fasteners 

pulling out (see Figure 3). FEMA has observed less 

damage to underside coverings from high-wind 

events where the covering material is wood (typically 

plywood sheathing). The use of wood or more rigid 

materials may not eliminate all damage during 

high-wind events, but it will minimize damage to the 

underside covering material from tear out around 

fasteners or buckling (see Figure 4). 

Designing the Complete Assembly 

If the area underneath an elevated building is 

categorized, by the code or building code official, 

such that it requires a fire-resistant-rated assembly 

and must meet flood-resistance requirements and 

adequately resistant wind loads, it will result in a 

complex assembly of materials. 

If common construction materials are to be used, 

a fire-resistant-rated assembly can be constructed 

using a standard plywood subfloor, floor joists with 

insulation between the joists, a layer of exteriorgrade plywood sheathing, and a layer of 5/8-inchthick Type X paperless gypsum wallboard. Although 

this approach exposes the gypsum wallboard to 

wind-borne debris, it will reduce the likelihood of 

plywood sheathing loss due to high winds. The 

plywood layer should be fastened to the floor joists 

to minimize plywood sheathing loss and deflection 

in high-wind events. The plywood sheathing layer 

will prevent the gypsum wallboard from deflecting 

in a high-wind event and thus minimize loss of the 

gypsum. (Reversing the drywall and the plywood 

layers requires the fasteners attaching the plywood 

to the floor joists to bridge the gypsum; these fasteners may then be a potential point of failure.) 

As a final step, the gypsum wallboard should be covered with an exterior-grade paint or sealant consistent 

with the gypsum wallboard manufacturer’s specifications. Any assembly requiring a fire-resistance rating must 

be verified with the appropriate building material listing service and by the local building official for building 

code compliance. 

Figure 3. Covering under an elevated building was lost when the 

vinyl soffit paneling tore around fastener heads during high winds 

(Plaquemines Parish, LA, Hurricane Isaac) 

Figure 4. Wood sheathing under a house near the one shown in 

Figure 3 did not fail; this is not a fire-resistant-rated assembly 

(Plaquemines Parish, LA, Hurricane Isaac) 
Minimizing Wind and Water Intrusion by Covering the Underside of Elevated Buildings December 2012 Page 4 of 4 

This Recovery Advisory describes one approach to designing an assembly, and while other techniques exist, 

designers must consider appropriate wind loads, use flood-damage-resistant materials, and provide fire 

resistance. For example, other materials, such as some fiber cement sheathing products, may meet the windloading requirements for the plywood sheathing and fire-resistance requirements of the gypsum wallboard. 

However, designers should always check with the manufacturer. The entire floor assembly should be assessed 

as a whole rather than as individual products. 

References 

APA, The Engineered Wood Association. 2009. Fire-Retardant-Treated (FRT) Plywood. 

(http://www.apawood.org) 

APA, The Engineered Wood Association. 2005. Fire-Rated Systems, Design/Construction Guide. 

(http://www.apawood.org) 

Federal Emergency Management Agency (FEMA). 2008a. National Flood Insurance Program (NFIP) Technical 

Bulletin 1, Openings in Foundation Walls and Walls of Enclosures. 

(http://www.fema.gov/national-flood-insurance-program-2/nfip-technical-bulletins) 

FEMA. 2008b. NFIP Technical Bulletin 2, Flood Damage-Resistant Materials Requirements. 

(http://www.fema.gov/national-flood-insurance-program-2/nfip-technical-bulletins) 

FEMA. 2008c. NFIP Technical Bulletin 5, Free-of-Obstruction Requirements. 

(http://www.fema.gov/national-flood-insurance-program-2/nfip-technical-bulletins) 

FEMA. 2008d. NFIP Technical Bulletin 9, Design and Construction Guidance for Breakaway Walls. 

(http://www.fema.gov/national-flood-insurance-program-2/nfip-technical-bulletins) 

International Code Council. International Building Code. 2006/2009/2012. (http://www.iccsafe.org) 

International Code Council. International Residential Code. 2006/2009/2012. 

(http://www.iccsafe.org) 
Minimizing Flood Damage to 

Electrical Service Components

HURRICANE ISAAC RECOVERY ADVISORY

Minimizing Flood Damage to Electrical Service Components December 2012 Page 1 of 4 

	 	 	 	 	 	 	 	

	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	 	 	 	 	 	

	 	 	 	

	 	 	 	 	 	 	 	

	 	 	 	

 RA2, December 2012 

Purpose 

The purpose of this Hurricane Recovery Advisory is to describe 

practices for minimizing damage to electrical service components 

during coastal and riverine flood events (see Figure 1). It’s primary 

focus is on services of less than 300 volts, which are typical of 

residential homes. Considering flood risks when designing and 

constructing electrical services can ensure that outage durations 

resulting from flooding are minimized and that utility and code 

requirements are met. 

Key Issues 

•	Floods can damage electrical utility meters and disconnect

switches and other electrical service components. Damaged 

components can delay recovery time and extend the duration of 

power outages. 

•	Preventing flood damage requires placing all electrical

equipment above the flood level, but utility company 

requirements and the National Electrical Code (NEC) place limits 

on where electrical service equipment can be located. 

The following information is intended to help homeowners and 

builders identify options for locating electrical service components 

to minimize flood risks. Figure 2 clarifies some terminology and 

shows some of the necessary clearance requirements. 

National Electrical Code and Local Utility 

Requirements 

Key Issues 

•	The NEC may dictate the locations for some electrical service

components because of clearance requirements 

•	NEC requirements do not directly address flood protection needs

•	Local utilities may have additional requirements that dictate the location of electrical service components

•	Local utilities may also require an external disconnection at the metering equipment so that emergency

response personnel can safely de-energize all power without entering the structure 

NEC Requirements 

NEC contains requirements for electrical services that significantly affect their design and construction. 

The code dictates: 

•	Clearance to energized conductors

•	Means to disconnect electrical power from a home

•	Clearances around electrical service components

Figure 1. Electrical components installed below 

the lowest floor system are subject to increased 

flood damages and lengthy outage durations (St. 

Tammany Parish, LA) 
Page 2 of 4 

	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	

Figure 2. Illustration identifies some of the electrical service components and some of the NEC requirements for 

residential electrical service. Other clearance requirements come into effect if the service drop (an overhead 

electrical line running from a utility pole to a home) is attached near a door or window or is attached to the side of 

the house rather than to the roof as shown in the illustration. 

NEC clearance requirements prevent people from coming in contact with energized conductors (electrical 

lines). Clearances above roofs, doors, windows, driveways, and walking surfaces (stair landings, decks, 

balconies, etc.) must meet NEC requirements. When electrical components are elevated to avoid flooding, the 

NEC requirements for clearance must still be maintained. 

NEC requirements for service disconnecting means ensures power to a building can be shut off in the event 

of an emergency like fire or flooding, or when electrical equipment must be de-energized for servicing. Main

circuit breakers mounted within electrical service panelboards are often used to disconnect the service. 

Separate enclosed circuit breakers or separate fused disconnect switches mounted between the electrical 

meters and the electrical panelboards can also be used. The NEC requires that service disconnecting means 

be readily accessible. The NEC allows the use of remote control as a disconnecting means if the remote 

control device is readily accessible. 
Minimizing Flood Damage to Electrical Service Components December 2012

	 	 	 	 	

	 	 	 	 	 	

	 	 	 	

	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	

The NEC also governs working space around electrical 

equipment, and requires a clear area around electrical 

equipment to allow a utility worker or electrician to 

work without obstructions. Meeting these requirements

often affects the placement and location of electrical 

service components. Equipment that must be serviced 

or repaired when energized must have sufficient 

working clearance to protect electricians as they 

perform service and repairs. 

Electrical Utility Company Requirements 

In addition to the NEC requirements for electrical 

services, electrical utility companies also have 

requirements that must be met. Utility companies 

commonly require the center of electrical meters to be 

placed within 4- to 6-feet of the finished grade to allow 

access for recording electrical usage from manually 

read meters. The 4- to 6-foot requirement also allows 

National Electrical Code and National 

Electrical Safety Code 

The National Fire Protection Association (NFPA)

70, also known as the National Electrical Code 

(NEC), is the minimum standard incorporated 

by many building codes and adopted by many 

States and municipalities. The NEC governs all 

wiring downstream of the electrical service point, 

which delineates on-premise wiring from that 

operated by the electrical utility. Wiring upstream 

of the electrical service point is governed by 

other standards, like the National Electrical 

Safety Code (NESC, ANSI/IEEE C2). 

For more information, refer to: 

http://standards.ieee.org/about/nesc/2012.html. 

utility workers to remove the electrical meters from meter boxes if they need to discontinue electric service to 

a home. The specific requirements for the elevation of the center of the meter above grade should be verified 

with the utility company. Some utility companies allow electric meters to be accessed from elevated stairs, 

walkways, or decks, particularly when not used solely for meter access (and thus more likely to be maintained 

in a serviceable condition). When accessible from elevated structures, the electrical meters and other service 

components can be elevated to reduce or alleviate flood risk without restricting access for utility company 

personnel. 

Choosing Locations for Electrical Service Components 

Key Issues 

•	Locating electrical service components above potential floodwaters

•	Maintaining access for utility workers

National Flood Insurance Program Requirements 

The National Flood Insurance Program (NFIP) requires that

buildings in a Special Flood Hazard Area: 

... be constructed with electrical heating, ventilation,
 

plumbing, and air conditioning equipment and other 


service facilities that are designed and/or located so as 


to prevent water from entering or accumulating within 


the components during conditions of flooding.
 

Although the NFIP does not regulate equipment owned by

utilities, such as electric meters, FEMA recommends that

electrical services be designed so that all equipment is 

elevated above flood levels to prevent flood damage 

(Figure 3) or that most of the electric service equipment be 

placed above flood levels to minimize flood damage 

(Figure 4). 

Figure 3 shows a house where the electrical meter and all 

other electrical service components are all located above the 

elevated lowest floor. For floods that do not rise above the 

level of the elevated lowest floor, service equipment will not be damaged by flood waters (with the possible 

exception of an easily repairable grounding conductor that bonds the meter enclosure and service panel to a 

ground rod below). Workers can easily access the electrical meter from the stairs and elevated deck to read 

the meter or remove it to shut off power to the home. 

Electric service 

equipment 

Figure 3. Example of the preferred method of elevating 

all electrical components (St. Tammany Parish, LA) 

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Minimizing Flood Damage to Electrical Service Components December 2012 Page 4 of 4 

Service 

disconnect 

Hookstick 

Electrical 

meter 

In some situations, elevating the meter may not be possible, 

but all other electrical service components may be elevated 

(see Figure 4). Because there are no stairs or elevated decks 

to provide access for an elevated meter, the utility meter is 

located within 4 to 6 feet of grade and remains vulnerable 

to flooding, but can be repaired or replaced after floodwaters 

recede. Flood risks to the electrical equipment, while not 

eliminated, are greatly reduced at this home. The service 

disconnecting means is mounted nearly 10 feet above grade; 

it is equipped with a hookstick that allows remote operation. 

The electrical service panel (located inside opposite the 

service disconnect) is also elevated and protected from 

flooding. 

Other Considerations 

•	In addition to adhering to the elevation requirements in

areas with high-velocity floodwaters, any utilities located 

below the design flood elevation should be placed on the 

landward side of the building and attached to foundation 

elements, such as piles or columns. 

•	Utilities such as meters, conduits, or service masts (see

Figure 2 for terminology) should not be attached to breakaway walls or elements that are not designed to 

resist flood loads. 

•	Conduits and electrical cables should not be mounted on breakaway walls or cross open areas below the

design flood elevation. 

•	All electrical components, both above and below the design flood elevation, should be designed to drain and

prevent the accumulation of water. 

•	Branch circuits and secondary electrical components placed below design flood elevations should be

designed so that they can be electrically isolated from the rest of the system. This will allow electrical power 

to be safely restored to the home before completing all flood-related electrical repairs. 

•	For additional information regarding the proper installation of electrical components in flood-prone areas,

see FEMA P-348, Protecting Building Utilities from Flood Damage (1999), and FEMA P-499, Home Builder’s 

Guide to Coastal Construction (2010). 

References and Resources 

The following references and resources provide information on proper installation of other portions of the 

electrical system and the other utilities. 

FEMA. 2010. FEMA P-499, Home Builder’s Guide to Coastal Construction. 

(http://www.fema.gov/library/viewRecord.do?id=2138) 

FEMA. 2008. NFIP Technical Bulletin 5-08, Free-of-Obstruction Requirements. 

(http://www.fema.gov/plan/prevent/floodplain/techbul.shtm) 

FEMA. 2008. NFIP Technical Bulletin 9-08, Design and Construction Guidance for Breakaway Walls. 

(http://www.fema.gov/plan/prevent/floodplain/techbul.shtm) 

FEMA. 1999. FEMA P-348, Protecting Building Utilities from Flood Damage. 

(http://www.fema.gov/library/viewRecord.do?id=1750) 

International Code Council (ICC). International Building Code. 2006/2009/2012. 

(http://www.iccsafe.org) 

ICC. International Residential Code. 2006/2009/2012. (http://www.iccsafe.org) 

National Fire Protection Association. NFPA 70: National Electrical Code. 2011.

(http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70&cookie%5Ftest=1) 

Figure 4. Other than the electrical meter, all the 

electrical components are elevated and protected 

from flooding at this home. The system incorporates an 

electrical service disconnect that is remotely operable 

with a hookstick (St. Tammany Parish, LA). 
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT E-1

EHigh Water Marks

High water mark (HWM) data for Hurricane Isaac was provided to the Mitigation Assessment 

Team (MAT) by the U.S. Geological Survey (USGS). However, all of the data points provided are 

located outside of the area protected by the Hurricane and Storm Damage Risk Reduction System 

(HSDRRS), so the team was unable to compare many of the HWMs to previous HWMs observed 

during Hurricane Katrina. Many of the affected areas during Hurricane Katrina were within the 

HSDRRS. To better understand the flood depths observed in the field, these data were compared 

to the effective base flood elevation (BFE), the post-Katrina Advisory Base Flood Elevation (ABFE), 

and the preliminary BFE (as applicable) in the New Orleans areas affected by Hurricane Isaac. 

Figure E-1 shows the locations of the HWMs used for this analysis. 

Table E-1 provides the comparison of elevations for the data points shown in Figure E-1. Most points 

located within the 100-year flood zone have HWM elevations that are lower than the effective, 

advisory, and preliminary BFEs for the location, indicating that Hurricane Isaac was below a design 

flood event. Some areas within the 500-year floodplain (Zone X shaded) did experience flooding 

during Hurricane Isaac. The HWMs for these areas mostly fall in St. John the Baptist Parish, which 

adopted preliminary maps in 2010. The highlighted rows in Table E-1 represent locations where the 

HWM elevation was higher than the effective BFE. All elevations in the table are referenced to the 

North American Vertical Datum of 1988 (NAVD 88).

Although the USGS points all lie outside of the HSDRRS, the U.S. Army Corps of Engineers found 

that the HSDRRS did generally perform as expected. With the HSDRRS in place, the levees and 

floodwalls were not overtopped. The limited extent of damage within the HSDRRS system also 

supports this determination.
E-2 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

HIGH WATER MARKS

Figure E‐1: Locations of USGS HWMs used in the MAT analysis.
HURRICANE ISAAC IN LOUISIANA MITIGATION ASSESSMENT TEAM REPORT E-3

HIGH WATER MARKS

Table E‐1: Elevations and Flood Zones for HWM Locations (elevations referenced to NAVD 88) 

HWM ID Latitude Longitude

HWM 

Elevation

Effective Zone 

(BFE, feet)

ABFE Zone 

(BFE, feet)

Preliminary Zone 

(BFE, feet) Parish

HWM-LA-JEF-005 29.75909 -90.10209 4.35 AE (EL 7) AE 8 AE (EL 8) Jefferson

HWM-LA-JEF-004 29.73223 -90.12875 3.93 AE (EL 8) AE 9 AE (EL 8) Jefferson

HWM-LA-JEF-001 29.68025 -90.10141 5.09 AE (EL 9) VE 10 VE (EL 11) Jefferson

HWM-LA-JEF-002 29.66820 -90.10934 4.92 VE (EL 11) VE 10 VE (EL 11) Jefferson

HWM-LA-JEF-003 29.73444 -90.12459 3.50 AE (EL 7) AE 9 AE (EL 8) Jefferson

HWM-LA-ORL-004 30.12564 -89.86719 5.19 V16 (EL 15) VE 16 VE (EL 14) Orleans

HWM-LA-ORL-003 30.14968 -89.74074 9.77 V19 (EL 15) VE 16 VE (EL 16) Orleans

HWM-LA-ORL-028 30.14508 -89.74825 6.09 V16 (EL 15) VE 16 VE (EL 15) Orleans

HWM-LA-ORL-001 30.07725 -89.84861 6.87 V16 (EL 13) VE 14 VE (EL 15) Orleans

HWM-LA-ORL-029 30.12434 -89.86669 5.87 V16 (EL 15) VE 16 VE (EL 14) Orleans

HWM-LA-ORL-002 30.06708 -89.83292 8.61 A14 (EL 13) AE 14 VE (EL 14) Orleans

HWM-LA-ORL-005 30.06643 -89.80586 9.74 A14 (EL 12) AE 13 VE (EL 16) Orleans

HWM-LA-ORL-017 30.6688 -89.80633 9.74 A14 (EL 12) AE 13 VE (EL 16) Orleans

HWM-LA-PLA-202 29.51200 -89.76480 7.97 A16 (EL 11) AE 12 AE (EL 12) Plaquemines

HWM-LA-PLA-010 29.25280 -89.35805 6.33 V21 (EL 15) VE 16 VE (EL 12) Plaquemines

HWM-LA-PLA-205 29.59507 -89.84190 7.80 A13 (EL 5) AE 10 VE (EL 15) Plaquemines

HWM-LA-PLA-201 29.76060 -90.01770 14.25 B AE 18 VE (EL 21) Plaquemines

HWM-LA-PLA-204 29.55910 -89.88480 7.10 A16 (EL 9) N/A AE (EL 11) Plaquemines

HWM-LA-STB-001 29.84669 -89.76403 11.33 A15 (EL 13) AE 16 AE (EL 17) St. Bernard

HWM-LA-STB-004 29.81886 -89.61126 9.40 A15 (EL 14) N/A VE (EL 18) St. Bernard

HWM-LA-STJ-006 30.08688 -90.44575 7.18 AE (EL 9) A 12 AE (EL 9) St. John the Baptist

HWM-LA-STJ-007 30.08590 -90.44424 5.75 AE (EL 9) A 12 AE (EL 9) St. John the Baptist

HWM-LA-STJ-005 30.08213 -90.46706 7.41 AE (EL 8) N/A AE (EL 8) St. John the Baptist

HWM-LA-STJ-210 30.06922 -90.45872 7.71 AE (EL 8) N/A AE (EL 8) St. John the Baptist

HWM-LA-STJ-001 30.08883 -90.50602 5.52 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-002 30.08830 -90.50597 5.08 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-003 30.08327 -90.51130 5.45 Shaded X N/A N/A St. John the Baptist
E-4 MITIGATION ASSESSMENT TEAM REPORT HURRICANE ISAAC IN LOUISIANA

HIGH WATER MARKS Table E‐1: Elevations and Flood Zones for HWM Locations (elevations referenced to NAVD 88) (concluded) HWM ID Latitude Longitude HWM Elevation Effective Zone (BFE, feet) ABFE Zone (BFE, feet) Preliminary Zone (BFE, feet) Parish HWM-LA-STJ-004 30.07714 -90.54957 5.60 Shaded X N/A N/A St. John the Baptist HWM-LA-STJ-200 30.07794 -90.57258 3.63 Shaded X N/A N/A St. John the Baptist HWM-LA-STJ-201 30.07639 -90.57231 4.89 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-202 30.07594 -90.59753 5.41 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-203 30.05756 -90.62594 6.45 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-204 30.05778 -90.63572 6.53 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-205 30.08775 -90.48217 6.00 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-206 30.08469 -90.48700 6.96 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-209 30.08131 -90.52483 5.56 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-211 30.05664 -90.46103 8.39 Shaded X N/A N/A St. John the Baptist

HWM-LA-STJ-207 30.09450 -90.48853 6.44 AE (EL 6) N/A AE (EL 6) St. John the Baptist

HWM-LA-STJ-208 30.09536 -90.49397 6.18 AE (EL 6) N/A AE (EL 6) St. John the Baptist

HWM = high water markBFE = base flood elevationABFE = Advisory Base Flood ElevationN/A = Not applicableNote: Highlighted rows represent locations where the HWM elevation was higher than the effective BFE.