Wind Retrofit Guide for 

Residential Buildings

FEMA P-804 / December 2010

Wind Retrofit Guide for 

Residential Buildings

FEMA P-804 / December 2010

Any opinions, findings, conclusions, or recommendations expressed in this 

publication do not necessarily reflect the views of FEMA. Additionally, neither FEMA 

nor any of its employees makes any warranty, expressed or implied, or assumes any 

legal liability or responsibility for the accuracy, completeness, or usefulness of any 

information, product, or process included in this publication. Users of information 

contained in this publication assume all liability arising from such use.
Authors

Omar Kapur, URS Corporation

Amit Mahadevia, URS Corporation

Jae Park, URS Corporation 

Samantha Passman, URS Corporation

Manny Perotin, PBS&J

Adam Reeder, PBS&J

Laura Seitz, URS Corporation

Adrienne Sheldon, URS Corporation

Scott Tezak, URS Corporation

FEMA Reviewers and Contributors

Katy Brown, FEMA Region IV

Brooke Buchanan, FEMA Region VIII

Franki Coons, FEMA HQ

Robin Danforth, FEMA Region III

John Ingargiola, FEMA HQ

Stephen Juszczyk, FEMA Mississippi Recovery Office

Dennis Kizziah, FEMA Mississippi Recovery Office

Ed Laatsch, FEMA HQ

John LaBrune, FEMA Mississippi Recovery Office

John Plisich, FEMA Region IV

Shabbar Saifee, FEMA HQ

Ed Smith, FEMA HQ

Jody Springer, FEMA HQ

Paul Tertell, FEMA HQ

Joyce Wells, FEMA Region IV

Charles Williams, FEMA Region IV

Brian Willsey, FEMA HQ

Reviewers and Contributors

Miles Anderson, Florida Division of Emergency Management

Brett Bowen, URS Corporation

Bill Coulbourne, Applied Technology Council 

Frank Lavelle, Applied Research Associates

Philip Line, URS Corporation

Dave Low, DK Low and Associates

Lee-Ann Lyons, URS Corporation

Fred Malik, Institute for Business and Home Safety

Shane Parson, URS Corporation 

Susan Patton, URS Corporation

Tim Reinhold, Institute for Business and Home Safety

Tom Reynolds, URS Corporation

Mike Rimoldi, Federal Alliance for Safe Homes

Billy Ruppert, URS Corporation 

Randy Schackleford, Simpson Strong-Tie

Amy Siegel, URS Corporation

Tom Smith, TLSmith Consulting

Jeff Suhr, URS Corporation

Scott Sundberg, Category X Coastal Consulting

William H. York, Institute for Business and Home Safety

Michael Young, RMS

Acknowledgements

This publication was funded under a HMTAP for Hazard Mitigation Support in Mississippi following Hurricane Katrina, 

FEMA-DR-1604-MS, under HSFEHQ-06-D-0162 (Prime), as Task Order #HSFEHQ-09-J-0012 (Task Order 12).
Wind Retrofit Guide for Residential Buildings i

Table of Contents

CHAPTER 1: Introduction ....................................................................................................................1-1

1.1 Need for Technical Guidance............................................................................................... 1-2

1.2 Wind Retrofit Project Type ................................................................................................... 1-2

1.3 Using This Guide................................................................................................................... 1-3

CHAPTER 2: Identifying the Risks and Desired Level of Protection.................................................2-1

2.1 Wind Hazards in the Hurricane-Prone Region ...................................................................2-1

2.2 Levels of Protection............................................................................................................... 2-3

2.2.1 Wind Hazards and Building Codes.......................................................................... 2-4

2.2.2 Recommended Protection and Best Practices......................................................... 2-5

CHAPTER 3: Evaluating Existing Homes ........................................................................................... 3-1

3.1 Evaluating a Home ................................................................................................................ 3-1

3.1.1 Basic and Intermediate Package Evaluations........................................................... 3-3

3.1.2 Advanced Package Evaluations.................................................................................3-4

3.2 Determining Whether a Home Is a Good Candidate for a Wind Retrofit Project ...........3-5

3.3 Deciding What Level of Protection to Achieve ................................................................... 3-7

Costs.......................................................................................................................................3-8

Benefits ..................................................................................................................................3-8

CHAPTER 4: Technical Design and Construction Methods ............................................................. 4-1

4.1 Basic Mitigation Package ...................................................................................................... 4-2

4.1.1 Option 1 – Improvements with Roof Covering Replacement................................. 4-2

4.1.2 Option 2 – Improvements without Roof Covering Replacement ......................... 4-10

4.1.3 Strengthening Vents and Soffits............................................................................. 4-11

4.1.4 Strengthening Overhangs at Gable End Walls ...................................................... 4-12

4.2 Intermediate Mitigation Package........................................................................................4-14

4.2.1 Protecting Openings................................................................................................4-14

4.2.2 Bracing Gable End Walls Over 4 Feet Tall............................................................. 4-18

4.2.3 Strengthening Connections of Attached Structures ............................................ 4-18

4.3 Advanced Mitigation Package ............................................................................................ 4-21

4.3.1 Developing a Continuous Load Path ..................................................................... 4-21

4.3.2 Protecting Openings............................................................................................... 4-27

4.4 Additional Mitigation Measures......................................................................................... 4-28

4.4.1 Exterior Wall Coverings.......................................................................................... 4-28

4.4.2 Tree Fall ................................................................................................................... 4-29

4.4.3 Exterior Equipment.................................................................................................4-30
ii Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects................................................................................ 5-1

5.1 Wind Retrofit Programs........................................................................................................ 5-1

5.1.1 Federal Emergency Management Agency ................................................................ 5-1

5.1.2 State Programs...........................................................................................................5-6

5.1.3 Federal Alliance for Safe Homes Program ..............................................................5-6

5.1.4 FORTIFIED for Existing HomesTM Program................................................................ 5-7

5.2 Factors to Consider When Implementing Wind Retrofit Projects ..................................... 5-7

5.2.1 Code Compliance Check .......................................................................................... 5-7

5.2.2 Permitting and Inspections ......................................................................................5-8

5.2.3 Construction Challenges ........................................................................................ 5-12

5.3 Addressing Other Hazards ................................................................................................. 5-13

APPENDIX A: FORTIFIED for Existing HomesTM..................................................................................A-1

APPENDIX B: Evaluation Guidance....................................................................................................B-1

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness 

of Retrofit Projects ......................................................................................................C-1

APPENDIX D: References, Resources, and Links.............................................................................. D-1

APPENDIX E: Acronyms and Abbreviations.......................................................................................E-1

List of Figures

Figure 1-1: HMA grant process.......................................................................................................... 1-3

Figure 2-1: Illustration of the hurricane-prone region of the United States.................................. 2-2

Figure 2-2: Roof structure failure on a house (Galveston, TX, 2008) ............................................ 2-3

Figure 2-3: Building built to the 2001 Florida Building Code (FBC) standards with no 

structural damage after Hurricane Charley (North Captiva Island, 2004) ................ 2-4

Figure 3-1: Example of a window product label ...............................................................................3-4

Figure 3-2: Continuous load path for wind uplift of a residential, wood-frame building .............3-5

Figure 4-1: Mitigation Packages for wind retrofit projects............................................................... 4-1

Figure 4-2: FEMA 499 Technical Fact Sheet No. 7.1, Roof Sheathing Installation.............................. 4-3

Figure 4-3: 4-foot end zones on gable and hip roofs........................................................................4-5

Figure 4-4: FEMA 499 Technical Fact Sheet No. 7.2, Roof Underlayment for Asphalt Shingle Roofs...4-6

Figure 4-5: FEMA 499 Technical Fact Sheet No. 5.2, Roof-to-Wall and Deck-to-Wall Flashing...........4-8

Figure 4-6: FEMA 499 Technical Fact Sheet No. 7.3, Asphalt Shingle Roofing for 

High Wind Regions.............................................................................................................4-8

Figure 4-7: FEMA 499 Technical Fact Sheet No. 7.6, Metal Roof Systems in High -Wind Regions...... 4-9

Figure 4-8: FEMA 499 Technical Fact Sheet No. 7.4, Tile Roofing for High Wind Regions ................ 4-9

Figure 4-9: Example of SPF adhesive application to secure roof deck panels.............................. 4-10
Wind Retrofit Guide for Residential Buildings iii

Figure 4-10: FEMA 499 Technical Fact Sheet No. 9.2, Repairs, Remodeling, Additions, and 

Retrofitting—Wind ........................................................................................................... 4-11

Figure 4-11: FEMA 499 Technical Fact Sheet No. 7.5, Minimizing Water Intrusion through 

Roof Vents in High-Wind Regions...................................................................................... 4-11

Figure 4-12: Typical soffit retrofit using wood supports................................................................... 4-12

Figure 4-13: Bracing gable end overhangs........................................................................................ 4-13

Figure 4-14: FEMA 499 Technical Fact Sheets No. 6.1, Window and Door Installation, and 

No. 6.2, Protection of Openings—Shutters and Glazing..................................................... 4-15

Figure 4-15: Conceptual gable end retrofit without overhangs....................................................... 4-19

Figure 4-16: Conceptual gable end retrofit with overhangs............................................................. 4-20

Figure 4-17: Roof structure that was poorly connected to the house (Jefferson Parish, LA) ....... 4-22

Figure 4-18: FEMA 499 Technical Fact Sheets No. 4.1, Load Paths and No. 4.3, Use of 

Connectors and Brackets.................................................................................................... 4-23

Figure 4-19: Load path connections of a roof system....................................................................... 4-24

Figure 4-20: Load path connections of a wall system....................................................................... 4-25

Figure 4-21: Load path connections of a foundation....................................................................... 4-26

Figure 4-22: FEMA 499 Technical Fact Sheets No. 5.3, Siding Installation in High-Wind 

Regions and No. 5.4, Attachment of Brick Veneer in High-Wind Regions........................... 4-29

Figure 4-23: A home damaged by fallen trees during Hurricane Katrina 

(Diamondhead, MS)......................................................................................................4-30

Figure 5-1: HMA grants cycle process showing roles and responsibilities of each stakeholder .... 5-2

Figure 5-2: FEMA 499 Technical Fact Sheet No. 9.2, Repairs, Remodeling, Additions, and 

Retrofitting—Wind .............................................................................................................5-8

Figure C-1: Example wind-damage function for a wood single-family (one-story) building........ C-4

List of Tables

Table 4-1: Fasteners Required for Wood Board Decking Attachment to Framing ......................... 4-3

Table 4-2: Fasteners Required for Structural Wood Panel Sheathing Attachment to Framing .....4-4

Table 5-1: Code Compliance Checks.................................................................................................. 5-9

Table C-1: FEMA BCA Tool Characteristics.......................................................................................C-2

Table C-2: Scenarios Representing Before-Mitigation and After-Mitigation Conditions............... C-3

Table C-3: Likelihood of Cost Effectiveness ...................................................................................... C-5

Table C-4: Hypothetical Mitigation Project Parameters................................................................... C-6

Wind Retrofit Guide for Residential Buildings 1-1

CHAPTER 1

Introduction

E

very year, homes along the coast are subject to high winds that cause extensive damage and 

threaten the safety and security of coastal residents. Much of this wind-related damage can 

be reduced or prevented by improving the performance of the buildings through retrofits 

that strengthen the building’s envelope (the shell of the house, including the doors, roof covering, 

windows, and walls), the adequacy of the home’s load path (the connections of each part of the 

structure, from roof to foundation), and their ability 

to transfer loads without failing.

The purpose of this Guide is to provide guidance 

on how to improve the wind resistance of existing 

residential buildings in Mississippi and across the Gulf 

Coast. Although this Guide was developed to support 

initiatives in the Gulf Coast region, the content of this 

document should serve as guidance on retrofitting 

existing buildings for improved performance 

during high-wind events in all coastal regions; it is 

applicable to one- and two-family dwellings, but not 

to manufactured housing. Although this guidance is 

primarily intended to be applied in the hurricaneprone region of the United States, it may also be 

applied to other regions. The Federal Emergency 

Management Agency (FEMA) has published many 

other guidance documents on coastal construction 

as well. In areas where this Guide does not address 

particular material types, building layouts, and other 

customizable factors of homes, the Coastal Construction 

Manual (FEMA 55, fourth edition to be published in 

2011) should be used as a reference, as discussed in 

later chapters of this Guide. 

There are multiple intended audiences for this Guide. 

Homeowners should be involved in the process of 

the wind retrofit project; they must understand the 

benefits and costs of each potential decision. Using 

this Guide, homeowners should work with their 

contractor, an evaluator, and a design professional 

(if necessary) to determine which package of wind 

retrofit activities is most appropriate for their home. 

This Guide summarizes the technical 

information needed for selecting and 

implementing cost-effective wind 

retrofit projects for residential buildings. 

Implementing the Mitigation Packages in 

this Guide on existing vulnerable homes 

within the hurricane-prone regions of the 

United States will result in their improved 

performance in high-wind events.

This Guide presents mitigation measures in 

packages. A package is a required set of 

retrofit measures that must be implemented 

for a home to provide a consistent level 

of protection. This Guide identifies three 

successive protection packages: Basic, 

Intermediate, and Advanced.

EVALUATOR

When implementing a wind retrofit project, 

homeowners or the local government will 

need to work with an evaluator, who will 

evaluate the existing condition of the home. 

The evaluation will help determine how a 

home can be retrofitted for the Mitigation 

Packages outlined in this Guide.

Evaluators must possess sufficient 

knowledge of the design and construction 

of residential buildings to perform these 

evaluations, but they need not be a 

registered engineer or architect. However, 

the evaluator should have knowledge of and 

familiarity with the wind retrofit Mitigation 

Packages and their intent as described in 

this Guide.
Wind Retrofit Guide for Residential Buildings

CHAPTER 1: Introduction

1-2

State and local governments and entities who have mitigation programs in hurricane-prone regions 

will also benefit from this Guide by using the information to pursue, develop, and deliver technical 

assistance to the public on successful wind retrofit mitigation projects for residential buildings.

1.1 Need for Technical Guidance

Hurricane Katrina damaged or destroyed 234,230 single-family homes (including manufactured 

homes) in Mississippi alone (FEMA, 2006a). Louisiana and Mississippi did not have strong 

residential building codes in their hurricane-prone regions prior to Hurricane Katrina. The impact 

of Hurricane Katrina has illustrated the importance of adopting and enforcing an effective building 

code. However, thousands of existing homes remain vulnerable to the effects of coastal high-wind 

events and are not designed to the same level of wind resistance required by today’s codes and 

standards. 

In response to Hurricane Katrina, the Mississippi Emergency Management Agency’s (MEMA’s) 

Mitigation Section, in coordination with the Mississippi Department of Finance and Administration 

(DFA), has applied for a Hazard Mitigation Grant Program (HMGP) grant under presidentially 

declared disaster number DR-1604 (Hurricane Katrina in Mississippi) to fund wind retrofit projects 

for homeowners in Mississippi. This program will fund up to 75 percent of eligible costs of retrofits 

such as adding roof deck attachments, roof-to-wall connections, and opening protection. 

Local and national FEMA staff have concluded that additional technical guidance is needed to 

facilitate the development of retrofit projects for residential buildings including: engineering-based 

prescriptive construction solutions, implementation guidance, and wind-damage function data to 

support user-identified damage curves for performing the related benefit-cost analysis (BCA). 

1.2 Wind Retrofit Project Type

The purpose of a residential wind retrofit project is to reduce the vulnerability of and damage to homes from wind and wind-driven rain intrusion during a high-wind event such as a hurricane. 

According to recent FEMA Mitigation Assessment Team (MAT) findings, there are three areas of 

the home that are typically vulnerable to failure due to high winds:

4 Roof and wall coverings

4 Openings (e.g., windows, doors)

4 Load path connections

Although nothing can guarantee total and 

absolute property and life protection from high 

winds, many types of wind retrofit projects can 

be effective and cost-beneficial in reducing 

damage from high-wind events.

Despite the significant damage experienced by all types of buildings during high-wind events, grant 

applications for wind retrofit projects have focused more on non-residential or commercial buildings 

and less on residential buildings. FEMA has developed this Guide to encourage wind mitigation of 

existing residential buildings. 

The retrofits in this Guide are intended to be applied 

throughout the hurricane-prone region, though they 

may be applied to any home to reduce the risk to 

wind-related damage. While the solutions described 

in this Guide were designed primarily for wood-frame 

residences, and though construction techniques can 

vary considerably throughout the United States and 

territories, the intent of the retrofits in this Guide may 

be applied to all homes. 
CHAPTER 1: Introduction

Wind Retrofit Guide for Residential Buildings 1-3

Through its Hazard Mitigation Assistance (HMA) grant programs, FEMA administers two grant 

programs that fund wind retrofit projects: the HMGP and the Pre-Disaster Mitigation (PDM) grant 

program. Hazard mitigation is defined as any sustained action taken to reduce or eliminate longterm risk to people and property from natural hazards and their effects. The HMA process cycles 

through five stages starting with mitigation planning and ending with successful execution of a 

project (Figure 1-1). Chapter 5 provides more information on the HMA process and the roles and 

responsibilities of different stakeholders at each stage of the process. 

FIGURE 1-1:

HMA grant process

1.3 Using This Guide

This Guide consists of five chapters and four appendices. Following is a brief description of each 

of these components. It is recommended that users review this Guide in its entirety before 

pursuing the development of a wind retrofit mitigation project.

Chapter 1. Introduction provides an overview of the Guide, summarizing its purpose and 

contents. 

Chapter 2. Identifying the Risks and Desired Level of Protection describes wind hazards, how 

to identify wind risks for a particular site or area, and how the wind hazard is addressed 

through building codes and best practices. 
Wind Retrofit Guide for Residential Buildings

CHAPTER 1: Introduction

1-4

Chapter 3. Evaluating Existing Homes explains how to assess homes to determine their 

vulnerabilities and what type of mitigation measures would be most appropriate and 

feasible.

Chapter 4. Technical Design and Construction Methods provides details and specific measures 

for each of the three Mitigation Package categories: Basic, Intermediate, and Advanced.

Chapter 5. Implementing Mitigation Projects describes how to move a project forward, important 

issues and challenges that should be considered, and details about potential sources of 

assistance. 

Appendix A. FORTIFIED for Existing HomesTM (FEH) summarizes the Institute for Business 

and Home Safety (IBHS) program. This program is also a “package-based” wind retrofit 

program for existing residential buildings that seeks to improve the performance of 

buildings during high-wind events. 

Appendix B. Evaluation Guidance provides guidance on conducting an evaluation of a home that 

is being considered for a wind retrofit project; this appendix supplements the information 

in Chapter 3.

Appendix C. Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit 

Projects contains information that can be used with the FEMA BCA Tool (Version 4.5.5) 

to model the post-mitigation effectiveness of the projects detailed in Chapter 4. A BCA must 

be performed as part of a FEMA mitigation grant application.

Appendix D. Resources, References, and Links provides details on where additional resources 

can be located, including information about FEMA funding programs and building science 

publications. It also includes a list of documents, publications, and other sources used to 

help develop this Guide.

Appendix E. Acronyms and Abbreviations
Wind Retrofit Guide for Residential Buildings 2-1

CHAPTER 2

Identifying the Risks and 

Desired Level of Protection

To better understand the wind-related risk to a house from hurricanes, it is important to know 

how wind hazards are defined. Further, to understand the level of protection provided by a 

house before and after implementing a retrofit project, homeowners should understand or 

try to identify the code to which their house was constructed and the methods and materials used 

during construction. 

This chapter discusses wind hazards in coastal regions and summarizes how and when building 

codes and standards started to address these hazards. Also included is a discussion on the level of 

protection provided by houses, and the level of protection or performance that is reasonable to 

expect after implementing a wind mitigation project. 

2.1 Wind Hazards in the Hurricane-Prone Region

High-wind natural hazards affecting the hurricane-prone region include 

hurricanes, tropical storms, typhoons, 

nor’easters, and tornadoes. The retrofits 

outlined in this Guide are specific to 

protecting existing houses from hurricane 

damage. Although most common in coastal 

areas, the damaging effects of hurricane-force 

winds are not limited to coastal counties. The 

American Society of Civil Engineers (ASCE) 

7-05, Minimum Design Loads for Buildings and Other Structures, defines the hurricane-prone region as 

the U.S. Atlantic Ocean and Gulf of Mexico coasts where the design wind speed is greater 90 miles 

per hour (mph), as well as Hawaii, Puerto Rico, Guam, Virgin Islands, and American Samoa. 

Figure 2-1 shows the hurricane-prone region 

of the United States mainland. The map shows 

the hurricane-prone region as defined in both 

the 2005 and 2010 editions of ASCE 7. ASCE 

7-05 defines the windborne debris region as 

areas within 1 mile of the coastal mean high 

water line where the basic wind speed is equal 

to or greater than 110 mph (and in Hawaii) 

and in areas where the basic wind speed is 

equal to or greater than 120 mph (130 mph 

Unless otherwise stated, all wind speeds used in this 

Guide are ASCE 7-05 3-second gust wind speeds 

and correspond to design requirements set forth in 

that document and the 2006 and 2009 editions of the 

International Residential Code (IRC). Due to changes 

in the development of the ASCE 7-10 wind speed map, 

it is not appropriate to use the ASCE 7-10 wind speed 

map in combination with the provisions of ASCE 7-05 

and the older codes.

THE APPLIED TECHNOLOGY COUNCIL (ATC) 

WIND SPEED WEB SITE

Products that help determine the applicable wind 

speed for a given location can provide a valuable 

service. One such product is ATC’s wind speed Web 

site (www.atcouncil.org/windspeed.html). ATC is a 

nonprofit corporation that develops applications for 

hazard mitigation.
Wind Retrofit Guide for Residential Buildings

CHAPTER 2: Identifying the Risks and Desired Level of Protection

2-2

and 140 mph in ASCE 7-10, respectively). Note that the map is for illustration purposes only and 

should not be used to determine (basic) design wind speed. 

ASCE 7 also defines exposure categories that reflect the terrain roughness for the building site 

(see text box). As the terrain becomes more open, there is more potential for wind damage. 

Conversely, areas that are densely populated or otherwise have a 

lot of potential windborne debris can be prone to other types of 

wind-related damage. In addition to the wind speed and location 

within the hurricane-prone region, the exposure category is also 

an important component in identifying a building’s vulnerability 

to wind-related damage.

Houses in hurricane-prone regions can be damaged by high 

wind pressures and wind-driven rain, as well as windborne debris. 

This last hazard requires special attention in the windborne 

debris region. High winds can produce large amounts of debris 

FIGURE 2-1: 

Illustration of the hurricane-prone region of the United States

EXPOSURE CATEGORIES 

FROM ASCE 7-05

B: Urban, suburban, wooded

C: Open terrain (includes 

shoreline in hurricane-prone 

regions)

D: Flat, unobstructed; exposed 

to wind flowing over open water 

at least 1 mile, but outside of 

the hurricane-prone region
CHAPTER 2: Identifying the Risks and Desired Level of Protection

Wind Retrofit Guide for Residential Buildings 2-3

that may become windborne and perforate the building envelope and openings. Once a building 

is perforated, wind-driven rain can enter the building, causing water damage to the interior and 

contents. A broken window or glass door may also allow wind pressures to increase within the 

house, leading to structural damage. As such, building codes require that new homes constructed 

in windborne debris regions protect glazing (windows and glass doors) against damage and impacts 

from windborne debris. Homeowners should consider adding protection to the openings in their 

existing home to mitigate this risk. The inset of Figure 2-1 illustrates the windborne debris region 

for several Gulf Coast States. Homeowners should consult their local building department for a final 

determination regarding their home’s location within the windborne debris region. Homeowners 

should understand their potential risk based on their location to determine which retrofit package 

is right for their house (see Chapter 3).

2.2 Levels of Protection

Over the past few decades, building codes have progressed toward addressing design and construction practices that will result in buildings that are more resistant to high winds. 

However, much of the existing building stock in hurricane-prone regions was designed and 

constructed to codes and standards that required far less than current codes to mitigate wind 

damage—or constructed to no codes at all. It is important for homeowners to be aware of the limits 

of the building code used to construct their house, the existing level of risk, and how and to what 

extent the risks can be mitigated. 

Properly designing and constructing a building to locally adopted building codes provides the 

minimum level of protection for the wind hazard at a particular site for new construction. However, 

older houses may not be wind resistant when compared to today’s codes and standards, even if 

constructed to adopted building codes at the time they were built. This Guide describes retrofits 

for those older buildings and for newer structures that were not designed to hazard resistant codes. 

Residential buildings can suffer extensive wind damage when wind speeds exceed the design levels 

or when they are improperly designed and constructed. For example, even though Hurricane Ike’s 

wind speeds were below the design wind speeds for much of the impacted area, many residential 

FIGURE 2-2: 

Roof structure failure on a house 

(Galveston, TX, 2008)

(SOURCE: FEMA P-757)
Wind Retrofit Guide for Residential Buildings

CHAPTER 2: Identifying the Risks and Desired Level of Protection

2-4

buildings suffered wind damage, some of which was disproportionate to the reported wind speeds. 

During Hurricane Ike, the house in Figure 2-2 sustained structural damage from wind speeds 

estimated at 93 mph, which was below the design wind speed. 

2.2.1 Wind Hazards and Building Codes

Many States and communities now regulate the construction of buildings by adopting and enforcing 

building codes. Most locally adopted building codes in the United States are based on model 

building codes. Examples of model building codes promulgated by the International Code Council 

(ICC) include:

4 International Building Code (IBC) (ICC, 2009a)

4 International Residential Code for One- and Two-Family Dwellings (IRC) (ICC, 2009b)

4 International Existing Building Code (IEBC) (ICC, 2009c)

The approaches to wind design in these model codes are based on modern wind engineering 

provisions of ASCE 7, as well as acceptable methods for enhancing wind hazard resistance. The 

IRC also incorporates, by reference, industry standards in addition to ASCE 7 that are specifically 

recognized as accepted engineering practice for one- and two-family dwellings in high-wind regions. 

These standards include: 

4 American Forest and Paper Association (AF&PA) Wood Frame Construction Manual for Oneand Two-Family Dwellings ([WFCM], 2001)

4 ICC Standard for Residential Construction in High-Wind Regions (ICC-600, 2008a)

4 American Iron and Steel Institute (AISI) Standard for Cold-Formed Steel Framing—Prescriptive 

Method for One- and Two-Family Dwellings (AISI S230, 2007)

While compliance with codes and standards for new construction is not the subject of this Guide, 

construction methods within those documents may serve as additional guidance for improving 

resistance to high winds. 

FIGURE 2-3: 

Building built to the 2001 Florida 

Building Code (FBC) standards 

with no structural damage after 

Hurricane Charley (North Captiva 

Island, 2004)

(SOURCE: FEMA 488)
CHAPTER 2: Identifying the Risks and Desired Level of Protection

Wind Retrofit Guide for Residential Buildings 2-5

Building codes and standards are typically refined to incorporate lessons learned after natural 

disasters. Buildings like the one shown in Figure 2-3, built using modern wind engineering 

provisions incorporated in codes after Hurricane Andrew, performed better than older buildings 

during the 2004 hurricane season. The lack of a locally adopted code, or use of older codes, will 

likely increase the vulnerability of homes to wind damage.

As hurricanes continued to affect coastlines, more States, including Florida in 2001–2002, began 

adopting and mandating the use of nationally recognized codes and standards. Prior to Hurricane 

Katrina in 2005, Louisiana communities had varying building and residential codes, and in many 

communities, no established building codes at all. This lack of building codes, or use of older 

codes, is often an indicator that the houses in the area were designed and constructed without the 

modern hazard-resistance techniques that have been incorporated into newer building codes. To 

ensure that new buildings would perform better in future hurricanes, Louisiana mandated the use 

of the 2003 IRC and IBC, with State-specific amendments in 2007. This action was consistent with 

the recommendations in FEMA’s 2006 MAT report, FEMA 549, Hurricane Katrina in the Gulf Coast 

(FEMA, 2006a). 

2.2.2 Recommended Protection and Best Practices

Many mitigation or retrofit projects may be implemented to improve the performance of residential 

buildings in coastal regions, especially those buildings built to older codes. Section 2.2.1 discussed 

wind hazards and the building codes and standards that have been 

implemented over the years to help ensure that buildings perform 

adequately in their environment. As our knowledge of wind 

hazards has grown, our understanding of building performance 

has also changed, and so has the level of protection provided by a 

“code-compliant” building. 

To improve the performance of a building in hurricane-prone 

regions, post-disaster investigations of impacted areas are 

conducted by FEMA, the building industry, and the insurance 

industry. Both independently and collaboratively, these groups 

have identified performance issues in older buildings. In general, 

the buildings that performed poorly did not have:

4 Roof and wall coverings capable of resisting high winds

4 Protection for openings (windows, doors, garage doors, soffits, and vents) to resist high 

winds, windborne debris, and wind-driven rain

4 Structural systems providing a continuous path for all loads (gravity, uplift, and lateral) to 

be passed from the building exterior surfaces to the ground through the foundation

This Guide presents Mitigation Packages that, if implemented correctly, will reduce the risks of 

damage to a residential building from a wind event. However, there are several factors to consider in 

the decision-making process to implement wind retrofit measures, such as: 

4 Whether the house is a good candidate for a wind retrofit project 

4 What Mitigation Packages are cost-effective for a house’s desired level of protection 

4 How much risk of wind-related damage is acceptable to the homeowner 

Based on observations 

from previous post-disaster 

investigations FEMA has 

conducted, it is highly unlikely 

that a single retrofit measure 

alone will provide improved 

protection and risk reduction 

from a wind event. This Guide 

presents groups of retrofit 

measures in “packages” for a 

more comprehensive solution 

to risk reduction. The Mitigation 

Packages are presented in 

Chapter 4.
Wind Retrofit Guide for Residential Buildings

CHAPTER 2: Identifying the Risks and Desired Level of Protection

2-6

These factors and others are discussed in further detail in Chapters 3 and 4 of this Guide. It is 

important to understand that although the individual retrofit measures of the Mitigation Packages 

are based on design methods in current building codes and standards, not all of the design elements 

required by modern building codes for wind hazard resistance will be included in the retrofit 

project. Therefore, depending on the Mitigation Package(s) implemented, residual risk will likely 

still exist, even though some of the strengthened elements of the implemented retrofits may meet or 

exceed local building code requirements. More information on residual risk and addressing other 

hazards can be found in Section 5.3.

Implementing mitigation measures to reduce risk is a personal decision for homeowners to 

protect their house and property. Having made the decision to pursue a wind retrofit project, the 

homeowner will also have to decide what level of protection is desired. A homeowner’s decision 

regarding the desired level of protection will likely involve weighing the wind hazard risk with the 

cost of mitigating that risk. The FEMA BCA Tool can be used as a reference point for determining 

whether the mitigation measures being considered are cost-effective. Use of this software is required 

when submitting a grant application to one of FEMA’s HMA 

programs (refer to Chapter 5 and Appendix C). It should not, 

however, be the only factor used to make decisions regarding the 

wind retrofit project. 

Each individual house is unique and exposed to risks that may be 

specific to a particular site or region. For example, implementing 

the Basic Mitigation Package may reduce risk, but may also leave 

too much residual risk; in this case, a homeowner may decide 

the additional cost of implementing the Intermediate Mitigation 

Package is more acceptable. Another cost consideration 

homeowners may face is the need to make improvements to their 

house before the Basic Mitigation Package described in this Guide 

can be implemented. Some houses may be previously damaged 

or may be undergoing improvements (addition or renovation). 

These houses may be candidates for a wind retrofit project, as 

components that are normally difficult to access may already be 

exposed. However, such conditions may also trigger substantial improvement/substantial damage 

(SI/SD) provisions of governing building codes, requiring further work on the house outside the 

scope of the wind retrofit project type. See Section 5.2.1 for more information. 

The wind retrofit Mitigation Packages described in this Guide are meant to improve the wind 

resistance of existing residential buildings. Retrofits described in this Guide should not be construed 

as providing protection comparable to that provided by safe rooms designed and constructed in 

accordance with FEMA 320, Taking Shelter from the Storm: Building a Safe Room for Your Home or Small 

Business (Third Edition, 2008a) and FEMA 361, Design and Construction Guidance for Community 

Safe Rooms (Second Edition, 2008b). Even where Mitigation Packages described in this Guide are 

implemented, evacuating hurricane-prone regions is still the best way to protect against injuries 

or loss of life during a hurricane event. Homeowners should always evacuate when told to do so by 

local or State authorities. If a homeowner’s ultimate goal of implementing a wind retrofit project is 

to protect building occupants from injury or death, FEMA recommends building a safe room. For 

additional information on safe rooms, see FEMA 320 and FEMA 361.

DETERMINING COST 

EFFECTIVENESS

The FEMA BCA Tool 

determines that a project 

is cost-effective when the 

benefit-cost ratio (BCR) is 1 

or above. The software, along 

with resource documents to 

guide users through the BCA 

process, can be downloaded 

from www.bchelpline.com.

Appendix C provides a stepby-step guide on using the 

FEMA BCA Tool with the wind 

retrofit packages presented in 

this Guide.
CHAPTER 2: Identifying the Risks and Desired Level of Protection

Wind Retrofit Guide for Residential Buildings 2-7

SAFE ROOMS: NEAR-ABSOLUTE PROTECTION

The level of occupant protection provided by a safe room is much 

greater than the protection provided by buildings that comply with 

the minimum requirements of most building codes or any level of 

protection detailed in this Guide. Safe rooms offer near-absolute 

protection (a very high probability of being protected from injury 

or death). FEMA 320, Taking Shelter from the Storm: Building 

a Safe Room for Your Home or Small Business (Third Edition, 

2008a), includes prescriptive designs that provide homeowners 

and their builders/contractors with information on how to construct 

a safe room for a house. For solutions not covered by FEMA 320, 

FEMA 361, Design and Construction Guidance for Community Safe 

Rooms (Second Edition, 2008b), contains design criteria for custom 

residential safe rooms.

Construction of a safe room in an existing house can be cost-effective 

when the house undergoes a wind retrofit project, even though 

construction of a safe room during new construction is typically 

more cost-effective. Because safe rooms must have heavy, debrisimpact-resistant walls (constructed of reinforced concrete, reinforced 

masonry, or wood with steel or masonry infill) that are secured to 

the foundation, they are more difficult to construct in an existing 

house. However, during a wind retrofit project for which walls, roofing 

systems, and load path connections are being retrofitted, constructing 

a safe room can be cost-effective. These retrofits are likely to occur 

while the homeowner is attempting to achieve an Advanced Mitigation 

Package designation. Installing a safe room during a retrofit helps 

to economize the design staff, labor, and materials already under 

contract and on site. For example, implementing the Advanced 

Mitigation Package described in Chapter 4 typically requires 

consultation with an engineer. If a homeowner is also considering 

adding a safe room to an existing structure, it would be cost-effective 

to include the safe room in the engineering consultation, whether or 

not the consultation is required by local building codes. 

FEMA continues to advocate for the design and construction of 

residential safe rooms as evidenced by its continuing support of safe 

room initiatives through several grant programs. Since the initiation 

of its safe room program, FEMA has provided support for over 

20,000 residential safe rooms with Federal funds totaling more than 

$75,000,000 (as of FY 2010). A growing number of these safe rooms 

have already saved lives in actual events. There have been no reported 

failures of any safe room constructed to FEMA criteria.

Wind Retrofit Guide for Residential Buildings 3-1

CHAPTER 3

Evaluating Existing Homes

Retrofitting existing buildings has always been a potentially complicated task. Existing 

homes may be custom designed to complex shapes and configurations. Material types and 

construction methods can vary widely. Codes to which buildings were originally designed and 

constructed can be well below modern requirements, and as previously mentioned, may even have 

been constructed in a location that had no adopted code at the time of construction. Therefore, in 

order to execute a successful retrofit on any home, an evaluation of its existing condition should be 

performed to determine: 

4 Age and condition of the home

4 Overall structural integrity of the home

4 Weaknesses in the home’s envelope

4 Weaknesses in the home’s structure

4 Weaknesses in the home’s foundation

4 Whether the home can be retrofitted to effectively improve resistance to wind-related 

damage 

4 How a home can be retrofitted for the different Mitigation Packages and how much each 

would cost

4 The most cost-effective retrofit project for the home

A qualified individual should evaluate the home and provide recommendations to the homeowner 

based on the findings. For the purposes of this Guide, this person will be referred to as an evaluator. 

An acceptable evaluator should possess the level of residential building construction knowledge 

that meets the minimum requirements of a State or local wind mitigation program. Acceptable 

evaluators may include building science professionals such as registered architects and engineers, 

building officials, and evaluators that are certified through State or locally recognized wind retrofit 

programs (such as the IBHS FEH program). 

3.1 Evaluating a Home

The purpose of the evaluation is to determine whether the home is a good candidate for any of the wind retrofit Mitigation Packages. It also serves to identify any repairs that must be performed 

before a wind retrofit project can be undertaken and clarify the applicability of the wind retrofit 

Mitigation Packages from a construction standpoint. The evaluation will also identify whether 
Wind Retrofit Guide for Residential Buildings

CHAPTER 3: Evaluating Existing Homes

3-2

prescriptive retrofits can be performed on the home or a specific engineering solution should be 

developed. The purpose of the evaluation is not to determine if the building meets current code.

Before an evaluation is performed, homeowners should compile any available documentation on 

the design and construction of the home. Where available, the following information should be 

provided to the evaluator:

4 Documentation regarding the foundation of the building

4 Documentation regarding the existing roof covering

9 If the roof covering has not been replaced, the purchase contract, building permit, or 

property tax record showing the age of the property

9 If at least a portion of the roof covering has been replaced, a copy of the work order for 

the roofing or a receipt for its installation

4 If a secondary water barrier (SWB) has been installed on the roof, a receipt for its 

installation 

4 If a termite inspection has been conducted within 12 months on the home, the termite 

inspection report or bond issued

4 Documentation regarding windows, entry doors, garage doors, and impact-rated products 

(such as shutters systems)

9 Owner’s manuals

9 Original labels

9 Any form of verification that they are impact-rated, if applicable

4 If insulating foam has been applied to the underside of the roof deck, information on the 

foam product used

4 Any additional documentation regarding the condition of the building or prior work done 

to the building, such as design plans or inspection reports

4 Photographic documentation of the building and any improvements (such as previous work 

performed, renovations, or deck construction)

Having all available information prepared for the evaluator when he/she arrives can greatly 

increase the accuracy and timeliness of the evaluation. When the evaluation begins, homeowners 

(and other parties involved in the decision-making process) should have an idea of which Mitigation 

Package they will implement based on available budget, perceived condition and age of the home, 

cost-effectiveness of retrofits, Federal assistance, and other savings. The evaluator should be able to 

provide preliminary advice on which Mitigation Package to consider; this can be discussed before 

the evaluation begins. The selected Mitigation Package will affect how invasive the evaluation will 

be. The evaluator should conduct a full walkthrough of the home, assessing the condition of the 

areas that will be retrofitted as well as the overall condition of the home. For example, if there are 

significantly damaged components within the roof system, the evaluator should provide a detailed 

description of the damage in the evaluation report, including a description of any needed repairs 

required before the home is a suitable wind retrofit project candidate and whether those repairs will 

require a professional engineer’s consultation.
CHAPTER 3: Evaluating Existing Homes

Wind Retrofit Guide for Residential Buildings 3-3

The following sections discuss the evaluation process for the building envelope and structure. 

Additional guidance on evaluating buildings before starting a wind retrofit project, including what 

should be documented in the building evaluation, is presented in Appendix B of this Guide. 

3.1.1 Basic and Intermediate Package Evaluations

For projects implementing the Basic or Intermediate Package, the evaluation should focus mainly 

on the building envelope. The following building elements should be inspected and their material 

type and existing condition documented during the evaluation:

4 Roof system (the roof covering and roof structural system beneath)

4 Attic ventilation systems (soffits, ridge, off-ridge, and gable end vents) 

4 Wall systems (wall framing and coverings, including gable end walls)

4 Openings (windows, skylights, entry doors, and garage doors)

4 Attached structures (porches, awnings, and carports)

Evaluation of these building elements for the Basic and Intermediate Packages will usually involve 

only minimal disturbance to the building during the evaluation. 

The evaluation of the roof covering will determine whether the 

roof covering needs to be replaced as part of the wind retrofit 

project. A home with a roof covering assessed as having 5 or more 

years of remaining useful life is a candidate for retrofit options 

that do not require roof covering replacement. To determine the 

remaining useful life of the roof covering, the evaluator should 

use any available documentation provided by the homeowner as 

well as visual observations of the roof covering condition. When 

evaluating the roof structure, the attic will need to be accessed in 

most cases. The evaluator should use a handheld metal-detecting scanner to assess the existing roof 

deck attachments without removing the roof covering or using other invasive measures. 

The evaluator should also verify whether the home already has completed any of the retrofit 

projects including in the Mitigation Packages. For example, a home being evaluated may already 

have window protection that meets the opening protection requirements of the Intermediate or 

Advanced Mitigation Package. The evaluator should verify that the opening protection (e.g., shutters 

over openings or pressure- and impact-rated windows and doors) provides the level of protection 

for the respective Mitigation Package as defined in Chapter 4 of this Guide, and is in a satisfactory 

condition (e.g., shutters are functional and are properly anchored to the building). In the case of 

opening protection, this is typically verified through labeling or documentation the homeowner 

may have for the product(s), as shown in Figure 3-1. Identifying whether the house already has any 

completed retrofit projects will increase the cost-effectiveness of the overall mitigation effort. 

The evaluation will include an 

assessment of the existing 

roof covering. While the 

homeowner may already know 

whether he or she wants to 

replace the roof covering, the 

evaluation will identify whether 

the roof covering is in need of 

replacement.
Wind Retrofit Guide for Residential Buildings

CHAPTER 3: Evaluating Existing Homes

3-4

3.1.2 Advanced Package Evaluations

Providing a continuous load path is a part of the Advanced Mitigation Package, but not part of the 

Basic or Intermediate Mitigation Packages. For the Advanced Mitigation Package, the structural 

connections that create a continuous load path from the roof to the foundation need to be evaluated. 

The evaluator will need to identify any locations where the 

continuous load path is broken. Some controlled, destructive 

actions may be necessary to access structural connections. 

The level of invasiveness of an assessment for the Advanced 

Mitigation Package will depend on the construction type and 

structural configuration of the home. 

A continuous load path is an important part of a building’s 

ability to resist wind-related damage. The continuous load path 

ensures that loads applied to any part of the building can be 

transferred through the building from the point of application 

(such as the roof or exterior walls) through the structure of 

the building and to the foundation (see Figure 3-2). A home 

for which the Advanced Mitigation Package is being sought does 

not have to have an existing continuous load path before the wind retrofit project is performed. 

However, having fewer adequate structural connections capable of transferring design wind loads 

usually correlates to higher costs when retrofitting the home to the Advanced Mitigation Package.

FIGURE 3-1:

Example of a window product label

Regardless of which Mitigation 

Package is chosen, the 

evaluation should cover the 

entire building envelope and look 

for conditions that would limit 

the effectiveness of the wind 

retrofit project. For example, if 

the wall covering is deteriorated, 

damaged, or not sufficiently 

fastened to the building, 

performing a wind retrofit would 

not provide the intended level of 

protection.
CHAPTER 3: Evaluating Existing Homes

Wind Retrofit Guide for Residential Buildings 3-5

3.2 Determining Whether a Home Is a Good Candidate for a 

Wind Retrofit Project

Once the evaluation has been completed, the evaluator and homeowner should discuss the findings of the evaluation. The evaluation process highlights any deficiencies found in the home 

that should be repaired to ensure that the wind retrofit project can be effectively implemented. 

Further, the evaluation should determine whether any prescriptive solutions provided in this Guide 

can be used for the project. If the evaluation finds that no prescriptive solutions apply, a design 

professional should be consulted to develop an engineered solution in place of the prescriptive 

solution. Some existing conditions may prevent the use of prescriptive solutions. 

FIGURE 3-2:

Continuous load path for wind uplift of a residential, wood-frame building
Wind Retrofit Guide for Residential Buildings

CHAPTER 3: Evaluating Existing Homes

3-6

The following conditions, if found to exist in the home being evaluated, would preclude the home 

from prescriptive criteria in this Guide:

4 Roof framing with:

9 Spacing greater than 24 inches on-center (o.c.)

9 Members less than nominal 2 inches 

4 Roof slope less than 2/12

4 Roof deck panels less than nominal 7/16-inch thickness (for wood structural panels)

4 Gable end walls with:

9 Structural panels less than nominal 7/16-inch thickness (or no structural panels)

9 Heights greater than 16 feet

4 Rooftop equipment that adds significant dead load to the roof

Although any home can be mitigated, it may be in such poor condition, may have been damaged, or 

may have an existing condition that must be addressed for any of the proposed Mitigation Packages 

to be effective. In these instances, additional work may be needed before, or during, the wind retrofit 

project. This does not mean that such a home cannot undergo wind retrofits in accordance with this 

Guide, but additional effort would likely need to be expended before the home can be considered a 

good candidate for one of the Mitigation Packages presented in this Guide. 

The outcome of the evaluation should be a report describing the evaluator’s findings. The report 

should include a description of the existing condition of the building and a recommendation of 

one or more of the Mitigation Packages. If repairs are needed before the wind retrofit project can 

proceed, a general assessment of the work required should be 

provided. Some conditions, if found to exist in the home, can 

require extensive and invasive work and have very high associated 

costs. Appendix B contains further guidance on such situations. 

In contrast, some homes may already incorporate some of the 

elements of the Mitigation Packages even before the retrofit 

process has begun. In this situation, the evaluator should verify 

that the existing components of the building are in accordance 

with the retrofits defined for the selected Mitigation Package. 

It should not be assumed that an evaluator will provide a cost 

estimate, but doing so in coordination with the evaluation 

report facilitates the decision-making process for the homeowner. The evaluation report should 

be detailed enough for an individual with an appropriate level of building science knowledge to 

use it to prepare a basic cost estimate. The cost estimate should be detailed enough to provide the 

homeowner and other decision-making parties with enough costing information to make a decision 

in most cases, but for a more complete estimate, it may be necessary to obtain cost estimates from 

building contractors. Based on the findings of the evaluation process, the report should result in 

one of three determinations:

The evaluation for a wind 

retrofit project may identify 

existing conditions that need 

to be remedied. Performing 

repairs while undergoing a wind 

retrofit project may be costeffective. Chapter 5 provides 

further information on repair/

improvement situations, as well 

as guidance on Federal grant 

funding.
CHAPTER 3: Evaluating Existing Homes

Wind Retrofit Guide for Residential Buildings 3-7

1. The prescriptive solutions in this Guide may be used for the retrofit projects. The report 

should identify which projects of the selected Mitigation Package can be implemented using 

prescriptive solutions. 

2. Some of the construction elements of the retrofit projects for the Mitigation Package are 

already present in the home. The report should identify which portions of the home already 

accomplish which items of the selected Mitigation Package, and how the remainder of the 

items can be addressed.

3. The prescriptive solutions in this Guide cannot be used because there are existing building 

conditions that differ from those assumed for this Guide; therefore, at least some portion 

of the wind retrofit project cannot be implemented as presented in this Guide without 

additional effort. A registered design professional should develop a solution for retrofits to 

any building elements for which prescriptive solutions cannot be used. 

Homes that fall under one of the first two determinations are typically the most cost-effective 

candidates, as less site-specific design work is needed. The third determination typically occurs 

when a home has a condition for which the prescriptive solutions in this Guide cannot be applied. 

3.3 Deciding What Level of Protection to Achieve

Buildings are not constructed to resist all damage from hazard events. Homeowners must decide what level of risk is acceptable to them. The cost of the wind retrofit project undertaken must 

be weighed against the potential of losses due to wind-related damages and higher insurance 

premiums. Doing no work on an existing building that is not well protected from wind-related 

damages represents high risk and high insurance premiums (but no associated project costs), while 

doing extensive work to retrofit a home as much as possible from wind-related damages represents 

a resulting lower risk and lower insurance premiums (but higher associated retrofitting costs). The 

mitigation presented in this Guide provides intermediate levels of protection and associated cost. It 

is important to remember that, whether a home is constructed beyond the minimum requirements 

of building codes or is being retrofitted to improve its hazard resistance, the homeowner must 

decide what level of risk from high-wind events is acceptable.

Once an evaluation has been performed, the homeowner—in consultation with the evaluator—

should make a final decision on the desired level of protection to achieve by the retrofits. Each level 

of the three Mitigation Packages described in this Guide—Basic, Intermediate, and Advanced—

provides increasing resistance to wind-related damage; each level of protection can only be achieved 

if the retrofit projects included in the lower levels have been implemented. For instance, the level of 

protection provided by the Advanced Mitigation Package can only be met if the projects included in 

both Basic and Intermediate Mitigation Packages have been implemented.

Different buildings will be better suited to different levels of retrofitting. Newer buildings that 

are built to more recent codes and standards may be easier to retrofit to the Advanced Mitigation 

Package level of protection. As discussed in Section 3.1, some buildings may even already meet one 

or more of the levels of mitigation described in this Guide. Further, a home may meet some of 

the criteria of one or more of the Mitigation Packages, and implementing the remaining retrofit 

projects may be a cost-effective solution. On the other hand, retrofitting an older building to provide 

a continuous load path, as required when applying the Advanced Mitigation Package, may not be 

cost effective. 
Wind Retrofit Guide for Residential Buildings

CHAPTER 3: Evaluating Existing Homes

3-8

When considering whether to undertake a retrofit project, homeowners should consider all of the 

benefits and costs of the project. The benefits and costs associated with implementing a wind retrofit 

project should be effectively conveyed by the evaluator and well understood by the homeowner 

before a decision is made. Some factors to consider when understanding the costs and benefits 

include the following:

Costs

The total cost for the wind retrofit project. The cost of the project is often the primary factor 

when determining whether to undertake a wind retrofit project and which Mitigation 

Package to implement. The project cost will be affected by several factors, one of which is 

whether the prescriptive solutions of this Guide are applicable for the project. If prescriptive 

solutions cannot be used for the project, then the services of a design professional will need 

to be obtained to develop specific solutions. This may result in higher costs for the project. 

Other factors that affect the project cost are the level of protection chosen (i.e., which 

Mitigation Package will be implemented) and the location of the home (which can affect 

opening protection and design wind speed requirements). 

Compliance with codes and local building departments. Modern building codes contain 

provisions for existing buildings that, when triggered by proposed work on the home, may 

require additional work. Similarly, requirements of local building departments can vary, 

and in some circumstances can place additional requirements on the wind retrofit project 

process. The evaluator should have a good understanding of the applicable building code 

provisions and local permitting and inspection requirements, because these are often 

specific to the community in which the project is being performed. Section 5.2 further 

discusses these issues.

Effects of construction. When considering a wind retrofit project, homeowners should consider 

that they may be displaced for a short time. While the displacement may not last long, there 

are costs and other obstacles associated with being displaced that the homeowner should 

take into account, even if it is only for a few days.

Benefits

Damage resistance. The reduction in anticipated damages for retrofitted houses is a quantifiable 

benefit to society and the individual. Homes that survive high-wind events achieve the 

benefits of avoided building damages, reduced damage to building contents, and reduced 

or no displacement of the occupants. When a BCA is performed for a home undergoing 

a wind retrofit project, these benefits are taken into account to determine the cost 

effectiveness of the project. 

Wind hazard insurance plans and premiums. Homes in areas prone to high-wind events generally 

have homeowners’ insurance policies that include coverage for wind damage. For these 

homes, risk-based premiums should account for the higher risk the home faces due to its 

location, as well as the increased likelihood and greater severity of losses after frequent 

high-wind events. Many insurance companies encourage their policyholders to retrofit 

their homes to resist wind-related damage, and some companies have established discount 

programs to reduce premiums, or other types of financial incentives, to reflect the risk 

reduction for homes that have been properly retrofitted. Some State insurance departments 
CHAPTER 3: Evaluating Existing Homes

Wind Retrofit Guide for Residential Buildings 3-9

also have put in place insurance discount programs for properly retrofitted homes. The 

IBHS FEH program has been designed with the support of IBHS member insurance 

companies, although each individual company makes its own decisions about how it is 

implemented. 

Federal assistance through HMA grant programs. As described in Chapter 5, homeowners can 

obtain Federal funding assistance for hazard mitigation projects. Through FEMA’s HMA 

grant programs, applications for an individual home or groups of homes undergoing 

wind retrofit projects can be submitted for approval. If applications are approved, Federal 

funding is provided for 75 percent of the total project cost, significantly reducing the 

homeowner’s expenses for the project. The remaining 25 percent of eligible project costs 

can be paid for directly, or covered by donated labor, time, and materials. Consult FEMA’s 

HMA Unified Guidance for more details on cost sharing. More information on Federal 

assistance through HMA programs can be found in Chapter 5.

Homeowners should consider both qualitative and quantitative benefits and costs when deciding 

on a wind retrofit project. To apply for Federal assistance through HMA programs (as described 

in Chapter 5), an analysis or comparison of the benefits to society compared to the cost of the 

project must be conducted. Benefits such as reduced insurance premiums are not considered in 

the equation because they are an individual benefit. To assist in the process of calculating the 

quantitative benefits and costs, the FEMA BCA Tool was created to provide a consistent approach 

for this determination (refer to Appendix C for additional information on using the FEMA BCA 

Tool). Communities are encouraged to use the software, regardless of whether they will apply for 

Federal funding or not. The software will calculate benefits gained by performing the project, such 

as avoided damage to the home, avoided displacement costs, and avoided loss of building contents. 

The evaluation report discussed in Section 3.2 should identify all of the necessary input data needed 

for using the FEMA BCA Tool. Appendix C provides a step-by-step guide to using the FEMA BCA 

Tool to evaluate the cost effectiveness of a wind retrofit project.

Wind Retrofit Guide for Residential Buildings 4-1

CHAPTER 4

Technical Design and 

Construction Methods

The wind retrofit projects described in this Guide are grouped into three possible Mitigation 

Package solutions: the Basic Mitigation Package (Section 4.1), the Intermediate Mitigation 

Package (Section 4.2), and the Advanced Mitigation Package (Section 4.3). Additional 

mitigation measures not included in the Mitigation Packages are discussed in Section 4.4. Each 

Mitigation Package consists of several wind 

retrofit mitigation measures to reduce future 

losses. The Packages should be implemented 

cumulatively, beginning with the Basic 

Mitigation Package. This means that for a 

home to successfully meet the criteria of the 

Advanced Mitigation Package, it must also 

meet the criteria of the Basic and Intermediate 

Mitigation Packages. Figure 4-1 illustrates the 

retrofits for each Package.

The wind mitigation retrofits for each 

Package, if implemented correctly, will 

improve the performance of residential 

buildings when subjected to high winds. 

Although the information in this chapter 

will be helpful to homeowners, it is primarily 

intended for evaluators, contractors, and 

design professionals. The retrofits described 

for each Mitigation Package and throughout 

this chapter are not necessarily listed in the 

order in which they should be performed. The 

order in which retrofits should be performed 

depends on the configuration of the home 

and should be determined once the desired 

Mitigation Package is chosen. For example, 

a home that seeks the Advanced Mitigation 

Package should consider retrofitting the roofto-wall connections when retrofitting the 

soffits (part of the Basic Mitigation Package). 

Therefore, the reader is encouraged to read 

this entire chapter and consider the most costeffective way to implement the wind retrofit 

project before starting construction. 

FIGURE 4-1: 

Mitigation Packages for wind retrofit projects
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-2

4.1 Basic Mitigation Package

The Basic Mitigation Package is the initial, most basic package for a residential wind retrofit 

project. It focuses on securing the roof system and improving the water intrusion resistance of 

the existing home.

The Basic Mitigation Package involves several steps: 

1. Improving the roof system through one 

of two options:

a) Option 1 – Improve roof with roof 

covering replacement

b) Option 2 – Improve roof without 

roof covering replacement

2. Strengthening vents and soffits

3. Strengthening overhangs at gable end 

walls (if gable end walls exist on the 

home)

4. Protecting openings (if located within 

the windborne debris region)

One of the first decisions to make when 

implementing the Basic Mitigation Package 

is whether to use Option 1 or Option 2. The 

evaluation process will identify whether the 

roof covering needs to be replaced (see Section 

3.1.1 for more information). 

If the home is located in a windborne debris region, the opening protection measures of the 

Intermediate Mitigation Package (see Section 4.2.1) should be performed for the Basic Mitigation 

Package in addition to the other retrofits. 

4.1.1 Option 1 – Improvements with Roof Covering Replacement

Option 1 of the Basic Mitigation Package involves removing the existing roof covering, securing 

the roof deck by adding roof deck-to-framing fasteners, installing an underlayment for protection 

against water infiltration, and installing a new roof covering. Option 1 is preferred over Option 2 

because replacing the roof covering ensures that the roof deck connections to the framing below 

will be checked and an adequate underlayment will be installed. It should also be noted that homes 

retrofitted to Option 1 will likely receive a greater reduction in insurance premiums than homes 

retrofitted to Option 2. 

4.1.1.1 Securing the Roof Deck and Replacing the Roof Covering

Strengthening the connections from the roof decking (sheathing) to the roof framing members is 

a cost-effective and beneficial retrofit to implement when the roof covering is being replaced. The 

evaluation process should identify any areas of the roof deck and roof framing members that are 

BASIC MITIGATION PACKAGE RETROFITS:

Option 1 – Improvements with Roof Covering 

Replacement

•	 Securing the roof deck and replacing the roof

covering

•	 Installing and improving secondary underlayments

•	 Improving roof coverings

Option 2 – Improvements without Roof Covering 

Replacement

•	 Securing roof deck attachment/providing

secondary water barrier using foam adhesive

Additional Required Retrofits

•	 Strengthening vents and soffits

•	 Strengthening overhangs at gable end walls

•	 Window and entry door protection from windborne

debris, garage door protection from wind 

pressure, and garage door glazing protection from 

windborne debris (if located within the windborne 

debris region)
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-3

damaged or deteriorated (refer to Chapter 3 and Appendix B). 

Any damaged members should be repaired before the roof deck 

is secured with additional fasteners. Existing fastening of the roof 

deck to framing members should be augmented as required to 

meet criteria shown in Table 4-1 for wood board decking and 

Table 4-2 for structural wood panel sheathing. Nails that have full 

round head configurations should be used (8d ring-shank [0.113-

in x 2-3/8-in] for structural wood panel sheathing and 8d common smooth-shank [0.131-in x 2-1/2-

in] for wood board decking); clipped head nails should not be used. For structural wood panels, 

different fastener schedules are provided in Table 4-2 for inside the 4-foot roof edge zones and 

outside of these zones. Figure 4-3 illustrates the 4-foot edge zones for hip and gable roofs. When 

using Table 4-2, note that there are several assumptions (listed as end notes to the table) that limit 

the use of this table. If project conditions exceed the assumptions stated in the table endnotes, a 

different prescriptive solution or a designed solution should be used instead. Technical Fact Sheet 

No. 7.1 (see Figure 4-2) of FEMA 499, Home Builder’s Guide to Coastal Construction Technical Fact Sheet 

Series (FEMA, 2010a), provides additional guidance on proper roof sheathing attachment.

TABLE 4-1: Fasteners Required for Wood Board Decking Attachment to Framing

Nominal Board 

Thickness 

(inch)

Nominal 

Board Width 

(inch)

Minimum 

Number of 

Nails

Nail Minimum 

Diameter (inch)

Nail Minimum 

Penetration into 

Framing (inch)

Maximum Framing 

Member Spacing 

(inch)

Up to 1 Less than 8 2 0.131 (8d common) 1-5/8 24

More than 8 3 0.131 (8d common) 1-5/8 24

1 to 2 Less than 8 2 0.162 (16d common) 1-5/8 24

More than 8 3 0.162 (16d common) 1-5/8 24

Note: Dimensions of common 

nails used in this guide are 

specified in American Society 

for Testing and Materials 

(ASTM) F1667.

FIGURE 4-2: 

FEMA 499 Technical Fact 

Sheet No. 7.1, Roof Sheathing 

Installation
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-4

TABLE 4-2: Fasteners Required for Structural Wood Panel Sheathing Attachment to Framing

ASCE 7-05 

Design 

Wind 

Speed 

(mph)

ASCE 7-10 

Design 

Wind 

Speed 

(mph)

Existing 

Fasteners

Existing 

Fastener 

Schedule

Required Additional 

Fastening Within 4-Foot 

Zone: 8d Ring Shank Nails 

(0.113-in x 2-3/8-in, 

Full Round Head)

Required Additional 

Fastening Outside 

4-Foot Zone: 8d Ring 

Shank Nails 

(0.113-in x 2-3/8-in, 

Full Round Head)

≤120 ≤155

Staples or 6d 

common nails 

(0.113-in x 

2-in)

Any 6-inch on center (o.c.) 

spacing between added 

fasteners along panel edges 

and intermediate framing

6-inch o.c. spacing 

between added fasteners 

along panel edges and 

intermediate framing

8d common 

smooth shank 

nails (0.131-in 

x 2-1/2-in)

≤ 6 inches 

o.c. along 

panel 

edges and 

intermediate 

framing

No additional fasteners 

required along panel edges; 

6-inch o.c. spacing between 

additional fasteners along 

intermediate framing

No additional fasteners 

required

8d common 

smooth shank 

nails (0.131-in 

x 2-1/2-in)

> 6 inches 

o.c.

6-inch o.c. spacing 

between existing and 

added fasteners along 

panel edges; 6-inch o.c. 

spacing between additional 

fasteners along intermediate 

framing 

6-inch o.c. spacing 

between existing and 

additional fasteners 

along panel edges and 

intermediate framing

8d ring shank 

nails (0.113-in 

x 2-3/8-in)

12 inches 

o.c. or less

6-inch o.c. spacing between 

existing and additional 

fasteners along panel edges 

and intermediate framing

6-inch o.c. spacing 

between existing and 

additional fasteners 

along panel edges and 

intermediate framing

>120 and 

≤150

>155 and 

≤194

Staples or 6d 

common nails 

(0.113-in x 

2-in)

Any 4-inch o.c. spacing between 

added fasteners along panel 

edges and intermediate 

framing

6-inch o.c. spacing 

between added fasteners 

along panel edges and 

intermediate framing

8d common 

smooth shank 

nails (0.131-in 

x 2-1/2-in)

< 6 inches 

o.c.

4-inch o.c. spacing between 

existing and added 

fasteners along panel 

edges; 6-inch o.c. between 

additional fasteners along 

intermediate framing

No additional fasteners 

required along panel 

edges; 6-inch o.c. spacing 

between added fasteners 

along intermediate 

framing

8d common 

smooth shank 

nails (0.131-in 

x 2-1/2-in)

≥ 6 inches 

o.c. 

4-inch o.c. spacing between 

existing and added 

fasteners along panel edges 

and intermediate framing

6-inch o.c. spacing 

between existing and 

added fasteners along 

panel edges; 6-inch 

o.c. spacing between 

added fasteners along 

intermediate framing

8d ring shank 

nails (0.113-in 

x 2-3/8-in)

≤ 12 inches 

o.c. 

4-inch o.c. spacing between 

existing and added 

fasteners along panel edges 

and intermediate framing

6-inch o.c. spacing 

between existing 

and added fasteners 

along panel edges and 

intermediate framing

Notes:

Minimum nominal 7/16 in. thickness wood structural panel sheathing.

Wind Exposure Category: Exposure C.

Mean roof height not to exceed 30 feet.

Roof framing specific gravity, G, not less than 0.55 (southern pine).

See Figure 4-3 for identification of 4-foot zone on roof.
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-5

FIGURE 4-3: 

4-foot end zones on gable 

and hip roofs

4.1.1.2 Installing Secondary Water Barriers

Under Option 1, a SWB should be installed after the roof deck connection to framing members has 

been sufficiently improved. Before installing the SWB, the roof deck should be broom-cleaned to 

ensure a smooth surface for the application of the SWB. If properly installed, a SWB provides an 

additional layer of water resistance to the roof system. SWBs for shingle, metal, clay, and tile roof 

coverings are discussed below. For other roof covering types, refer to FEMA 55. 

Secondary Water Barriers for Roofs with Shingle or Metal Roof Coverings

This section provides guidance for installing SWBs over structural wood panel sheathing. The SWB 

should be applied after the roof deck has been adequately strengthened and before a new roof 

covering is installed. FEMA 499 Technical Fact Sheet No. 7.2 (see Figure 4-4) provides guidance 

on the installation process that should be followed when installing SWBs beneath asphalt shingle 

roof coverings. Although not specifically addressed, Technical Fact Sheet No. 7.2 can also provide 

guidance on installing SWBs over wood board decking.
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-6

One of the following underlayment alternatives for roofs 

with shingle or metal coverings should be selected (note that 

Alternative 3 is only applicable in areas with a design wind 

speed less than or equal to 110 mph). 

Shingle or Metal Roof Alternative 1

1. The entire roof deck should be covered with a full 

layer of self-adhering, modified bitumen membrane 

meeting the criteria described in ASTM D1970. 

2. To prevent the roof covering from bonding with 

the membrane (which can lead to damage of the 

sheathing when the roof covering is replaced later), 

the membrane should be covered with a bond break 

underlayment meeting ASTM D226 Type I (#15). 

3. The underlayment should be fastened to the roof to 

sufficiently hold it in place until installment of the 

shingles can affix the underlayment to the roof deck.

Shingle or Metal Roof Alternative 2

1. A self-adhering modified bitumen flashing tape at 

least 4 inches wide should be applied directly to the roof deck along the horizontal and 

vertical joints in the roof sheathing. Do not nail or staple the tape to the roof sheathing. 

Refer to manufacturer’s recommendations for installation instructions.

2. Two layers of an underlayment meeting ASTM D226 Type II (#30) should be installed 

over the self-adhering tape. The underlayment should be attached using annular ring 

or deformed shank roofing fasteners with a minimum of 1-inch-diameter caps at 6-inch 

o.c. spacing along all laps and at 12 inches o.c. in the field (or a more stringent fastener 

schedule if required by the manufacturer for high-wind installations). Horizontal laps 

should be a minimum of 2 inches, and end laps should be a minimum of 6 inches. Nails 

with plastic or metal caps should be used where the design wind speed is less than 140 mph. 

For areas where the design wind speed is greater than or equal to 140 mph, metal caps 

should be used rather than plastic caps. 

3. A self-adhering polymer modified bitumen 

membrane complying with ASTM D1970 should be 

installed over this underlayment for areas where 

the design wind speed is equal to or greater than 

120 mph. 

Shingle or Metal Roof Alternative 3 (for design wind speeds 

of 110 mph or less)

1. A self-adhering modified bitumen flashing tape at 

least 4 inches wide should be applied directly to the 

roof deck along horizontal and vertical joints. 

Note: When applying a selfadhering membrane directly to 

oriented strand board (OSB), the 

adhesiveness of the membrane 

may be reduced depending on 

surface texture, amount of wax on 

the sheathing panel, and job site 

conditions. In such cases, a primer 

should be applied to the OSB panels 

to improve adhesion between 

membrane and sheathing.

FIGURE 4-4: 

FEMA 499 Technical Fact Sheet 

No. 7.2, Roof Underlayment for 

Asphalt Shingle Roofs
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-7

2. A single layer of ASTM D226 Type I (#15) or ASTM D4869 Type II felt should be installed 

over the self-adhering tape. The underlayment should be held in place using tacks before 

shingles are applied.

Secondary Underlayments for Concrete and Clay Tile Roofs

For concrete and clay tile roofs, one of the following underlayment alternatives should be followed.

Tile Roof Alternative 1

1. The entire roof deck should be covered with a full layer of self-adhering polymer modified 

bitumen membrane meeting ASTM D1970. Note that some local building departments, 

such as Miami-Dade and Broward Counties in Florida, prohibit the use of this system. The 

local building department should be consulted before implementing this alternative.

Tile Roof Alternative 2

1. Self-adhering modified bitumen flashing tape at least 4 inches wide should be applied 

directly to the roof deck along horizontal and vertical joints in the roof sheathing. Do not 

nail or staple the tape to the roof sheathing. Refer to the underlayment manufacturer’s 

recommendations for installation instructions.

2. An underlayment meeting ASTM D226 Type II (#30) should be installed over the selfadhering tape. The underlayment should be attached using annular ring or deformed 

shank roofing fasteners with a minimum of 1-inch-diameter caps at 6-inch o.c. spacing 

along all laps and at 12 inches o.c. in the field (or a more stringent fastener schedule if 

required by the manufacturer for high-wind installations). Horizontal laps should be a 

minimum of 2 inches, and end laps should be a minimum of 6 inches. Nails with plastic 

or metal caps should be used only where the design wind speed is less than 140 mph. Only 

metal caps should be used for areas where the design wind speed is greater than or equal to 

140 mph.

3. A self-adhering polymer modified bitumen membrane complying with ASTM D1970 should 

be installed over this underlayment. 

Tile Roof Alternative 3

1. A self-adhering modified bitumen flashing tape at least 4 inches wide should be applied 

directly to the roof deck along horizontal and vertical joints in the roof sheathing. 

2. An underlayment meeting ASTM D226 Type II (#30) should be installed over the selfadhering tape. The underlayment should be attached using annular ring or deformed 

shank roofing fasteners with a minimum of 1-inch-diameter caps at 6-inch o.c. spacing 

along all laps and at 12 inches o.c. in the field (or a more stringent fastener schedule if 

required by the manufacturer for high-wind installations). Horizontal laps should be a 

minimum of 2 inches and end laps should be a minimum of 6 inches. Nails with plastic or 

metal caps should be used only where the design wind speed is less than 140 mph. Only 

metal caps should be used in areas where the design wind speed is greater than or equal to 

140 mph.
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-8

3. The underlayment should be hot mopped using hot 

asphalt, with a #90 mineral surface cap sheet applied 

over the hot asphalt. 

Drip Edge and Flashing 

When replacing roof coverings, a drip edge should be 

installed at eaves and gables. Guidance can be found in 

FEMA 499 Technical Fact Sheet No. 5.2 (see Figure 4-5) and 

in FEMA 55.

4.1.1.3 Installing a New Roof Covering

Historically, damage to roof coverings is one of the leading 

causes of building performance problems in high-wind 

events. The failure of roof covering on a home can lead to 

substantial water damage to interior finishes and contents. 

The existing roof covering should be removed entirely; the 

new roof covering should not be installed over an existing 

roof covering. The new 

roof covering should be 

rated for the design wind 

speed for the project 

location and should be 

installed in accordance 

with the manufacturer’s 

recommendations for highwind regions. Various roof 

covering types are readily 

available; this Guide 

provides information on 

replacing asphalt shingles, clay and concrete tiles, and metal 

panels with prescriptive retrofitting solutions for projects that 

involve replacing the roof covering. FEMA 499 Technical 

Fact Sheets and FEMA 55 provide guidance on roof covering 

material types.

Asphalt Shingles

Two of the most common causes for damage to asphalt shingle 

roof coverings in high-wind events are improper installation 

and use of shingles that are not rated for the wind speeds 

identified in the building code and improper installation. It 

is important to understand the wind-resistance ratings and 

special installation methods for asphalt shingles used in highwind, coastal regions. 

FIGURE 4-5: 

FEMA 499 Technical Fact Sheet 

No. 5.2, Roof-to-Wall and Deck-toNote: When applying a new Wall Flashing

roof covering, the benefits 

of installing a reflective roof 

covering should be considered. 

Reflective roofs can reduce a 

building’s heat gain, enhance 

the life expectancy of the roof, 

and provide energy savings 

to the homeowner. For more 

information, go to www.

energystar.gov.

FIGURE 4-6: 

FEMA 499 Technical Fact Sheet 

No. 7.3, Asphalt Shingle Roofing for 

High Wind Regions
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-9

Asphalt shingles should be installed on homes in accordance 

with the criteria discussed in FEMA 499 Technical Fact Sheet 

No. 7.3 (see Figure 4-6), which explains asphalt shingle 

installation, wind-resistance ratings, and weathering and 

durability. Durability ratings (indicated by warranty life) are 

relative and not standardized; although shingles with a longer 

warranty (e.g., 30-year instead of 20-year) will probably have 

greater durability in coastal climates, the durability rating is 

not an indicator of the shingle’s ability to resist a particular 

wind speed. The warranty for a shingle product indicates 

the ability of the product to resist deterioration from climate 

conditions. The warranty is an important characteristic to 

consider when selecting a shingle product, but it does not 

signify wind resistance. A shingle product that has a class 

rating equal to or greater than the design wind speed (for the 

location as specified in the building code) should be selected. 

For more information on wind-resistance ratings of asphalt 

shingles, see Technical Fact Sheet No. 7.3.

Metal Roof Systems

A variety of metal panel systems and metal shingles 

are available for both low- and steep-slope roofs. MAT 

investigations have found that some metal roofing systems 

have sufficient strength to resist high winds, while others 

have failed from wind speeds that were below design 

requirements. If installing a metal roof system, FEMA 499 

Technical Fact Sheet No. 7.6 (see Figure 4-7) provides 

guidance on selecting and installing panel or shingle system. 

Clay and Concrete Tiles

Clay and extruded concrete roof tiles are available in a variety 

of profiles and attachment methods. MAT investigations have 

found that tile coverings applied using foam- and mechanicalset attachment methods have historically performed better 

than applied using the mortar-set attachment method. 

Therefore, tile roof coverings in high-wind areas should 

not be installed using the mortar-set attachment method 

should not be used to install tile roof coverings in high-wind 

areas. However, all methods are prone to failure when not 

properly installed. Uplift loads and resistance should meet 

the requirements of the design wind speed and exposure 

category for the project location. FEMA 499 Technical Fact 

Sheet No. 7.4 provides guidance for the installation of tile 

roof coverings (Figure 4-8).

FIGURE 4-7: 

FEMA 499 Technical Fact Sheet 

No. 7.6, Metal Roof Systems in HighWind Regions

FIGURE 4-8: 

FEMA 499 Technical Fact Sheet 

No. 7.4, Tile Roofing for High Wind 

Regions
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-10

All Other Roof Coverings

Roof coverings other than those specified above may be used. If HMA grant funds are being 

sought, appropriate documentation from the manufacturer should be included with the project 

subapplication for the product so it can be reviewed; the documentation should include installation 

instructions for high-wind regions. When using other roof coverings, documentation showing that 

the roof covering and attachments were designed for the component, cladding wind pressures for 

the appropriate design wind speed (of up to 150 mph), and exposure category should be provided. 

All roof coverings, regardless of type, should be installed in accordance with the manufacturer’s 

installation instructions for the appropriate design wind speed. 

4.1.2 Option 2 – Improvements without Roof Covering Replacement

Option 2 of the Basic Mitigation Package is recommended when the existing roof covering is not 

replaced as part of the wind retrofit project. Option 2 involves applying spray polyurethane foam 

(SPF) adhesive to the underside of the roof deck at the joints between roof sheathing panels and 

along all intersections between the roof deck and framing members as shown in Figure 4-9. This 

retrofit serves two purposes: 

1. The connection between the roof deck and supporting structural members is enhanced, 

which increases the ability of the roof deck to resist uplift during high-wind events. 

2. The SPF adhesive seals the joints of the roof deck to help prevent water intrusion. While 

not as effective as installing an underlayment, the SPF adhesive will help minimize water 

infiltration.

The SPF product selected should be one that has been successfully tested in accordance with Testing 

Application Standard (TAS) 202-94, Criteria for Testing Impact and Non-Impact Resistant Building Envelope 

Components Using Uniform Static Air Pressure (ICC, 1994); design uplift pressure for the SPF should be 

FIGURE 4-9: 

Example of SPF adhesive 

application to secure roof deck 

panels
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-11

equal to or greater than 110 pounds per square foot (psf). 

The product should also be a two-component SPF system that 

complies with ASTM D1622, Standard Test Method for Apparent 

Density of Rigid Cellular Plastics. FEMA 499 Technical Fact 

Sheet No. 9.2 (Figure 4-10) cites an additional reference, 

Not Ready to Re-Roof? Use Structural Adhesive to Strengthen 

the Attachment of Roof Sheathing (S.C. Sea Grant Extension 

Program 2001), which provides guidance on securing roof 

deck connections using spray foam adhesive.

4.1.3 Strengthening Vents and Soffits

Much of the damaged caused by past high-wind events has 

been due to attic ventilation openings that are not capable 

of resisting failure from high-wind forces. These vulnerable 

components should be retrofitted as part of the Basic 

Mitigation Package, regardless of whether Option 1 or 

Option 2 is chosen. Attic ventilation openings include the 

following: 

4 Soffit vents

4 Ridge vents

4 Off-ridge vents

4 Gable rake vents

4 Turbines

FEMA 499 Technical Fact Sheet No. 7.5 (see Figure 4-11) 

provides retrofit criteria for each type of attic ventilation 

opening. Work on soffits in particular provides an excellent 

opportunity to retrofit the roof-to-wall connections, which 

is one of the Advanced Mitigation Package retrofits. 

Strengthening the roof-to-wall connections will maximize the 

engagement of the existing uplift resistance in the walls and 

connections to the foundation; though this is not required 

under the Basic Mitigation Package, it is an important retrofit 

and can often be accomplished cost effectively while doing 

work on soffits as part of the Basic Mitigation Package.

Depending on the condition 

of existing soffits (determined 

during the evaluation process 

described in Chapter 3 and 

Appendix B), the soffit panels 

should be either removed 

and reinstalled or replaced 

with new material. The most 

critical soffit installations are 

FIGURE 4-10: 

FEMA 499 Technical Fact Sheet 

No. 9.2, Repairs, Remodeling, 

Additions, and Retrofitting—Wind

FIGURE 4-11: 

FEMA 499 Technical Fact Sheet 

No. 7.5, Minimizing Water Intrusion 

through Roof Vents in High-Wind 

Regions

Note: Number 8 wood 

screws specified in this 

Guide should comply with 

ANSI/ASME (American 

Society of Mechanical 

Engineers) B18.6.1 and be 

0.164 inch in diameter (or 

equivalent).
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-12

those with vinyl or aluminum soffit panels. Aluminum soffit panels can also be vulnerable because 

of aluminum’s corrosion potential in a salt environment. If the house is within 3,000 feet of saltwater, 

aluminum soffits should be removed completely, and a new soffit system installed according to the 

guidance of Technical Fact Sheet No. 7.5. Figure 4-12 shows a typical detail for retrofitting soffits. 

It should be noted that although many homes have different soffit configurations from the one 

depicted here, the intent of the retrofit as shown in Figure 4-12 (to provide continuous edge support 

and appropriate intermediate support for the soffit) should be carried out by the applied retrofit 

project. Additionally, the selected soffit products may have more restrictive installation instructions 

when installed in high-wind regions, in which case the more restrictive installation method should 

be used. Soffits should also be secured using sealant and screws as described in Technical Fact Sheet 

No. 7.5. 

4.1.4 Strengthening Overhangs at Gable End Walls

Gable end walls are particularly vulnerable to damage in high-wind events due to their structural 

configuration. Loads created by high winds can quickly overwhelm the capacity of gable end walls 

FIGURE 4-12: 

Typical soffit retrofit using wood supports
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-13

that do not have adequate structural connections. Ensuring that there are adequate connections 

between gable end walls and roof framing is an important component of a wind retrofit project. If a 

home undergoing a wind retrofit project has gable end walls, they should be retrofitted as described 

in this section. 

FEMA 55 has detailed design guidance on the connections for gable end walls, including bracing 

recommendations. To be applicable for these prescriptive retrofit criteria, the overhangs should be 

at least nominal 2x4 members spaced no greater than 24 inches o.c. The overhangs and gable end 

wall framing or truss framing should not be notched. 

To retrofit the overhangs at gable ends, a saddle type hurricane clip should be added to connect 

the overhang to the gable end wall/truss (see Figure 4-13). A joist hanger should also be added 

to secure the overhang member to the roof framing member. Figure 4-13 shows a conceptual 

retrofit that may not be applicable for different configurations. Although configurations may vary, 

it is important that the intent of the retrofit as described in Figure 4-13 be accomplished. This 

retrofit should be completed before the roof sheathing is strengthened, regardless of whether that is 

implemented by re-nailing the roof sheathing or applying an SPF adhesive to the underside of the 

sheathing (see Sections 4.1.1 and 4.1.2). When retrofitting soffits, accessing the overhang and gable 

end connections may be easier (see Section 4.1.3). 

FIGURE 4-13: 

Bracing gable end overhangs
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-14

4.2 Intermediate Mitigation Package

The Intermediate Mitigation Package is the second level 

of high-wind mitigation described in this Guide. For this 

package to be effective, the mitigation measures identified for 

the Basic Mitigation Package must first be successfully completed. 

The Intermediate Mitigation Package includes retrofits to protect 

openings, further strengthen gable ends that are over 4 feet in 

height (if applicable), and improve the anchorage of attached 

structures such as porches and carports.

4.2.1 Protecting Openings

Building openings include windows, skylights, entry doors, and 

garage doors. If these components fail, wind-driven rain can 

enter the building and cause costly water damage. In addition, the 

increase in internal wind pressure is likely to increase the chance for a structural failure. Opening 

protection can be provided by one of two methods for the Intermediate Mitigation Package:

4 An approved impact-resistant covering capable of resisting windborne debris impacts can 

be installed over an existing, unprotected opening (such as a window or door). Types of 

impact-resistant coverings include shutter systems and fabric and screen products.

4 An approved, impact-resistant product (such as a new window or door assembly) can be 

installed in place of a product that is not designed to resist such forces or as an alternative 

to impact-resistant shutters or screens. However, these are systems or “assemblies,” and 

protecting only the glass (or glazing) is not adequate. A tested and approved system that 

includes the frame and the glazing system must be used. 

Note that shutters, screens, and other panel systems that protect 

glazing from debris impacts are often not rated to reduce wind 

pressures on the opening they protect. A system that has a pressure 

rating has typically been rated for resistance to that pressure 

for avoiding blow-off or excessive deflection, not for decreasing 

pressure on the window or door that the system protects. While 

this is not true for all impact-resistant covering products, product 

specifications and test criteria should be scrutinized carefully in 

the planning process of a wind retrofit project. More information 

on opening protection can be found in Chapter 10 of FEMA 

P-762, Local Officials Guide for Coastal Construction (FEMA, 2009b). 

Opening protection guidance provided in this Guide is primarily 

focused on identifying the test criteria to which an approved 

product should be certified, as well as general guidance on 

selecting the type of protection. For further guidance on protecting openings, see FEMA 499 

Technical Fact Sheet No. 6.2 (Figure 4-14). FEMA 499 Technical Fact Sheet No. 6.1 also provides 

guidance on proper installation of windows and doors. 

INTERMEDIATE MITIGATION 

PACKAGE RETROFITS:

•	 Window and entry door

protection from windborne 

debris, garage door 

protection from wind 

pressure, and garage door 

glazing protection from 

windborne debris 

•	 Bracing gable end walls over

4 feet tall

•	 Strengthening connections of

attached structures

Note: For homes located in 

a windborne debris region, 

the windows, entry doors, 

and garage doors need to 

be protected, even if only the 

Basic Mitigation Package 

is being implemented. The 

opening protection retrofits 

to implement for windows, 

entry doors, and garage 

doors in windborne debris 

regions are presented under 

the Intermediate Mitigation 

Package described in this 

section.
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-15

4.2.1.1 Windows

Windows can be retrofitted using either of the previously 

described opening protection methods for the Intermediate 

Mitigation Package. Though installing an impact-resistant 

window is typically more expensive than installing an impactresistant covering, it is also a more complete method of protecting 

the window. This is because impact-resistant coverings, such 

as shutter systems, do not typically cover openings at all times. 

Shutter systems must be set in place before the wind event occurs 

to be effective. This can be problematic if no one is present to 

install or operate the shutter system or, if operated electronically, 

if the power fails before someone has a chance to close them. 

Before a particular product is chosen, it should be confirmed 

that it has been certified to the appropriate standards. 

Impact-resistant covering products should be tested to 

demonstrate compliance with ASTM E1996 in accordance with 

the procedures defined in ASTM E1886. Testing includes both 

missile impact testing and cyclical pressure differential testing. 

Products certified to resist the “D Missile” defined in ASTM 

E1996 are recommended (a 9-pound [lb], 8-foot-long, 2x4 board 

member traveling horizontally at 34 mph). 

The manufacturer’s instructions for the appropriate design wind 

speed should be followed when installing any form of opening 

protection. FEMA 499 Technical Fact Sheet No. 6.1 provides 

FIGURE 4-14: 

FEMA 499 Technical Fact Sheets No. 6.2, Protection of Openings—Shutters and 

Glazing, and No. 6.1, Window and Door Installation

SKYLIGHTS

Due to their varying 

configurations, approved 

impact-resistant coverings 

(such as shutters) for skylights 

are not readily available. If 

a home has skylights, the 

solutions to meet the level 

of protection offered by 

the Intermediate Mitigation 

Package are:

•	 Replace the existing

skylights with an approved, 

impact-resistant skylight (if 

available)

•	 Remove the skylight and

secure the opening (this may 

require a design professional)
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-16

guidance on proper installation of windows. Documentation of 

the certified level of protection for the product should be readily 

available. The 2009 IBC and IRC both require labeling on exterior 

windows; Section R612.6 of the 2009 IRC requires exterior 

windows to be labeled in conformance with Standard/Specification 

for Windows, Doors, and Unit Skylights (AAMA, 2007), a standard 

that prescribes labeling requirements for windows, doors, and 

unit skylights. While some jurisdictions may not have adopted 

this requirement, labeling of products such as windows, doors, 

and shutter systems showing the level of protection to which the 

product has been certified should be readily available. 

Shutter systems are the most common form of impact-resistant 

covering products, and are either temporarily or permanently 

installed. Temporary shutters are lower in cost compared to 

permanent shutters, but require ongoing effort on the part of the 

homeowner to use them effectively for opening protection.

Temporarily Installed Shutters

Though lower in cost than permanent shutters, temporary shutters must be installed and removed 

every time they are needed, and require storage space when not in use. Installation of temporary 

shutters before a storm is often left to the homeowner, and can be difficult on upper level windows 

of homes that are two or more stories high. For this reason, it is recommended that windows above 

the ground floor be protected by a permanent shutter system or that existing windows be replaced 

with impact-resistant windows.

One form of commonly used temporary shutters is wood structural panels. While wood structural 

panels are inexpensive, they tend to have shorter useful life spans and require storage conditions 

where the wood will not become warped, which causes rapid installation to be difficult. Wood 

structural panel shutters are typically comprised of a variety of combinations of panels, fasteners, 

and anchoring hardware. Detailed installation instructions, storage, handling, and maintenance 

procedures for specific combinations of materials needed for the shutter system to perform as 

expected are generally not available. Further, a standard “missile” will breach the code-prescribed 

wood structural panel shutter, and the desired level of protection is no breaching of the shutter. 

Because they may not provide the desired level of protection, wood structural panel shutters are not 

eligible for inclusion in an HMA grant application. However, if wood structural panels are the only 

affordable solution to protect the windows of a home, they may be considered outside of an HMA 

grant application. More information on using wood structural panels as shutters can be found at 

www.apawood.org/level_b.cfm?content=app_bas_wind.

Permanently Installed Shutters

Shutter systems that are permanently installed are more expensive than temporary shutters, but they 

are always in place and ready to be closed. Permanent shutter systems are operated either manually 

or by a motor. Manually operated shutters are less expensive than motorized shutters, but are closed 

from the outside. Motorized shutters are easily closed from the interior, but are among the most 

expensive type of shutter system. Motorized shutters should also be able to be operated manually 

in the event of loss of power. If a shutter system is used to protect windows, it should be sufficiently 

USING FILMS FOR OPENING 

PROTECTION 

Opening protection products 

such as films and other 

overlays are not appropriate 

methods of opening protection 

for a wind retrofit project. An 

overlay on glazing does not 

provide certified protection 

for the opening unless the 

whole assembly—including the 

glazing, opening frame, and 

overlay product—are tested 

together and certified to the 

appropriate test criteria. 
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-17

anchored into the wall around the window frame so that wind loads are transferred to the structure 

of the building. 

If impact-resistant windows are the desired form of window protection, the existing window 

assemblies should be removed and replaced with new assemblies that meet the appropriate criteria. 

Similar to impact-resistant coverings, impact-resistant windows should be tested to demonstrate 

compliance with ASTM E1996 (using the “D Missile”) in accordance with the procedures defined in 

ASTM E1886. Additionally, the selected window product should be tested to demonstrate compliance 

with ASTM E1233 (a cyclical air pressure differential test). 

4.2.1.2 Entry Doors

As part of the Intermediate Mitigation Package, all exterior entry doors should be protected from 

windborne debris and design wind pressure; at least one entry door should be operable from 

inside the living space if opening protection is in place. Entry doors should be protected by either 

protecting the existing door with an impact-resistant covering or providing an impact-resistant door. 

Regardless of whether the chosen product is an impact-resistant covering or an impact-resistant 

door, it should be tested to demonstrate compliance with ASTM E1996 (using the “D Missile”) in 

accordance with the procedures defined in ASTM E1886. An impact-resistant door should also be 

tested to demonstrate compliance with ASTM E1233. 

4.2.1.3 Garage Doors

Garage doors are typically large, unreinforced openings that are commonly damaged during highwind events. As part of the Intermediate Package, any garage doors on a home should be capable 

of resisting design wind pressure. For garage doors with glazing that is less than 1 square foot (for 

one-car garages) or 1.8 square feet (for two-car garages), the garage door may be retrofitted to resist 

design wind pressures through one of two methods:

4 Install a garage door that is certified to resist the design wind pressure for the location.

4 Protect the existing garage door by installing an impact-resistant covering that protects the 

entire door and is certified to resist the design wind pressure for the location.

If a garage door has glazing that is greater than 1 square foot (for one-car garages) or 1.8 square 

feet (for two-car garages), it should be certified to resist both windborne debris impacts and the 

design wind pressure for the location. This can be achieved through one of two retrofits:

4 Install a garage door that is certified to resist both missile impacts and the design wind 

pressure for the location.

4 Protect the existing garage door by installing an impact-resistant covering that protects the 

entire door and is certified to resist the design wind pressure for the location.

Acceptable test standards for design pressure resistance of garage door products include American 

National Standards Institute (ANSI)/Door and Access Systems Manufacturers Association 

(DASMA) 108 and ASTM E330. For the impact resistance of glazing, the product should be tested 

to demonstrate compliance with ANSI/DASMA 115. Section R612.7 of the 2009 IRC requires that 

garage doors be tested in accordance with either ASTM E330 or ANSI/DASMA 108; however, these 

standards do not establish test pressures, and therefore certification data must be closely examined 

to determine if the labeled product is appropriate for the design wind pressures. Also, while some 
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-18

manufacturers provide wind speed and exposure ratings for their products, labels on many garage 

doors do not include wind speed or wind pressure ratings. While not required to be included on 

the product labeling, ANSI/DASMA 108 does require that the positive and negative pressure used 

in testing be recorded on the ANSI/DASMA 108 Test Report Form. The standard also requires that 

the model number, description, and operating hardware be documented. Where wind speed or 

wind pressures are not specifically provided for the product, the Test Report Form documents that 

the garage door assembly has been tested to resist the appropriate design wind pressures. 

4.2.2 Bracing Gable End Walls Over 4 Feet Tall

If gable ends on the home are 4 feet (or more) tall, they should be retrofitted as part of the 

Intermediate Mitigation Package. This retrofit builds upon the Basic Mitigation Package item for 

strengthening overhangs at gable end walls (see Section 4.1.4).

One method to retrofit gable end walls for the Intermediate Mitigation Package involves:

1. Strengthening vertical framing members of the gable end using retrofit studs.

2. Bracing the top and bottom of the gable end with horizontal braces to allow lateral loads to 

transfer to the roof and ceiling diaphragms.

3. Making connections between horizontal braces and retrofit studs using metal straps and 

fasteners. 

4. Connecting the bottom of the gable end to the wall below using metal bracket connectors.

A conceptual detail showing these measures is provided in Figure 4-15 for a gable end wall without 

an overhang and in Figure 4-16 for a gable end wall with an overhang. Prescriptive solutions to 

address this retrofit can be used or a professional engineer may be needed to provide specific 

solutions in cases where prescriptive solutions are not applicable. The IEBC 2012 and the FEH 

program both contain prescriptive solutions that can be used to perform this retrofit. Although 

configurations may vary, it is important that the intent of the retrofit as shown in Figures 4-15 and 

4-16 be accomplished.

4.2.3 Strengthening Connections of Attached Structures

For the purpose of this Guide, “attached structures” are connected to the home (and the main 

wind force resisting system of the home) and have a roof. Examples may include porches and 

carports. Attached structures can be significant hazards to a home during high-wind events if there 

is insufficient capacity to resist forces. Attached structures are typically supported by horizontal 

beam members connected to vertical columns, which are in turn connected to the foundation. If 

the structure has this typical configuration, the connections should be retrofitted by adding metal 

connectors that meet or exceed loads and installed according to manufacturer’s recommendations. 

These measures will strengthen the load path for the attached structure to transfer applied wind 

loads to the foundation. The connectors should be added to the following areas of the attached 

structure:

Between supporting roof members and horizontal beams. Wood-to-wood connections should 

be strengthened using a saddle-type hurricane clip. If the uplift load required is less than 

800 lbs, the clip may be installed on either side of the beam. If the uplift load required is 

greater than 800 lbs, the clip should be installed on both sides of the beam. 
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-19

FIGURE 4-15: 

Conceptual gable end retrofit without overhangs
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-20

FIGURE 4-16: 

Conceptual gable end retrofit with overhangs
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-21

At each beam-to-column connection. A connector should be chosen that is appropriate for 

the location of the connection (e.g., corner beam-to-column connections will require a 

different connector than inside beam-to-column connections), the required uplift load, and 

the dimensions of the beam and column. The metal connector should be rated for exterior 

weather exposure and should be stainless steel if the home is within 3,000 feet of the coast. 

At each column-to-foundation connection. A metal column hold-down connector should be used 

to strengthen the column-to-foundation connection. A moisture barrier should be provided 

between the connector and concrete foundation. The metal connector should be rated for 

exterior weather exposure. 

If the attached structure is not supported in the configuration described above, it should be 

evaluated to determine whether it can be retrofitted to resist the required uplift loads using a 

different prescriptive solution. If no prescriptive solution exists, a professional engineer should be 

engaged to provide a site-specific retrofit solution. Required loads should be calculated using the 

wind load criteria in ASCE 7. Some organizations involved in high-wind retrofits have worksheets 

that can be used to evaluate the required uplift load at each connection. One example of this is the 

“Uplift Worksheet” in the FORTIFIED for Existing HomesTM Engineering Guide (IBHS, 2010), which 

defines a typical attached structure configuration that matches the criteria described above. The 

Uplift Worksheet uses a step-by-step method to calculate the required uplift loads for an attached 

structure using the dimensions of the structure and an uplift pressure table. 

4.3 Advanced Mitigation Package

The Advanced Mitigation Package is the most comprehensive package of retrofits in this Guide. This Package can only be effective if the Intermediate Mitigation Package and Basic Mitigation 

Package (with or without replacing the roof covering) are also 

implemented as part of the wind retrofit project. The Advanced 

Mitigation Package requires a more invasive inspection protocol 

than the previous two packages. Homes that are undergoing 

substantial renovation or are being rebuilt after a disaster 

are typically the best candidates for the Advanced Mitigation 

Package. The Advanced Mitigation Package includes retrofits to 

provide a continuous load path and protect openings (beyond the 

requirements of the Intermediate Mitigation Package).

4.3.1 Developing a Continuous Load Path

While structural failures are not as common as other wind-related damage such as damage to 

the building envelope or wind-driven rain intrusion, such failures have been observed on homes 

that sustained winds below modern building code requirements. The performance of the home’s 

structural system during a high-wind event depends on whether there is a continuous load path 

that can transfer loads applied anywhere on the building envelope through the structure and to 

the foundation. If there is not a continuous load path in the building, the loads may cause a failure 

related to the missing point of connection. For example, Figure 4-17 shows a house observed by the 

Hurricane Ike MAT. This home had inadequate connections to transfer loads applied to the roof 

structure down to the foundation and as a result, the roof structure was destroyed. The wind speeds 

at this location were estimated to be only 50 mph.

ADVANCED MITIGATION 

PACKAGE RETROFITS:

•	 Developing a continuous

load path 

•	 Protecting openings from

windborne debris and wind 

pressure
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-22

Implementing a continuous load path through an existing building typically requires the assistance 

of a professional engineer, although some retrofit programs and guides contain prescriptive solutions 

to provide continuous load paths through existing residential structures. The FEH program (see 

Appendix A) is an example of a residential retrofit program that provides prescriptive solutions 

to develop a load path for homes meeting certain criteria and characteristics. However, due to the 

large potential variation in structural configuration, construction techniques, and material types, 

prescriptive solutions for continuous load paths are limited to very simple structures. As a result, 

most homes will not be eligible for the prescriptive retrofits and will need to engage the services of a 

professional engineer to develop a retrofit solution specific to the home. 

FEMA 499 Technical Fact Sheets No. 4.1 and 4.3 provide guidance on the concept of a continuous 

load path through the home (Figure 4-18). FEMA 55 provides more detailed guidance and examples 

of each link through the continuous load path. A solution should be followed that starts at the top of 

the home (at the roof sheathing), implementing an appropriate fastening schedule and attachment 

to the roof framing members (see Sections 4.1.3 and 4.1.4 of this Guide), and continuing to the 

foundation.

The connections between the roof and load-bearing walls should be capable of transferring design 

loads corresponding to the design wind speed (see Figure 4-19). For homes with both hip and gable 

roof ends, both types of roof-to-wall connections should be retrofitted, but pay special attention to 

gable end roof-to-wall connections. Priority should also be given to connecting the corners of the 

roof to the wall below where the roof members have the greatest span. The retrofits should ensure 

that the roof truss and rafter retrofitted tie-down is adequate to resist the uplift force and lateral 

force in two directions at the top of the supporting wall. 

Technical Fact Sheet No. 4.3 also discusses wall-to-floor and 

wall-to-wall connections (see Figure 4-20). These connections 

continue to transfer loads from the roof system (as well as those 

picked up by exterior walls) all the way to the foundation and 

FIGURE 4-17: 

Roof structure that was poorly 

connected to the house 

(Jefferson Parish, LA)

(SOURCE: FEMA P-757)

Note: For information on 

evaluating shear wall capacity, 

see Appendix B, Evaluation 

Guidance.
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-23

into the ground. Figure 4-21 shows foundation connections. The foundation is the last link in a 

continuous load path. It is critical to ensure that the loads are being transferred to the foundation 

where large loads must be resisted. 

Ensuring Chimneys are Adequately Anchored 

If a wood-frame chimney on a home collapses during a high-wind event, significant damage can 

occur to the home as well as surrounding buildings. Therefore, if a home undergoing a wind retrofit 

project has a chimney framed with wood, it should be anchored to the structure as part of the 

continuous load path retrofit so that loads applied to it are transmitted through the load path and 

adequately resisted. Wood-frame chimneys that are on the interior of the roof and extend 5 feet or 

less from the roof deck can be retrofitted using prescriptive requirements. The following retrofits 

should be performed on a qualifying chimney:

1. Tensions straps with a minimum tension capacity of 700 lbs at each end should be fastened 

to the stud at each corner of the chimney and to the roof framing members below the 

chimney.

2. Wood structural panels with a minimum nominal thickness of 7/16 inch should be applied 

to the chimney framing on all sides. 

3. Continuous wood blocking supports should be fastened to roof framing members around 

the base perimeter of the chimney framing using joist hangers. Wood blocking should have 

minimum dimensions of 2 inches x 4 inches and should be continuous around the chimney 

framing. 

FIGURE 4-18: 

FEMA 499 Technical Fact Sheets No. 4.1, Load Paths and No. 4.3, Use of 

Connectors and Brackets
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-24

FIGURE 4-19: 

Load path connections of a roof system

(SOURCE: FEMA 499)
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-25

FIGURE 4-20: 

Load path connections of a wall system

(SOURCE: FEMA 499)
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-26

FIGURE 4-21: 

Load path connections of a foundation

(SOURCE: FEMA 499)
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-27

For more information on this type of solution, consult retrofit programs such as the IBHS FEH 

program for prescriptive details. If the wood-frame chimney is on the interior of the roof, the 

entire chimney structure is supported by the roof framing members, which allows the use of the 

prescriptive solution described above. If the chimney is located along the roof edge, the chimney 

structure is supported by both roof framing members and a load-bearing wall on the exterior of 

the building, making a prescriptive retrofit more difficult. Similarly, larger chimneys may require 

a more detailed and less generic solution to adequately anchor the chimney to the structure. If a 

chimney exists on the home that extends farther than 5 feet above the roof deck or extends along 

the roof perimeter, a professional engineer should be engaged to develop a detailed solution. The 

solution should address the following:

4 Chimney wall framing adequacy

4 Overturning stability and base shear requirement

4 Adequacy and bracing requirements for roof support members

4 Attachment schedule of chimney structure to the roof structure

A professional engineer will typically be required to complete the continuous load path retrofit 

portion of the Advanced Mitigation Package. An engineered solution may involve installing 

additional metal connectors at the roof level if the side wall framing members are continuous from 

the bearing wall framing. It may include altering the member size and spacing of roof framing 

members to support the load from the chimney, installing wood posts at each end of the wall if the 

chimney side wall framing members start from the top of the supporting wall, or setting posts at the 

interior side of the wall framing at each corner. A retrofit solution for a masonry chimney will be 

more difficult than for a wood-frame chimney, and would likely require rebuilding the chimney (at 

least for the portions above the roof line).

4.3.2 Protecting Openings

The Advanced Mitigation Package provides greater opening protection than the retrofits of the 

Intermediate Mitigation Package. The Intermediate Mitigation Package opening protection retrofit 

(see Section 4.2.1) can be completed by installing window and entry door protection that mitigates 

only windborne debris impacts and not design pressures, and by protecting garage doors from wind 

pressures and only the glazing the garage doors (if applicable) from windborne debris impacts. In 

contrast, the Advanced Mitigation Package retrofits address resistance for windows, entry doors, and 

garage doors (both glazing and door) to both windborne debris impacts and design pressures. The 

design pressure for an opening is based on factors such as the design wind speed for the project 

location, exposure category applicable for the surrounding terrain, and the area and location of the 

opening on the building. Existing opening products that are not rated to resist the design pressures 

specific to the project location should be removed and replaced with products that do. 

Window, skylight, and door products should be tested to demonstrate compliance with ASTM E1233 

for the applicable design pressures. Garage doors should be tested to demonstrate compliance 

with ANSI/DASMA 108 for the applicable design pressures. All windows, skylights, entry doors, 

and garage doors that should be impact resistant (including opening coverings such as shutter 

systems) should be tested to demonstrate compliance with ASTM E1996 (using the “D Missile” for 

the Large Missile Test) in accordance with the procedures defined in ASTM E1886. If a garage 

door has glazing that is greater than 1 square foot (for one-car garages) or 1.8 square feet (for two-
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-28

car garages), the glazing should be tested to demonstrate compliance with ANSI/DASMA 115 for 

impact resistance and cyclical pressure testing. The frame and track of any garage doors should also 

be checked to ensure the wind load being applied to the strengthened door is transferred into the 

structural system of the garage.

For windows, entry doors, and garage doors, this retrofit should be done using one of the following 

two methods:

1. Use window and door assemblies in building openings that are rated to resist design 

pressures (regardless of whether they are existing products or new products installed as 

part of the wind retrofit project). Protection from windborne debris impacts must then be 

provided by impact-resistant coverings that are installed on windows and doors. Coverings 

should be provided to protect the entire opening and transfer loads to the structural system 

of the house.

2. Use window and door assemblies in building openings that are rated to resist both design 

pressures and windborne debris impacts. This configuration, therefore, does not require a 

covering product to be installed. 

The homeowner should work with the contractor, evaluator, and professional engineer (if 

engineering services are solicited) to determine the most cost-effective method to provide opening 

protection, as either method may be the most cost-effective choice depending on the scenario. For 

example, a home could already have a shutter system in place over the windows and doors that is 

certified to meet the appropriate standards for impact resistance. In such a situation, the most costeffective retrofit might be to replace any existing windows and doors that are not rated to resist the 

design pressure with new products that are appropriately rated. 

Due to the lack of readily available impact-resistant covering products for skylights, they should be 

replaced by a product that is certified to resist design wind pressures and windborne debris impacts, 

rather than be protected by an impact-resistant covering. 

4.4 Additional Mitigation Measures

The remainder of this chapter discusses retrofits that mitigate the residual risk of wind-related damages remaining after the Mitigation Packages are implemented. The Mitigation Packages 

described in this Guide include important retrofits to reduce the risk that a home will experience 

wind-related damage; however, the risk of damage from a high-wind event cannot be eliminated 

entirely. By maintaining awareness of the vulnerabilities of and around a home, the risk from windrelated damages can be mitigated even further. While these issues are important to understand, 

they are not a part of the Mitigation Packages and are not eligible for HMA Program funding. 

4.4.1 Exterior Wall Coverings

Exterior wall coverings can be blown off of a building, even during wind events with wind speeds 

below the design wind speed. Common exterior wall coverings include vinyl siding, brick veneer, 

fiber-cement siding, and wood and hardboard siding. All types of wall coverings can perform well in 

high winds if they are properly installed for high winds. 
CHAPTER 4: Technical Design and Construction Methods

Wind Retrofit Guide for Residential Buildings 4-29

Guidance on the proper installation of vinyl, wood, and fiber cement siding material types is 

provided in FEMA 499 Technical Fact Sheet No. 5.3 (see Figure 4-22). 

FEMA 499 Technical Fact Sheet No. 5.4 (Figure 4-22) provides guidance on the attachment of 

brick veneer in high-wind regions. Construction guidance such as tie fastener type, spacing, and 

installation methods are discussed.

FEMA 55 provides guidance on many issues that affect the wall coverings of homes along the coast, 

as well as guidance on other types of wall coverings not discussed in this Guide.

FIGURE 4-22: 

FEMA 499 Technical Fact Sheets No. 5.3, Siding Installation in High-Wind 

Regions and No. 5.4, Attachment of Brick Veneer in High-Wind Regions

4.4.2 Tree Fall

Damage caused by tree fall is commonly observed following high-wind events (see Figure 4-23). 

Beyond damaging buildings, trees can block roads and driveways, and create a fire hazard. Branches 

near and over a house should be trimmed and large trees next to a home removed. Homeowners 

should consult a tree removal professional or botanist to assess the vulnerabilities of any trees on 

their property. They should consider removing trees that are diseased, have voids in trunks that 

significantly reduce their ability to withstand wind forces, or are otherwise vulnerable to collapse on 

nearby structures.
Wind Retrofit Guide for Residential Buildings

CHAPTER 4: Technical Design and Construction Methods

4-30

FIGURE 4-23: 

A home damaged by fallen 

trees during Hurricane Katrina 

(Diamondhead, MS)

(SOURCE: FEMA 549) 

4.4.3 Exterior Equipment

Damage may result from exterior equipment that either falls or is torn off a building during a highwind event. While the Basic Mitigation Package includes retrofits to some rooftop elements such as 

vents and turbines, not all potential rooftop equipment is covered. Any exterior equipment should be 

protected from wind-related damage. Unsecured rooftop exterior equipment such as exhaust fans, 

fan cowlings, and vent hoods can blow off during high-wind events. When this occurs, water can 

infiltrate the area where they are ripped off of the home; additionally, the equipment can become 

windborne debris and cause damage to surrounding property. Generally, inadequate anchorage, 

inadequate strength of the equipment itself, and corrosion of fasteners and straps are the sources of 

failure of these elements. FEMA 55 provides guidance on mitigating these elements.
Wind Retrofit Guide for Residential Buildings 5-1

This chapter offers guidance for implementing residential building wind retrofit projects 

and the factors to consider when implementing them, and also discusses possible funding 

of resources. Factors to consider for wind retrofit projects include code compliance, local 

permitting and inspection requirements, and general construction challenges. Addressing hazards 

other than high-wind events is also discussed.

5.1 Wind Retrofit Programs

Several Federal, State, and nonprofit retrofit programs are currently available to homeowners and local governments. These programs include FEMA’s HMA Grant Programs, the IBHS FEH 

program, Rebuild Northwest Florida, the Residential Construction Mitigation Program (RCMP), 

SC Safe Home, Mississippi Windstorm Underwriting Association Retrofit Mitigation Program, 

and the Federal Alliance for Safe Homes (FLASH) Blueprint for Safety Program®. This section 

briefly describes each of these programs. Appendix D of this Guide includes a list of FEMA’s HMA 

and other funding programs, as well as links to them. However, this Guide does not provide an 

exhaustive list of all such programs. Additionally, there are other retrofit programs offered through 

different States, but these are generally disaster specific and have limited operational time frames. 

Each of the retrofit programs provides guidance on mitigating wind hazards; some of the programs 

also offer funding assistance.

5.1.1 Federal Emergency Management Agency

FEMA administers several programs that provide grant funding for mitigation projects as 

described below (see Appendix D for links to FEMA resources). FEMA funds both structural and 

non-structural retrofits to existing buildings for wind hazard mitigation. Wind mitigation retrofit 

projects are defined as modifications to the elements of a building to reduce or eliminate the risk of 

future wind damage and to protect inhabitants. The PDM Program and HMGP are both applicable 

for wind retrofit projects. These programs comply with local, State, or national building codes, 

standards, and regulations—such as the IBC, the FBC, and the ASCE and ASTM standards—for 

structural retrofits.

Pre-Disaster Mitigation Program. FEMA’s PDM Program provides nationally competitive grants to 

States, territories, federally recognized Indian Tribal governments, and local governments 

for hazard mitigation planning and implementing mitigation projects before a disaster event. 

Funding these plans and projects reduces overall risks to the population and structures, as 

well as reliance on funding from actual disaster declarations to rebuild after disasters. 

CHAPTER 5

Implementing Mitigation 

Projects
Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects

5-2

Hazard Mitigation Grant Program. FEMA’s HMGP provides grants to States, territories, 

federally recognized Indian Tribal governments, local governments, and private nonprofit 

organizations to implement long-term hazard mitigation measures after a major disaster 

declaration in a given State. The purpose of HMGP is to reduce the loss of life and property 

due to natural disasters and to enable mitigation measures to be implemented during 

recovery from a disaster.

Figure 5-1 shows the process for FEMA grant applications and approvals. It is divided into five stages, 

starting with mitigation planning and ending with the successful execution of a project. The process 

requires coordination among FEMA, the State, and the local government. This is represented by the 

three rings in the figure.

Whether PDM or HMGP funds will be used, the FEMA grants cycle process includes the following 

five stages.

FIGURE 5-1: 

HMA grants cycle process showing roles and responsibilities of each stakeholder
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-3

Stage 1. Mitigation Planning

A State Multi-Hazard Mitigation Plan is a prerequisite for both HMGP and PDM project grants. 

The State Multi-Hazard Mitigation Plan lays out the process for identifying the hazard risks of a 

community and the actions that will help reduce those risks. Wind retrofit projects that are proposed 

for FEMA funding under these programs must be consistent with the State’s mitigation plan. The 

mitigation planning process requires public participation and identification of measures to reduce 

risks, and is therefore a good opportunity for homeowners to address concerns about high-wind 

hazards. More information is available on the FEMA Web site at www.fema.gov/plan/mitplanning.

Stage 2. Program Funding

HMA Programs enable hazard mitigation measures to be implemented before, during, and after 

disasters. Funding depends on the availability of appropriation funding or is based on disaster 

recovery expenditures, as well as any directive or restriction made with respect to such funds. HMGP 

funding depends on Federal assistance provided for disaster recovery following a Presidential 

disaster declaration in a State, while PDM funding is appropriated annually by Congress on a 

competitive basis to all States and tribes. Once the application period is open, the State notifies the 

local governments of the availability of funds and relays information on the application process, 

project requirements, and eligibility criteria for the local government. Homeowners should work 

with their local government to express their interest in participating in a wind retrofit project; the 

local government can then submit a subapplication to the State and request HMA funding.

Stage 3. Application Development

Individuals and businesses are not eligible to apply for HMA funds, so individual homeowners must 

work with their local government to develop a complete project subapplication on their behalf. 

Local governments may submit a retrofit project for a single home as an individual subapplication 

or combine it with other homes as part of an aggregate subapplication. Aggregating benefit and 

cost values is allowed for multiple structures if they are all vulnerable to damage as a result of 

similar hazard conditions. Users of this Guide should refer to the latest HMA Unified Guidance at 

www.FEMA.gov for information on aggregating projects in an application.

Key steps for wind retrofit applications are:

1. Identify the property to be mitigated.

2. Identify key project personnel and roles such as evaluator, inspector, and design 

professional.

3. Identify the approach that will be used, such as the IBHS FEH program, to establish the 

target level of risk to which the structure will be mitigated.

4. Have an evaluator or other professional inspect the structure utilizing the approach 

identified in Stage 3 (if possible; if not done at this stage, it must be done during Stage 4, 

Project Implementation).

5. Select a Mitigation Package (Basic, Intermediate, Advanced) and its associated retrofit 

projects based on the evaluation.

6. Develop a project cost estimate and work schedule.
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5-4

7. Conduct a BCA using the FEMA BCA Tool (refer to 

Appendix C for additional information); if the benefit-cost 

ratio (BCR) is 1.0 or more, the project is cost effective. 

FEMA requires a BCR of 1.0 or greater for funding.

8. Ensure that properties located in designated Special Flood 

Hazard Areas (SFHAs) will obtain flood insurance and 

that this condition will be recorded on the property deed. 

The local government submits the subapplication to the State. The State then selects projects 

based on its priorities and submits applications to FEMA for review. FEMA reviews the projects 

for eligibility, completeness, engineering feasibility, cost-effectiveness, cost reasonableness, and 

environmental and historic preservation documentation. The review process also confirms that all 

hazard mitigation activities adhere to all relevant statutes, regulations, and program requirements 

including other applicable Federal, State, Indian Tribal, and local laws, implementing regulations, 

and executive orders, which are detailed in the HMA Unified Guidance. Once FEMA approves and 

awards the project, the grant funds are distributed by the State to the local governments, who will 

distribute it to individuals, as appropriate. No construction activities should begin until after the 

money has been awarded because HMA funding is not available for activities initiated or completed 

prior to award or final approval.

Stage 4. Project Implementation

Once the State has awarded the funds to the local government, the next stage in the process is 

project implementation. HMA projects have to be completed within a specific amount of time 

called a period of performance, which is usually not more than 36 months. The homeowner or 

local government should secure the professional services of a contractor (and engineer for nonprescriptive solutions) at this stage to develop a detailed construction plan. If the scope of work or 

cost estimate changes as a result, consult the HMA Unified Guidance for direction on how to revise 

the scope of work prior to construction.

During the period of performance, the local government must maintain a record of work and 

expenditures for the quarterly reports that the State submits to FEMA. To ensure that mitigation 

retrofits are being implemented in a manner that will effectively reduce the home’s risk to windrelated damage as approved, inspections should be conducted during the project. For example, if 

a wind retrofit project involves replacing the roof covering, the selection and spacing of fasteners 

should be verified by an evaluator before the underlayment and new roof covering are installed. 

Conducting inspections while the project is underway can ensure that any improperly installed 

components can be corrected before additional work is implemented, which can help reduce or 

eliminate unanticipated construction costs. The basic steps for implementing an HMA mitigation 

wind retrofit project are:

1. Evaluate the building to identify the viable Mitigation Package(s) and associated hazard 

mitigation projects (unless already completed during Stage 3, Application Development).

2. Select viable Mitigation Package(s) and eligible hazard mitigation projects (unless already 

completed during Stage 3, Application Development).

3. Secure professional services to complete the approved project.

SFHA

The SFHA is the area covered 

by the floodwaters of the 100-

year flood. NFIP’s floodplain 

management regulations must 

be enforced in the SFHA.
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-5

4. Complete installation of the approved hazard mitigation.

5. Inspect the completed hazard mitigation elements and verify other program requirements. 

Stage 5. Project Closeout

Once the wind retrofit project has been completed, a professional should conduct a final 

verification to ensure that the project was implemented as intended. This will allow project closeout 

documentation and confirm that the building provides the desired level of protection. In addition, 

the State or the FEMA Region will verify that the work was completed in accordance with the 

approved scope of work and closeout procedures. If the house is located in an SFHA, the local 

government must provide documentation of flood insurance for the structure and a copy of the 

recorded deed amendment. The HMA Unified Guidance should be referenced to ensure all closeout 

requirements are addressed.

Eligible and Ineligible Costs

Allowable mitigation costs for FEMA wind retrofit projects are for project components, such as design 

and building costs, directly related to and necessary for providing increased hazard protection from 

wind and wind-driven rain intrusion during a high-wind event . FEMA will only compensate costs 

that are consistent with the Basic, Intermediate, and Advanced Mitigation Packages described in 

this Guide. Eligible costs consistent with these Mitigation Packages include key personnel (such as 

the evaluator, inspector, and design professional); structure evaluation and inspection; planning 

and design activities; site preparation, building materials, and construction; structural systems 

capable of resisting design wind loads (including roof decking and roof support structures); soffits, 

vents, and turbines; protective envelope components such as walls, ceiling/roof systems, and doors; 

and other retrofit hardening activities that meet the criteria in this Guide. Performance-related 

improvements may also be eligible costs under FEMA’s grant programs.

FEMA wind retrofit projects are not intended to result in activities such as structure elevation or 

mitigation reconstruction. The structure evaluation process, as discussed in Chapter 3 and Appendix B, 

should identify existing conditions that must be addressed for the proposed Mitigation Packages to 

be effective. The structure evaluation may identify alternate or additional hazard mitigation measures 

that should be completed, such as a wind retrofit in combination with a structure elevation. In these 

cases, the local government developing the HMA project subapplication should modify the scope of 

work to accurately reflect all eligible hazard mitigation activities being requested. 

Ineligible costs include, but are not limited to, project activities and components not consistent 

with the Basic, Intermediate, or Advanced Mitigation Packages described in this Guide, uncertified 

construction products, costs related to functionality or outfitting such as furniture, interior or 

exterior decorative elements and fixtures, floor treatments, electrical and plumbing utilities, and 

other finishing materials that do not enhance the structural performance of the home. In addition, 

costs associated with the repair of gross negligence by a homeowner, previous homeowner, or bank 

are ineligible. This includes, but is not limited to, negligence, lack of maintenance and subsequent 

damage, termite infestation, and damage where there was a lack of termite inspections and termites 

were a known hazard. 
Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects

5-6

5.1.2 State Programs

Some States also offer funding for a wind retrofit project or, in some cases, insurance credits. 

Some examples of State programs and organizations that educate homeowners, fund wind retrofit 

projects, and reduce insurance premiums for residential buildings are described below. 

Rebuild Northwest Florida

Rebuild Northwest Florida is a public/private partnership that 

coordinates need-based recovery initiatives for citizens impacted 

by Hurricane Ivan in Santa Rosa and Escambia Counties, Florida. 

Current Rebuild Northwest Florida clients may qualify for 

residential wind retrofit funding through a partnership with the 

Florida Hurricane Relief Fund. The program is designed to help 

citizens fortify their living structures against future storm damage 

by funding items such as hurricane ties, straps, and shutters.

Residential Construction Mitigation Program (Florida)

The RCMP receives $7 million annually from the Florida 

Hurricane Catastrophe Trust Fund for the Mobile Home TieDown Program, hurricane research conducted by Florida 

International University, and to improve the wind resistance 

of residences through loans, subsidies, grants, and cooperative 

programs with local and Federal governments. The RCMP 

complies with the mitigation requirements outlined in their 

Hurricane Retrofit Guide (Florida Division of Emergency Management, 2007), a prescriptive guide 

to help homeowners decide how to protect their homes against the winds and rains of hurricanes. 

The guide includes ideas for homeowners on protecting their homes from wind hazards as well as 

technical help for people familiar with construction or in the construction business. 

South Carolina Comprehensive Hurricane Damage Mitigation Program (SC Safe Home)

The South Carolina Department of Insurance established the SC Safe Home Grant Program in 2007 

to provide grants to individual homeowners for retrofitting primary single-family residences. The 

program is based on the principle that retrofitted homes are less vulnerable to hurricane damage, 

resulting in fewer and lower insurance claims. This program requires a home inspection by a 

certified wind inspector prior to applying for a grant. The program awards up to $5,000 in matching 

funds for eligible retrofits, including roof covering , roof attachments , opening protection, and load 

path strengthening. Manufactured homes are eligible to receive funds for tie-downs only.

Mississippi Windstorm Underwriting Association Retrofit Mitigation Program

This program gives homeowners up to 30 percent in credit on their wind insurance premiums for 

retrofitting their homes to help protect the structure from loss due to windstorms. Insurance credit 

can be obtained when homeowners implement one of four groupings of wind retrofit projects. Each 

retrofit item in a particular grouping must be completed to receive credit for that group.

5.1.3 Federal Alliance for Safe Homes Program

The FLASH Program’s mission is to provide residential builders and citizens with accurate, 

current, and reliable information about how to make homes more disaster resistant. The FLASH 

FLORIDA WINDSTORM 

INSURANCE SAVINGS 

CALCULATOR

The Florida Division of 

Emergency Management 

has an online insurance 

savings calculator. It allows 

homeowners and builders 

to estimate wind insurance 

savings that Florida insurance 

companies make available for 

new construction and retrofits, 

such as those outlined in the 

Florida retrofit programs and 

this Guide.

The calculator is available at 

floridadisaster.org/mitdb.
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-7

program uses the Blueprint for Safety: Contractor’s Field Manual (FLASH, 2010) guidance to implement 

residential wind retrofit improvements. The Blueprint for Safety Field Manual supports FLASH’s 

mission to build, remodel, or restore homes using disaster-resistant techniques, technologies, and 

products specifically for wind hazards. 

5.1.4 FORTIFIED for Existing HomesTM Program

The FEH program was developed by the IBHS. The FEH program was developed in conjunction 

with this Guide, and as a result, the framework for these two programs is similar. Both guides 

were developed based on FEMA’s MAT observations and guidance documents, as well as modern 

engineering codes and standards. While the FEH program does not provide grants for projects, 

IBHS has developed the program in coordination with many prominent insurance companies. In 

doing so, homeowners who participate in the FEH program may be eligible for reductions in their 

home insurance premiums. 

Similar to this Guide, the FEH program involves an accredited FEH evaluator evaluating the home 

in its existing condition. The evaluator assesses the home and provides a report to the homeowner 

of the current condition of the home and retrofit options. The FEH program outlines three levels of 

increasing protection to retrofit a home to: Bronze, Silver, and Gold. More information on the FEH 

program can be found in Appendix A. 

5.2 Factors to Consider When Implementing Wind Retrofit 

Projects

Retrofitting existing buildings can be a complicated process. Building configurations, material types, construction methods, and local code and ordinances can all differ widely. This section 

discusses these issues so that the homeowner, local government, evaluator, contractor, and design 

professional can consider how such concepts may apply to their project and what potential issues 

may need to be addressed over the course of the project. Code compliance, local permitting and 

inspection requirements, and general construction hazards are also addressed in this section. 

5.2.1 Code Compliance Check

Modern building codes contain provisions for existing buildings to ensure that renovations, 

alterations, repairs, and relocations of space are completed in a manner that does not compromise 

the structural integrity of the building. While a wind retrofit project should improve the structural 

integrity of a home rather than reduce it, every wind retrofit project should still undergo a code 

compliance check to verify that the project does not trigger provisions for existing buildings. These 

types of provisions for existing buildings can potentially disrupt a wind retrofit project by creating 

additional work to implement the selected Mitigation Package. Additional information on these 

provisions, and the type of work they apply to, can be found in FEMA 499 Technical Fact Sheet 

No. 9.2 (see Figure 5-2 ).

As with new construction, individual retrofit measures and the measures that are part of the 

Mitigation Packages should comply with the ICC model building codes (or the effective building 

code adopted by the community, if it is more restrictive). This Guide does not intend for any retrofit 

measures to be performed that would result in a conflict with the building code as it applies to the 

hardening of residential buildings. 
Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects

5-8

One type of provision that is prevalent in existing building 

codes is for homes undergoing extensive repairs or 

improvements. Homes that experience severe damage from 

a storm may require repairs that would have to comply with 

substantial damage code triggers in the building code or 

the local flood ordinance. The resulting code compliance 

checks are generally triggered when work is considered to be 

a result of substantial improvement/substantial damage (SI/

SD) of the home. The SI or SD provisions are not likely to be 

triggered unless other work is being done at the same time 

as the retrofit measures. More information on SI/SD can 

be found in FEMA P-758, Substantial Improvement/Substantial 

Damage Desk Reference (FEMA, 2010b). 

A summary of code compliance checks for the 2009 IEBC; 

2009 IRC; and 2007 FBC: Existing Building (ICC, 2008b) 

is provided in Table 5-1. Table 5-1 also includes a brief 

commentary on how the provision may apply to a wind 

retrofit project. Note that there may be additional provisions 

not included in Table 5-1; this should be verified before 

implementing a wind retrofit project.

5.2.2 Permitting and Inspections

Homeowners should ensure that their retrofit projects are 

properly permitted through their local building department 

and that inspections required by the local building 

department are carried out. Permitting and inspection 

procedures in coastal areas are usually more involved than 

those in inland areas, and, if unanticipated, can complicate 

a wind retrofit project. For instance, in addition to meeting 

all of the Federal, State, and local requirements, the design 

plans and specifications may need to be sealed by a design 

professional. Building permit submittals must often include 

detailed drawings and information for all elements of the 

wind-resisting load path, including sheathing material, 

sheathing nailing, strap and tie-down descriptions, 

bolted connections, and pile description and placement. 

Local building department requirements vary with each 

community and should be considered as early as possible in 

the process of developing a wind retrofit project.

This Guide provides only an overview of the permitting and 

inspection process. Homeowners should be aware that most 

of the retrofit projects described in Chapter 4 of this Guide 

would be considered repairs, alterations, or additions. These 

terms have specific meanings with regard to building codes, 

and may trigger a special permitting process, depending on 

local code provisions as described above. 

SUBSTANTIAL IMPROVEMENT/

SUBSTANTIAL DAMAGE (SI/SD)

Section R112.2.1 of the IRC defines 

SI as “any repair, reconstruction, 

rehabilitation, addition or 

improvement of a building or 

structure, the cost of which equals 

or exceeds 50 percent of the market 

value of the building or structure 

before the improvement or repair is 

started. If the building or structure 

has sustained substantial damage, 

all repairs are considered substantial 

improvement.” (IRC, 2009)

Section 1612.2 of the IBC defines 

SD as “damage of any origin 

sustained by a structure whereby 

the cost of restoring the structure to 

its before-damage condition would 

equal or exceed 50 percent of the 

market value of the structure before 

the damage occurred.” (IBC, 2009)

FIGURE 5-2: 

FEMA 499 Technical Fact Sheet 

No. 9.2, Repairs, Remodeling, 

Additions, and Retrofitting—Wind
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-9

Code Check IEBC1 IRC FBC3 Comments

Flood 

Hazard 

Areas

303.2: Any alteration 

that constitutes SI/SD 

shall comply with flood 

damage requirements 

for new construction.

AJ102.5: Any 

alteration 

that 

constitutes 

SI shall 

comply with 

the flood 

damage 

requirements 

of new 

construction.

All Packages: Applicable 

if done simultaneously with 

SI/SD and located in a flood 

hazard area.

Existing 

Structural 

Elements 

Carrying 

Gravity Load

303.3: Any existing 

gravity load-carrying 

structural element for 

which an alteration 

causes an increase 

in design load of 

more than 5% shall 

be strengthened, 

supplemented, 

replaced or otherwise 

altered to carry the 

increased load.

606.2.1: Addition or 

replacement of roofing 

or equipment resulting 

in additional dead load 

greater than 5% or a 

second layer of roof 

covering weighing more 

than 3 psf over an existing, 

single layer roof covering 

results in the need for 

reroofing and equipment 

to comply with the vertical 

load requirements of the 

FBC.

Basic Package: New roof 

covering may weigh more 

than the previous roof 

covering (or greater than 5% 

of the previous in the case 

of the FBC).

IEBC: Existing load-carrying 

structural elements should 

not require strengthening 

to carry increased gravity 

loads from retrofits.

FBC: It is recommended 

that a roof covering product 

less than 5% heavier than 

the existing roof covering be 

selected.

Wall 

Anchors for 

Concrete 

and Masonry 

Buildings

606.2.1: Re-roofing 

more than 25% of 

roof area if concrete 

and masonry building 

is in seismic design 

category D, E, or F, 

work shall include 

installation of wall 

anchors to resist IBC 

seismic forces.

Basic Package: Applicable 

if re-roofing in an area that 

is both hurricane- and 

earthquake-prone (e.g., 

Charleston, SC) with 

concrete and masonry 

construction.

Voluntary 

LateralForceResisting 

System 

Alterations

707.6: Alterations 

of existing and new 

structural elements 

intended to increase the 

lateral force-resisting 

strength need not be 

designed for the IBC 

forces if an engineering 

analysis is submitted to 

show: lateral loading is 

not increased beyond 

10%; new elements are 

detailed and connected 

according to IBC; and 

a dangerous condition 

does not result.

All Packages: Applicable if 

wind retrofit project qualifies 

as a Level 2 alteration;2 an 

engineer may be needed to 

conduct an analysis.

Wind retrofit projects should 

not qualify as a Level 2 

alteration unless additional 

work is being done to the 

home.

TABLE 5-1: Code Compliance Checks
Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects

5-10

Code Check IEBC1 IRC FBC3 Comments

Structural 

Alterations

807.4: If a Level 3 

alteration results, all 

structural elements 

of the lateral forceresisting system in 

buildings shall comply 

with 807.4.2 below.

All Packages: Applicable 

if the wind retrofit project 

results in a Level 3 

alteration.

Wind retrofit projects should 

not qualify as a Level 3 

alteration unless additional 

work is being done to the 

home.

Substantial 

Structural 

Alterations

807.4.2: Where more 

than 30% of the total 

floor and roof areas of 

the building have been 

proposed to be involved 

in a structural alteration 

in a 1-year period, an 

analysis must show 

the altered building 

complies with the IBC 

for wind loading and 

reduced seismic forces.

All Packages: Applicable 

if the wind retrofit project 

results in Level 3 alterations.

Wind retrofit projects should 

not qualify as a Level 3 

alteration unless additional 

work is being done to the 

home.

NOTE: 30% of the total 

floor and roof area includes 

tributary areas to vertical 

load-carrying components.

Roof 

Diaphragm

606.3.2: Where roofing 

materials are removed 

from more than 50% 

of the roof diaphragm 

or if the building is 

located where the 

basic wind speed is 

greater than 90 mph 

or in a special wind 

region, the integrity 

of the roof diaphragm 

shall be evaluated and 

connections need be 

provided or replaced to 

meet IBC requirements.

606.3: Where roofing 

materials are removed 

from more than 50% 

of the roof diaphragm, 

the integrity of the roof 

diaphragm shall be 

evaluated and connections 

need be provided or 

replaced to address 

deficiencies.

Basic Package: Applicable 

only if home has “defective” 

roof sheathing, and such a 

home would not generally 

be considered a good 

candidate for a retrofit 

project.

IEBC: Provision applies only 

if roof structure and not roof 

covering is at least 50% 

replaced. This condition 

should not occur for eligible 

candidates.

Roof 

Covering

611.1.1: Not more than 

25% of the total roof 

area or roof section shall 

be repaired, replaced or 

recovered in any 1-year 

period unless the entire 

roofing system or section 

conforms to the FBC: 

Existing Building.

Basic Package: Applicable 

when reroofing.

NOTE: The entire roof 

system and section must 

conform to the FBC, 

but the roof diaphragm 

does not have to meet 

the requirements for new 

buildings.

TABLE 5-1: Code Compliance Checks (continued)
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-11

Homeowners or their contractors will need: (1) construction documents consisting of plans and a 

bill of materials; and (2) descriptions of the proposed project, including a scope of the work that 

complies with the requirements of any funding source that may be sought (refer to Section 5.1) and 

the local building code. 

Homeowners should be aware that retrofit actions may trigger the requirement for code verification; 

additionally, those elements of the home affected by the retrofit may be required to be brought up to 

the current building code as discussed in Section 5.2.1. These elements may include the structural, 

electrical, mechanical, or plumbing systems, or the method by which the structure provides fire 

protection. If there is a local building department, inspections may be required throughout the 

process in addition to a final inspection. 

If there is no building department or building codes are not 

being enforced, it is important that the evaluator who performed 

the home evaluation (or the designer involved in the project, if 

applicable) inspect the construction of the retrofit to ensure that 

the work was performed as outlined in the Mitigation Package. 

Multiple evaluations during the course of the project (as well 

as once the project has been completed) should be performed 

to verify that the work is completed in a manner consistent with 

the plans (see Chapter 3). At the conclusion of the retrofit, it is 

important that the homeowner obtain written documentation 

from the individual performing the final inspection to verify that 

the retrofit was properly installed and that the materials used were 

consistent with the requirements of the construction plans. If the 

homeowner is anticipating an insurance premium adjustment, a 

TABLE 5-1: Code Compliance Checks (continued)

ADDITIONAL INFORMATION 

ON PERMITTING AND 

INSPECTIONS:

Chapter 4 of FEMA P-762, 

Local Officials Guide for 

Coastal Construction, presents 

important regulatory facts, 

management tools, detailed 

information for conducting 

effective and efficient building 

permit application reviews, 

sample organizational 

structures, and a permitprocessing flowchart.

1) The IBC states that there is an alternative compliance with the IEBC in place of the IBC for existing structures (any retrofit 

projects would fall into this category). It should be noted that most of the provisions of the IBC are similar to the IEBC, but 

the IBC is not as stringent in its requirements.

2) Levels of alteration correspond to the three levels defined in the IEBC, IRC, IBC, and FBC: Existing Building.

3) 2007 FBC including the 2009 supplement.

Code Check IEBC1 IRC FBC3 Comments

Roof-to-Wall 

Connections

611.8 and 611.8.1: When 

the roof covering is 

removed and replaced 

in a windborne debris 

region and the home 

has an insured value of 

$300,000 or more, if the 

building is uninsured, has 

a just valuation for the 

structure for the purposes 

of ad valorem taxation of 

$300,000 or more, roof to 

wall connections shall be 

improved to meet the uplift 

loads specified in the FBC: 

Existing Building. 

Basic Package: Applicable 

when reroofing a home 

that triggers this provision, 

unless the gable-end work 

costs more than 15% of the 

roof covering work.

If provision is triggered, 

some roof-to-wall 

connections may have to be 

installed, even for the Basic 

Package.
Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects

5-12

passing “notice of the final inspection” from the building department or written documentation 

from a design professional will need to be submitted.

It is important to verify that the retrofit project, or projects being done simultaneously with the 

retrofit project, do not constitute a substantial improvement if the building is located in the 

SFHA (refer to Section 5.2.1 for additional discussion). In the event that the project meets the 

substantial improvement designation, per the building code or local ordinances, additional work 

may be required. Whether the work will meet the substantial 

improvement designation should be verified prior to submitting 

the permit application or, if there is no permitting process, before 

beginning the work.

It is also important to make sure that the retrofits performed 

comply not only with the codes, but with local ordinances. Historic 

structures may need to comply with additional standards to 

maintain the designation as a historic structure. Noncompliance 

can lead to fines, work stoppage, and possibly legal issues. While 

variances are granted by local building departments for certain 

projects and are considered part of the construction process, the 

issuance of a variance is rare and should not be considered an 

alternative to compliance with codes and ordinances.

5.2.3 Construction Challenges

The process for implementing a retrofit project should be carefully planned before removing the 

first piece of siding or pulling off the first shingle. Homeowners should consider a variety of factors, 

including how the exterior of their home will look after the retrofit is completed, how to optimize 

labor versus material costs for the retrofit project, selection and proper use of connectors, availability 

of materials, and home maintenance.

Ideally, the resulting retrofitted house will have an exterior that looks similar to the house before 

the retrofit. Exterior building materials should be carefully removed if they are to be replaced. 

Access to the soffit or rafter system may be another instance where careful planning will pay off 

for the homeowner. One method of retrofitting may cost more in materials but require less labor 

to install, or may require fewer repairs to the house in order to install them. For example, the 

homeowner may wonder whether it is more cost effective to retrofit a gable end wall with lumber 

and fewer connectors. Although this may be a cost-effective solution, if the attic access is very small, 

a retrofit using more metal connectors may be a more practical 

solution. The work (and associated cost of labor) required to 

implement a retrofit should be discussed among the homeowner, 

evaluator, contractor, and design professional (if applicable) in 

detail and considered in the homeowner’s decision process. 

The selection of the proper fasteners and connectors is critical to 

the success of a retrofit. Connectors are designed to use specific 

fasteners and used in specific situations. Manufacturers provide 

information on how the connectors should be used, how many 

fasteners are required, and what size fasteners are required. They 

VARIANCE

A variance is a process 

that allows a building to be 

constructed in a manner that 

is usually prohibited by either 

the building code or local 

ordinances. The criteria for this 

are usually very specific, and 

typically the requirement is that 

it will be granted only if there is 

a unique characteristic to the 

land or historically significant 

structures.

ADDITIONAL 

CONSIDERATIONS

Additional information on 

issues to consider before 

starting a retrofit can be 

found in FEMA 499 Technical 

Fact Sheet No. 9.2, Repairs, 

Remodeling, Additions, 

and Retrofitting—Wind (see 

Figure 5-2).
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-13

should never be bent or forced into a location; this compromises the strength of the connector 

and can result in an ineffective retrofit. In some situations, longer fasteners may be required. For 

example, if uplift connectors are being attached between the rafter and the wall top plate, a longer 

fastener may be needed if exterior sheathing is covering the top plate. The connectors are designed 

to be used with fasteners that have a minimum embedment into the top plate, so the fastener 

would need to be longer to account for the thickness of the exterior sheathing. The construction 

techniques used to build the house and the accessibility of the work space may dictate the selection 

of the connectors and fasteners. 

Another consideration is the availability of materials. Consider that although a nominal 2x2 may be 

the minimum required size, a nominal 2x4 may be a cheaper alternative. An experienced contractor 

can assist homeowners with this type of decision before beginning the retrofit project. Terms such 

as “minimum” used in retrofitting guides (e.g., those described in Section 5.1) may be clues that 

other design solutions exist and, if the work space permits, that a more cost-effective solution may 

be available that provides the same or better level of protection. Retrofit guides may list numerous 

fastener options. Some construction materials may respond better to certain types of fasteners, or 

some fasteners may be easier to use in specific locations.

Remember that the effectiveness of a retrofit rests on the ability of the materials to maintain their 

strength through time. Maintenance of the home is critical to maintaining the level of protection 

desired; this is especially true in corrosive environments common to coastal areas, where wood 

should be regularly inspected for decay, and metal connectors and fasteners should be inspected for 

corrosion. Replacement of these materials may be required periodically to maintain the strength of 

the system. When determining which Mitigation Package to implement, it is important to evaluate 

the ease with which materials can be maintained or replaced as needed. The level of effort required 

for maintenance is generally proportionate to the accessibility of the retrofit. More information on 

the selection of construction materials can be found in FEMA 499 Technical Fact Sheet No. 1.7, 

Coastal Building Materials.

5.3 Addressing Other Hazards

The retrofits described in this Guide are intended to be implemented in hurricane-prone regions, but may be applied elsewhere. The most significant natural hazards that affect the coastlines 

of the United States and its territories can be divided into tornadoes, coastal flooding, erosion, 

earthquakes, and other hazards. Additionally, homeowners should be aware that residual risk to their 

home always exists, even when properly implemented hazard resistance projects are undertaken. 

When applying for a FEMA grant, residual risk must be identified.

Tornadoes: Although a tornado is a high-wind hazard, it is not specifically addressed in this 

Guide. Tornadoes require special consideration for mitigation. PDM and HMGP funds may 

be used for the construction of a tornado or combined hurricane/tornado safe room that 

provides near-absolute protection if constructed according to guidelines of FEMA 320 and 

FEMA 361. For more information on the FEMA safe room program, see Chapter 2 of this 

Guide. PDM and HMGP funds are not available for construction of general population 

shelters, including evacuation or recovery shelters intended to provide longer-term services 

and housing. For more information, refer to the HMA Unified Guidance.
Wind Retrofit Guide for Residential Buildings

CHAPTER 5: Implementing Mitigation Projects

5-14

Flooding: Coastal flooding often results in significant 

damage to homes in coastal areas. Hurricanes, 

tropical cyclones, other coastal storms, and tsunamis 

generate the most significant coastal flood hazards. 

Their floodwaters can create hydrostatic and 

hydrodynamic forces, wave effects, and floodborne 

debris effects that can significantly affect the 

performance of residential buildings. In addition, 

there is the risk of riverine flooding for buildings 

farther from the coast. For guidance on retrofitting 

homes for flood hazards, see FEMA 259, Engineering 

Principles and Practices of Retrofitting Floodprone 

Structures (FEMA, 2001). If retrofitting is considered 

a substantial improvement (see text box in Section 

5.2.1) and the home is in an SFHA, the construction 

must comply with local or NFIP floodplain 

regulations. To determine if a home is in an SFHA, 

visit the FEMA Map Service Center (msc.fema.gov) 

or check with your local floodplain management 

official.

Storm Surge: Storm surge is distinct from the coastal 

flooding that defines the SFHA. Storm surge is the 

water that is pushed toward the shore by the high 

winds associated with tropical storms and hurricanes. 

This increases the mean water level and can cause 

severe flooding that reaches farther inland, beyond 

the SFHA. Storm surge is particularly high when 

combined with the normal high tide. The Sea, Lake, 

and Overland Surge from Hurricanes (SLOSH) 

model maps five categories of storm surge. SLOSH 

models and storm surge maps are available from 

State emergency management departments. For 

examples of coastal storm surge maps, see MEMA’s 

Web page on hurricanes (www.msema.org/

preparation/hurricanes.html).

Erosion: Erosion is the wearing or washing away of land and 

is one of the most complex hazards to understand 

and predict at a given site. Typically, erosion refers 

to the horizontal recession of a shoreline. Erosion 

is capable of threatening coastal buildings by 

destroying dunes or other natural protective features, 

destroying erosion control devices, lowering ground 

elevations, undermining shallow foundations, 

reducing depths of deep foundations such as 

piles, supplying overwash sediments that can bury 

structures farther landward, breaching low-lying 
CHAPTER 5: Implementing Mitigation Projects

Wind Retrofit Guide for Residential Buildings 5-15

coastal barrier islands, and sometimes exposing structures on the mainland to increased 

flood and wave effects. 

Earthquakes: Earthquakes can affect coastal areas through ground shaking, liquefaction, surface 

fault ruptures, other ground failures, and the generation of tsunamis. Therefore, coastal 

construction in seismic hazard areas must take earthquake hazards into account. Proper 

design in seismic hazard areas employs techniques to stabilize or brace the building against 

violent accelerations and shaking due to earthquakes. For guidance on seismic retrofits 

of existing homes, see FEMA 232, Homebuilders’ Guide to Earthquake Resistant Design and 

Construction (FEMA, 2006b).

Other Hazards: Other hazards that coastal construction may be exposed to include a wide variety 

of hazards whose incidence and severity may be highly variable and localized. Examples 

include subsidence and uplift, landslides and ground failures, salt spray and moisture, rain, 

hail, wood decay and termites, wildfires, floating ice, snow, and atmospheric ice. These 

hazards do not always come to mind when coastal hazards are mentioned, but should be 

considered in design and construction decisions. 

Residual Risk: While homeowners may retrofit their houses to mitigate wind hazards, residual 

risk will remain. No wind retrofit project completely protects a home against wind damage; 

furthermore, the risk from hazards described above will remain unless specifically 

addressed. The failure to properly identify and design to mitigate other hazards in 

coastal areas and hurricane-prone regions can lead to severe consequences, such as 

building damage or even destruction. When following the guidance presented in this 

Guide, homeowners should understand the elements of risk that remain in their homes. 

Publications such as FEMA 55, Coastal Construction Manual, FEMA P-762, Local Officials 

Guide for Coastal Construction, and FEMA 499, Home Builder’s Guide to Coastal Construction can 

help homeowners further understand the residual risks from wind retrofit projects and to 

successfully account for and mitigate other relevant coastal hazards. Appendix D of this 

Guide includes a list of links to FEMA and other building science publications that should 

be considered when planning a wind retrofit project. 

Wind Retrofit Guide for Residential Buildings A-1

APPENDIX A

FORTIFIED for Existing HomesTM

A.1 Program Overview

The IBHS FEH program provides prescriptive solutions for retrofitting single-family homes in 

hurricane-prone regions. The prescriptive solutions proposed by FEH were developed in part from 

FEMA best practice and guidance publications and the FEMA MAT findings, in much the same way 

this Guide was written. The FEH program has three designations, Bronze, Silver, and Gold, and 

prescribes evaluation protocols and encourages insurance premium reductions.

The FEH program was developed by focusing on the observed damages and losses caused by 

different hurricane events. The designation levels follow a prioritized strategy for retrofitting homes, 

which is outlined in detail in the FEH manuals on each level. 

IBHS developed FEH in consultation with the insurance industry to ensure that the homes achieving 

a FORTIFIED designation also receive a standardized insurance premium reduction. Greater 

insurance premium reductions are awarded at the higher designation levels. 

A.2 Inspections and Evaluations

One notable component of the FEH program is the standardized inspection process each home 

must undergo prior to retrofitting. To determine whether the home is suitable for a wind retrofit 

project, an FEH accredited evaluator performs an evaluation of the home in accordance with the 

FEH inspection criteria.

A.3 Summary of the Bronze Level of Protection

The Bronze designation is the lowest hurricane-resistance designation a home can achieve. There 

are two options to consider when retrofitting a home to achieve the Bronze FEH designation. One 

option involves replacing the roof covering, while the other option does not. 

4 When the roof covering will not be replaced, the retrofits for a Bronze designation are 

required to:

9 Strengthen the anchorage of the gable end walls

9 Secure soffits and protect roof vents

9 Secure roof sheathing by using SPF adhesive on the underside of the roof sheathing 
Wind Retrofit Guide for Residential Buildings

Appendix A: FORTIFIED for Existing HomesTM

A-2

4 When the roof covering will be replaced, the retrofits for a Bronze designation are 

required to:

9 Secure roof sheathing through the addition of fasteners in accordance with a designated 

schedule

9 Install a secondary underlayment

9 Strengthen the anchorage of gable end walls

9 Secure soffits and protect roof vents

9 Install a new roof covering 

A.4 Summary of the Silver Level of Protection

The Silver designation is the second level in the FEH designations. To achieve the Silver designation, 

the home must meet the requirements of the Bronze designation in addition to the retrofits specific 

to the Silver designation. 

4 Retrofits required to achieve a Silver designation include: 

9 Protect building openings (windows, entry doors, and garage doors) from windborne 

debris

9 Further strengthen gable ends

9 Strengthen the anchorage of attached structures such as porches and carports

The Silver designation provides a higher level of protection against wind damage than the Bronze 

designation, and consequently has a higher project cost. However, the Silver designation should 

provide a greater reduction in insurance premiums than a Bronze designation.

A.5 Summary of the Gold Level of Protection

The Gold designation is the highest level that can be achieved in the FEH program. To achieve the 

Gold designation, homes must first meet both the Bronze and Silver requirements as well as the 

additional retrofit requirements specific to the Gold designation.

4 Retrofits required to achieve a Gold designation include: 

9 Develop a continuous load path

9 Protect building openings from windborne debris and wind pressure

A Gold designation requires a more invasive inspection and has a greater project cost. However, the 

Gold designation also provides the most significant reduction in insurance premiums and highest 

level of protection of all designations within the FEH program.

Prescriptive solutions to develop a continuous load path for simple building shapes and types of 

construction are provided in the FEH manual to meet the continuous load path requirement of the 

Gold designation. FEH does not require that a professional engineer be consulted to achieve the 

Gold designation if a prescriptive solution can be used. 
Wind Retrofit Guide for Residential Buildings B-1

APPENDIX B

Evaluation Guidance

This appendix provides information and guidance to home evaluators on the evaluation process 

that should be followed to initiate a wind retrofit project. The purpose is to set the framework for 

an evaluator to assess a home being considered for a wind retrofit project. This guidance is not 

intended to be used as a comprehensive “checklist” for evaluators, but rather to outline the type of 

information that should be obtained during the evaluation process and how it should be conveyed as 

findings and recommendations that can be used to identify and select appropriate wind mitigation 

activities. The evaluation process set forth in this appendix in Sections B.4 to B.6, when executed by 

a qualified evaluator, will enable a consistent and thorough evaluation that accurately assesses the 

condition of the home and its vulnerability to damage from wind and windborne debris. With this 

guidance, an evaluator can recommend the course of action moving forward. 

B.1 Qualifications of an Evaluator

Evaluators must possess sufficient knowledge of the design and construction of residential buildings 

to perform these evaluations, but they need not be a registered engineer or architect. However, the 

evaluator should have knowledge of and familiarity with the wind retrofit Mitigation Packages and 

their intent as described in this Guide. 

B.2 Evaluation Report

The evaluation process should result in a report that describes the building condition, building 

characteristics, and building vulnerability information to identify which Mitigation Package from 

this Guide should be implemented. This information will help homeowners determine whether 

they should proceed with a wind retrofit project, and specifically which Mitigation Package would 

be the most appropriate. The evaluation report must specifically address the proposed Mitigation 

Package(s) being considered. The level of protection associated with the different Mitigation 

Packages will reduce risk from wind hazards to some degree. It is important for the evaluation report 

to convey how much existing risk will be mitigated by the retrofit project and how much residual risk 

may remain; this is especially true if only the Basic Mitigation Package is being considered and the 

home is located in a well-defined wind hazard area. The report should also have a clearly marked 

“BCA Input” section that lists all data needed to perform a wind retrofit BCA, as described in Section 

B.4, Key Information to Collect for an Evaluation Report. Section B.6, Summary of Guidance for 

Evaluators, contains questions regarding each component of the building being evaluated to guide 

the evaluation process. These questions, in addition to the data described in Sections B.4 and B.5 

should help the evaluator gather the necessary information for the evaluation report. 
Wind Retrofit Guide for Residential Buildings

APPENDIX B: Evaluation Guidance

B-2

B.3 Benefit-Cost Considerations

The evaluation process should obtain all information necessary for a grant program manager, local 

official, homeowner, or other entity to perform a BCA using the FEMA BCA Tool (Version 4.5.5). 

This is important because the results of the BCA may be used to understand whether the proposed 

wind retrofit Mitigation Package is a cost-effective project for the home, and if the proposed wind 

retrofit Mitigation Package addresses risk adequately or leaves homeowners with residual risk after 

mitigation that they may find unacceptable.

B.4 Key Information to Collect for an Evaluation Report

The following information should be collected during the evaluation process and shown in the 

report:

4 Owner information (name, contact information)

4 Property information (building address, replacement cost, year of construction)

4 Building dimensions (total square footage, mean roof height, number of stories)

4 Design wind and flood hazard information (design wind speed based on ASCE 7, exposure 

category, flood zone for the property per the applicable Flood Insurance Rate Map, and 

Elevation Certificate)

4 Photographs of the exterior of the home

4 Design information of the home (construction and renovation plans, if available)

4 Observations on the following components:

a) Roof covering (age of covering, wind rating, if available)

b) Roof structure

c) Windows, skylights, entry doors, and garage doors

9 Opening protection devices or systems (design pressure and debris impact-resistance 

criteria, if applicable). This may be in the form of shutters, screens, or panels used 

to protect openings from debris impact. It may also be in the form of a laminated, 

polycarbonate, or other pressure-rated and debris-impact resistant glazing system.

d) Exterior envelope components that will be affected by the proposed mitigation action

e) Exterior envelope components that would reduce risk if mitigated, but are not part of 

any Mitigation Package (such as wall coverings) 

f) Exterior walls (both load-bearing and non-load-bearing)

g) Attached structures

h) Structural connections

i) Foundation

4 Information to support the development of cost estimates for Mitigation Packages (such 

as roof square footage, soffit area to be mitigated, number and sizes of openings to be 

protected, etc.)
APPENDIX B: Evaluation Guidance

Wind Retrofit Guide for Residential Buildings B-3

In addition to collecting data on the construction type and condition of the building, the data 

required to evaluate the cost-effectiveness of a project using the FEMA BCA Tool should be collected 

and provided to the homeowners. This will allow a user to easily follow the guidance in Appendix C 

of this Guide; completing a BCA is a necessary step when applying for FEMA grant funding. The 

following should be provided in a clearly marked “BCA Input” section of the evaluation report:

4 Wind hazard information for the area

4 Building type (wood or masonry; note: for masonry structures, existing reinforcement 

should be documented)

4 Number of stories

4 Roof shape (hip or gable)

4 Whether secondary water barrier exists on the roof

4 Fastener size and spacing for roof deck attachments

4 Attachment of the roof-to-wall connection 

4 Whether there are shutters on the home and if they are required by the current building 

code for new construction in this jurisdiction

4 If a garage is present, the condition of the garage door

Regardless of whether the homeowner is considering applying for funding for the wind retrofit 

project, these BCA inputs should be provided on the report. The FEMA BCA Tool will help 

determine whether a project is cost effective (i.e., whether the benefits of the project outweigh the 

costs). More information on using the FEMA BCA Tool to analyze a wind retrofit project is provided 

in Appendix C of this Guide. 

B.5 Identifying Damage and Deficiencies

The evaluation process should identify if any significant deficiencies or conditions exist that must 

be addressed for the proposed solutions of the Mitigation Packages to be effective mitigation. 

Construction conditions, older techniques, or poor condition of building materials are just a few 

of the items that may need to be addressed or corrected, in addition to the actual retrofit action, to 

ensure the home meets the basic performance assumptions of this Guide. However, the corrective 

work may or may not be an eligible cost under the wind retrofit project type. Building elements that 

require corrective work may include, but are not limited to, the following:

4 Foundations that are inadequate or do not provide safe and stable support for a residential 

building in a hurricane-prone region (such as dry-stacked concrete masonry units, 

foundations with no load path from the floor or wall connection to the ground, or 

damaged/undermined foundations)

4 Building elements weakened by insect damage or infestation

4 Rot or deterioration of the structure or envelope systems that would prevent the home from 

carrying the loads it was designed to withstand
Wind Retrofit Guide for Residential Buildings

APPENDIX B: Evaluation Guidance

B-4

4 Elevation of the home if located in a Zone V and not properly elevated on an open 

foundation per the NFIP or local flood plain ordinance

If any such deficiency exists for an element in the home being evaluated, an estimate of the degree 

of repair required should be provided, if possible. In some situations, a design professional may 

need to be involved to effectively assess the magnitude of the condition and the work required to 

repair it. If the conditions are difficult to repair and have high associated costs, it is possible that the 

home is not a candidate for wind mitigation retrofitting using the Mitigation Packages in this Guide. 

Information regarding a home’s deficiencies and overall condition can greatly aid homeowners, 

both for the purpose of executing the wind retrofit project and to understand the condition of 

their home. 

B.6 Summary of Guidance for Evaluators

The following guidance can help evaluators collect the data necessary to produce the evaluation 

report.

Envelope Assessment

Goals:

4 Identify weaknesses in the home’s envelope where wind or wind-driven rain can enter the 

home 

4 Identify ways to mitigate those weaknesses 

4 Determine what Mitigation Package is appropriate

Roof Covering:

4 What is the existing roof covering type? (e.g., asphalt shingles, clay or concrete tile, etc.)

4 What is the existing roof covering age? (in years) 

4 What is the expected remaining useful life of the roof covering? (in years) 

4 What is the roofing design wind speed? (in mph) 

(“Unknown” if roof covering has a design wind speed that is not documented)

a) Is the design wind speed in fastest mile or 3-second gust? 

4 Is a secondary water barrier present beneath the roof deck and roof covering? If so, provide 

details.

Roof Sheathing and Connections:

4 What is the roof sheathing type? (e.g., wood boards, wood structural panels)

4 What is the roof sheathing thickness? (in inches)

4 How is the roof sheathing secured to the roof framing:

a) Within 4 feet of eaves hips, ridges, and gable ends?
APPENDIX B: Evaluation Guidance

Wind Retrofit Guide for Residential Buildings B-5

b) In other areas of the roof deck?

4 Are there any observable shattered or broken sheathing panels in the attic?

4 Are sheathing or truss shiners visible from inside the attic? If so, how many?

Attic Ventilation Systems:

4 What attic ventilation system is in place? (soffits, ridge vents, gable vents, etc.)

4 Are soffit vents braced or otherwise protected to resist wind pressures and prevent winddriven rain entry? 

4 Are gable vents braced or otherwise protected to resist wind pressures and prevent winddriven rain entry?

4 Are off-ridge vents braced or otherwise protected to resist wind pressures and prevent winddriven rain entry?

4 What are the lengths of overhangs at gables (if applicable) and eaves?

4 Are there other overhangs? (e.g., carports, porches, breezeways)

Openings:

4 Windows

a) What are the sizes and quantities of all windows?

b) For each window, is glazing protection present?

c) For each window, is there a provided differential pressure rating and/or impact rating 

of the window or protection? If so, provide details. 

d) Are skylights present on the home? If so, are they protected?

4 Doors

a) What are the sizes and quantities of all entry doors?

b) For each entry door, is a differential pressure rating and/or impact rating of the door or 

protection provided? If so, provide details.

c) What are the sizes and quantities of all garage doors?

d) For each garage door, is a differential pressure rating provided?

e) For each garage door with glazing, is the impact rating for the glazing provided?

Attached Structures:

4 Are there any attached structures present? (e.g., porches, carports)

a) If so, is there a continuous load path in the attached structures?

b) How are the structures attached to the home?
Wind Retrofit Guide for Residential Buildings

APPENDIX B: Evaluation Guidance

B-6

Structural Assessment

Goals: 

4 Identify weaknesses in the home’s structural system that can fail when exposed to wind 

loads 

4 Identify ways to mitigate those weaknesses 

4 Determine what level of mitigation is achievable 

Roof Framing:

4 For homes with engineered wood trusses:

a) Are truss members and connector plates damaged or deteriorated?

b) Have alterations or repairs of any truss member been made? If so, do the repairs ensure 

that members can safely carry the appropriate gravity and uplift loads?

4 For homes with wood roof rafter and ceiling joist framing:

a) Are any roof framing members damaged or deteriorated?

Wall Construction:

4 What are the wall heights for each story?

4 Do any exterior walls have significant window and/or door area? 

4 For exterior bearing walls:

a) Is the wall framing system capable of supporting vertical and lateral wind loads?

b) Are connections between walls and structural framing members at the top and bottom 

of the wall capable of adequately transferring vertical and lateral wind loads?

c) For homes with multiple stories, are wall framing systems capable of supporting 

cumulative wind loads?

4 For interior bearing walls:

a) Is the interior wall framing system capable of supporting the gravity load and vertical 

and lateral wind loads?

b) Are connections at the top and bottom of interior wall framing systems capable of 

transferring the gravity load and vertical and lateral wind loads?

c. Is the foundation, floor framing, or bearing wall capable of supporting the wall framing 

system?

Gable End Walls (if applicable):

4 What are the heights of all gable end walls?

4 Do gable end walls have structural sheathing? If not, identify sheathing type (e.g., foam 

sheathing, no sheathing).
APPENDIX B: Evaluation Guidance

Wind Retrofit Guide for Residential Buildings B-7

Floor Framing:

4 Is the floor framing system capable of supporting the gravity load and vertical and lateral 

wind loads?

4 Is the floor framing system adequately supported?

Foundation:

4 Is the foundation support system capable of resisting uplift and shear forces and 

transmitting them to the ground?

4 Is the foundation in good condition? Are there signs of failure or duress in the foundation?

Chimney (if applicable):

4 Was the chimney designed for high wind loads?

4 Are there anchors, straps, or other elements that provide a means for the structure to resist 

wind loads?

Continuous Load Path:

4 Is there a continuous and adequate load path from the roof to the foundation of the home?

4 Are roof-to-wall connections capable of resisting uplift loads?

4 For multi-story homes, are wall-to-wall connections capable of resisting accumulated uplift 

and shear forces?

4 Are wall-to-foundation connections capable of resisting accumulated uplift and shear 

forces?

Wind Retrofit Guide for Residential Buildings C-1

APPENDIX C

Using the Hurricane Wind 

Module for Determining 

Cost Effectiveness of Retrofit 

Projects 

C.1 Introduction

The FEMA BCA Tool (Version 4.5.5) is used to determine the cost-effectiveness of proposed 

mitigation projects submitted for funding under FEMA mitigation grant programs. The software 

estimates the economic consequences that may occur during a natural disaster (flood, hurricane, 

tornado, earthquake, or wildfire) based on two scenarios, with and without the proposed mitigation 

measure. For hurricane wind, losses are estimated using wind-damage functions developed to 

predict wind impacts to the building, its contents, and loss of use of the building following a storm. 

The wind-damage functions relate peak gust wind speeds to predicted percentages of damage that 

would be expected for a building exposed to storms at a given recurrence interval. The recurrence 

intervals of hurricane wind speeds are based on the building’s location (using either the building 

zip code or latitude/longitude and wind speed data derived from HAZUS-MH). The anticipated 

damages vary based on the type of building and its construction attributes. Wind-damage functions 

are a critical factor in the economic analysis for determining the cost-effectiveness of proposed 

mitigation measures aimed at reducing losses during high-wind events. 

The purpose of this appendix is to provide guidance on using the FEMA BCA Tool to complete a 

BCA for the retrofit solutions and best practices for single-family homes outlined in FEMA P-804, 

Wind Retrofit Guide for Residential Buildings. This appendix identifies the wind-damage functions 

in the FEMA BCA Tool that best represent the Mitigation Packages outlined in this Guide (see 

Figure 4-1); it provides a brief background and introduction to the software and step-by-step 

instructions on how to complete a BCA to evaluate cost effectiveness.

C.2 Background

As part of the process for developing this Wind Retrofit Guide for Residential Buildings, FEMA convened 

an expert panel to identify and develop the wind-damage functions to estimate the cost effectiveness 

of the mitigation projects outlined in this Guide. The panel reviewed the various characteristics 

and construction attributes that affect the wind-damage functions for a residential single-family 

building in the FEMA BCA Tool (see Table C-1 below).
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-2

Characteristic Value Comments

Building Type Wood or Masonry Indicates if the single-family residence is wood or 

masonry.

Number of Stories One Story, or Two or More 

Stories

Indicates if the single-family residence is one or more 

stories.

Roof Shape Hip or Gable Indicates if the single-family residence has a hip or gable 

roof.

Secondary Water 

Resistance Yes or No

Identifies whether there is a secondary water resistance 

barrier to prevent water penetration through the roof 

decking after the loss of the roof covering.

Roof Deck Attachment

6d Nails at 6/12, 8d Nails 

at 6/12, 6d/8d Mix at 6/6, 

or 8d Nails at 6/6

Refers to the size (e.g., 6d nails) and spacing of the nails 

(6/12 is 12 inches o.c., 6/6 is 6 inches o.c.) that attach the 

roof decking.

Roof-Wall Connection Toe-Nail or Strap

Indicates if the load path of the single-family residence 

can transfer loads from the roof to the foundation. In 

general, a strap provides a better connection from the 

roof framing to the walls than solely nails. The roof-wall 

connection has been a primary point of failure in past 

hurricanes.

Shutters Yes or No

This characteristic indicates if the single-family residence 

has shutters, thereby reducing windborne debris damage 

to the building and contents.

Garage

None, Weak Door, 

Standard Door, or South 

Florida Building Code 

(SFBC) 94 (if shuttered)

Indicates whether the residence has a garage, and, if 

present, the strength of the garage door. Reinforced 

garage doors are considered standard and unreinforced 

doors are considered weak.

Masonry Reinforcing Yes or No This characteristic indicates if a masonry single-family 

residence has reinforced or unreinforced masonry walls. 

Based on the expected building performance accomplished by the retrofits associated with the 

Mitigation Packages outlined in this Guide, the scenarios presented in Table C-2 represent beforeand after-mitigation conditions in the FEMA BCA Tool. Building properties in yellow highlighted 

cells are those that normally change as a result of implementing the retrofit project and therefore 

differ before versus after the mitigation, depending on existing building properties.

After a user selects the characteristics outlined in Table C-2, the FEMA BCA Tool automatically 

applies wind-damage functions to reflect before- and after-mitigation conditions. If necessary, 

the user can override the wind-damage functions with proper justification and documentation. 

Figure C-1 shows an example of a wind-damage function. It illustrates the expected ratio of building 

damages to building value before and after implementing each of the mitigation retrofit packages 

described in the Guide.

TABLE C-1: FEMA BCA Tool Characteristics
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-3 Mitigation Package Roof Replace- ment Exposure Garage Construction Type Building Type Shutters Garage Roof Shape Masonry Reinforcing3 Secondary Water Resistance Roof-Wall Connection Roof Deck Attachment Without Shutters1 With Shutters2 User Chooses B/C Yes/No Wood or Masonry Single- Family/ One/Two or More Stories Yes/No None/Weak/ Strong/ SFBC 1994 Hip/ Gable N/A, Yes (RM), No (URM) Yes/No Toe-Nail/ Strap Before Mitigation Existing Building4 No Yes No Weak N/A No Toe-Nail 6d at 6/12 Yes No No None N/A No Toe-Nail 6d at 6/12 After Mitigation

BasicNo

Yes No Weak N/A Yes Toe-Nail 8d at 6/12

No No None N/A Yes Toe-Nail 8d at 6/12

Yes

Yes No Weak N/A Yes Toe-Nail 8d at 6/6

No No None N/A Yes Toe-Nail 8d at 6/6

IntermediateNo Yes Yes N/A SFBC 1994 Yes Toe-Nail 8d at 6/12 No Yes N/A None Yes Toe-Nail 8d at 6/12 Yes Yes Yes N/A SFBC 1994 Yes Toe-Nail 8d at 6/6

No Yes N/A None Yes Toe-Nail 8d at 6/6

AdvancedNo

Yes Yes N/A SFBC 1994 Yes Strap 8d at 6/12

No Yes N/A None Yes Strap 8d at 6/12

Yes

Yes Yes N/A SFBC 1994 Yes Strap 8d at 6/6

No Yes N/A None Yes Strap 8d at 6/6

TABLE C-2: Scenarios Representing Before-Mitigation and After-Mitigation Conditions

1) This characteristic will be N/A when the building has shutters.2) This characteristic will be N/A when the building does not have a garage or shutters.3) This characteristic will be N/A when the building construction type is wood.4) This is representative of the worst case scenario.NOTE: Yellow highlight indicates building properties that commonly change after implementing the retrofit project.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-4

FIGURE C-1: Example wind-damage function for a wood single-family (one-story) building

In addition to identifying appropriate wind-damage functions, the expert panel applied some 

general assumptions to evaluate the cost effectiveness of hypothetical wind retrofit mitigation 

projects similar to those described in this Guide. The panel assumed:

Building Exposure = B (urban and dense suburban)

Building Size = 1,600 square feet

Building Replacement Value (BRV) = $111.07/square foot

Building Contents Value = FEMA standard value of 50 percent of the BRV 

(in this case, $88,856)

Displacement Cost = FEMA standard value of $1.44/square foot/month

(in this case, $2,304/month)

Estimated Mitigation Project Cost = Calculated for each retrofit package using each of the 

characteristics described in Table C-1. The assumed project 

costs are shown in Table C-3.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-5

Roof 

Type

One-Story Two-Story

Assumed 

Cost1

Cost 

Effective2

Assumed 

Cost1

Cost 

Effective2

Basic without replacing roof cover Hip $3,150 Less likely $1,950 Less likely

Basic without replacing roof cover Gable $4,350 Less likely $3,150 Less likely

Basic with replacing roof cover Hip $7,110 Less likely $4,150 Less likely

Basic with replacing roof cover Gable $9,310 Less likely $6,350 Less likely

Basic with opening protection 

without replacing roof cover Hip $7,150 Less likely $5,950 Less likely

Basic with opening protection 

without replacing roof cover Gable $8,350 Less likely $7,150 Less likely

Basic with opening protection 

with replacing roof cover Hip $11,110 Less likely $8,150 Less likely

Basic with opening protection 

with replacing roof cover Gable $13,310 Less likely $10,350 Less likely

Intermediate without replacing roof cover Hip $8,850 Likely $8,650 Likely

Intermediate without replacing roof cover Gable $10,350 Highly likely $10,150 Highly likely

Intermediate with replacing roof cover Hip $13,810 Likely $11,850 Likely

Intermediate with replacing roof cover Gable $15,310 Highly likely $13,350 Highly likely

Advanced without replacing roof cover Hip $20,000 Less likely $23,800 Less likely

Advanced without replacing roof cover Gable $21,500 Likely $25,300 Likely

Advanced with replacing roof cover Hip $24,960 Less likely $27,000 Less likely

Advanced with replacing roof cover Gable $26,460 Likely $28,500 Likely

More than 600 BCAs for hypothetical mitigation projects were completed using various locations 

throughout the United States, including San Juan, PR; Miami, FL; Pascagoula, MS; Bay Saint Louis, 

MS; New Orleans, LA; Houston, TX; and Boston, MA. These locations vary widely in their risk of 

experiencing hurricane winds, thereby allowing the expert panel to evaluate the sensitivity of the 

model and the likelihood of each retrofit package being cost effective. Individual retrofit projects are 

considered cost effective if the project is determined to have a BCR of 1.0 or greater. Aggregation of 

benefit and cost values is allowed for multiple structures if they are vulnerable to damage as a result 

of similar hazard conditions. Users of this document should check for the latest HMA guidance at 

www.FEMA.gov for the application of aggregation within a grant application .

The results are shown in Table C-3. In applying the assumptions outlined above, the results varied 

most based on whether the building had a hip or gable roof shape, as well as the building’s height 

(number of stories). The same living area was applied for one- and two-story residences, giving the 

one-story residence a larger building footprint and roof than the two-story residence. Table C-3 

illustrates the results and likelihood of the analysis being cost effective for the range of locations 

outlined above. Note that likelihood of cost effectiveness is highly dependent on location of the 

home (e.g., residences in the windborne debris region or areas susceptible to high winds are much 

more likely to be cost effective).

TABLE C-3: 

Likelihood of Cost Effectiveness

1. Maintenance costs are not included in the total project cost estimate.

2. Cost effectiveness ratings:

Highly likely = Cost effective more than 66 percent of the time

Likely = Cost effective more between 33 and 66 percent of the time

Less likely = Cost effective less than 33 percent of the time

(Likelihood varies based on project location)
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-6

Table C-3 shows the general likelihood of a retrofit being cost effective and is intended to provide 

users of this appendix with a preliminary probability before investing time in collecting the data 

necessary to complete a BCA. Structures in high-risk regions, such as Exposure C (Open), will have 

different results than those summarized in Table C-3. As a result, it is important to complete a BCA, 

especially if the characteristics or costs differ from the assumptions outlined above. Instructions for 

completing a BCA are provided in Section C.3.

C.3 Instructions

Table C-4 provides parameters for a hypothetical mitigation project in Fort Lauderdale, FL 

developed for the purpose of illustrating the steps required for a user to complete a BCA utilizing 

the FEMA BCA Tool. Note that the software has a built-in help feature that addresses frequently 

asked questions while the user navigates the BCA. Alternatively, users can visit the FEMA BCA Web 

site at www.fema.gov/government/grant/bca.shtm#1 for additional resources and guidance. 

Mitigation Project Intermediate Package without replacing roof cover

Address 123 1st Street, Fort Lauderdale, FL 33155

Project Useful Life 20 years

Cost $10,350

Annual Maintenance Cost $150

Exposure B (urban and dense suburban)

Building Size 1,600 square feet

Building Replacement Value $111.07/square foot

Building Description

Unreinforced masonry, single-family, one-story residence with a gable roof, 

without shutters, without reinforced garage, without secondary water resistance, 

without a load path, and minimal roof sheathing nailing (6d at 6/12)

TABLE C-4: Hypothetical Mitigation Project Parameters
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-7

Step 1: Getting Started

4 Press the BCA 4.5.5 Tool button to get started.

4 Press the Help button at any time for on-line support.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-8

Step 2: Create Structure 

4 Select the Structures button.

4 Press the New button.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-9

Step 2 (continued):

4 Select the State and county.

4 Enter a zip code or latitude and longitude to allow the software to auto-populate default 

wind speed data for the structure location.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-10

Step 3: Create Project

4 Select the Projects button.

4 Press the New button.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-11

Step 3: (continued)

The point of contact is the person who can answer questions about the project (not the point of 

contact for the structure). For example, this might be the local grant administrator.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-12

Step 3 (continued):

To associate the structure with the project, double click on the project name in the Project Inventory.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-13

Step 3 (continued):

Select the Add/Remove Structures button and associate the structure with the project.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-14

Step 3 (continued):

Associate the structure with the project by selecting the structure in the left-hand column and 

clicking the double right arrow.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-15

Step 4: Import Wind Speed Data

4 To complete a Hurricane Wind BCA using the software’s zip code and latitude and 

longitude function, users must first import the wind speed data.

4 Select the Import/Export button.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-16

Step 4 (continued):

4 The data is typically stored at C:\Documents and Settings\All Users\Application Data\

FEMA upon installation of the software.

4 You may have to search the hard drive.

4 Search for: LatLonWindSpeed.dat file or download it from www.bchelpline.com/Download.

aspx.

4 This data only needs to be uploaded once on each computer.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-17

Step 5: Begin Mitigation Project Analysis

Select Hurricane Wind to begin the mitigation project analysis.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-18

Step 6: Select Applicable Mitigation Types

4 Select the hazard mitigation measure(s)/project type(s) that apply to the scope of work 

(shutter, load path, and/or roof retrofit)

4 Retrofit projects by Mitigation Package are:

Basic – Roof

Intermediate – Roof and Shutters

Advanced – Roof, Shutters, and Load Path

NOTE: Since this project will implement the Intermediate Package, there are no load path retrofits involved.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-19

Step 7: Enter Project Useful Life and Cost

4 A FEMA standard project useful life for wind retrofit projects is 15 years (without 

documentation required).

4 Projects meeting the requirements of this Guide can estimate a project useful life of 20 

years without documentation required.

4 The project useful life can be more than 20 years as long as it is justified and documented 

by the benefit-cost analyst.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-20

Step 8: Populate Wind Speed

4 Select zip code or latitude and longitude for structure location to populate the wind speed 

default values.

4 Note: if the zip code or latitude and longitude were not saved when creating the new 

structure, the user must go back and update the structure data and save it.

4 To update the structure data, select Structures from the toolbar, select the structure name 

from the Structure Inventory, select the Update button at the bottom of the screen, enter 

the zip code and/or latitude/longitude, and select the Save button.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-21

Step 8 (continued):

4 Default wind speed data in 3-second gusts for multiple return periods are auto-populated 

based on zip code or latitude and longitude values.

4 If necessary, the user can override the wind speed data with proper justification and 

documentation.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-22

Step 9: Enter Structure Information

4 Select exposure category (typically B or C).

4 Enter building size (square feet).

4 Enter value of building (BRV in dollars per square foot).

4 Select Yes to indicate the building is residential.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-23

Step 10: Select Building Properties

4 Select the building properties based on existing and proposed building characteristics.

4 Refer to Table C-2, Scenarios Representing Before-Mitigation and After-Mitigation 

Conditions, for guidance on selecting building properties that best represent the three 

Mitigation Packages outlined in this Guide.

4 For this hypothetical mitigation project, the selected Mitigation Package is ‘Intermediate 

w/out replacing roof cover’ and the after-mitigation building properties reflect those in 

Table C-2: 

Shutters – Yes

Garage – SFBC 1994

Roof Shape – Gable

Masonry Reinforcing – No (URM)

Secondary Water Resistance – Yes

Roof Wall Connection – Toe-Nail

Roof Deck Attachment – 8d at 6/12
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-24

Step 11: Building Contents and Displacement

4 Input data for value of building contents and displacement costs.

4 Provide justification and documentation if needed.

4 Justification and documentation is not required when using the FEMA default values in the 

software.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-25

Step 12: Wind-Damage Functions

4 The software will automatically populate this field.

4 If necessary, the user can override the wind-damage functions with proper justification and 

documentation by entering user-entered percentages.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-26

Step 13: Review

4 Review results.

4 The proposed mitigation project is considered cost effective if the BCR is greater or equal 

to 1.0.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-27

Step 14: Save, Print, and Export

4 To save or print a report, return to the Project Structures Summary screen (by selecting 

Projects from the toolbar and then the Project Name from the Project Inventory).

4 Select the Print Report button to print or export the BCA report.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-28

Step 14: (continued)

The report includes a summary of the overall project showing the total costs and benefits and 

the BCR.
APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

Wind Retrofit Guide for Residential Buildings C-29

Step 14 (continued): 

To export the BCA.zip file to send to a reviewer and/or submit to FEMA, select Import/Export

from the navigation tool bar.
Wind Retrofit Guide for Residential Buildings

APPENDIX C: Using the Hurricane Wind Module for Determining Cost Effectiveness of Retrofit Projects

C-30

Step 14 (continued): 

Select the BCA Export tab, check the project to export, and click BCA Export.
Wind Retrofit Guide for Residential Buildings D-1

APPENDIX D:

References, Resources, and 

Links

References

American Architectural Manufacturers Association, 2007. Standard/Specification for Windows, Doors, 

and Unit Skylights, AAMA/WDMA/CSA 101/I.S.2/A440.

American Forest and Paper Association, 2001. Wood Frame Construction Manual for One- and TwoFamily Dwellings. 

American Iron and Steel Institute, 2007. Standard for Cold-Formed Steel Framing—Prescriptive Method 

for One- and Two-Family Dwellings, AISI S230.

American Society of Civil Engineers, 2005. Minimum Design Loads for Buildings and Other Structures, 

ASCE/SEI 7-05.

American Society of Civil Engineers, 2010. Minimum Design Loads for Buildings and Other Structures, 

ASCE/SEI 7-10.

American Society of Mechanical Engineers, 1981 (reaffirmed 2008). Wood Screws (Inch Series),

ANSI/ASME B18.6.1.

American Society for Testing and Materials, 2002. Standard Test Method for Structural Performance 

of Exterior Windows, Doors, Skylights and Curtain Walls by Uniform Static Air Pressure Difference, 

ASTM E330.

American Society for Testing and Materials, 2005a. Standard Specification for Asphalt-Saturated Organic 

Felt Underlayment Used in Steep Sloop Roofing, ASTM D4869.

American Society for Testing and Materials, 2005b. Standard Test Method for Performance of Exterior 

Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Missile(s) and Exposed to 

Cyclic Pressure Differentials, ASTM E1886.

American Society for Testing and Materials, 2006. Standard Test Method for Structural Performance of 

Exterior Windows, Doors, Skylights, and Curtain Walls by Cyclic Air Pressure Differential, 

ASTM E1233.

American Society for Testing and Materials, 2008. Standard Test Method for Apparent Density of Rigid 

Cellular Plastics, ASTM D1622.

American Society for Testing and Materials, 2009a. Standard Specification for Self-Adhering Polymer 

Modified Bituminous Sheet Materials Used as Steep Roofing Underlayment for Ice Dam Protection, 

ASTM D1970.

American Society for Testing and Materials, 2009b. Standard Specification for Asphalt-Saturated 

Organic Felt Used in Roofing and Waterproofing, ASTM D226.
Wind Retrofit Guide for Residential Buildings

APPENDIX D: References, Resources, and Links

D-2

American Society for Testing and Materials, 2009c. Standard Specification for Performance of Exterior 

Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Windborne Debris in 

Hurricanes, ASTM E1996.

American Society for Testing and Materials, 2009d. Standard Specification for Performance of Exterior 

Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Windborne Debris in 

Hurricanes, ASTM E1996.

American Society for Testing and Materials, 2010. Standard Specification for Driven Fasteners: Nails, 

Spikes and Staples, ASTM F1667.

Door & Access Systems Manufacturers’ Association, 2005a. Standard Method for Testing Sectional 

Garage Doors: Determination of Structural Performance under Uniform Static Air Pressure Difference, 

ANSI/DASMA 108.

Door & Access Systems Manufacturers’ Association, 2005b. Standard Method for Testing Sectional 

Garage Doors and Rolling Doors: Determination of Structural Performance under Missile Impact and 

Cyclic Wind Pressure, ANSI/DASMA 115.

FEMA, 2001. Engineering Principles and Practices of Retrofitting Floodprone Structures, FEMA 259. Second 

Edition. June 2001.

FEMA, 2005. Mitigation Assessment Team Report: Hurricane Charley in Florida, FEMA 488. April 2005.

FEMA, 2006a. Mitigation Assessment Team Report: Hurricane Katrina in the Gulf Coast, FEMA 549. 

July 2006.

FEMA, 2006b. Homebuilders’ Guide to Earthquake-Resistant Design and Construction, FEMA 232. 

June 2006.

FEMA, 2008a. Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business, 

FEMA 320. Third Edition. August 2008.

FEMA, 2008b. Design and Construction Guidance for Community Safe Rooms, FEMA 361. Second 

Edition. August 2008.

FEMA, 2009a. Mitigation Assessment Team Report: Hurricane Ike in Texas and Louisiana, FEMA P-757. 

April 2009.

FEMA, 2009b. Local Officials Guide for Coastal Construction, FEMA P-762. February 2009.

FEMA, 2010a. Home Builder’s Guide to Coastal Construction Technical Fact Sheet Series, FEMA 499. 

December 2010.

FEMA, 2010b. Substantial Improvement/Substantial Damage Desk Reference, FEMA P-758. May 2010.

FEMA, 2011 (revision pending publication). Coastal Construction Manual: Principles and Practices of 

Planning, Siting, Designing, Constructing, and Maintaining Residential Buildings in Coastal Areas, 

FEMA 55. Fourth Edition. Publication anticipated March 2011.

Federal Alliance for Safe Homes, Inc. (FLASH), 2010. Blueprint for Safety: Contractor’s Field Manual. 

Florida Division of Emergency Management, 2007. Hurricane Retrofit Guide. www.floridadisaster.

org/mitigation/rcmp/hrg/index.asp. Accessed: November 22, 2010.

Institute for Business and Home Safety, 2010. FORTIFIED for Existing HomesTM Engineering Guide. 

International Code Council (ICC), 1994. Criteria for Testing Impact & Nonimpact Resistant Building 

Envelope Components Using Uniform Static Air Pressure, TAS 202-94.

ICC, 2008a. Standard for Residential Construction in High-Wind Regions, ICC 600-2008. 
APPENDIX D: References, Resources, and Links

Wind Retrofit Guide for Residential Buildings D-3

ICC, 2008b. 2007 Florida Building Code: Existing Building. February 2008.

ICC, 2009a. International Building Code. February 1.

ICC, 2009b. International Residential Code for One- and Two- Family Dwellings. March 1.

ICC, 2009c. International Existing Building Code. January 1.

S.C. Sea Grant Extension Program, 2001. Clemson University. Not Ready to Re-Roof? Use Structural 

Adhesive to Strengthen the Attachment of Roof Sheathing. Clemson, SC. www.haznet.org/haznet_

pdf/adhesives.pdf. Accessed: November 22, 2010.

Truss Plate Institute, 2007. National Design Standard for Metal Plate Connected Wood Truss Construction.

ANSI/TPI 1.

Resources and Links

Links to FEMA HMA and Other Funding Program

HMA Application and Award Resources

HMA Overview www.fema.gov/government/grant/hma/index.shtm

HMA Helpline Telephone: 866-222-3580 

E-mail: hmagrantshelpline@dhs.gov

HMGP www.fema.gov/government/grant/hmgp/index.shtm

PDM www.fema.gov/government/grant/pdm/index.shtm

Other Funding Programs

Florida Department of Emergency 

Management: Residential Construction 

Mitigation Program

www.floridadisaster.org/Mitigation/rcmp/index.htm

Mississippi Windstorm Underwriting 

Association Retrofit Mitigation Program www.msplans.com/mwua

Rebuild Northwest Florida www.rebuildnwf.org

Safe Room Funding Options www.fema.gov/plan/prevent/saferoom/funding.shtm

SC Safe Home scsafehomes.com

StormSmart Coasts stormsmartcoasts.org

Links to Wind Retrofit Programs

FLASH Blueprint for Safety www.blueprintforsafety.org

Florida Department of Emergency 

Management: Residential Construction 

Mitigation Program

www.floridadisaster.org/Mitigation/rcmp/index.htm

Florida National Homebuilders 

Association www.fhba.com/index.cfm

Institute for Business and Home Safety: 

FORTIFIED www.ibhs.org/property_protection/default.asp?id=8

SC Safe Home scsafehomes.com

Rebuild Northwest Florida www.rebuildnwf.org
Wind Retrofit Guide for Residential Buildings

APPENDIX D: References, Resources, and Links

D-4

Links to FEMA and Other Building Science Publication

FEMA Resources

FEMA Building Science Branch www.fema.gov/rebuild/buildingscience

Catalog of FEMA Flood and Wind 

Publications, and Training Courses www.fema.gov/library/viewRecord.do?id=3184

FEMA Mitigation Assessment Team 

Reports www.fema.gov/rebuild/mat/mat_reprts.shtm

Safe Room Resources www.fema.gov/plan/prevent/saferoom/sr_resources.

shtm

Building Codes and Standards 

Florida Building Code www2.iccsafe.org/states/florida_codes

American Society of Civil Engineers 

Publications www.pubs.asce.org

International Code Council: Codes and 

Standards www.iccsafe.org/cs
Wind Retrofit Guide for Residential Buildings E-1

APPENDIX E:

Acronyms and Abbreviations

AF&PA American Forest and Paper Association

AISI American Iron and Steel Institute

ANSI American National Standards Institute

ASCE American Society of Civil Engineers

ASME American Society of Mechanical Engineers 

ASTM American Society for Testing and Materials

ATC Applied Technology Council

BCA Benefit-cost analysis

BCR Benefit-cost ratio

BRV Building replacement value

DASMA Door and Access Systems Manufacturers Association

DFA Mississippi Department of Finance and 

Administration

FBC Florida Building Code 

FEH FORTIFIED for Existing HomesTM

FEMA Federal Emergency Management Agency

FLASH Federal Alliance for Safe Homes

HAZUS-MH Hazards U.S. – Multi-Hazard risk assessment tool

HMA Hazard Mitigation Assistance

HMGP Hazard Mitigation Grant Program 

IBC International Building Code

IBHS Institute for Business and Home Safety

ICC International Code Council

IEBC International Existing Building Code

IRC International Residential Code

lbs Pounds

MAT Mitigation Assessment Team

MEMA Mississippi Emergency Management Agency

mph Miles per hour
Wind Retrofit Guide for Residential Buildings

APPENDIX E: Acronyms and Abbreviations

E-2

o.c. On center

OSB Oriented Strand Board

PDM Pre-Disaster Mitigation 

psf Pounds per square foot

RCMP Residential Construction Mitigation Program

SFBC South Florida Building Code

SFHA Special Flood Hazard Area

SI/SD Substantial improvement/substantial damage

SLOSH Sea, Lake, and Overland Surge from Hurricanes

SPF Spray polyurethane foam

SWB Secondary water barrier

TAS Testing Application Standard

WFCM Wood Frame Construction Manual 

FEMA P-804

Catalog No: 10320-1