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1 5. Buildings

2 5.1. Introduction

3 This chapter presents guidance for setting performance goals for buildings in a community resilience

4 plan. Building stock within a community varies widely, in terms of use, occupancy, ownership, age, 

5 construction type and condition. The variability in occupancy and use leads to different performance 

6 goals between buildings; variability in age and condition results in different performance levels, even 

7 within the same class of building; and variability in ownership, such as public or private, can present

8 challenges in implementing minimum performance goals, particularly for existing buildings. This chapter 

9 discusses the various classes and uses of buildings, performance goals, and past and current codes and 

10 standards that support community resilience.

11 5.1.1. Social Needs and Systems Performance Goals

12 Buildings fulfill a multitude of social needs from the most basic, such as providing shelter, to housing 

13 necessary services like medical care and food. Many buildings also house goods or businesses that can be 

14 closed following a hazard event; but such buildings will hopefully require only modest repairs. Therefore,

15 performance goals for buildings depend specifically on what each individual building houses or the 

16 function it serves. Some buildings must be functional immediately, or soon after, the disaster, while other

17 buldings need to be stable so they do not collapse or place the life safety of the occupants at risk. Because 

18 buildings fulfill a wide variety of social needs, the recovery time and sequence of recovery must be 

19 evaluated at the community level. Section 5.2 discusses building classes and uses; Section 5.3 provides 

20 guidance for developing performance goals based on the methodology in Chapter 3.

21 5.1.2. Reliability v. Resilience

22 Buildings are an integrated set of systems – structural, architectural, utilities, etc. – that perform together 

23 to serve the intended function of the building. When discussing building performance, each of these 

24 systems must perform adequately because each system supports the building function in different ways. 

25 Structural systems provide a stable system that carries gravity loads based on building construction and 

26 contents and must resist forces imposed by hazard events. Architectural systems supply protection from 

27 outside elements through the cladding systems (e.g., roof, exterior walls or panels, doors, windows, etc.) 

28 and interior finishes. Utility systems deliver needed services that support the building function.

29 Buildings designs focus on the building’s intended purpose and on occupant safety for fires and natural 

30 hazard events. Building designs are based on provisions in building codes and standards, though some 

31 designs are performance-based and allow alternative solutions. Structural systems for buildings are

32 typically designed for a minimum required level of hazard intensity, based on a target reliability level for 

33 building performance. For buildings, structural reliability refers to the probability that a structural 

34 member or system will not fail. For gravity, wind, snow, and flood loads, structures are designed for 

35 member reliability, with a low probability of failure, so that structural members are not expected to fail

36 during a design event. For seismic events, structures are designed for system reliability conditional on the 

37 design seismic event, where the structural system is not expected to fail or collapse, but individual 

38 members may fail. Thus, for wind, snow, and flood events, the structural system is expected to sustain

39 little or no damage under a design hazard event. For seismic hazard events, the structure is expected to 

40 afford life safety to the occupants, such that while structural damage may occur, the building will not 

41 collapse. Therefore, while a building is expected to protect its occupants during a seismic event, it may 

42 not be functional afterwards and may even need to be demolished.

43 Wind, floods and winter storm events may also disrupt services, such as water supply, and create power 

44 outages, which also affect building functionality. If water pressure cannot be maintained, then fire 

45 hydrants and fire suppression systems are out of service, and buildings cannot be occupied. If fuel for 

46 generators is depleted during long term power outages, buildings are not functional. 
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47 While structural reliability is important, it is not synonymous with resilience. If a building has sustained 

48 damage such that, following a hazard event, it cannot perform its pre-disaster function, that may 

49 negatively affect a community’s resilience. An example is a fire station where the building itself has 

50 sustained little or no structural damage, but the doors cannot open, preventing fire trucks from exiting to 

51 fight fires. Some buildings may need to be functional sooner than others. Providing a minimum level of 

52 reliability ensures buildings do not collapse, but does not ensure they will remain functional after a 

53 design-level hazard event.

54 Designing a resilient building requires understanding the functions that building supports in the 

55 community, and the performance required to ensure those functions during or after a hazard event. Some 

56 requirements may actually exceed those required by model building codes and standards.

57 5.1.3. Interdependencies

58 A community’s resilience depends on the performance of its buildings. The functionality of most 

59 buildings depends, in turn, on the utilities that supply power, communication, water/wastewater, and the 

60 local transportation system. Alternatively, some buildings support the utility systems. Buildings and 

61 supporting infrastructure systems must have compatible performance goals to support community 

62 resilience. Refer to other chapters of this framework for infrastructure system resilience 

63 recommendations.

64 In many instances, infrastructure systems are unavailable immediately after a hazard event to support

65 specific buildings when they must be operational. For example, emergency operation centers and 

66 hospitals must function immediately after a hazard event. However, power and water infrastructure

67 systems may be damaged. Therefore, during short-term recovery, critical facilities should plan to operate 

68 without external power and water until those services are expected to be recovered.

69 In many instances, the functionality of specific buildings depends on the occupants as well as the physical 

70 building. First responders need to reach the buildings where equipment is housed to provide emergency 

71 services. Therefore, community resilience requires the buildings and supporting infrastructure systems

72 consider dependencies that must be addressed to be functional.

73 5.2. Buildings Classes and Uses 

74 5.2.1. Government

75 In most communities, the emergency operations centers, first responder facilities, airports, penitentiaries, 

76 and water and wastewater treatment facilities are government-owned buildings. These buildings provide 

77 essential services and shelter occupants and equipment that must remain operational during and after a

78 major disaster event. Therefore, essential buildings should remain operational, as defined by Category A

79 (safe and operational) in Chapter 3 and Table 5-1.

80 Other government buildings may not need to be functional immediately following a hazard event (e.g.,

81 City Hall or county administrative building, public schools, mass transit stations and garages, judicial 

82 courts, and community centers). However, these buildings may be needed during the intermediate 

83 recovery phase following the hazard event. A performance goal for these types of buildings might be 

84 either Category A or Category B, safe and usable during repair, depending on their role in the community 

85 recovery plan. 

86 Categories C and D are provided to help communities evaluate the anticipated performance of their 

87 existing buildings for a hazard event. Older construction that is poorly maintained, or has features known 

88 to be prone to failure, such as unreinforced masonry walls and a lack of continuous load path to the 

89 foundation, need to be documented as part of the community resilience plan.

90 Typically, buildings are designed according to risk categories in the American Society of Civil Engineers 

91 Standard 7 (ASCE 7) and International Building Code. Risk categories relate the criteria for design loads 

92 or resulting deformations to the consequence of failure for the structure and its occupants. Risk categories 
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93 are distinct from occupancy category, which relates primarily to issues associated with fire and life safety

94 protection, as opposed to risks associated with structural failure. Risk categories rank building 

95 performance with a progression of the anticipated seriousness of the consequence of failure from lowest 

96 risk to human life (Risk Category I) to the highest (Risk Category IV).

97 Essential buildings fall under Risk Category IV, which has the highest level of reliability, and provisions 

98 for seismic events that require nonstructural systems to remain operable. Some buildings that may be 

99 deemed essential are classified as Risk Category III, which includes buildings and structures that house a 

100 large number of people in one place or those having limited mobility or ability to escape to a safe haven 

101 in the event of failure, including elementary schools, prisons, and healthcare facilities. This category has 

102 also includes structures associated with utilities required to protect the health and safety of a community, 

103 including power-generating stations and water treatment and sewage treatment plants. Risk Category III

104 requires a higher level of reliability than a typical building associated with Risk Category II, but there are 

105 fewer nonstructural system requirements for seismic events than a Risk Category IV building. 

106 Table 5-1. Building Performance Categories

Category Performance Standard

A. Safe and operational These are facilities that suffer only minor damage and have the ability to function without 

interruption. Essential facilities such as hospitals and emergency operations centers need to have this

level of function.

B. Safe and usable 

during repair

These are facilities that experience moderate damage to their finishes, contents and support systems. 

They will receive green tags when inspected and will be safe to occupy after the hazard event. This 

level of performance is suitable for shelter-in-place residential buildings, neighborhood businesses 

and services, and other businesses or services deemed important to community recovery.

C. Safe and not usable These facilities meet the minimum safety goals, but a significant number will remain closed until 

they are repaired. These facilities will receive yellow tags. This performance may be suitable for 

some of the facilities that support the community’s economy. Demand for business and market 

factors will determine when they should be repaired or replaced.

D. Unsafe – partial or 

complete collapse

These facilities are dangerous because the extent of damage may lead to casualties.

107 5.2.2. Healthcare

108 Emergency medical facilities are critical to response and recovery efforts following a major disaster.

109 Therefore hospitals, essential healthcare facilities, and their supporting infrastructure, must be functional

110 (Category A) during and following a hazard event. This does not mean the entire facility has to be fully 

111 operational, but critical functions, such as the emergency room and life support systems, should be 

112 operational until other functions can be restored. Currently, hospitals are designed to Risk Category IV 

113 requirements, with some local communities or federal agencies imposing additional requirements. For 

114 example, California requires that all hospital designs, regardless of location or ownership (municipal or 

115 private), be reviewed and construction overseen by a state agency.

116 Nursing homes and residential treatment facilities that house patients who cannot care for themselves may 

117 also need to be immediately functional after a hazard event. Other healthcare facilities, such as doctors’

118 offices, pharmacies, and outpatient clinics, may not all need to be immediately available. Communities

119 should determine if a subset of these buildings will be needed shortly after the event. Medical office 

120 buildings and pharmacies may need to be designed to suffer limited damage that can be repaired in a 

121 reasonable period of time, either Category A or Category B, depending on their role in community 

122 recovery and resilience. In most cases, buildings for these types of medical offices are currently designed 

123 as Risk Category II buildings.

124 5.2.3. Schools and Daycare Centers

125 Many communities have primary (K-12) schools that are designed to a higher performance level (Risk 

126 Category III) because they have large assemblies of children. Often, school gymnasiums or entire school 
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127 buildings are designated to serve as emergency shelters during the hazard event and as emergency staging 

128 areas after the event. Additionally, the research that went into the SPUR Resilience City Initiative found a 

129 perception that when children can return to school, things are returning to normal and parents can return 

130 to work. Thus, expeditious resumption of function is important for primary schools across a community.

131 There can be a dichotomy of performance requirements for a school. On the one hand, providing 

132 enhanced performance and returning to operation quickly places a school in Category B, stable with 

133 moderate damage. However, if the school or some portion of the school is used as an emergency shelter, 

134 that requires Category A, stable with minor damage. Depending on the hazard, the Risk Category III 

135 provisions to which most primary schools are designed may provide Category A or B performance.

136 Therefore, any school that will be designated as an emergency shelter should be evaluated to determine its 

137 intended role in the community and that it is appropriately designed for Category A or B performance. 

138 Evaluation would determine which schools are anticipated to perform adequately and which may need to 

139 be upgraded to a higher performance level.

140 Higher education facilities are generally regulated as business or assembly occupancies with exceptions 

141 for specific uses, such as laboratory and other research uses. Research universities are also often 

142 concerned with protecting their research facilities, long-term experiments, associated specimens and data.

143 Daycare centers house young children that require mobility assistance and are unable to make decisions; 

144 but daycare populations may not meet assembly requirements. Therefore, such centers may be located in 

145 buildings that meet either Risk Category II or III performance requirements and code requirements for 

146 these types of facilities vary. In some cases there are heightened requirements; and in other instances 

147 there are few constraints beyond basic code requirements for Risk Category II buildings. Communities 

148 may require daycare centers to be designed to a higher level of performance, similar to school buildings.

149 5.2.4. Religious and Spiritual Centers

150 Religious and spiritual centers play a special role in many communities. They can offer a safe haven for 

151 people with emotional distress following a hazard event. Logistically, these buildings are often critical 

152 nodes in the post-disaster recovery network. Many religious organizations operate charity networks that 

153 provide supplies to people following a hazard event. In past disasters, many religious institutions opened

154 their doors to provide temporary housing. In most cases, however, these buildings are designed as typical 

155 Risk Category II buildings. Compounding the issue, these buildings are often among the oldest in a 

156 community and are built with materials and construction methods that perform poorly in hazard events.

157 If these facilities fill an important role in the community recovery plan, Category B would be a desired 

158 performance. However, a number of factors could influence a community to accept a lesser performance 

159 goal. First, most of these institutions are nonprofit entities, with little funding for infrastructure 

160 improvement. Second, many historic buildings would have to be modified, unacceptably disrupting their 

161 historic fabric to meet this higher performance category. Therefore, a community should understand the 

162 anticipated performance of its churches and spiritual centers and their role in community recovery.

163 5.2.5. Residential and Hospitality

164 Communities should consider whether residential buildings and neighborhoods will shelter a significant 

165 portion of the population following a hazard event. Houses, apartment buildings, and condominiums need 

166 not be fully functional, like a hospital or emergency operation center, but they should safely house 

167 occupants to support recovery and re-opening of businesses and schools. Not being fully functional could 

168 mean that a house or apartment is without power or water for a reasonable period of time, but can safely

169 shelter its inhabitants. The significant destruction of housing stock led to the migration of a significant 

170 portion of the population following Hurricane Katrina’s impact on New Orleans. Such a shelter-in-place 

171 performance level is - key to the SPUR Resilient City initiative and prompted the City of San Francisco to 

172 mandate a retrofit ordinance for vulnerable multi-family housing.
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173 Currently multi-unit residential structures are designed to Risk Category II provisions, except where the 

174 number of occupants is quite large (e.g., > 5,000 people); then they designs meet Risk Category III

175 criteria. For multi-family residential structures, there are two dominant construction types: light frame 

176 (wood and cold formed steel light frame) construction and steel or reinforced concrete construction. Light 

177 frame residential structures have different performance issues than steel or reinforced concrete structures,

178 which are typically larger. 

179 Most one and two-family dwellings are constructed based on pre-engineered standards using the

180 prescriptive requirements of the International Residential Code. There has been debate as to whether the 

181 IRC provides comparable performance to the International Building Code. In some cases, such as the 

182 Loma Prieta and Northridge earthquakes, one and two-family dwellings performed as well as or better 

183 than engineered buildings. Further investigation regarding a possible discrepancy in requirements

184 between the IBC and the IRC is essential, because of the importance of residential housing. 

185 In addition, an effective response to most hazard events may require supplemental first responders and 

186 personnel from outside the community. If most residential buildings are not functional or safe to occupy, 

187 demand for temporary shelter may compete with the need to temporarily house response and recovery 

188 workers. Hotels and motels can support response and recovery efforts if they are back in operation shortly 

189 after the event. Typically these buildings are designed to meet Risk Category II criteria, like multi-family 

190 residential structures.

191 5.2.6. Business and Services

192 While it would be ideal to have all community businesses open shortly after a hazard event, such an 

193 outcome is not economically practicable. Many business offices, retail stores, and manufacturing plants

194 are located in older buildings that may not perform well during a hazard event or, if constructed more 

195 recently, are designed to Risk Category II criteria. Not all commercial buildings are designed to the code 

196 minimum requirements, and they may have higher performance capabilities.

197 Each community should select design and recovery performance goals for its businesses and services, 

198 depending on their role in the community during recovery. Certain types of commercial buildings may be

199 critical to the recovery effort. The community needs to designate businesses and their buildings that are 

200 critical retail and able to meet a higher performance level. Some businesses and services are commonly 

201 essential to recovery:

202  Grocery stores and pharmacies. People need food, water, medication, and first aid supplies following 

203 a hazard event. Regional or national grocery stores and pharmacies typically have robust distribution 

204 networks outside the affected area that can bring supplies immediately after the hazard event.

205 Although the common preparedness recommendation is for people to have 72 hours of food and water 

206 on hand, the potential for disruption beyond the first three days should be evaluated for a 

207 community’s hazards. For example, the Oregon Resilience Plan recommends two weeks of food and 

208 water for a Cascadia earthquake event.

209  Banks or financial institutions. Banks or structures that house automated teller machines provide 

210 access to money. 

211  Hardware and home improvement stores. These businesses provide building materials for repairs,

212 reconstruction, and emergency shoring of damaged buildings.

213  Gas stations and petroleum refineries. Many communities are arranged so residents need

214 automobiles to carryout basic functions, like shopping and commuting to work. A disruptive event 

215 may impact fuel delivery systems and gasoline may be difficult to obtain for a period of time. 

216  Buildings that house industrial and hazardous materials or processes. Buildings and other 

217 structures containing toxic, highly toxic, or explosive substances may be classified as Risk Category 

218 II structures if it can be demonstrated that the risk to the public from a release of these materials is 

219 minimal. However, communities need to verify that the risk management plan address community 

220 hazards, and any potential releases that may occur during or after a hazard event.
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221 The resilience needs of other types of businesses and the buildings that house them depend to a large 

222 extent on the business and community’s tolerance for those businesses to be delayed in reopening or 

223 closed. Many professional service businesses rely on employees working remotely from home or alternate

224 office spaces. Conversely, manufacturing businesses, retail, and food service businesses do not have that 

225 luxury. Their location is critical to the ability of the business to function. If a restaurant or store cannot 

226 serve the public or a factory is unable to manufacture its product, then the business may fail. Losing these 

227 businesses can adversely impact the community’s recovery and long-term resilience because of lost jobs

228 and other economic impacts. 

229 5.2.7. Conference and Event Venues

230 Convention centers, stadiums, and other large even venues are important for the long term recovery of 

231 many communities because of the revenue that these types of events typically generate. Additionally, a 

232 venue hosting major events following a hazard event can uplift morale for a community, like hosting the 

233 Super Bowl in New Orleans following Hurricane Katrina. Typically these venues are designed to Risk 

234 Category III because of the large number of occupants, so they have a greater performance capability than 

235 typical buildings. 

236 5.2.8. Detention and Correctional Facilities

237 Many communities have standalone detention and correctional facilities (prisons). Building codes 

238 typically require some higher design requirements on these types of facilities because the people housed 

239 in them cannot evacuate without supervision. The level of enhanced design requirements varies based on 

240 the facility requirements and state or local jurisdiction. Within this framework, it is suggested that these 

241 types of facilities be designed to Category A or B.

242 5.3. Performance Goals 

243 The resilience matrices in Chapter 3 provide examples of performance goals for buildings and 

244 infrastructure systems at the community level for fictional community, Centerville, USA. The example 

245 matrices provide a visual method communities can use to determine their desired performance goals in 

246 Table 5-2 through Table 5-4 address each of the three hazard levels discussed in Chapter 3 – routine, 

247 expected, and extreme – for Centerville, USA. An individual community may start with one or more of 

248 the hazard levels. Some communities may decide that for routine events the infrastructure should have

249 little to no disruption and the extreme event is too much to plan for, so they base their planning on the 

250 expected event. However, examining the response of the physical infrastructure to three levels of a hazard 

251 can provide insight and understanding regarding system performance. One or more systems may not 

252 perform well at the routine level, and cause cascading effects. Such performance indicates that frequent 

253 repairs may be required for that system. Alternatively, if there are substantial differences between the

254 desired and anticipated performance of one or more systems, the performance at several hazard levels 

255 may help a community prioritize retrofit or mitigation strategies.

256 A community first needs to identify clusters, or groupings, of buildings for which the same performance 

257 goals are desired. The cluster groups and assignment of buildings within each cluster may be unique to 

258 each community. The types of buildings selected by Centerville are listed in the left column, and are 

259 categorized under critical facilities, emergency housing, housing/neighborhoods, and community 

260 recovery. The categories also reflect the sequence of building types that need to be functional following a 

261 hazard event. Each building cluster then needs to be evaluated for its role in the community recovery. The 

262 rate of recovery is indicated by percentages, 30 %, 60%, and 90%, to show how many buildings within 

263 the cluster are recovered and functioning during the three recovery phases in the top row of the table.

264 The examples in Table 5-2 through Table 5-4 illustrate a large urban/suburban community. Smaller or 

265 more distributed communities may elect to create different clusters, while major metropolitan areas may 

266 create even finer clusters of buildings. The Centerville example shows that, for a routine hazard in Table 
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267 5-2, almost all buildings are desired to be functioning within one to two days, and anticipated to be fully 

268 functional within one to three days. For the expected hazard in Table 5-3, only critical buildings and 

269 emergency housing are desired to be functioning within one day of the event, but these facilities are not 

270 anticipated to be functional for more than four months to two years. For the extreme hazard in Table 5-4, 

271 only emergency operation centers and first responder facilities are desired to be functional within a day, 

272 but the anticipated performance is that they will not be functional for more than three years. 

273 Recovery of function may not initially be full recovery of function, but a minimum or interim level 

274 necessary to perform the essential tasks of that specific building to start the recovery process. For 

275 example, a city hall that has an emergency operation center may only provide for enough power to 

276 support lighting, phones, and computers for the EOC room, but not the entire building. The building’s 

277 structure and exterior cladding would also need to be stable and intact to provide a safe environment and 

278 allow the EOC to be occupied.
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279 Table 5-2. Example Building Performance Goals for Routine Event in Centerville, USA 

Disturbance Restoration times

(1) Hazard Any (2) 30% Restored

Affected Area for Routine Event Localized 60% Restored

Disruption Level Minor 90% Restored

(3) X Current

280

Functional Category: Cluster

(4) 

Support 

Needed

(5) 

Target 

Goal

Routine Hazard Level

Phase 1 – ShortTermPhase 2 --

Intermediate

Phase 3 – LongTerm

Days Wks Mos

0 1 1-3 1-4 4-8 8-12 4 4-24 24+

Critical Facilities .... A

Emergency Operation Centers 90% X

First Responder Facilities 90% X

Acute Care Hospitals 90% X

Non-ambulatory Occupants (prisons, 

nursing homes, etc.) 90% X

Emergency Housing B

Temporary Emergency Shelters 90% X

Single and Multi-family Housing (Shelter 

in place) 90% X

Housing/Neighborhoods B

Critical Retail 90% X

Religious and Spiritual Centers 90% X

Single and Multi-family Housing (Full

Function) 90% X

Schools 90% X

Hotels & Motels 90% X

Community Recovery C

Businesses - Manufacturing 60% 90% X

Businesses - Commodity Services 60% 90% X

Businesses - Service Professions 60% 90% X

Conference & Event Venues 60% 90% X

281 Footnotes:

1 Specify hazard being considered

Specify level – Routine, Expected, Extreme

Specify the size of the area affected – localized, community, regional

Specify severity of disruption – minor, moderate, severe

2 30% 60% 90% Restoration times relate to number of elements restored within the cluster

3 X Estimated 90% restoration time for current conditions based on design standards and current inventory

Relates to each cluster or category and represents the level of restoration of service to that cluster or category

Listing for each category should represent the full range for the related clusters

Category recovery times will be shown on the Summary Matrix

"X" represents the recovery time anticipated to achieve a 90% recovery level for the current conditions

4 Indicate levels of support anticipated by plan

R Regional

S State

MS Multi-state

C Civil Corporate Citizenship 

5 Indicate minimum performance category for all new construction. 

See Section 3.2.6

282
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283 Table 5-3. Example Building Performance Goals for Expected Event in Centerville, USA

Disturbance Restoration times

(1) Hazard Any (2) 30% Restored

Affected Area for Expected Event Community 60% Restored

Disruption Level Moderate 90% Restored

(3) X Current

284

Functional Category: Cluster

(4) 

Support 

Needed

(5) 

Target 

Goal

Expected Hazard Level

Phase 1 – ShortTermPhase 2 --

Intermediate

Phase 3 – LongTerm

Days Wks Mos

0 1 1-3 1-4 4-8 8-12 4 4-24 24+

Critical Facilities .... A

Emergency Operation Centers 90% X

First Responder Facilities 90% X

Acute Care Hospitals 90% X

Non-ambulatory Occupants (prisons, nursing 

homes, etc.) 90% X

Emergency Housing B

Temporary Emergency Shelters 30% 90% X

Single and Multi-family Housing (Shelter in 

place) 60% 90% X

Housing/Neighborhoods B

Critical Retail 30% 60% 90% X

Religious and Spiritual Centers 30% 60% 90% X

Single and Multi-family Housing (Full 

Function) 30% 60% 90% X

Schools 30% 60% 90% X

Hotels & Motels 30% 60% 90% X

Community Recovery C

Businesses - Manufacturing 30% 60% 90% X

Businesses - Commodity Services 30% 60% 90% X

Businesses - Service Professions 30% 60% 90% X

Conference & Event Venues 30% 60% 90% X

285 Footnotes: See Table 5-2, page 8.
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286 Table 5-4. Example Building Performance Goals for Extreme Event in Centerville, USA

Disturbance Restoration times

(1) Hazard Any (2) 30% Restored

Affected Area for Extreme Event Regional 60% Restored

Disruption Level Severe 90% Restored

(3) X Current

287

Functional Category: Cluster

(4) 

Support 

Needed

(5) 

Target 

Goal

Extreme Hazard Level

Phase 1 – ShortTermPhase 2 --

Intermediate

Phase 3 – LongTerm

Days Wks Mos

0 1 1-3 1-4 4-8 8-12 4 4-36 36+

Critical Facilities .... A

Emergency Operation Centers 90% X

First Responder Facilities 90% X

Acute Care Hospitals 30% 60% 90% X

Non-ambulatory Occupants (prisons, nursing 

homes, etc.) 30% 60% 90% X

Emergency Housing B

Temporary Emergency Shelters 30% 60% 90% X

Single and Multi-family Housing (Shelter in 

place) 30% 60% 90% X

Housing/Neighborhoods B

Critical Retail 30% 60% 90% X

Religious and Spiritual Centers 30% 60% 90% X

Single and Multi-family Housing (Full

Function) 30% 60% 90% X

Schools 30% 60% 90% X

Hotels & Motels 30% 60% 90% X

Community Recovery C

Businesses - Manufacturing 30% 60% 90% X

Businesses - Commodity Services 30% 60% 90% X

Businesses - Service Professions 30% 60% 90% X

Conference & Event Venues 30% 60% 90% X

288 Footnotes: See Table 5-2, page 8.
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289 It is difficult for designers to specifically target an amount of damage that can be repaired in a given 

290 timeframe, as there are numerous sources of uncertainty. However, it is possible to design for estimated

291 levels of damage and based on that, assign a likelihood that the buildings within a cluster will be 

292 functional.

293 Communities primarily consist of existing buildings that have been designed and constructed under the 

294 building code at that time, potentially creating a range of expected performance levels for the same 

295 category of buildings. Sometimes, older buildings were designed using provisions that were later found to 

296 be inadequate, but rarely were the new provisions retroactively applied. Figure 5-1 shows a partially 

297 collapsed unreinforced masonry building following a major earthquake. This type of construction is

298 unsafe in earthquakes, but many communities have not mandated retrofitting these types of buildings to 

299 avoid damage or collapse.

300 As part of developing performance goals for building clusters, the community should identify if any types 

301 of buildings or construction pose a significant safety hazard to occupants or the public. Mitigation or 

302 retrofit programs can be developed to address buildings that pose a significant safety hazard, such as

303 unreinforced masonry building retrofit ordinances that have been adopted by many California cities, 

304 requirements for elevated construction in a flood plan, or requiring storm shelters in new homes.

305 When selecting recovery goals, a community must decide which performance category is appropriate for 

306 buildings within each cluster.

307 Category A buildings should require little repair to return to function. Often recovery is limited by 

308 outside factors such as power or water not being available, which is why onsite power and water is often 

309 required by communities for essential facilities. There may be some damage to a Category A building, but 

310 the damage can easily be cleaned up (i.e., toppled shelves or cosmetic damage to the structure) as shown 

311 in Figure 5-2. 

Figure 5-1: Failure of unreinforced masonry wall 

during an earthquake event. (Photo courtesy of 

Degenkolb Engineers)

Figure 5-2: Non-structural damage to interior 

finishes following an earthquake event. (Photo 

Courtesy of Degenkolb Engineers)
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312 Similarly, for flood events, buildings that sustain minor damage and thus fall into Category A are 

313 expected to have damage limited primarily to the exposed portions of the building exterior. If buildings 

314 are properly elevated, floodwaters may 

315 reach subflooring and building 

316 infrastructure systems but should not

317 overtop the first floor or wet the interior. 

318 However, if the building has a basement, 

319 there could be damage to power sources, 

320 utilities and appliances located there.

321 Buildings subject even to low flood depths

322 may need some drying to remove residual 

323 moisture and cleaning to prevent mold 

324 growth and may not be safe for occupants 

325 until this process has occurred. Figure 5-3

326 shows an example of minor flood damage.

327 Buildings that have experienced minor 

328 damage as the result of wind will generally 

329 have some roof covering damage, a limited amount of damage to openings (e.g., less than 10 % of doors 

330 and windows broken) and minimal exterior finish damage. Figure 5-4 illustrates minor damage as the 

331 result of wind.

332 Category B buildings are expected to sustain damage, but the damage should not affect the building’s 

333 structural stability. There may be significant nonstructural damage, but the building can be used while the 

334 repairs are made. Figure 5-5 shows pictures of significant nonstructural damage inside a building that is 

335 structurally stable following an earthquake event. In such cases, the amount of work required to clean up 

336 the fallen contents or fix the damaged to the walls may take a couple days to a couple weeks.

Figure 5-4: Damage to roof covering, vinyl 

siding and fascia as the result of wind 

(courtesy AECOM)

Figure 5-5: Significant nonstructural damage inside a 

building that is structurally stable after an earthquake 

event. (Photo Courtesy of Degenkolb Engineers)

337 Buildings that have been damaged by flooding and sustained moderate damage may experience a limited 

338 depth of flooding over the first floor; the foundation may be inundated or have minor undermining or 

339 scour; exterior and interior walls may have water stains and possible contamination that requires

340 replacement. Subflooring and floor finishes may also require replacement along with some electrical 

341 wiring. While the building may be structurally stable, it may not be safe for habitants until properly dried 

342 and cleaned due to the potential for mold blooms and growth. Figure 5-6 show examples of moderate 

343 damage as the result of flooding.

Figure 5-3: Floodwaters reached just under the first 

floor on this building (photo courtesy of AECOM)
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344 Moderate damage sustained as the result of wind events may include moderate to major roof covering 

345 damage, some minor instances of roof sheathing failure, and some interior water damage, and damage to 

346 the exterior finish. Figure 5-7 shows moderate damage as the result of wind. 

Figure 5-6: As a result of an estimated 3-4 feet 

of flooding, interior walls had to be replaced in 

this building as well as an exterior door and 

window (photo courtesy of FEMA) [getting a 

better quality version]

Figure 5-7: Siding loss and minor envelope damage 

on low-rise building from a wind event. (photo 

courtesy of FEMA) [getting a better quality version]

347 Category C buildings are expected to have significant nonstructural and some structural damage. The 

348 structural damage should not cause a loss of structural stability, but may require shoring while repairs are 

349 conducted. It is assumed that damage such as this would take weeks to months to repair. Figure 5-8 shows

350 structural damage, but the global structure is stable. Figure 5-9 shows a fractured brace connection in a 

351 building damaged in an earthquake. There were about ten of these damaged braces on one story of a four 

352 story building and it took over three months from the disaster until the repairs were completed and the

353 building could be reoccupied.

Figure 5-8: Apartment building with damaged 

structural members that is globally stable. 

(courtesy of Degenkolb Engineers)

Figure 5-9: Fractured brace connection in a 

building damaged in an earthquake (courtesy of 

Degenkolb Engineers)

354 For buildings severely damaged by flooding, flood depths will likely be several feet above the first floor 

355 and may result in foundation damage that could include settlement and severe scour and undermining. 
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356 Exterior walls may be severely damaged with large missing sections. Interior floor and wall finishes e 

357 will need replacement. Limited deformation of the structural frame may be evident. As with less severely 

358 flood damaged buildings, proper drying and cleaning is necessary prior to re-occupation of the building 

359 due to the potential for mold growth. Figure 5-10 shows severe damage as the result of flooding.

360 Severe damage incurred due to a wind event may include major roof sheathing loss, extensive interior 

361 water damage, and minor to major envelope damage. Additionally, roof uplift damage may be evident. In 

362 instances where significant water intrusion damage has occurred, buildings may not be safe for use until 

363 adequate drying and cleaning has occurred due to the potential for mold bloom. Figure 5-11 demonstrates

364 severe wind damage to buildings. 

Figure 5-10: Foundation wall collapse due to 

hydrostatic pressure from floodwaters (courtesy 

of FEMA) [getting a better quality version]

Figure 5-11: Wind and wind-borne debris resulted 

in considerable damage to glazing on this building 

(courtesy of FEMA) [getting a better quality 

version]

365

366 Category D buildings cannot be used or occupied 

367 after a hazard event. Destruction or collapse of 

368 buildings may occur because the building was not 

369 designed and constructed to withstand the severity 

370 of a particular event, or because a building was 

371 constructed to older building codes, or no codes at 

372 all, or because the codes were not properly 

373 followed or enforced. Figure 5-12 shows examples 

374 of destruction and collapse as the result of flood 

375 and wind events.

376 5.4. Regulatory Environment

377 Model building codes are developed at the 

378 national level for adoption across the country, and 

379 adopted by states or local jurisdictions. However, 

380 federal buildings are designed and constructed to 

381 federal government standards. In the U.S., two organizations publish model building codes for adoption

382 by federal agencies or state and local governments. One is published by the International Code Council, 

383 which formed as a merger of three organizations that published regional model building codes. The other

384 code is published by the National Fire Protection Association. The ICC’s International Building Code is 

385 the most widely adopted model building codes; and the National Fire Protection Code is the most widely 

386 adopted model fire code in the U.S. Most federal agencies also use these codes, with agency-specific 

387 amendments, as the basis for their building requirements. These codes contain many reference standards 

Figure 5-12: Collapse of 5-story building due to 

undermining (from flooding) of shallow 

foundation (courtesy of FEMA)
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388 that are typically published by not-for-profit standards development organizations, professional societies, 

389 and industry groups. Model building codes and the referenced standards are typically modified by federal, 

390 state, and local agencies for their specific purposes.

391 While the model building codes specify minimum requirements that are applicable throughout the 

392 country, states and local municipalities may modify the model building codes to achieve specific goals for 

393 local or regional hazards. For example, in areas of Florida, building codes were changed to require more 

394 hurricane-resilient construction following Hurricane Andrew, requiring certain types of roofing materials, 

395 stronger windows and doors, and greater inspection and enforcement.

396 Some states and localities adopt, but remove requirements in model building codes, to make them less 

397 stringent. Some jurisdictions only adopt the model code for government owned or specific occupancy 

398 buildings, but not for all buildings in their community. Some communities do not adopt or enforce any 

399 building code.

400 Enforcing building codes and construction standards is as important as adopting building codes and 

401 standards. The level of enforcement can significantly impact resilience. Even if the most up-to-date 

402 building code and standards are in effect, buildings designed and constructed in a substandard manner 

403 negatively impact community resilience. Therefore, having a properly trained building department to 

404 review designs for code conformance and inspect construction for conformance with the approved plans, 

405 is an essential component of community resilience.

406 5.5. Standards and Codes

407 The International Building Code, a commonly adopted model building code, was developed to provide 

408 design requirements that “safeguard public health, safety and general welfare through structural strength, 

409 means of egress facilities, stability, sanitation, adequate light and ventilation, energy conservation, safety 

410 to life and property from fire and other hazards attributed to the building environment, and to provide 

411 safety to fire fighters and emergency responders during emergency operations.” 

412 The expected performance of each building depends upon the codes and standards in-force at the time of 

413 construction, as well as the level of enforcement and maintenance. Building codes and standards are 

414 dynamic and ever-changing. Many changes come in response to disasters, while others come from a 

415 perceived weakness to natural disasters brought about by research on the subject. The evolving nature of 

416 building codes and enforcement, combined with the degradation that occurs over time, results in a 

417 building stock with variable capacities to resist hazard events. 

418 Building codes and standards primarily regulate new construction and are based on the current consensus 

419 of best practices and design methods at the time they are written. After a significant hazard event, the 

420 building code may be modified based on observed damage or failures. Some provisions, when changed, 

421 become retroactive or are enforced during renovations. Examples of these are egress protection, 

422 accessibility for differently abled persons, and fire suppression system requirements.

423 Communities primarily consist of existing buildings, and most do not conform to current code standards. 

424 The mix of building types, construction, and age can create significant challenges when developing plans 

425 for a resilient community. Construction materials, construction quality, structural configuration, 

426 architectural finishes, redundancy of the mechanical and electrical systems can all affect the resilience of 

427 one building compared to another.

428 5.5.1. New Construction

429 Design criteria for new construction form the foundation for future resilience planning. Additions to the 

430 model codes may be desired to support a community’s performance goals for resilience. Such changes 

431 typically add modest, incremental costs, whereas trying to require retrofit of existing construction after an 

432 event can be prohibitively expensive.
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433 Building codes and standards have primarily focused on life safety of occupants during major natural 

434 hazard events, specifically in their structural design criteria. Early building codes addressed routine 

435 environmental design loads for frequent hazards such as wind and snow. The hazard design load and self436 weight and occupancy live loads were used to design a structure. This approach produced structures that 

437 withstood routine, moderate hazards. However, the 1906 San Francisco Earthquake demonstrated that in 

438 particular seismic hazards induced large forces that were difficult to resist without any structural damage.

439 This realization led to a philosophy of designing buildings for seismic hazards so buildings remained

440 stable during the event with some structural damage, but did not collapse. The same concept applies to 

441 fire safety. By limiting fire spread with passive compartmentation, areas of the building outside the area 

442 of fire origin and adjacent buildings can often be saved from damage. Reduced fire damage allows more 

443 rapid recovery of functionality in the building.

444 Building codes provide design loads based on return periods for various hazards. In addition to design 

445 loads, there are often design provisions associated with the specific hazard. Table 5-5 (copied from 

446 Chapter 3) lists the various return periods for the routine, expected (design level), and extreme hazards. 

447 Table 5-5: Design Loads for Buildings and Facilities (ASCE 7-10)

Hazard Routine Expected Extreme

Ground Snow 50 year 300 to 500 year1 TBD

Rain 2 2 2

Wind – Extratropical 50 year 700 year 3,000 year3

Wind – Hurricane 50 to 100 year 700 year 3,000 year3

Wind – Tornado 3 3 3

Earthquake4 50 year 500 year 2,500 year

Tsunami 50 year 500 year 2,500 year 

Flood 100 year 100 to 500 year TBD

Fire – Wildfire 4 4 4

Fire –Urban/Manmade 4 4 4

Blast / Terrorism 5 5 5

1

For the northeast, 1.6 (the LRFD factor on snow load) times the 50-year ground snow load is equivalent to the 300 to 500 year 

snow load. 

2 Rain is designed by rainfall intensity of inches per hour or mm/h, as specified by the local code. 

3 Tornado and tsunami loads are not addressed in ASCE 7-10. Tornadoes are presently classified by the EF scale. Tsunami loads 

are based on a proposal for ASCE 7-16.

4 Hazards to be determined in conjunction with design professionals based on deterministic scenarios. 

5 Hazards to be determined based on deterministic scenarios. Reference UFC 03-020-01 for examples of deterministic scenarios.

448 Wind hazards. ASCE 7-10 prescribes design wind speeds for each Risk Category with different return 

449 periods. For Risk Category I, the mean return period is 300 years for facilities that have a low risk to 

450 human life and are typically unoccupied buildings. For Risk Category II facilities, that include typical 

451 buildings and other structures, the return period is 700 years. For Risk Category III and IV facilities, the 

452 return period is 1,300 years. The wind speeds derived from these return periods are based on extratropical 

453 winds and hurricane winds. Tornadic wind speeds are not currently addressed.

454 The majority of the wind design requirements are for the structural frame and the cladding. There are 

455 some requirements for attachment strength of nonstructural components. Requirements for serviceability 

456 and functionality are not explicitly codified, but are indirectly addressed through elastic design methods at 

457 specified wind speeds for desired performance levels. The International Building Code requires 

458 consideration of a drift limit under a reduced wind load (the factor used intends to approximate the 100-

459 year return period wind). There are no explicit structural design requirements to preserve the building 

460 envelope so post-disaster function is not impacted, but there are some prescriptive requirements on the 

461 requirements of doors and windows. Nor are there requirements that exterior equipment, fire pumps, or 

462 generators must be functional following the design windstorm.
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463 Snow hazards. Snow design uses a 50-year mean recurrence interval for ground snow loads. It is 

464 increased with an importance factor for higher Risk Category structures. 

465 Rain hazards. Rain design uses a 100-year rain storm as the design hazard, with loads increased by 60% 

466 to account for uncertainty in predicting rainfall in a major event. However, the majority of rain design 

467 provisions relate to providing proper drainage and stiffness to the roof to prevent ponding. There are no 

468 code requirements in a design rain event that the building envelope must maintain its ability to keep water 

469 out. In many instances this is accomplished without explicit code requirements because of the liability 

470 seen with water intrusion and its adverse effects, such as mold.

471 Flood hazards. Flood design provisions for all buildings are typically based on a 100-year mean 

472 recurrence interval for flood elevation, though 500-year flood elevations are recommended for design of 

473 critical facilities. Recommended practice is to locate buildings out of the 100-year flood zone. If they 

474 must be within this flood zone, floodplain management provisions and building codes require that they be 

475 elevated to or above the design flood elevation which is, at a minimum, the elevation of the 100-year 

476 flood. Buildings with nonresidential uses may also be dry flood-proofed up to the design flood elevation

477 if they are not subject to coastal flood forces or high velocity flooding. For structures subject to flood 

478 forces, the current provisions provide methods to avoid or resist flood forces, but are not necessarily 

479 meant to preserve functionality of the building during a flood event. Evacuation of flood prone areas 

480 during flood events is expected especially with days or even weeks of warning. 

481 Flood design provisions are neither fully prescriptive or performance based. Instead, they are a mixture of 

482 the two. Elevation requirements are considered prescriptive because they elevation is mandated by flood 

483 maps and local codes. Other requirements that require design and vary between structures are considered 

484 performance based, such as building designs that resist flotation, collapse, and lateral movement. 

485 Seismic hazards. Since the beginning of earthquake design, it has been recognized that designing for the 

486 hazard in the same way as other hazards would not be practical or economical. Therefore, the approach 

487 adopted prescribes forces and design requirements that allow buildings to be damaged, but not collapse.

488 Following the 1971 San Fernando earthquake, hospitals were required to be designed to a higher 

489 standard, significantly improving their likelihood of remaining functional following the design 

490 earthquake.

491 The emphasis placed on the design of nonstructural systems is a very important distinction between 

492 seismic design provisions and design provisions for other hazards. All nonstructural systems have bracing 

493 requirements. In addition to the bracing requirements, nonstructural systems in essential facilities or those 

494 systems that relate to the life-safety system of the facility are required to maintain function or return to 

495 function following the design earthquake shaking hazard. The design earthquake shaking level is 

496 currently defined as 67% of the Risk Targeted Maximum Considered Earthquake shaking level.

497 Fire hazards. The performance of new and existing buildings during fires is addressed specifically 

498 through fire codes and in a complementary manner by building codes. Typically, fire prevention officers 

499 within local fire departments enforce the fire code, in conjunction with building inspectors. A fire code is 

500 primarily intended for preventing and containing fires and making certain that necessary training and 

501 equipment is on hand if a fire occurs. Fire codes also address inspection and maintenance requirements of 

502 passive and active fire protection systems.

503 The codes originated as life safety documents; but after the WTC disaster, many requirements establish 

504 additional redundancy, robustness and resilience. The (IBC) building code has been expanded to include 

505 protection for emergency responders following a major event.

506 Another key requirement is for automatic sprinkler systems in residential, healthcare, and assembly 

507 buildings as well as most other types of structures. Sprinklers limit the fire to the area of origin and can 

508 significantly reduce the level of smoke and fire damage.
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509 There are currently very few, if any, code requirements for design of buildings in wild fire hazard areas.

510 Some methods of construction could provide greater resilience than conventional construction in those 

511 regions, but nothing has been mandated.

512 Man-made hazards. Codes and standards do not have explicit structural design requirements for man513 made hazards (e.g., arson, explosions or impact events), although some nominal provisions attempt to 

514 provide robustness to arrest the spread of damage so disproportionate collapse does not occur. Many 

515 requirements in the IBC require facility layout and hazard mitigation measures to prevent explosions of 

516 building contents. Guidelines for design of man-made hazards do exist for specific classes of buildings, 

517 like federal buildings and industrial facilities. Often these guidelines are restricted because they contain 

518 proprietary or security-sensitive information. 

519 5.5.2. Existing Buildings

520 Existing buildings pose an even greater challenge than new buildings. For new buildings, codes can be 

521 amended or re-written. Although construction costs may increase, new buildings would be designed for 

522 the state-of-the-practice. Retrofit of existing buildings to the state-of-the-practice level of resilience, in 

523 contrast, can require significant financial commitment and necessitate major disruption to the building’s 

524 function, which tends to dissuade building owners from retrofit.

525 The cost and disruption associated with retrofit has made mandating retrofit measures a politically 

526 unpopular decision. In California, only the class of building deemed most prone to collapse in an 

527 earthquake – Unreinforced Masonry Buildings – has had widespread, albeit not universal, acceptance as 

528 something that should be mandated for retrofit.

529 For buildings constructed prior to development of flood provisions or a community’s adoption of flood

530 provisions, there is a trigger for requiring that they be retrofit to meet current flood provisions. Buildings 

531 within designated flood hazard areas (generally the 100-year floodplain) that sustain damage of any 

532 origin, for which the cost to repair the building to its pre-damage conditions equals or exceeds 50 percent 

533 of the market value of the building, must be brought into compliance with current flood provisions. The 

534 same is true for improvements or rehabilitation of buildings when the cost equals or exceeds this 

535 threshold. However, enforcement of this requirement can be challenging, particularly in a post-disaster 

536 environment when communities are anxious to support building owners in reconstruction.

537 When existing buildings are evaluated for expected performance relative to resilience goals and required 

538 retrofit actions, standards for new construction are typically applied to the structural design. This 

539 application often leads to excessive requirements for improvements to obtain the desired performance.

540 However, recent advancement in performance-based engineering has led to development of specific 

541 standards for existing buildings with regards to evaluation and retrofit.

542 One of the biggest impediments to retrofit of existing buildings lies in the conservatism embedded in 

543 current engineering codes and standards. Under-predicting a building’s performance in a given hazard 

544 because the standards are conservative can lead to significant retrofit requirements. Those requirements 

545 can make the retrofit economically unappealing to building owners.

546 5.6. Strategies for Implementing Community Resilience Plans

547 5.6.1. Available Guidance

548 Current engineering standards provide tools to support assessment of the structural safety of buildings.

549 ASCE 41, the existing building seismic standard, provides a methodology to assess the performance of 

550 buildings for both safety and the ability to be reoccupied following an earthquake. ATC 45 provides an 

551 assessment methodology for flood and wind events. Similar standards do not exist for other hazards.

552 Building code provisions can be used to determine whether a building has sufficient fire resistance, 

553 egress, and other occupant safety-related issues. These methodologies are useful for individual buildings 

554 safety, but do not address damage versus recovery time to function.
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555 HAZUS provides a platform for communities to assess vulnerabilities to earthquakes, hurricanes, and 

556 other hazards. HAZUS is useful for assessing effects of a disaster on a community. However, the existing 

557 building stock must be adequately reflected in the model, which can require significant data gathering.

558 Several existing resources exist for property owners, designers and communities to use to better 

559 understand best practices for flood resistant design and construction including:

560  FEMA P-55 (Volume I and II), Coastal Construction Manual: Principles and Practices of Planning, 

561 Siting, Designing, Constructing, and Maintaining Residential Buildings in Coastal Areas 

562  FEMA P-499, Home Builder’s Guide to Coastal Construction: Technical Fact Sheet Series

563  FEMA P-550, Recommended Residential Construction for Coastal Areas: Building on Strong and 

564 Safe Foundations

565 Existing resources addressing wind include the ATC Design Guide 2, Basic Wind Engineering for Low566 Rise Buildings.

567 5.6.2. Strategies for New/Future Construction

568 For new and future construction, desired performance goals and anticipated performance for adopted 

569 building codes needs to be evaluated to determine if additional local requirements are required. Risk 

570 categories currently in the building codes can support the desired levels of performance and resilience 

571 goals. By clearly defining the desired building performance for a hazard event in terms of performance

572 and recovery time for return of function, communities can tailor local building codes and standards to 

573 support specific resilience goals.

574 For flood-resistant design and construction, best practices exist for communities or individuals to 

575 implement in addition to code minimum requirements. One basic but effective practice is locating all new 

576 construction outside of flood zones. Additionally, using additional height, or freeboard, in building design

577 is also effective. 

578 Stronger design and construction practices for wind resistance are encouraged through a variety of 

579 existing resources with primary goals of improving continuous load path connections, strengthening 

580 building envelopes, and protecting openings.

581 For fire hazards, sole reliance on active fire protection through automatic extinguishing systems (AES) to 

582 provide property protection in combustible construction is not appropriate for communities with hazards

583 that compromise the performance of the AES, such as seismic events.

584 5.6.3. Strategies for Existing Construction

585 Building codes and standards evolve, but little retroactive compliance is required. This is a major issue in 

586 communities because the cost of retrofit exceeds, by orders of magnitude, the cost of adding resilience to 

587 a new building. A strong resistance to building retrofit because of cost, inconvenience to the building 

588 occupants, and disruption of operations creates a significant challenge for community resilience planning.

589 A strategy to prioritize retrofit requirements is to identify the most significant hazards posed by potential 

590 failures by various types of buildings and to mandate retrofit or demolition of those buildings. There have 

591 also been programs specifically aimed at critical facilities (e.g., hospitals and fire stations), where those 

592 buildings must be retrofit or replaced.

593 Given the aforementioned challenges with existing construction, community resilience planning should

594 take a long-term view to achieve resilience. For example, the City of Los Angeles just instituted an 

595 ordinance requiring older concrete buildings that present significant collapse hazard in major earthquake 

596 be retrofit within the next 30 years. 

597 The risk associated with existing flood-prone construction can be addressed primarily through retrofitting:
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598  Elevation – Elevation is one of the most common flood retrofitting techniques because it provides a 

599 high level of protection and does not require the owner to relocate. Elevation involves raising an 

600 existing building so the lowest floor or lowest horizontal structural member is at or above the 

601 regulated flood level. Common elevation techniques include elevation on piles, piers or columns, and 

602 elevation on extended foundation walls. Other elevation techniques involve leaving the home in place 

603 and building a new elevated floor system within the building or adding a new upper story and wet 

604 floodproofing the ground level. 

605  Relocation – Relocation offers the greatest security from flooding. It involves moving an existing 

606 building to an area that is less vulnerable to flooding or completely outside the floodplain. The 

607 building owner usually selects the new site, often in consultation with a designer to ensure factors 

608 such as accessibility, utility service, cost, and owner preferences meet engineering and local 

609 regulatory requirements. Relocation includes lifting a building off its foundation, placing it on heavy610 duty moving dollies, hauling it to a new site, and lowering it onto a pre-constructed foundation.

611  Floodproofing – There are two types of floodproofing: wet floodproofing and dry floodproofing. Wet 

612 floodproofing allows floodwaters to enter the building and quickly reach the same level as the 

613 floodwaters on the building exterior. Equalizing the water level greatly reduces the effects of 

614 hydrostatic pressure and buoyancy. Wet floodproofing is generally used to limit damage to enclosures 

615 below elevated buildings, basements, crawlspaces, or garages. Wet floodproofing is not practical for 

616 areas used as habitable space. Dry floodproofing involves completely sealing the exterior of a 

617 building to prevent entry of floodwaters. All openings below the flood level are sealed and the walls 

618 of the building are relied on to keep water out. Internal drainage systems, such as sump pumps, 

619 remove any seepage. Due to large hydrostatic pressures, dry floodproofing is practical only for 

620 buildings with reinforced concrete or masonry walls; it is typically not practical for residential 

621 buildings or for buildings where flood depths exceed 2 to 3 feet.

622 Additional information on these techniques is found in FEMA P-259, Engineering Principles and 

623 Practices for Retrofitting Flood-Prone Residential Structures and FEMA P-936, Floodproofing Non624 Residential Buildings.

625 For buildings subject to a wind hazard, the following strategies are widely accepted as among the 

626 most effective to address potential damage.

627  Improving roof and wall coverings – Roof and wall coverings are important components of the 

628 building envelope. If the building envelope is breached during a storm, wind pressures can drastically 

629 increase internal pressures and fail the structural system of the building. Wind driven rain may cause 

630 extensive water damage to interior contents. Improving roof coverings may involve reinforcing the 

631 roof deck or removing the existing covering, securing the roof deck, and installing a new roof 

632 covering. Improving wall coverings may involve installing moisture barriers and ensuring proper 

633 fastener spacing is used or removing the existing covering and installing a new wall covering that is 

634 rated for high winds. 

635  Protecting openings – Openings (e.g., windows, doors, skylights, soffits, and vents) are an important 

636 component of the building envelope. Glazed openings, such as windows, are often vulnerable to 

637 debris impact and wind driven rain intrusion. Protecting openings usually involves installing an 

638 impact-resistant covering (such as a storm shutter) over an existing unprotected opening or installing 

639 impact-resistant products (such as a new window or door assembly).

640  Continuous load path – The term “continuous load path” refers to the structural condition required to 

641 resist all loads – such as lateral and uplift wind pressures – applied to a building. A continuous load 

642 path starts at the point or surface where loads are applied, moves through the building, continues 

643 through the foundation, and terminates where the loads are transferred to the soils that support the 

644 building. To be effective, each link in the load path – from the roof to the foundation – must be strong 

645 enough to transfer loads without breaking. An existing building may be retrofitted if load paths are 

646 incomplete or if the load path connections are not adequate. Continuous load path design or retrofit 
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647 considerations typically involve several connections such as the roof sheathing to roof framing; roof 

648 framing to wall; wall to floor; and floor to foundation.

649 In some states, existing programs reward wind retrofit measures via homeowners’ insurance discounts. 

650 FEMA P-804, Wind Retrofit Guide for Residential Buildings provides additional information on specific 

651 techniques for wind retrofitting residential buildings. Additionally, the Insurance Institute for Business 

652 and Home Safety developed a program called “Fortified” that encourages wind retrofits for both new and 

653 existing construction.

654 Many resources are available that describe seismic retrofit methods and performance-based methods.

655 Examples are:

656  ASCE 41-13: Seismic Evaluation and Retrofit of Existing Buildings. This is a consensus standard 

657 that allows users to perform and evaluation and retrofit using performance-based provisions which 

658 match a selected earthquake shaking intensity with a specific performance level. It is referenced by 

659 many building codes and jurisdictions.

660  FEMA 549: Techniques for Seismic Retrofit. This publication provides examples of methods to 

661 seismically retrofit various types of construction materials and structural configurations. It contains 

662 example retrofit strategies and details to address identified deficiencies based on structural material.

663 5.7. References

664 ASCE/SEI 41 (2013) Seismic Evaluation and Retrofit of Existing Buildings, American Society of Civil 

665 Engineers, Structural Engineering Institute, Reston, VA 

666 ASCE/SEI (2010) Minimum Design Loads for Buildings and Other Structures, American Society of Civil 

667 Engineers, Structural Engineering Institute, Reston, VA 

668 ASCE 24 (2014) Flood Resistant Design and Construction, American Society of Civil Engineers, 

669 Structural Engineering Institute, Reston, VA 

670 IBC (2015) International Building Code, International Code Council, http://shop.iccsafe.org/codes/2015-

671 international-codes-and-references/2015-international-building-code-and-references.html

672 IRC (2015) International Residential Code, International Code Council, 

673 http://shop.iccsafe.org/codes/2015-international-codes-and-references/2015-international-residential674 code-and-references.html

675 FEMA 549 (2006) Hurricane Katrina in the Gulf Coast: Mitigation Assessment Team Report, Building 

676 Performance Observations, Recommendations, and Technical Guidance, Federal Emergency 

677 Management Agency, Washington DC

678 FEMA P-55 (Volume I and II), Coastal Construction Manual: Principles and Practices of Planning, 

679 Siting, Designing, Constructing, and Maintaining Residential Buildings in Coastal Areas, Federal 

680 Emergency Management Agency, Washington DC

681 FEMA P-499, Home Builder’s Guide to Coastal Construction: Technical Fact Sheet Series, Federal 

682 Emergency Management Agency, Washington DC

683 FEMA P-550, Recommended Residential Construction for Coastal Areas: Building on Strong and Safe 

684 Foundations, Federal Emergency Management Agency, Washington DC

685 SPUR (2009). The Resilient City: What San Francisco Needs from its Seismic Mitigation Policies, San 

686 Francisco Planning and Urban Research Association. San Francisco, CA.

687 Oregon (2013) The Oregon Resilience Plan, Reducing Risk and Improving Recovery for the Next 

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689 Safety Policy Advisory Commission, Salem, OR, 

690 http://www.oregon.gov/OMD/OEM/osspac/docs/Oregon_Resilience_Plan_draft_Executive_Summary.pdf