Flood Damage-Resistant Materials Requirements

Transcription

1 Flood Damage-Resistat Materials Requiremets for Buildigs Located i Special Flood Hazard Areas i accordace with the Natioal Flood Isurace Program Techical Bulleti 2 / August 2008

2 Table of Cotets Itroductio...1 NFIP Regulatios...2 Required Use of Flood Damage-Resistat Materials...2 Flood Damage-Resistat Material...2 How Flood Damage-Resistat Materials Affect Flood Isurace Rates...3 Classificatio of Flood Damage-Resistat Materials...3 Notes Regardig Classificatio of Materials...5 Fasteers ad Coectors...12 Costructio Examples...13 Buildigs i Zoes A, AE, A1-A30, AR, AO, ad AH...13 Buildigs i Zoes V, VE, ad V1-V Additioal Uses of Flood Damage-Resistat Materials...14 Accessory Structures...14 Wet Floodproofig...15 Buildigs Outside of SFHAs...16 The NFIP...17 NFIP Techical Bulletis...17 Orderig Techical Bulletis...17 Further Iformatio...18 Glossary...19 Commets o the Techical Bulletis should be directed to: Departmet of Homelad Security FEMA Mitigatio Directorate 500 C Street, SW. Washigto, D.C Techical Bulleti 2-08 replaces Techical Bulleti 2-93, Flood-Resistat Materials Requiremets for Buildigs Located i Special Flood Hazard Areas i accordace with the Natioal Flood Isurace Program.

3 Itroductio Protectig buildigs that are costructed i special flood hazard areas (SFHAs) from damage caused by flood forces is a importat objective of the Natioal Flood Isurace Program (NFIP). I support of this objective, the NFIP regulatios iclude miimum buildig desig criteria that apply to ew costructio, repair of substatially damaged buildigs, ad substatial improvemet of existig buildigs i SFHAs. The base flood is used to delieate SFHAs o Flood Isurace Rate Maps (FIRMs) prepared by the NFIP. The base flood is the flood that has a 1-percet chace of beig equaled or exceeded i ay give year (commoly called the 100-year flood). Certai terms used i this Techical Bulleti are defied i the Glossary. The NFIP regulatios require the use of costructio materials that are resistat to flood damage. The lowest floor of a residetial buildig must be elevated to or above the base flood elevatio (BFE), while the lowest floor of a o-residetial buildig must be elevated to or above the BFE or dry floodproofed to the BFE. All costructio below the BFE is susceptible to floodig ad must cosist of flood damage-resistat buildig materials. The purpose of this Techical Bulleti is to provide curret guidace o what costitute materials resistat to flood damage ad how ad whe these materials must be used to improve a buildig s ability to withstad floodig. Uder the NFIP, the lowest floor is the floor of the lowest eclosed area of a buildig. A ufiished or flood-resistat eclosure that is used solely for parkig of vehicles, buildig access, or storage is ot the lowest floor, provided the eclosure is built i compliace with applicable requiremets. As used by the NFIP, a eclosure is a area that is eclosed o all sides by walls. The NFIP defies a basemet as ay area that is below-grade o all sides. The regulatios do ot allow basemets to exted below the BFE. Table 1 describes five classes of materials ragig from those that are highly resistat to floodwater damage, to those that have o resistace to floodig. Materials are broadly described as structural materials ad fiish materials based o how they are used i ormal costructio practices. Table 2 lists materials by geeric ames, ad otes whether the materials are acceptable or uacceptable for use below the BFE. All buildig materials are i some way fasteed or coected to the structure. Fasteers ad coectors, as described i this Techical Bulleti, also must be resistat to flood damage. A brief descriptio of the process used to idetify or determie whether the materials listed are flood damage-resistat is provided, followed by some simplified examples with diagrams to illustrate the use of these materials below the BFE. Three additioal circumstaces where flood damage-resistat materials are used or recommeded are described: accessory structures, limited use of wet floodproofig, ad buildigs outside of SFHAs. Questios about use of flood damage-resistat materials should be directed to the appropriate local official, NFIP State Coordiatig Office, or oe of the Federal Emergecy Maagemet Agecy s (FEMA s) Regioal Offices. Techical Bulleti 2 AUGUST

4 NFIP Regulatios The NFIP regulatios for flood damage-resistat materials are codified i Title 44 of the Code of Federal Regulatios, i Sectio 60.3(a)(3), which states that a commuity shall: Review all permit applicatios to determie whether proposed buildig sites will be reasoably safe from floodig. If a proposed buildig site is i a floodproe area, all ew costructio ad substatial improvemets shall...(ii) be costructed with materials resistat to flood damage... Proposals for substatial improvemet of existig buildigs i SFHAs, ad proposals to repair those that have sustaied substatial damage, must comply with the requiremets for ew costructio. As part of issuig permits, commuity officials must review such proposals to determie whether they comply with the requiremets, icludig the use of flood damage-resistat materials. Refer to the Classificatio of Flood Damage-Resistat Materials sectio of this Techical Bulleti for additioal details. Further iformatio o substatial improvemet ad substatial damage is foud i Aswers to Questios About Substatially Damaged Buildigs (FEMA 213). The NFIP Techical Bulletis provide guidace o the miimum requiremets of the NFIP regulatios. Commuity or State requiremets that exceed those of the NFIP take precedece. Desig professioals should cotact the commuity to determie whether more restrictive provisios apply to the buildig or site i questio. All other applicable requiremets of the State or local buildig codes must also be met for buildigs i all flood hazard areas. Required Use of Flood Damage-Resistat Materials Flood Damage-Resistat Material Flood [damage]-resistat material is defied by the NFIP as ay buildig product [material, compoet or system] capable of withstadig direct ad prologed cotact with floodwaters without sustaiig sigificat damage. The term prologed cotact meas at least 72 hours, ad the term sigificat damage meas ay damage requirig more tha cosmetic repair. Cosmetic repair icludes cleaig, saitizig, ad resurfacig (e.g., sadig, repair of joits, repaitig) of the material. The cost of cosmetic repair should The Iteratioal Buildig Code (IBC ), by referece to ASCE 24 Flood Resistat Desig ad Costructio, ad the Iteratioal Residetial Code (IRC ), require the use of flood damage-resistat materials. also be less tha the cost of replacemet of affected materials ad systems. I additio to these requiremets, idividual materials that are cosidered flood damage-resistat must ot cause degradatio of adjacet materials or the systems of which the material is a part. 2 Techical Bulleti 2 AUGUST 2008

5 All buildig materials below the BFE must be flood damage-resistat, regardless of the expected or historic flood duratio. For example, buildigs i coastal areas that experiece relatively short-duratio floodig (geerally, floodig with a duratio of less tha 24 hours) must be costructed with flood damage-resistat materials below the BFE. As oted i Table 2, oly Class 4 ad Class 5 materials are acceptable for areas below the BFE i buildigs i SFHAs. I some istaces, materials that are ot flood damage-resistat materials, such as wirig for fire alarms ad emergecy lightig, are allowed below the BFE if specifically required to address life safety ad electric code requiremets for buildig access ad storage areas. How Flood Damage-Resistat Materials Affect Flood Isurace Rates Careful attetio to compliace with the NFIP regulatios for flood damage-resistat materials is importat durig desig, pla review, costructio, ad ispectio. Compliace iflueces both the buildig s vulerability to flood damage ad the cost of NFIP flood isurace. Flood isurace will ot pay a claim for fiish materials located i basemets or i eclosed areas below the lowest floor of elevated buildigs, eve if such materials are cosidered to be flood damage-resistat. NFIP claims for damage below the BFE are limited to utilities ad equipmet, such as furaces ad water heaters. Classificatio of Flood Damage-Resistat Materials The iformatio i this Techical Bulleti was iitially developed based o iformatio i the U.S. Army Corps of Egieers Flood Proofig Regulatios (1995), ad has bee updated based o additioal iformatio from FEMA-fuded studies ad reports, techical experts, ad idustry ad trade groups. Table 1 classifies buildig materials accordig to their ability to resist flood damage. Techical Bulleti 2 AUGUST

6 Table 1. Class Descriptios of Materials NFIP Class Class Descriptio ACCEPTABLE UNACCEPTABLE Highly resistat to floodwater 1 damage, icludig damage caused by movig water. 2 These materials ca survive wettig ad dryig ad may be successfully cleaed after a flood to reder them free of most harmful pollutats. 3 Materials i this class are permitted for partially eclosed or outside uses with essetially umitigated flood exposure. Resistat to floodwater 1 damage from wettig ad dryig, but less durable whe exposed to movig water. 2 These materials ca survive wettig ad dryig ad may be successfully cleaed after a flood to reder them free of most harmful pollutats. 3 Materials i this class may be exposed to ad/or submerged i floodwaters i iterior spaces ad do ot require special waterproofig protectio. Resistat to clea water 4 damage, but ot floodwater damage. Materials i this class may be submerged i clea water durig periods of floodig. These materials ca survive wettig ad dryig, but may ot be able to be successfully cleaed after floods to reder them free of most 3 harmful pollutats. Not resistat to clea water 4 damage. Materials i this class are used i predomiatly dry spaces that may be subject to occasioal water vapor ad/or slight seepage. These materials caot survive the wettig ad dryig associated with floods. Not resistat to clea water 4 damage or moisture damage. Materials i this class are used i spaces with coditios of complete dryess. These materials caot survive the wettig ad dryig associated with floods. Notes: 1. Floodwater is assumed to be cosidered black water; black water cotais pollutats such as sewage, chemicals, heavy metals, or other toxic substaces that are potetially hazardous to humas. 2. Movig water is defied as water movig at low velocities of 5 feet per secod (fps) or less. Water movig at velocities greater tha 5 fps may cause structural damage to buildig materials. 3. Some materials ca be successfully cleaed of most of the pollutats typically foud i floodwater. However, some idividual pollutats such as heatig oil ca be extremely difficult to remove from ucoated cocrete. These materials are flood damageresistat except whe exposed to idividual pollutats that caot be successfully cleaed. 4. Clea water icludes potable water as well as gray water; gray water is wastewater collected from ormal uses (laudry, bathig, food preparatio, etc.). MODIFIED FROM: USACE 1995 Flood Proofig Regulatios Table 2 lists structural materials ad fiish materials commoly used i costructio of floors, walls, ad ceiligs. For the purpose of this Techical Bulleti, structural materials ad fiish materials are defied as follows: Structural materials iclude all elemets ecessary to provide structural support, rigidity, ad itegrity to a buildig or buildig compoet. Structural materials iclude floor slabs, beams, subfloors, framig, ad structural buildig compoets such as trusses, wall paels, I-joists ad headers, ad iterior/exterior sheathig. 4 Techical Bulleti 2 AUGUST 2008

7 Fiish materials iclude all coverigs, fiishes, ad elemets that do ot provide structural support or rigidity to a buildig or buildig compoet. Fiish materials iclude floor coverigs, wall ad ceilig surface treatmets, isulatio, cabiets, doors, partitios, ad widows. Notes Regardig Classificatio of Materials The classificatios i Table 2 are based o the best iformatio available at the time of publicatio. However, flood damage-resistace is determied by factors that may be a fuctio of the specific applicatio ad by the characteristics of the floodwaters. Each situatio requires soud judgmet ad kowledge of probable cotamiats i local floodwaters to select materials that are required to resist flood damage. For materials ad products that are listed i Table 2, maufacturers use ad istallatio istructios must be followed to esure maximum performace. Masory ad wood products used below the BFE must comply with the applicable stadards published by the America Society for Testig ad Materials (ASTM), the America Cocrete Istitute (ACI), the Truss Plate Istitute (TPI), the America Forest & Paper Associatio (AF&PA), ad other appropriate orgaizatios. 1. Materials Not Listed: Table 2 does ot list all available structural materials ad fiish materials. For materials ad products ot listed, maufacturers literature (i.e., specificatios, materials safety data sheets, test reports) should be evaluated to determie if the product meets flood damage-resistace requiremets. Materials ad products that are ot listed i Table 2 may be used if accepted by the local official. Acceptace should be based o sufficiet evidece, provided by the applicat, that the materials proposed to be used below the BFE will resist flood damage without requirig more tha cosmetic repair ad cleaig. 2. Uacceptable Materials: Class 1, 2, ad 3 materials are uacceptable for below-bfe applicatios for oe or more of the followig reasos: Normal adhesives specified for above-grade use are water soluble or are ot resistat to alkali or acid i water, icludig groudwater seepage ad vapor. The materials cotai wood or paper products, or other materials that dissolve or deteriorate, lose structural itegrity, or are adversely affected by water. Sheet-type floor coverigs (lioleum, rubber tile) or wall coverigs (wallpaper) restrict dryig of the materials they cover. Materials are dimesioally ustable. Materials absorb or retai excessive water after submergece. 3. Impact of Material Combiatios: I some cases, the combiatio of acceptable structural ad fiish materials ca egatively impact the classificatio of idividual materials. This is illustrated by the followig examples: Techical Bulleti 2 AUGUST

8 Viyl tile with chemical-set adhesives is a acceptable fiish floorig material whe placed o a cocrete structural floor. However, whe the same viyl tile is applied over a plywood structural floor, it is o loger cosidered acceptable because the viyl tile must be removed to allow the plywood to dry. Polyester-epoxy or oil-based paits are acceptable wall fiishes whe applied to a cocrete structural wall. However, whe the same pait is applied to a wood wall, it is o loger cosidered acceptable. Recet FEMA-supported studies by Oak Ridge Natioal Laboratory have foud that low-permeability pait ca ihibit dryig of the wood wall. 4. Impact of Log-Duratio Exposure ad/or Cotamiats: The classificatios of materials listed i Table 2 do ot take ito accout the effects of log-duratio exposure to floodwaters or cotamiats carried by floodwaters. This is illustrated by the followig examples: Followig Hurricae Katria, FEMA deployed a Mitigatio Assessmet Team (MAT) to examie how buildig materials performed after log-duratio exposure (2 to 3 weeks) to floodwaters (FEMA 549). The field survey revealed that some materials absorbed floodbore biological ad chemical cotamiats. However, it is ot kow at this time if a shorter duratio flood evet would have sigificatly altered the absorptio rates of those cotamiats. Buildig owers, desig professioals, ad local officials should cosider potetial exposure to floodbore cotamiats whe selectig flood damage-resistat materials. For example, Table 2 lists cast-i-place cocrete, cocrete block, ad solid structural wood (2x4s, etc.), as acceptable flood damage-resistat materials. However, experiece has show that buildigs with those materials ca be redered uacceptable for habitatio after beig subjected to floodwaters with sigificat quatities of petroleum-based products such as home heatig oil. Commoly used cleaig ad remediatio practices do ot reduce the off-gassig of volatile hydrocarbos from embedded oil residues to acceptable levels that are established by the U.S. Evirometal Protectio Agecy. Other materials, whe exposed to these types of cotamiats, may also ot perform acceptably as flood damage-resistat materials. 6 Techical Bulleti 2 AUGUST 2008

9 Table 2. Types, Uses, ad Classificatios of Materials Types of Buildig Materials Structural Materials (floor slabs, beams, subfloors, framig, ad iterior/exterior sheathig) Uses of Buildig Materials Floors Walls/ Ceiligs Asbestos-cemet board Brick Face or glazed Classes of Buildig Materials Acceptable Commo (clay) Cast stoe (i waterproof mortar) Cemet board/fiber-cemet board Cemet/latex, formed-i-place Clay tile, structural glazed Cocrete, precast or cast-i-place Cocrete block 1 Gypsum products Uacceptable Paper-faced gypsum board No-paper-faced gypsum board Greeboard Keee s cemet or plaster Plaster, otherwise, icludig acoustical Sheathig paels, exterior grade Water-resistat, fiber-reiforced gypsum exterior sheathig Hardboard (high-desity fiberboard) Tempered, eamel or plastic coated All other types Mieral fiberboard Orieted-strad board (OSB) Exterior grade Edge swell-resistat OSB All other types Particle board Plywood Marie grade Preservative-treated, alkalie copper quaterary (ACQ) or copper azole (C-A) Techical Bulleti 2 AUGUST

10 Table 2. Types, Uses, ad Classificatios of Materials (cotiued) Types of Buildig Materials Structural Materials (floor slabs, beams, subfloors, framig, ad iterior/exterior sheathig) Uses of Buildig Materials Floors Walls/ Ceiligs Preservative-treated, Borate 2 Exterior grade/exposure1 (WBP weather ad boil proof) Classes of Buildig Materials Acceptable Uacceptable All other types Recycled plastic lumber (RPL) Commigled, with 80-90% polyethylee (PE) Fiber-reiforced, with glass fiber strads High-desity polyethylee (HDPE), up to 95% Wood-filled, with 50% sawdust or wood fiber Stoe Natural or artificial o-absorbet solid or veeer, waterproof grout All other applicatios Structural Buildig Compoets Floor trusses, wood, solid (2x4s), decay-resistat or preservative-treated Floor trusses, steel 3 Headers ad beams, solid (2x4s) or plywood, exterior grade or preservative-treated Headers ad beams, OSB, exterior grade or edge-swell resistat Headers ad beams, steel 3 I-joists Wall paels, plywood, exterior grade or preservative-treated Wall paels, OSB, exterior grade or edge-swell resistat Wall paels, steel 3 8 Techical Bulleti 2 AUGUST 2008

11 Table 2. Types, Uses, ad Classificatios of Materials (cotiued) Types of Buildig Materials Structural Materials (floor slabs, beams, subfloors, framig, ad iterior/exterior sheathig) Wood Uses of Buildig Materials Floors Walls/ Ceiligs Classes of Buildig Materials Acceptable Solid, stadard, structural (2x4s) Uacceptable Solid, stadard, fiish/trim Solid, decay-resistat 4 Solid, preservative-treated, ACQ or C-A Solid, preservative-treated, Borate 2 Fiish Materials (floor coverigs, wall ad ceilig fiishes, isulatio, cabiets, doors, partitios, ad widows) Asphalt tile 5 With asphaltic adhesives All other types Cabiets, built-i Wood Particle board Metal 3 Carpetig Ceramic ad porcelai tile With mortar set With orgaic adhesives Cocrete tile, with mortar set Corkboard Doors Wood, hollow Wood, lightweight pael costructio Wood, solid Metal, hollow 3 Metal, wood core 3 Metal, foam-filled core 3 Fiberglass, wood core Epoxy, formed-i-place Techical Bulleti 2 AUGUST

12 Table 2. Types, Uses, ad Classificatios of Materials (cotiued) Types of Buildig Materials Fiish Materials (floor coverigs, wall ad ceilig fiishes, isulatio, cabiets, doors, partitios, ad widows) Uses of Buildig Materials Floors Walls/ Ceiligs Classes of Buildig Materials Acceptable Glass (sheets, colored tiles, paels) Glass blocks Isulatio Sprayed polyurethae foam (SPUF) or closed-cell plastic foams Iorgaic fiberglass, mieral wool: batts, blakets, or blow All other types (cellulose, cotto, opecell plastic foams, etc.) Uacceptable Lioleum Magesite (magesium oxychloride) Mastic felt-base floor coverig Mastic floorig, formed-i-place Metals, o-ferrous (alumium, copper, or zic tiles) Metals No-ferrous (alumium, copper, or zic tiles) Metals, ferrous 3 Pait Polyester-epoxy ad other oil-based waterproof types Latex Partitios, foldig Wood Metal 3 Fabric-covered Partitios, statioary (free-stadig) Wood frame Metal 3 Glass, ureiforced Glass, reiforced Gypsum, solid or block 10 Techical Bulleti 2 AUGUST 2008

13 Table 2. Types, Uses, ad Classificatios of Materials (cotiued) Types of Buildig Materials Fiish Materials (floor coverigs, wall ad ceilig fiishes, isulatio, cabiets, doors, partitios, ad widows) Uses of Buildig Materials Floors Walls/ Ceiligs Polyurethae, formed-i-place Classes of Buildig Materials Acceptable Uacceptable Polyviyl acetate (PVA) emulsio cemet Rubber Moldigs ad trim with epoxy polyamide adhesive or latex-hydraulic cemet All other applicatios Rubber sheets or tiles 5 With chemical-set adhesives 6 All other applicatios Silicoe floor, formed-i-place Steel (paels, trim, tile) With waterproof adhesives 3 With o-waterproof adhesives Terrazo Viyl asbestos tile (semi-flexible viyl) 5 With asphaltic adhesives All other applicatios Viyl sheets or tiles (coated o cork or wood product backigs) Viyl sheets or tiles (homogeeous) 5 With chemical-set adhesives 6 All other applicatios Wall coverigs Paper, burlap, cloth types Viyl, plastic, wall paper Wood floor coverigs Wood (solid) Egieered wood floorig Plastic lamiate floorig Wood compositio blocks, laid i cemet mortar Wood compositio blocks, dipped ad laid i hot pitch or bitume Techical Bulleti 2 AUGUST Notes:

14 1 Ufilled cocrete block cells ca create a reservoir that ca hold water followig a flood, which ca make the blocks difficult or impossible to clea if the floodwaters are cotamiated. 2 Borate preservative-treated wood meets the NFIP requiremets for flood damge-resistatce; however, the borate ca leach out of the wood if the material is cotiuously exposed to stadig or movig water. 3 Not recommeded i areas subject to salt-water floodig. 4 Examples of decay-resistat lumber iclude redwood, cedar, ad black locust. Refer to Sectio 2303 of the Iteratioal Buildig Code (IBC) ad Sectio R324 of the Iteratioal Residetial Code (IRC) for guidace. 5 Usig ormally specified suspeded floorig (i.e., above-grade) adhesives, icludig sulfite liquor (ligi or "lioleum paste"), rubber/asphaltic dispersios, or "alcohol" type resious adhesives (culmar, oleoresi). 6 Examples iclude epoxy-polyamide adhesives or latex-hydraulic cemet. Fasteers ad Coectors The term fasteers typically refers to ails, screws, bolts, ad achors. The term coectors typically refers to maufactured devices used to coect two or more buildig compoets. Joist hagers, post bases, hurricae ties ad clips, ad mud-sill achors are examples of coectors. Fasteers ad coectors are materials ad thus must be made of flood damage-resistat materials i order to comply with the NFIP requiremets. Specificatios for fasteers ad coectors used i buildigs i SFHAs are i ASCE 24, a stadard refereced by the IBC. Chapter 23 of the IBC has specific requiremets for coectios ad fasteers used with wood, icludig preservative-treated wood. Similar specificatios are i Chapter 3 of the IRC. Table 2 does ot specifically address fasteers ad coectors. However, it is clear that the performace of buildigs that are exposed to floodig is, at least i part, a fuctio of the fasteers ad coectors used to put the compoets together. Whe preservative-treated woods are used, particular attetio is required for fasteers ad coectors because some treatmets are more corrosive tha others, which could shorte the service life of the fasteers ad coectors. For example, alkalie copper quaterary (ACQ) treatmets are more corrosive tha traditioal acid copper chromate (ACC) treatmets. If corrosio occurs, buildigs are less likely to withstad flood loads ad other loads. Fasteers ad coectors made of stailess steel, hot-dipped zic-coated galvaized steel, silico broze, or copper are recommeded for use with preservative-treated wood. This Techical Bulleti, cosistet with ASCE 24 ad the Iteratioal Code Series, recommeds that stailess steel or hot-dip galvaized fasteers ad coectors be used below the BFE i both ilad (ocorrosive) ad coastal (corrosive) areas. I coastal eviromets where airbore salts cotribute to corrosio, it is recommeded that corrosio-resistat fasteers ad coectors be used throughout the buildig where they may be exposed. For additioal guidace, see Techical Bulleti 8, Corrosio Protectio for Metal Coectors i Coastal Areas. Also see TPI/WTCA Guidelies for Use of Alterative Preservative Treatmets with Metal Coector Plates for further guidace o metal plate coected wood trusses maufactured with preservative treated lumber ( 12 Techical Bulleti 2 AUGUST 2008

15 Costructio Examples Buildigs i Zoes A, AE, A1-A30, AR, AO, ad AH Figure 1 illustrates a solid foudatio wall (crawlspace) elevated to meet the miimum requiremet that the lowest floor be at the BFE. Figure 2 illustrates framed walls that may be used for eclosures below the BFE that are used for parkig of vehicles, buildig access, ad storage. To maximize allowable use of eclosures below the BFE, it is a commo practice to exted the foudatio a full story, eve though that puts the lowest floor well above the BFE. I such cases, while the NFIP requiremet is that flood damage-resistat materials be used oly below the BFE, it is strogly recommeded that such materials be used for all costructio below the lowest floor. This will reduce flood damage to the eclosed area i the evet floodig exceeds the BFE. For additioal guidace o eclosures i A zoes, see Techical Bulleti 1, Opeigs i Foudatio Walls ad Walls of Eclosures Below Elevated Buildigs i Special Flood Hazard Areas. Figure 1. Buildig elevated o solid foudatio walls meetig the miimum NFIP requiremets for Zoes A, AE, A1- A30, AR, AO, ad AH Techical Bulleti 2 AUGUST

16 BFE Lowest floor Flood opeig No more tha 1 foot Wood/steel stud Sole plate Floor joists/ trusses Framed wall aroud eclosure Iterior grade Floor coverig Sub-floor Flood damage-resistat materials Figure 2. Framed eclosure uder buildig elevated i accordace with NFIP requiremets for Zoes A, AE, A1-A30, AO, ad AH Exterior grade Buildigs i Zoes V, VE, ad V1-V30 The NFIP regulatios require that the bottom of the lowest horizotal structural member of the lowest floor (usually the floor beam or girder) of buildigs i Zoes V, VE, ad Vl-V30 be at or above the BFE. Therefore, all materials below the bottom of those members must be flood damage-resistat materials. This requiremet applies to lattice work ad screeig, ad also to materials used to costruct breakaway walls that eclose areas below the lowest floor. Depedig o the desig parameters selected, breakaway walls may remai i place durig low-level floods ad must be flood damage-resistat so that they ca be readily cleaed ad ot deteriorate over time due to wettig. Figure 3 illustrates the requiremet. For additioal guidace o breakaway walls used to eclose areas uder buildigs i V zoes, see Techical Bulleti 9, Desig ad Costructio Guidace for Breakaway Walls Below Elevated Coastal Buildigs. Additioal Uses of Flood Damage-Resistat Materials Accessory Structures Accessory structures may be allowed i SFHAs provided they are located, istalled, ad costructed i ways that comply with NFIP requiremets. Some commuities allow accessory structures that are limited to the uses specified for eclosures below the BFE: parkig of vehicles ad storage. As with other buildigs, accessory structures below the BFE are required to be costructed with flood damage-resistat materials. I additio, accessory structures must be achored to resist flotatio, collapse, ad lateral movemet ad comply with other requiremets based o the flood zoe. For additioal iformatio ad requiremets, cotact the appropriate commuity permittig office. 14 Techical Bulleti 2 AUGUST 2008

17 Figure 3. Flood damage-resistat buildig material requiremets for buildigs elevated i accordace with NFIP requiremets for Zoes V, VE, ad V1-V30 Wet Floodproofig Wet floodproofig is a method to reduce damage that typically ivolves three elemets: allowig floodwaters to eter ad exit to miimize structural damage, usig flood damage-resistat materials, ad elevatig utility service ad equipmet. Whe a buildig is retrofitted to be wet floodproofed, o-flood damage-resistat materials that are below the BFE should be removed ad replaced with flood damage-resistat materials. This will reduce the costs of repair ad facilitate faster recovery. Wet floodproofig is ot allowed i lieu of complyig with the lowest floor elevatio requiremets for ew residetial buildigs (or dry floodproofig of oresidetial buildigs i A zoes). The exceptio is accessory structures, as oted o the previous page. Wet floodproofig may also be used to volutarily retrofit buildigs that are older tha the date of the commuity s first FIRM (commoly referred to as pre-firm ), provided the requiremet to Techical Bulleti 2 AUGUST

18 brig such buildigs ito compliace is ot triggered (called substatial improvemet ). Figure 4 illustrates some suggested retrofittig of iterior walls i a pre-firm buildig. However, please ote that the techiques illustrated i Figure 4 caot be used to brig a substatially damaged or substatially improved buildig ito compliace with the NFIP. For additioal iformatio o wet floodproofig, see Techical Bulleti 7, Wet Floodproofig Requiremets. Batt isulatio above gap Preservative-treated lumber Elevated outlets Chair rail Chair rail Maximum expected flood level 6 iches ½-ich gap i wallboard to prevet wickig Flood-resistat (o-paper-faced gypsum) wallboard Closed-cell or plastic foam isulatio Replaceable waiscot Water-resistat floorig Figure 4. Partial wet floodproofig techique usig flood damage-resistat materials for fiished wall costructio. Buildigs Outside of SFHAs FEMA reports that up to 25 percet of NFIP flood isurace claims are paid o buildigs that are outside of the mapped SFHA. This occurs for may reasos, icludig out-of-date maps ad local draiage problems. I areas kow to be proe to floodig that are ot subject to the NFIP requiremets, it is recommeded that flood damage-resistat materials be used for costructio of ew buildigs ad for repair or reovatio of existig buildigs. Figure 4 illustrates some optios. 16 Techical Bulleti 2 AUGUST 2008

19 The NFIP The U.S. Cogress established the NFIP with the passage of the Natioal Flood Isurace Act of The NFIP is a Federal program eablig property owers i participatig commuities to purchase isurace as protectio agaist flood losses, i exchage for State ad commuity floodplai maagemet regulatios that reduce future flood damages. Participatio i the NFIP is based o a agreemet betwee commuities ad the Federal Govermet. If a commuity adopts ad eforces adequate floodplai maagemet regulatios, FEMA will make flood isurace available withi the commuity. Title 44 of the U.S. Code of Federal Regulatios cotais the NFIP criteria for floodplai maagemet, icludig desig ad costructio stadards for ew ad substatially improved buildigs located i SFHAs idetified o the NFIP s FIRMs. FEMA ecourages commuities to adopt floodplai maagemet regulatios that exceed the NFIP criteria. As a isurace alterative to disaster assistace, the NFIP reduces the escalatig costs of repairig damage to buildigs ad their cotets caused by floods. NFIP Techical Bulletis This is oe of a series of Techical Bulletis that FEMA has produced to provide guidace cocerig the buildig performace requiremets of the NFIP. These requiremets are cotaied i Title 44 of the U.S. Code of Federal Regulatios at Sectio The bulletis are iteded for use by State ad local officials resposible for iterpretig ad eforcig the requiremets i their floodplai maagemet regulatios ad buildig codes, ad by members of the developmet commuity, such as desig professioals ad builders. New bulletis, as well as updates of existig bulletis, are issued periodically, as ecessary. The bulletis do ot create regulatios; rather, they provide specific guidace for complyig with the requiremets of existig NFIP regulatios. Users of the Techical Bulletis who eed additioal guidace should cotact their NFIP State Coordiator or the appropriate FEMA regioal office. The User s Guide to Techical Bulletis ( lists the bulletis issued to date. Orderig Techical Bulletis The quickest ad easiest way to acquire copies of FEMA s Techical Bulletis is to dowload them from the FEMA website ( shtm). Techical Bulletis also may be ordered free of charge from the FEMA Publicatios Warehouse by callig , or by faxig a request to , Moday through Friday betwee 8 a.m. ad 5 p.m. EST. Please provide the FEMA publicatio umber, title, ad quatity of each publicatio requested, alog with your ame, address, zip code, ad daytime telephoe umber. Writte requests may be also be submitted by mail to the followig address: Techical Bulleti 2 AUGUST

20 FEMA Publicatios. P.O. Box Jessup, MD Further Iformatio The followig publicatios provide further iformatio cocerig the use of flood damageresistat materials. Alga, H. ad Wedt, R Pre-Stadard Developmet for the Testig of Flood-Damage-Resistat Residetial Evelope Systems, Compariso of Field ad Laboratory Results - Summary Report, Oak Ridge Natioal Laboratory, Jue America Red Cross, FEMA Repairig Your Flooded Home, FEMA 232, ARC America Society of Civil Egieers, Structural Egieerig Istitute Flood Resistat Desig ad Costructio, ASCE/SEI America Society of Civil Egieers, Structural Egieerig Istitute Miimum Desig Loads for Buildigs ad Other Structures, ASCE/SEI Brick Istitute of America,.d. Techical Notes for Brick Costructio, Brick Istitute of America, McLea, Virgiia. Califoria Itegrated Waste Maagemet Board Recycled Plastic Lumber, Califoria Itegrated Waste Maagemet Board, web page, last updated Jue 22, ( Departmet of Eergy Eergy-Efficiet Flood-Damage-Resistat Home Recostructio,. ( pdf). FEMA Aswers to Questios About Substatially Damaged Buildigs, FEMA 213. FEMA Wet Floodproofig Requiremets, Techical Bulleti 7-93, FIA-TB-7. FEMA Corrosio Protectio for Metal Coectors i Coastal Areas, Techical Bulleti 8-96, FIA-TB-8. FEMA Coastal Costructio Maual, FEMA 55CD (3rd editio). FEMA Home Builder s Guide to Coastal Costructio: Techical Fact Sheet Series, FEMA 499. FEMA Mitigatio Assessmet Team Report: Hurricae Katria i the Gulf Coast, FEMA Techical Bulleti 2 AUGUST 2008

21 FEMA Natioal Flood Isurace Program: Flood Isurace Maual, Revised October Iteratioal Code Coucil, Ic Iteratioal Buildig Code, IBC Iteratioal Code Coucil, Ic Iteratioal Residetial Code, IRC Simpso Strog-Tie Techical Bulleti: Preservative-Treated Wood, Simpso Strog-Tie. T-PTWOOD08-R, July 2008 ( TPI/WTCA TPI/WTCA Guidelies for Use of Alterative Preservative Treatmets with Metal Coector Plates, updated Jue 4, 2007, ( U.S. Army Corps of Egieers Flood Proofig Systems ad Techiques, U.S. Army Corps of Egieers, December U.S. Army Corps of Egieers Flood Proofig Regulatios, Chapters 9 ad 10, U.S. Army Corps of Egieers, EP Wood Truss Coucil of America (WTCA) The Load Guide: Guide to Good Practice for Specifyig ad Applyig Loads to Structural Buildig Compoets, ( loads.php). World Floor Coverig Associatio (WFCA)..d., Aaheim, Califoria. ( Glossary Accessory structure A structure that is o the same parcel of property as a pricipal structure, the use of which is icidetal to the use of the pricipal structure. Base flood The flood havig a 1-percet chace of beig equaled or exceeded i ay give year, commoly referred to as the 100-year flood. The base flood is the atioal stadard used by the NFIP ad all Federal agecies for the purposes of requirig the purchase of flood isurace ad regulatig ew developmet. Base flood elevatio (BFE) The height of the base (1-percet aual chace or 100-year) flood i relatio to a specified datum, usually the Natioal Geodetic Vertical Datum of 1929, or the North America Vertical Datum of Basemet Ay area of a buildig havig its floor subgrade (below groud level) o all sides. Eclosure or eclosed area Areas created by a crawlspace or solid walls that fully eclose areas below the BFE. Techical Bulleti 2 AUGUST

22 Federal Emergecy Maagemet Agecy (FEMA) The Federal agecy that, i additio to carryig out other activities, admiisters the Natioal Flood Isurace Program. Flood Isurace Rate Map (FIRM) The official map of a commuity o which FEMA has delieated both the special flood hazard areas (SFHAs) ad the risk premium zoes applicable to the commuity. Floodproe area Ay lad area susceptible to beig iudated by floodwater from ay source. Lowest floor The lowest floor of the lowest eclosed area of a buildig, icludig a basemet. Ay NFIP-compliat ufiished or flood-resistat eclosure usable solely for parkig of vehicles, buildig access, or storage (i a area other tha a basemet) is ot cosidered a buildig s lowest floor, provided the eclosure does ot reder the structure i violatio of the applicable desig requiremets of the NFIP. Mitigatio Directorate The compoet of FEMA directly resposible for admiisterig the flood hazard idetificatio ad floodplai maagemet aspects of the NFIP. Registered Desig Professioal A idividual who is registered or licesed to practice their respective desig professio as defied by the statutory requiremets of the professioal registratio laws of the State or jurisdictio i which the project is to be costructed. Special Flood Hazard Area (SFHA) A area delieated o a FIRM as beig subject to iudatio by the base flood ad desigated as Zoe A, AE, A1-A30, AR, AO, AH, A99, V, VE, or V1-V30. Substatial damage Damage of ay origi sustaied by a structure whereby the cost of restorig the structure to its before-damaged coditio would equal or exceed 50 percet of the market value of the structure before the damage occurred. Structures that are determied to be substatially damaged are cosidered to be substatial improvemets, regardless of the actual repair work performed. Substatial improvemet Ay recostructio, rehabilitatio, additio, or other improvemet of a structure, the cost of which equals or exceeds 50 percet of the market value of the structure (or smaller percetage if established by the commuity) before the start of costructio of the improvemet. This term icludes structures that have icurred substatial damage, regardless of the actual repair work performed. 20 Techical Bulleti 2 AUGUST 2008