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This document was prepared by

URS Group, Inc.

200 Orchard Ridge Drive, Suite 101

Gaithersburg, MD 20878

Acknowledgements

Federal Emergency Management Agency (FEMA)

L. Gina White, FEMA Region IV, Mitigation, Project Monitor

David Kennard, FEMA Region IX, Mitigation

Daniel Powell, FEMA Region IX, Mitigation

Dennis Tewksbury, FEMA Region I, Mitigation

Christopher Hudson, FEMA HQ, Mitigation

State of California

Ernylee Chamblee, California Department of Forestry and Fire Protection

Greg Griswold, California Department of Forestry and Fire Protection (San Diego Unit)

Tom OKeefe, California Department of Forestry and Fire Protection (San Bernardino Unit)

Ken Worman, Governors Office of Emergency Services

Local California Officials

Cliff Hunter, Rancho Santa Fe Fire Protection District

Clay Westling, City of San Diego

Bill Metcalf, North County Fire District

Technical Assistance Contractor Team

Christopher M. Barkley, PE, URS Group, Inc., Task Order Coordinator

Diana Burke, ELS, URS Group, Inc.Sherry Crouch, PE, URS Group, Inc.

Michael Gayrard, URS Group, Inc.

Rich Schell, RPF #1978, RWS Consulting

Thomas L. Smith, AIA, TLSmith Consulting, Inc.

Chris White, Anchor Point Group

Cover photo: Anchor Point Group, Boulder, CO

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FS No. 1 Wildland/Urban Interface Construction HomeBuildersGuidetoCon structionin WildreZones 09/08 Page1 of 5

Wildland/UrbanInterface Construction

Home Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 1

Purpose

Toprovideinformationaboutwildrebehaviorandrecommendationsforbuildingdesignand

constructionmethodsinthewildland/urbaninterface.Implementationoftherecommended

designandconstructionmethodscangreatlyincreasethechancesofabuildingssurvivalina

wildre(seeFigure1).

Background

Wildresareacommon,natural,andessentialoccurrenceintheforests,woodlands,

brushlands,andgrasslandsoftheUnitedStates.Whenconditionsareacceptable,re

professionalsuseretorevitalizetheecosystemandreduceaccumulatedvegetationthatcan

fuelawildreundercertainconditions.

Althoughtheseverityandtimingofreseasonsvarywidelyfromregiontoregion,wildresoften

poseathreattolives,property,andresources.Duringanaveragereseason,hundredsof

homesaredamagedordestroyedbywildre,andinextremereconditions,thousandsofhomes

canbedamagedordestroyed.Severereweatherinareaswithsignicantamountsofwildland

fuelscanleadtoextremerebehavior.

WildlandfuelsvarythroughouttheUnitedStates.InthePacicnorthwestandtheLakeStates,

forestsarethepredominatewildlandfuel.InsouthernCalifornia,chaparralbrushpredominates.

Theplainsstateshavegrassandoakwoodlands,NewJerseyhasPineBarrens,andthe

southeasthaspineandhardwoodforests.

Figure 1. Ahomeinthewildland/

urbaninterfacethatsurvived

awildre(AnchorPointGroup,

Boulder,CO).

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Page2of5 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 1 Wildland/Urban Interface Construction

Wildrescandamagebuildingsthroughdirectamecontact,convection(heatthatrisesfrom

areandcreatesasmokecolumn),conduction(heatthattransfersthroughmaterialsuchas

metalroofsandrailings),andradiation(heatfromarenexttothebuilding).Wildrescanalso

createburningembersthatriseinthesmokecolumnandfallonbuildings.Firebrands(large

piecesofwind-driven,burningmaterial)canbeblownthroughwindowsorlodgedagainsta

buildingandleadtoignitionofthebuilding.

Traditionaleffortstoprotectbuildingsfromwildreshavefocusedonghtingtherebefore

itreachesthebuildings.Withtheexpansionofresidentialconstructionintopreviously

undevelopedforestsandwildlands,morebuildingsarenowatriskfromwildres.Fighting

orsuppressingthereisoftendifcultorimpractical;buildingsmustthereforealsobe

constructedtobere-resistant.Nobuildingcanbecompletelyreproof,butimplementingthe

recommendationsthataredescribedintheseFactSheetsshouldgreatlyreducethepotentialfor

damagetoabuildingandgreatlyincreaseitschanceofsurvival.

Construction in the Wildland/Urban InterfaceThefollowingfactorsaffecttheprobabilitythatabuildingwillsurviveawildre:

Topographyandweather

Defensiblespace

Buildingenvelope

Communityinfrastructure

Topography and Weather

Wildresgenerallyfolloworaredrivenbyterrainandweather.Buildingsatthetopofacanyon

orridgeline,atmid-slope,orinaravinehaveahigherriskfordamagefromawildreduetotheinteractionofthesefeatureswithstrongwindsthanatlocationssuchasvalleybottoms.When

aconstructionsiteisselected,thetopographicfeaturesonandsurroundingasiteshouldbe

evaluatedfortheirpotentialcontributiontotheexposureofabuildingtoawildre.Abuildings

congurationandlocationonasiteshouldbepredicatedonminimizingtheriskfromthese

topographicfeatures.

SeeFactSheet#3,SelectingtheConstructionSite.

Defensible Space

Wildrestravelquicklyinareaswherevegetationisdryandabundant.Adefensiblespace

aroundabuildingcanimprovetheprobabilitythatthebuildingwillsurviveawildre.Adefensible

spaceisanareawherecombustiblematerial,includingvegetation,hasbeentreated,clearedor

modiedtoslowtherateandintensityofanadvancingwildreandtocreateasaferareaforre-

suppressionoperationstooccur.Buildingssurroundedbyzonesofnon-vegetatedareasorareas

populatedbyre-resistantvegetationaremorelikelytosurvive.

SeeFactSheet#4,DefensibleSpace.

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FS No. 1 Wildland/Urban Interface Construction HomeBuildersGuidetoCon structionin WildreZones 09/08 Page3 of 5

Building Envelope

Duringawildre,combustibleexteriorbuildingcomponentssuchasroofcoverings,siding,and

deckscanignite,leadingtoseveredamagetoortotallossofthebuilding.Therefore,theuse

ofnoncombustibleorre-resistantmaterialsshouldbeconsideredforexteriorcomponents.

Figure2showsthecomponentsofthebuildingenvelope.

Alsocriticalisthecongurationofthenoncombustibleorre-resistantmaterials.Unless

constructionmeasuresthatprovideprotectionfromawildreareimplemented,heatand

emberscanpenetratethebuildingenvelopeatvents,unsealedmechanicalorelectrical

openings,andthroughwindowsbrokenbyheatorwind-blownrebrands.Whentheseopenings

arepenetrated,thebuildingcanburnfromtheinsideout.

Iftheenvelopehasbeendesignedandconstructedtobere-resistant,boththeexteriorand

interiorofthebuildingwillbemorecapableofresistingawildrelongenoughforthedangerto

passorforreghterstoarrive.

SeeFactSheets#5through#16.

Community Infrastructure

Ahomethathasbeenconstructedtobere-resistantandhasadefensiblespacemaynot

besufcienttopreventdamagefromawildre.Survivingawildremayalsodependon

infrastructuresuchaslocalwaterresourcesforreghtingandroadsthataredesignedfor

emergencyvehicleaccess.Thebuildingsiteshouldalsohaveadequateinfrastructuretoensure

accessforreghtingcrews.

SeeFactSheet#17,CommunityInfrastructure.

Figure 2. Thebuildingenvelope.

Building Envelope

Vents

Garage door Exterior door

Siding

Roof Deck

Fence

Windows

Eaves

Foundation

Gutters

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Page4of5 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 1 Wildland/Urban Interface Construction

Prioritizing Fire-resistant

Construction Techniques

Theriskofwildrevariesgreatlyanddepends

onlocalfuels,weather,andtopography.Therisk

atabuildingsitemustbedeterminedbeforethe

appropriatedesignandconstructionmethods

foraneworexistingbuildingcanbeselected

andthemeasurescanbeprioritized.

Hazard and Risk Assessments

Thefoundationofanaccuratehazardandrisk

assessmentisinformationonwildrefuels,

weather,topography,assetsatrisk,andthe

probabilityofawildreoccurrence.Asitecan

beinanareawithaveryhighhazard(highlyvulnerabletowildre)buthavealowriskof

wildre,suchasasiteatahighaltitude.This

informationcanbeusedtodesignateFire

SeverityZones.Thezonescanthenbegiven

arating,fromlowtoextreme,asshownin

Figure3.

Ahazardandriskassessmentcanhelp

determinethelevelofmitigationthatisneededforabuilding.Theassessment,whichcanbe

conductedataregional,state,orlocallevel,needstobebothcredibleandprofessionalto

ensurethattheanalysisisaccurate,comprehensive,andveriable.Someregional,state,andlocalagenciesproducehazardriskmapssimilartothoseshowninFigures3and4.Thesemaps

maybefoundinstate,tribal,andlocalagencyhazardmitigationplansthathavebeenapproved

bytheFederalEmergencyManagementAgency(FEMA).

New Buildings

Fornewconstruction,FEMArecommendsfollowingthedesignandconstructionguidance

providedinthisseriesofFactSheets.

Existing Buildings

FEMArecognizesthatitmaynotbenanciallypossibleforthehomeownertoimplementall

ofthemeasuresthatarerecommendedinthisseriesofFactSheets.FEMArecommends

thathomeownersconsultwithlocalreandbuildingcodeofcialsorotherremanagement

specialiststoperformavulnerabilityassessmentanddevelopacustomized,prioritizedlistof

recommendationsforremedialworkondefensiblespaceandthebuildingenvelope.

Helpfulinformationaboutthevulnerabilitiesofthebuildingenvelopeisavailableathttp://

recenter.berkeley.edu/default.htm.TheHomeownersWildreAssessmentsurveyonthis

Figure 3. Exampleofarehazardratingmap.

Firehazardratingscanhelpdeterminethe

levelofmitigationthatisnecessaryforwildre

management(AnchorPointGroup,Boulder,CO).

http://firecenter.berkeley.edu/default.htmhttp://firecenter.berkeley.edu/default.htmhttp://firecenter.berkeley.edu/default.htmhttp://firecenter.berkeley.edu/default.htmhttp://firecenter.berkeley.edu/default.htm

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FS No. 1 Wildland/Urban Interface Construction HomeBuildersGuidetoCon structionin WildreZones 09/08 Page5 of 5

websiteisahelpfultoolthatpropertyownerscanusetolearnaboutthespecicrisksa

particularbuildinghasandthemeasuresthatcanbetakentoaddressthem.

Construction Standards

Manycommunitiesenforceregulationsregardingwhereandhowbuildingsmaybesited,

designed,andconstructed.Theregulations,however,refertominimumstandards.Individual

propertyownershavetheoptiontoexceedthesestandards,anddoingsoveryoftenincreases

theprobabilitythatthehomewillsurviveawildre.

Resources

CenterforFireResearchandOutreach.UniversityofCalifornia,Berkeley:CollegeofNatural

Resources.http://recenter.berkeley.edu/default.htm.

Christman,L.2008.Trial by Fire: Can Your Home Take the Heat? Redding.com:Home&Garden.

http://www.redding.com/news/2008/Feb/16/trial-re-can-your-home-take-heat/.

Underwood,J.1995.Fire-ResistantDetails.Fine Homebuilding96:9093.http://www.

taunton.com/nehomebuilding/how-to/articles/re-resistant-details.aspx.

Figure 4. Exampleofafuelmodel

map.Fuelmodelsthatdemonstrate

thelocationofcombustible

vegetationarepartofthefoundation

forrebehaviorcalculations(Anchor

PointGroup,Boulder,CO).

http://firecenter.berkeley.edu/default.htmhttp://firecenter.berkeley.edu/default.htmhttp://www.redding.com/news/2008/Feb/16/trial-fire-can-your-home-take-heat/http://www.taunton.com/finehomebuilding/how-to/articles/fire-resistant-details.aspxhttp://www.taunton.com/finehomebuilding/how-to/articles/fire-resistant-details.aspxhttp://www.taunton.com/finehomebuilding/how-to/articles/fire-resistant-details.aspxhttp://www.taunton.com/finehomebuilding/how-to/articles/fire-resistant-details.aspxhttp://www.redding.com/news/2008/Feb/16/trial-fire-can-your-home-take-heat/http://firecenter.berkeley.edu/default.htm

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FS No. 2 Summary of Recommendations HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of5

Summary of WildreConstruction

RecommendationsHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 2

Stateandlocalcodesshouldincluderequirementsforwildremitigationforbothnew

constructionandupgradestoexistingbuildingsinwildrezones.Inareaswherebuildingsare

particularlyvulnerabletotheriskofwildre,implementingmeasuresthatexceedthecodescan

improvetheprobabilitythatabuildingwillsurviveawildre.

TheUnifed Hazard Mitigation Assistance GuidanceandtheWildfre Mitigation Policyforthe

HazardMitigationGrantProgram(HMGP)andPre-DisasterMitigation(PDM)Programprovide

informationonwhichactivitiesareconsideredeligibleforfundingbytheFederalEmergency

ManagementAgency(FEMA)forwildremitigationactivities.

ThisseriesofTechnicalFactSheetsfromFEMAprovideinformationabouthowtominimizethe

potentialfordamagetoordestructionofbuildingsinwildrezonesfromwildres.Theinformation

pertainstobothnewandexistingbuildings.

TheFactSheetsareavailableontheFEMAwebsite( www.fema.gov)asAdobePortableDocument

Format(PDF)les.YoumusthaveAdobeReadertoviewthePDFles.ThelatestversionofAdobe

Readerisrecommendedandcanbedownloadedfrom www.adobe.com.

ThefollowingisasummaryoftherecommendationscontainedinFactSheets#3through#17.

Fact Sheet #3: Selecting the Construction Site

Topographicfeaturessuchasslopesandcanyons,local

vegetation,andweathercangreatlyinuencewildrebehavior.

Homebuildersshouldconsiderthesefactorscarefullywhen

selectingaconstructionsite

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Page2of5 09/08 HomeBuildersGuidetoConstructioninWildreZone FS No. 2 Summary of Recommendations

Fact Sheet #5: Roofs

Ofthecomponentsofthebuildingenvelope,theroofisthemost

vulnerableinawildrebecauseofitssizeandorientation.The

probabilitythatahomewillsurviveawildreisgreatlyinuenced

bythecomponentsoftheroofassembly.ClassAratedroofassemblieswithnoncombustiblecoveringsarerecommended.

Fact Sheet #6: Eaves, Overhangs, and Softs

Windborneembersandconvectiveandradiantheatcanbe

trappedneareavesandsofts,whichcanigniteifnotconstructed

ofnoncombustibleorre-resistantmaterials.Eaveswithshortoverhangsandatsoftswithaminimumofa1-hourre-

resistanceratingarerecommended.

Fact Sheet #7: Exterior Walls

Howwellexteriorwallsareabletoresistawildredependslargely

onthematerialsusedtoconstructthewall.Exteriorwallcoverings

thatarenoncombustibleorre-resistantandnotsusceptibleto

meltingarerecommended.Aminimumre-resistanceratingof

1hourforthewallassemblyisrecommended

Fact Sheet #4: Defensible Space

Creatingadefensiblespace,whichcanoftenbedonebythe

homeowner,isrecommended.Adefensiblespaceisanarea

aroundahomeinwhichvegetation,debris,andothertypes

ofcombustiblefuelshavebeentreated,cleared,orreduced.

Landscapemanagementcreatesabarrierbetweenahomeandawildre.Withoutadefensiblespace,reghtersmaynotattemptto

protectthehomebecausedoingsowouldbetoohazardous.

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Fact Sheet #9: Gutters and Downspouts

Combustibledebrissuchasleavesandpineneedlescanbecome

trappedingutters.Thedebriscanbeignitedbyyingembersor

rebrandsduringawildre,andtherecanspreadtotheroof.

Noncombustibleleafguardsoverguttersandguttersconstructedofnoncombustiblematerialsarerecommended.

Fact Sheet #10: Windows and Skylights

Flames,rebrands,radiantheat,andfailedframescancause

glazingtobreakorotherwisefail.Glazing(glass,plastic,or

translucentmaterial)thatfailsallowseasypassageofembersandhotgasesintotheinteriorofabuilding.Insulatedglazingunitsare

recommended.Thereratingofwindowassembliesshouldbe

commensuratewiththereratingofthewall.

Fact Sheet #11: Exterior Doors

Combustibledoorsandframescanbeignitedinawildre,and

openingsbetweenthedoorandframeandglassinthedoorcan

bepenetratedbyames,hotgases,orembers.Thereratingof

thedoorshouldbecommensuratewiththereratingofthewall.

Weatherstrippingandnoncombustibleorre-resistanttrimare

recommended.

Fact Sheet #8: Vents

Embersandhotgasescanbeblownorpulledintoventopenings

andenteratticspaces,crawlspaces,andductwork,leadingto

ignitionoftheinteriorofthebuilding.Ventsthatareaminimum

of10feetfrompropertylinesandotherbuildings,constructedof

metalproducts,andhavecorrosive-resistantmetalmeshscreensarerecommended.

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Fact Sheet #14: Landscape Fences and Walls

Onceignited,afenceconstructedofcombustiblematerialsthatis

attachedtoornearabuildingcanignitethebuilding.Fencesand

wallsconstructedofnoncombustiblematerialssuchasconcrete,stone,andmasonryarerecommended.Attachingafenceor

walltothebuildingshouldbeavoidedunlessthefenceorwallis

constructedofnoncombustiblematerials

Fact Sheet #15: Fire Sprinklers

Theinteriorofabuildingcanignitefromawildreevenwhenthe

exteriordoesnot.Interiorandexteriorresprinklerscanprevent

substantialdamagetothebuilding,protectnearbybuildings,and

preventtherefromignitingnearbycombustiblevegetation.

Fact Sheet #13: Decks and Other Attached Structures

Embers,rebrands,andhotgasescanbecometrappedunder

decksandotherattachedstructures.Decksconstructedofheavy

timberornoncombustiblematerialsarerecommended.Isolating

theattachedstructurebysurroundingitwithnoncombustiblematerialsuchasgravel,brick,andconcretepavers,andenclosing

theundersideofthedeckwithre-resistantskirtingarealso

recommended.

Fact Sheet #12: Foundations

Embers,rebrands,andhotgasescanignitecombustible

foundationwallsandpenetratecrawlspaceventsandbreached

basementwindows.Walls,vents,andwindowsinclosed

foundationsshouldbeconstructedinaccordancewiththe

guidanceintheseFactSheets.Inhomeswithopenfoundations,protectingtheundersideoftheoorstructurewithre-resistant

materialsisrecommended.

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FS No. 2 Summary of Recommendations HomeBuildersGuidetoConstructioninWildreZones 09/08 Page5of5

Fact Sheet #17: Community Infrastructure

Accessroadsanddrivewaysthatarewideandstrongenough

toaccommodateemergencyvehiclesandprovideaccessfor

reghtingeffortsarenecessary.Waterresourcesforwildre

suppressionmustbeaccessible.Roadsandwatersourcesshouldbewellmarkedonsignsconstructedofre-resistantmaterialsfor

easeofusebyemergencyresponsepersonnel.

Fact Sheet #16: Utilities and Exterior Equipment

Mostutilitiesrequirepenetrationofthebuildingsenvelope

forductingandconduit.Utilityconnectionsshouldbeinstalled

underground,ifpossible,andgapsandpenetrationsinexterior

wallsandroofsshouldbesealedwithre-resistantproducts.Fuel

shouldbestoredundergroundorsurroundedbyanoncombustiblebarrier.

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FS No. 3 Selecting the Construction Site HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of4

Selecting theConstruction Site

Home Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 3

Purpose

Tohelppropertyownerswhoplantobuildhomesorotherstructuresinwildrezonesunderstand

therelationshipbetweenwildrebehaviorandfuels,weather,andtopographysotheycanselect

constructionsitesthatminimizethepotentialfordamagefromwildres.Theguidancelistedin

thisFactSheetappliesonlytonewbuildings.

Key Issues

Wildresspreadmorequicklyonupslopedterrainthan

onlevelterrain(seeFigure1).Topographicfeaturessuch

asslopes,saddles,ridges,andcanyonscantherefore

inuencewildrebehavior(seebelowforadescriptionof

thesefeatures).Theinteractionofwindandradiantheat

withsomeofthefeaturesisalsoanimportantfactorin

wildrebehavior.

Thedirectionaslopefacesinuencesthegrowthof

vegetation,andvegetationinuenceswildrebehavior

becauseitprovidesfuelforthewildre.

Implementingthere-mitigationmeasuresdescribedintheotherFactSheetscannotentirelyoffsetthepotential

fordamagefromawildreathigh-risksiteswith

topographicandvegetationfeaturesthatcancontribute

toextremerebehavior.

Topography

Sloped terrain. Wind-drivenwildresfollowwinddirectionandareminimallyinuencedby

topography.Intheabsenceofastrongwind,wildrefollowstopography,burningprimarily

upslopeandup-canyon.Wildresspreadupslopequicklybecauseheatrisesandpreheats

andignitesfuelssuchasbuildingsandvegetation.

Saddles. Whereavalleycrossesaridge,

asaddleiscreatedbetweentwopeaks

(seeFigure2).Saddlesactaswindfunnels

andareoneofthemosthazardous

locationsforhomesintermsofwildre.

Figure 1.Firespreadsmorequicklyon

upslopedterrainthanonlevelterrain.

Fuel,topography,andweatherarethethree

principalenvironmentalelementsthataffect

wildrebehavior.Fuels(vegetation)and

localtopographyshouldbeconsideredwhen

choosingasiteforahometoincreasethe

chancethehomewillsurviveawildre.

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Ridgetops and hilltops. Wind speeds onridgetopsandhilltopscanbeunpredictable

buttendtobehigherthanthoseinthe

surroundinglowerareasbecauseofthe

higherelevationandbecausewindspeed

increasesasitowsoverabruptchangesintopography.Buildingsintheselocations

canhave360-degreedownhillexposureto

wildre.

Canyons. Awildreatthebottomofa

vegetatedcanyoncanleadtoextremely

hazardousconditionsupslope.Acanyon

actslikeachimney,collectinghotgases

anddirectingsuperheatedconvectionand

radiantheatupslope.Canyonsfunnelwinds

(seeFigure3)thatcanfanareandleadtoextremerebehavior(rapidspreadofthe

wildreandignitionofanentirearea).An

entirecanyoncanpre-heatfromrisinghotair

andgasesandexplodeinames,creatinga

restorm.

Vegetation

Vegetationactsasafuelforwildres.Vegetationbothonandadjacenttoasitecanaffect

theprobabilityofdamagetoabuildingfromawildre.Characteristicsofvegetationsuchas

density,continuity,andtypecaninuencewildrebehavior(seeFactSheet#4,Defensible

Space,formoreinformation).

South-andwest-facingslopesgenerallyretainlessmoisture,producelessvegetation,and

dryoutearlierintheyearthannorth-andeast-facingslopes.Firesondryerslopestendto

ignitemoreeasily,travelmorerapidly,andburnoutfasteraslightfuelsareconsumed.The

moreheavilyvegetatedmoistslopeshavealowerpotentialforignitionbutcansustainamore

intensereoflongerdurationthandryslopes.

Guidance

Byunderstandinghowtopographyandvegetationcaninuencewildrebehavior,propertyownerscanselectconstructionsitesinwildrezonesthatreducethepotentialfordamagetoabuilding

fromawildre.Followingtheguidancelistedbelowcanincreasetheprobabilitythatabuildingwill

surviveawildre.

Avoidselectingaconstructionsitealongagullyorinanarrowcanyon.

Avoidselectingaconstructionsiteinoradjacenttoasaddleornarrowmountainpass.

Avoidconstructingahomeadjacenttooronasteepslope.Ifaridgetopsiteisselected,choose

Figure 2. Windbehavioroverasaddle.

Figure 3.Windbehaviorthroughacanyon.

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FS No. 3 Selecting the Construction Site HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of4

anareathatallowsforaminimum

50-footsetbackfromwildland

vegetationonthedownslopeside

(seeFigure4).Increasethesetback

atsiteswithheavierfuelssuchasin

aforestedenvironment.ImplementthemeasuresinFactSheet#4,

DefensibleSpace;FactSheet#12,

Foundations;andFactSheet#13,

Decks.

Orientthenarrowestwallofthe

buildingtowardthelikelypathof

awildretominimizetheriskofstructuralignition.Orientthebuildingbasedonwindand

fuelssothatdebris,embers,andrebrandsdonotaccumulatenexttothebuildingswalls,

especiallyneartheinsidecornersofentriesandotheroff-setwalls.

Minimizethenumberofwindowsonthesideofthebuildingfacingthelikelypathofawildretoreducetheriskofradiantheatorrebrandsandyingdebrisbreakingthewindows,allowing

theretoenterthebuilding.

Considerations

Considerthevegetationcharacteristicsonandadjacenttothesiteincludingdensity,continuity,

andtype.Ifthesitehasheavy,continuousvegetation,avegetationmanagementplanmaybe

neededtoreducethehazard.Creatingadefensiblespacecanenhancereresistance(see

FactSheet#4,DefensibleSpace).

Consideraccesstothehome.Steepdrivewaysandnarrowroadscanlimitaccessibilitybyre-ghtingequipment(seeFactSheet#17,CommunityInfrastructure).

Evaluatethevulnerabilitytoreofneighboringproperties.Iftheneighboringpropertieshave

rehazardsbuttheneighborsareunwillingtocooperateindevelopingamutualdefensible

space,considerthatinformationinselectingre-resistancemeasuresforthebuilding.

Effectiveness

Theeffectivenessoftherecommendedmeasurescanvarysignicantly,dependingonthe

interactionoffuels,weather,topography,andwildrebehavior.

Resources

Barkley,Y.C.,C.Schnepf,andJ.Cohen.2005. Protecting and Landscaping Homes in the

Wildland/Urban Interface.StationBulletin#67.Moscow,Idaho:IdahoForest,Wildlifeand

RangeExperimentStation.www.treesearch.fs.fed.us/pubs/22257.

CaliforniaDepartmentofForestryandFireProtection.www.re.ca.gov.

CaliforniaFireSafeCouncil. www.resafecouncil.org.

Figure 4.Exampleofsetbackfromwildlandvegetation.

50feet

http://www.treesearch.fs.fed.us/pubs/22257http://www.treesearch.fs.fed.us/pubs/22257http://www.fire.ca.gov/http://www.fire.ca.gov/http://www.treesearch.fs.fed.us/pubs/22257http://www.fire.ca.gov/

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FirewiseCommunitiesProgram. www.rewise.org/newsroom/faq.htm.

NationalWildreCoordinatingGroup. www.nwcg.gov.

Slack,P.2000.Firewise Construction Design and Materials.ColoradoStateForestService.

http://www.firewise.org/newsroom/faq.htmhttp://www.firewise.org/newsroom/faq.htmhttp://www.nwcg.gov/http://www.nwcg.gov/http://www.nwcg.gov/http://www.firewise.org/newsroom/faq.htm

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FS No. 4 Defensible Space HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of4

Defensible SpaceHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 4

PurposeToprovideinformationaboutcreatingadefensiblespacetoreducethepotentialfordamageto

homesfromwildres.Guidancepertainstobothnewandexistingbuildings.

Background

Adefensiblespaceisanareaaroundabuildinginwhichvegetation,debris,andothertypesof

combustiblefuelshavebeentreated,cleared,orreducedtoslowthespreadofretoandfrom

thebuilding.Informationaboutlocalvegetation,weather,andtopographyisusedtodetermine

theFireSeverityZoneofanarea,whichcanhelpdeterminethemosteffectivedesignofa

defensiblespace.

Adefensiblespaceisoneofthemostcost-effectivewaystoprotectabuildingfromawildreand

canoftenbecreatedbythepropertyowner.

Key Issues

Wildlandvegetationsuchasgrass,brush,andtimbercanbeextremelycombustible.The

vegetationcanburnwithgreatintensityandproducerebrandsandburningembersthatcan

becomewind-drivenhazards.

Landscapevegetationcanbeascombustibleaswildlandvegetation.

Combustibleplantshavethesecharacteristics:

Volatileresinsandoils(generallyaromatic

whencrushed)

Narrowleavesorlong,thinneedlessuchas

coniferneedles

Waxyorfuzzyleaves

Anaccumulationofdeadleavesandtwigson

andundertheplant

Looseorpaperybark

Awildrecanmovehorizontallyfromshrubto

shrubandtreetotree.

Awildrecanalsotravelverticallyfromthegroundupintothetreetops,resultingina

catastrophiccrownre(arethatcantravelatanincrediblepacethroughthetopofaforest).

Figure1showsarethatisspreadingverticallyfromgrassestoshrubstolowbranches.

Accessorybuildingsandstructuresandotheritemscommonlyfoundinyardsthataremade

Figure 1.Firespreadsverticallythroughvegetation(AnchorPointGroup,Boulder,CO).

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Page2of4 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 4 Defensible Space

ofcombustiblematerialscanalsoputan

otherwisere-resistantbuildingatriskof

ignitionanddestruction.

Combustiblevegetationandmaterialsarounda

building(seeFigure2)can:

Increasetheriskofbuildingignition

Restrictthespacenecessarytoprovide

reghtersarelativelysafeplacetoprotect

abuilding

Increasethechancethatabuildingonre

willigniteadjacentwildlands

Guidance

Assessboththehorizontalandverticalaspectsofvegetationwhendesigningthedefensible

space.

Topreventthehorizontalspreadofwildre,thinshrubsandtreessothecrownsdonot

intersectandthereisspacebetweenindividualshrubsandtrees.

Topreventtheverticalspreadofwildre,keepthelowesttreebranchesprunedandtrimmed

tomaintainverticalseparationfromthetopofshrubsandgrassestothelowesttreebranches.

Theverticaldistanceneededwillvarysignicantly,dependingonthespeciesoftreeand

compositionoftheunderstory.

Createthreeconcentriczonesaroundthebuilding(seeFigure3).Zone1,thezoneclosest

tothebuilding,normallyhasthegreatestneedforfuelmodicationwithprogressivelyless

modicationintheothertwozones.ThehighertheFireSeverityZone,thelargertheconcentriczonesshouldbe.Consultthelocalorstatereagencyforassistance.Thethreezonesare

discussedfurtherbelow.

Zone 1

EliminateallcombustiblematerialsinZone1(within30feetofthehome)suchasre-prone

vegetation,rewoodstacks,combustiblepatiofurniture,umbrellas,anddimensionedlumber

decking(seeFigure4).Desirablesubstitutionsincludeirrigatedgrass,rockgardens,stone

patios,metalpatiofurniture,andnoncombustibledecking(seeFactSheet#13,Decksand

OtherAttachedStructures).

Beforereseasonbegins,removecombustiblelitteronroofsandguttersandtrimtreebranchesthatoverhangtheroofandchimney(seeFactSheet#9,Gutters).

Zone 2

EnsurethatZone2includesonlyindividualandwell-spacedclumpsoftreesandshrubs

and/orafewislandsofvegetationthataresurroundedbyareaswithnoncombustible

materials.

Figure 2.Combustiblematerialsadjacenttoabuildingcreateahazard(AnchorPointGroup,

Boulder,CO).

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FS No. 4 Defensible Space HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of4

Usehardscapefeaturessuchasdrivewaysandpavedorgravelwalkwaysorpatiostocreate

rebreaksthroughouttheyard.

Plantre-resistant,low-volumevegetationthatretainsmoisturewellandneedsminimum

maintenancesuchaspruningandremovingdeadanddyingbranches.

Separateauxiliarystructuressuchasadetachedgarage,pumphouse,pergola,andutilityshed

fromthehomebyatleast50feet.Increasethedistanceifthestructureisusedforthestorage

ofcombustiblematerials.

Complywithrecommendedconstructionpracticesrelatedtoreresistanceforauxiliary

structures.SeeFactSheets#5to#16forguidanceonplanninganddesigningastructureina

wildrezone.

Ensurethatpatiofurnitureiseithermadeof

noncombustiblematerialsuchasmetaloris

atleast30feetawayfromthebuilding.Store

patiofurnitureinalocationthatisprotected

fromignitionbyawildre.

Placewoodpilesatleast30feetfromthe

buildingandstorethewoodinavegetation-

freezonesuchasagraveledarea.

Storefueltanksawayfromastructureatthe

minimumdistancethatisrequiredbycode

orgreater(seeFactSheet#16,Utilities)and

placeundergroundoronanoncombustible

pad.

Figure 4.AnoncombustiblegroundcoverinZone1

helpedthishomesurviveawildre(AnchorPoint

Group,Boulder,CO).

Figure 3.Thethreeconcentriczonesofdefensiblespace.

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Zone 3

Reducefuelsthatarefartherthan100feetfromthebuildingbythinningandpruningvegetation

horizontallyandverticallyasdiscussedabove.ThinningandpruninginZone3canbemore

limitedthaninZone2.ThegoalsinZone3aretoimprovethehealthofthewildlandsandhelp

slowanapproachingwildre.Zone3isalsoanaesthetictransitionbetweenthemoreheavily

modiedZone2andtheunmodiedsurroundings.

Considerations

Consultthelocalorstatereagencyorqualiedremanagementspecialistaboutcodes,

requirements,andstandardsrelatedtodefensiblespace.Codes,requirements,andstandards

normallyrepresenttheminimumthatshouldbedone.Considerationshouldbegivento

providingenhancedprotectionmeasuresbeyondtheminimumrecommendedorrequired.

Maintainingadefensiblespacerequiresroutinemaintenanceofvegetation,whichincludes

pruningandremovingdeadbranchesandleaves.Characteristicsoflow-maintenance

plantsare:

Drought-resistant

Pest-resistant

Nativetothearea

Noninvasive

Slow-growing

Wind-resistant

Sustainablewithoutsupplementalfertilization

Vegetationmodicationmustbeperformedincompliancewithlocal,state,andfederalenvironmentalregulations.

Effectiveness

AllmitigationmeasureslistedinthisFactSheetareeffectiveinallFireSeverityZones.

Resources

Barkley,Y.C.,C.Schnepf,andJ.Cohen.2005. Protecting and Landscaping Homes in the

Wildland/Urban Interface.StationBulletin#67.Moscow,Idaho:IdahoForest,Wildlifeand

RangeExperimentStation.www.treesearch.fs.fed.us/pubs/22257.

FirewiseCommunitiesProgram. www.rewise.org/newsroom/faq.htm.

NationalFireProtectionAssociation(NFPA)1144:StandardforReducingStructureIgnition

HazardsfromWildlandFire.2008. http://dnrc.mt.gov/forestry/Fire/Prevention/documents/

WUIrewrite/NFPA1144.pdf.

NationalWildreCoordinatingGroup. www.nwcg.gov.

http://www.treesearch.fs.fed.us/pubs/22257http://www.firewise.org/newsroom/faq.htmhttp://www.firewise.org/newsroom/faq.htmhttp://dnrc.mt.gov/forestry/Fire/Prevention/documents/WUIrewrite/NFPA1144.pdfhttp://dnrc.mt.gov/forestry/Fire/Prevention/documents/WUIrewrite/NFPA1144.pdfhttp://www.nwcg.gov/http://www.nwcg.gov/http://www.nwcg.gov/http://dnrc.mt.gov/forestry/Fire/Prevention/documents/WUIrewrite/NFPA1144.pdfhttp://dnrc.mt.gov/forestry/Fire/Prevention/documents/WUIrewrite/NFPA1144.pdfhttp://www.firewise.org/newsroom/faq.htmhttp://www.treesearch.fs.fed.us/pubs/22257

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FS No. 5 Roofs HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of5

RoofsHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 5

PurposeToprovidegeneralguidanceonthedesignandconstructionofroofassembliesonbuildingsin

wildrezones.Guidancepertainstobothnewandexistingbuildings.

Key Issues

Roofassembliesarethemostvulnerable

componentofthebuildingenvelopein

awildrebecauseoftheirhorizontal

orientationandsize.

Embersandrebrandscanignitetheroofcovering,otherroofcomponents,anddebris

ontheroof.Oncetheroofhasignited,there

commonlypropagatesintotheinteriorofthe

building,resultinginsubstantialdamageto

ortotallossofthebuilding.

Theprobabilitythatahomewillsurviveawildreisgreatlyinuencedbythecomponentsofthe

roofassembly.Thetypeandarrangementofthecomponentsgoverntheirpotentialforignition

andtheirpropensitytotransferheatintotheinteriorofthebuilding.

Thecomplexityoftheroofsshapealsoinuencesthepotentialforignition.Aroofwithvalleys

androof/wallintersectionswherecombustibledebrissuchasleavesandneedlescancollect

hasmorepotentialforignitionthanaroofwithoutthem.

Fire-rated Roof Assemblies

Theresistanceofroofassembliestoexternalre

isratedbytheAmericanSocietyofTestingand

Materials(ASTM),usingtestmethodE108.The

methodincludesmeasurementsofthesurface

spreadofame,theabilityoftheroofassemblyto

resistrepenetrationfromtheexteriorofthebuildingtotheundersideoftheroofdeck,andthepotential

fortheroofcoveringtodevelopyingbrandsofburningmaterial.Roofassembliesarerated

ClassA(highestrating),B,orC.Assembliesthatfailthetest(donotmeettheClassA,B,orC

criteria)areunrated.

ClassAprovidesthegreatestdegreeofreresistance,butthereisarangeofprotectionwithin

theClassArating.Forexample,someClassAratedassemblieshavenoncombustibleroof

Roof covering: Theexteriorroofcoveror

skinoftheroofassembly(e.g.,shingles,

tiles,slate,metalpanels,roofmembrane).

Roof assembly:Anassemblyofinteractingroofcomponents,includingtheroofdeck,

vaporretarder(ifpresent),insulation

(ifpresent),insulationcoverboards(if

present),andtheroofcovering.

ASTME108testconditionsdonot

replicateactualwildreconditions.In

manycases,actualwildreexposures

aremuchmoreseverethanthose

inducedduringthetesting.

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Page2of5 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 5 Roofs

coverings(suchasclayorconcretetilesandmetalpanels),whileothershavecombustible

coverings(suchasasphaltshinglesandlow-slopemembranes).

Guidance for New Buildings

ManytypesofroofassembliesareratedClassA.RecommendationsforvariouscomponentsofroofassembliesthatareratedClassAareprovidedbelow.

Steep-slope Roof: Covering

Asteep-sloperoofisaroofwithaslopegreaterthan3:12.Thefollowingdesignandinstallation

practicesarerecommended:

Tile. Clayandconcretetilearenoncombustibleandbecauseoftheirrelativelylargethermal

mass,retardthetransferofheat.Lightweighttileproductsareavailable,butnormal-weight

tilesarerecommendedbecauseoftheirgreatermass.Iftilesareinstalledoverwoodbattens,

embersmaybeblownunderthetilesandignitethebattens.Fire-retardant-treatedbattensare

thereforerecommended.Iftileisused,thefollowingarealsorecommended:

Eaves, hips, and ridges. Emberscanbeblown

undertilesattheeaves,hips,andridges.

Birdscanbuildnestsinthespacebetween

theunderlaymentandthebottomofthetilesif

thespaceisaccessible,providingcombustible

debristhatcanbeignitedbyembers.Installing

birdstopsateavesandfullymortaringhipsand

ridgesarebothrecommendedtoavoidthe

accumulationofdebrisundertilesandtokeep

embersout(seeFigure1).

Valleys. Unlessspecialmetalashingis

installed,combustibledebriscanaccumulatein

valleysandthenunderthetiles.Flatandplain

tilesshouldbespeciedtobetightlybuttedtoformaclosedvalley,andpiecesofmetal

ashingshouldbeinstalledundereachtilecoursealongthevalleycenterline.Forproled

tile,leadorexibleashingshouldbeused,asrecommendedbythetilemanufacturer

(seeFigure2).

Metal shingles and panels. Metalshinglesandpanelsarenoncombustible,buttheyreadily

transferheat.Iftheyareinstalledoverwoodbattens,re-retardant-treatedbattensshouldbe

speciedandinstalled.Ifshinglesorpanelsareinstalledoverwooddecking,5/8-inchgypsum

Figure 1.Abirdstopattheeave.

Birdstops prevent debris

from accumulating under tiles

OnlyClassAratedroofassemblies

arerecommendedforhomesin

wildrezones.

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FS No. 5 Roofs HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of5

roofboardcomplyingwithASTMC11771shouldbe

installedoverthedecking.

Fiberglass-reinforced asphalt shingles. Althougha

roofassemblythathasberglass-reinforcedasphalt

shinglescanberatedasClassA,theseshingles

containcombustiblematerial(e.g.,asphalt).Ifthistypeofshingleisused,a5/8-inchgypsumroof

boardthatcomplieswithASTMC1177overthe

wooddeckingshouldbeinstalledforenhanced

protectionofthedecking.Careneedstobetaken

whentheshinglesarenailedthatthenailsarenot

overdriven.

Wood shingles and shakes . Roofassembliesthat

havewoodshinglesandshakescanberated

ClassAiftheshinglesorshakesarere-retardant-

treatedandaspeciccapsheetunderlaymentisinstalled.Withouttheunderlayment,themaximumratingisClassB.Notethatwhenshinglesorshakesarere-retardant-treated,they

cannotbeimpregnatedwithpreservativetreatment.

Ifre-retardant-treatedshinglesorshakesareinstalledoverwooddecking,installing

a5/8-inchgypsumroofboardthatcomplieswithASTMC1177overthedeckingis

recommendedinadditiontothespecialunderlaymentthatisrequiredtoachievea

ClassArating.

Steep-slope Roof: Underlayment

Emberscanbeblownundersometypesofsteep-

slopecoveringssuchastile,slate,andmetal

shinglesandpanels.Iftilesbecomedislodgedor

cracked,emberscanlandontheunderlayment

below(seeFigure3).Installinganunderlayment

thathasenhancedreresistanceisrecommended

toprovideprotectionfromembersthatreachthe

underlayment.

Anexampleofanenhancedunderlaymentisa

mineral-surfacecapsheetthatisratedforusein

aClassAratedassembly.2

Ifamineral-surfacecapsheetisusedundermetalpanelsorshingles,

measuresshouldbetakentopreventthemetalfrombearingdirectlyonthecapsheetandthe

capsheetfromabradingthemetal(therebymakingthemetalsusceptibletocorrosion).

1Boardsthatare5/8-inchthickaretypeX(specialre-resistant).Boardsthatare1/2-inchand1/4-inchthickare

nottypeX.2Althoughcapsheetsarenormallythenishedsurfaceofabuilt-upormodiedbituminousroofcovering,acapsheetcan

alsobeusedasanunderlayment.

Figure 3. Displacedtilesallowemberentry.

Figure 2.Specialvalleyashingtoavoid

debrisaccumulationbetweenandbelow

tiles(photographcourtesyofMonierLifetile).

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Steep-slope Roof: Decking

Mosthomeshaveroofdecksthatareconstructedofwood,typicallyplywoodororientedstrand

board.Fire-retardant-treateddeckingcanbespeciedtoavoidignitionofthedeck.Formore

protection,5/8-inchgypsumroofboardscanbespeciedinadditiontothere-retardant-

treateddeck.

Althoughnotcommoninhomes,noncombustibledeckssuchassteelorconcrete,including

concretetoppingoversteeldecking,canbespecied.Inadditiontobeingnoncombustible,

concretedecksoffergreatresistancetoheattransferandrepenetrationthroughthedeckfrom

theexterior.

Low-slope Roof: Covering and Underlayment

Low-sloperoofshaveslopeslessthan3:12.

Avarietyoflow-sloperoofcoveringsand

assembliesareavailablewithaClassA

rating.

Ifalow-slopeassemblyisselected,the

followingrecommendationsshouldbe

followed:

Polyisocyanurateroofinsulationshould

bespecied(seeFigure4).

A5/8-inchgypsumroofboardthat

complieswithASTMC1177immediately

belowtheroofmembrane(seeFigure4)

shouldbespecied.

Forenhancedreresistance,inadditiontotheaboverecommendations,theroofmembrane

shouldbeprotectedwithheavyweight(i.e.,17poundspersquarefootminimum)concrete

pavers(seeFigure5).

Ifpaversareplacedoverabuilt-upormodiedbitumenmembrane,alayerofextruded

polystyreneinsulation(intendedforprotectedmembranesystems)overthemembrane

shouldbespecied.

Figure 5.Concretepaversover

membrane(FEMA55).

Mortar-facedextruded polystyrene

Roofparapet

Extrudedpolystyrene

Concretepavers

Membrane

Polyisocyanurateinsulation

Roofmembrane

5/8-inch

gypsum board

Roof deck

Figure 4. Componentsofalow-slopedroof.

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Additionally,forsmooth-surfacedbuilt-upandmodiedbitumenmembranes,asheet

ofpolyethylene(minimumof4mils)shouldbespeciedbetweenthemembraneand

polystyrenetokeepthepolystyrenefrombondingtothemembrane.

Toprotectthebaseashings,amortar-facedextrudedpolystyreneboardshouldbeinstalled

overthebaseashing(seeFigure5).

Low-slope Roof: DeckingRoofdeckingdesignandconstructionarethesameforsteep-slopeandlow-sloperoofs.Seethe

discussionundersteep-sloperoofsabove.

Guidance for Existing Buildings

ForhomeownerswithroofassembliesthatarenotClassArated,theonlylong-term,reliable

waytoreduceroofvulnerabilitytowildreistoreroof.Reroongnormallyinvolvesremovingthe

materialsabovetheroofdeckandreplacingthemwithnewmaterials.Therecommendationsthat

arelistedabovefornewbuildingsareapplicabletoreroongdesignandinstallation.

RoofassembliesthathavewoodshinglesorshakesandarenotratedClassAandroofswith

organic-reinforcedasphaltshinglesarevulnerabletoawildre.Thesetypesofroofsshouldbe

replacedassoonaspossible.

Considerations

Thehomeownershouldhaveroofdebrisremovedfromtheroofsurfaceandguttersregularly.

Agingdoesnotaffecttheignitionpotentialoftile.However,someroofcoverings,suchaswood

orberglass-reinforcedasphaltshingles,becomemoresusceptibletoignitionastheyage.The

roofcoveringshouldbereplacedbeforedeteriorationofthecoveringsignicantlydegrades

resistancetoignition.

Birdstopsshouldbeinspectedannuallytoensurethattheyhavenotfallenoutofplace.

Forrecommendationsonvents,seeFactSheet#8,Vents.

Forrecommendationsonguttersanddownspouts,seeFactSheet#9,Guttersand

Downspouts.

Effectiveness

AllmitigationmeasuresrecommendedinthisFactSheetareeffectiveinallFireSeverityZones.

Resources

AmericanSocietyofTestingMaterials(ASTM).2007.Standard Test Methods for Fire Tests of Roof

Coverings.ASTME108-07a.

FEMA.2003.Coastal Construction Manual.FEMA55.

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FS No. 6 Eaves, Overhangs, and Softs HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of3

Eaves, Overhangs,and Softs

Home Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 6

Purpose

Toprovideguidanceonthedesignandconstructionofeaves,overhangs,andsoftsinwildre

zones.Theguidancepertainstobothnewandexistingbuildings.

Key Issues

Windborneembers,convectiveheat,andradiantheatcanbetrappedunderoverhangsand

intheupperportionofexteriorwalls.Overhangsandwallscanigniteifnotconstructedof

noncombustibleorre-resistantmaterials.

Typicalconstructionmaterialsforeaves,overhangs,andsoftsarenotre-resistantandare

thereforesusceptibletoignitionbyembersandhotgases.

Onceaneave,overhang,orsofthasignited,recanspreadontotheroof,intotheattic,or

ontoandthroughtheexteriorwall.

Softsnormallyhaveventsaspartoftheatticventilationsystem.Unprotectedventscanallow

embersandhotgasestoentertheattic(seeFactSheet#8,Vents).

Typical Design and Construction

Eaves.Eavesarelocatedatthedown-slopeedgeofaslopedroofandserveasthetransition

betweentheroofandfascia/wall.Aneavetypicallyhasametaledgeashingandgutterthatare

attachedtoawoodfasciatrimboard.

Overhangs.Overhangsareextensionsoftheroofbeyondtheexteriorwall(i.e.,thejoists,

rafters,ortrussesandthedeckingtheysupport

cantileverpastthewall).Anoverhangprotects

theupperportionofthewallthatitisattached

tofromrainfall,anditalsoshadesthewindows

underitfromthesun.Overhangscanbeopen,

inwhichthetrusses/raftersanddeckingareexposed(seeFigure1),orenclosedbyasoft.

Softs.Asoftenclosestheundersideofsloped-

orat-roofoverhangs.Softsarecommonly

constructedfromber-cementpanels,metal

panels,stucco,vinylpanels,orwoodsheathing.

Metalpanels,untreatedwoodpanels,andvinyl

Attic vents

Figure 1. Anopenoverhang.Theexposedtimber

raftersanddeckingaresusceptibletoignition,and

embersandhotgasescanentertheatticthrough

unprotectedvents.

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Page2of3 09/08 HomeBuildersGuidetoConstructioninWildr eZones FS No. 6 Eaves, Overhangs, and Softs

panelsarevulnerabletodamagefromwildres.Metalpanelsconductheatandcandistortand

allowpassageofembersandhotgases.Untreatedwoodpanelscanignite,andvinylpanelscan

meltandfallaway.

Guidance for New Buildings

Considerdesigningthebuildingwithout

overhangs(seeFigure2)toavoidthere-

relatedproblemsassociatedwithsoftsor

minimizeasmuchaspossibletheextent

oftheoverhangtoreducethepotentialfor

entrapmentofembersandhotgases.

Ifnooverhangsorshortoverhangsare

unacceptablebecauseofaestheticsor

adesiretoprotectthewallsfromrainfall

orwindowsfromthesun,implementthefollowingrecommendedmeasures:

Encloseoverhangswithsoftsthathave

aminimum1-hourre-resistancerating

topreventembersandhotgasesfrommakingcontactwiththejoists,raftersortrusses,or

theundersideoftheroofdecking.

Useat,horizontalsofts(seeFigure3)insteadofattachingthesoftstotheslopedjoists,

whichcreatesslopedsofts.Aatsoftreducesthepotentialforentrapmentofembers

andhotgases.

Forthefascia,usenoncombustibleorre-resistantmaterials(e.g.,re-retardant-treated

lumber,ber-cementboard).

Foreavevents,followtheguidanceinFactSheet#8,Vents.

Embers andhot gases

from fire

Exterior wall

cladding

Fascia

Gutter

Rafter

Underside of

roof deck

Figure 3. An enclosed

overhangwitha

horizontalsoft.

Figure 2.Aneavewithessentiallynooverhang.

Gutter

Embers and hotgases from fire

Horizontalsoffit

Exteriorwallcladding

Fascia

Rafter

Undersideof roof deck

Soffitframing

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FS No. 6 Eaves, Overhangs, and Softs HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of3

Guidance for Existing Buildings

Installasoftunderopenoverhangsaccordingtotheguidanceprovidedabove.

Evaluatethere-resistanceofexistingsoftsandreplacesoftsthatarenotre-resistant

accordingtotheguidanceprovidedabove.Someexistingsofts(suchasthoseconstructedof

plywood)canbecoveredwithanoncombustibleorre-resistantmaterialsuchasber-cement

boardorstucco.

InveryhighFireSeverityZones,installexterior5/8-inchre-resistantgypsumboardbetween

theexistingandnewsoftmaterialsforenhancedreresistance.

Ifthefasciaiscombustible,coverthefasciaboardwithanoncombustibleorre-resistant

material(e.g.,re-retardant-treatedlumber,ber-cementboard).

Foreavevents,followtheguidanceinFactSheet#8,Vents.

Considerations

Plantingcombustiblevegetationundereavesandoverhangsshouldbeavoided(seeFact

Sheet#4,DefensibleSpace).

Effectiveness

AllmitigationmeasureslistedinthisFactSheetareeffectiveinallFireSeverityZones.

Resources

UnderEaveSFMStandard12-7A-3,2001CaliforniaReferencedStandardCodes(Part12,

Title24,C.C.R.).http://www.re.ca.gov/re_prevention/downloads/Part_12_CA_SFM_12-

7A-3_Test_Standards.pdf.

http://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdf

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FS No. 7 Exterior Walls HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of3

Exterior WallsHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 7

PurposeToprovideguidanceonthedesignandconstructionofexteriorwallsinwildrezones.Guidance

pertainstobothnewandexistingbuildings.

Key Issues

Exteriorwallsaresusceptibletowildre

ames,conductiveheat,andradiantheat.

Flamesandheatcanignitecombustiblewall

coverings.Whenexteriorwallsignite,the

recanspreadtoothercomponentsofthebuildingsuchastheroof,soft,windows,and

doors,resultinginsubstantialdamagetoor

totallossofthebuilding.

Windborneembersandrebrandsarealso

sourcesofignition.Emberscanbecome

trappedincracksinwalls,windowopenings,

anddoortrimboardsandignitecombustible

materials.Windbornerebrandscanignite

wallcoverings.

Thereresistanceofexteriorwallsdependsprimarilyonwhatthewallsareconstructedofandtheamountofnearbycombustiblematerial.

Sometypesofconstructionmaterialssuchasvinylsidingdonotburnbutcanmeltwhen

exposedtohightemperatures(seeFigure1),allowingtheretoreachtheunderlyingwall

componentsandpenetratetheinteriorofthebuilding.

Guidance for New Buildings

Forthebestprotection,ensurethatexteriorwallcoveringsarenoncombustibleorre-resistant

andnotsusceptibletomelting.Concrete,ber-cementpanelsorsiding,exteriorre-retardant-

treatedwoodsidingorpanels,stucco,masonry,andmetalarerecommendedmaterials.With

thesecoverings,thecoveringitselfshouldnotigniteandfuelthere.Examplesofthetypes

ofcoveringsthatarenotrecommendedarewoodsidingthatisnotre-retardant-treated,vinyl

siding,metalsidingsusceptibletowarping,andanexteriorinsulationnishsystem.

Ensurethattheentirewallassemblyhasare-resistanceratingtestedinaccordancewith

AmericanSocietyforTestingandMaterials(ASTM)E119.Althoughtheaboverecommended

typesofcoveringsprovideaninitialbarriertoames,heatmaypassthroughthecovering

Figure 1.Vinylsidingthatmeltedandwarped

duringawildre(recenter.berkeley.edu).

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Page2of3 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 7 Exterior Walls

andigniteunderlyingwallcomponents.Are-resistanceratingindicateshowlongundertest

conditionsawallassemblycanpreventamesandheatfrompassingthroughthewall.A

minimumre-resistanceratingof1hourisrecommended,buthigherratingsprovidegreater

protection.

Complywiththerequirementsofthere-ratedassembly,includingusingtheexacttypeof

materials,conguration,andattachmentusedduringthetestingthatestablishedtherating.

Forexceptionalreresistance,useinsulatedconcreteform(ICF)walls,cast-in-placeconcrete,

orfullygroutedconcretemasonryunits.IfICFisselected,useastuccoormasonrywall

coveringtoprotecttheplasticfoamforms.

Ifber-cementormetalwallcoveringsare

used,installonelayerof5/8-inchtypeX

exteriorgypsumboardwithtapedjoints

underneathhousewrap(seeFigure2).

Forber-cementsiding,thegypsumboard

providessecondaryprotectionifthesiding

decomposesandfallsawayduringare.For

metalpanels,thegypsumboardminimizes

thetransferofheatradiatedfromthemetal

panelstootherwallcomponents.

Forvinylsiding(notethatvinylsidingisnot

recommended),installonelayerof5/8-inch

typeXexteriorgypsumboardwithtaped

jointsunderneathhousewrap.Ifthevinyland

housewrapmeltduringare,theunderlyinggypsumboardwillprovidesomeprotection.

Usenoncombustibleorre-resistantmaterialsuchasexteriorre-retardant-treatedwoodor

ber-cementfortrimboardsarounddoors,windows,eaves,andcorners.

Guidance for Existing Buildings

Replaceexteriorwallcoveringsthatarecombustible,aresusceptibletomelting,orcanreadily

transmitheatwithoneoftherecommendedcoveringslistedabove.Examplesofthetypes

ofcoveringsthatneedtobereplacedarewoodsidingthatisnotre-retardant-treated,vinyl

siding,metalsiding,andanexteriorinsulationnishsystem.

Beforereplacingvinylormetalsiding,checkwhetherthereisanunderlyinggypsumboard

substrate.Ifso,remedialworkmaynotbeneeded.

Determinewhetherkeepingtheexistingcoveringandcoveringitwith5/8-inchtypeX

gypsumboardandanewcoveringisaviableoption.

Considerations

Forstudwalls,metalstudscanbeusedinlieuofwoodstuds.Metalstudsdonotignite,but

theytransferheatmorereadilythanwoodstudsandcandeformandcollapseattemperatures

thatcanoccurinawildre.Currentdataareinsufcientregardingthewildreperformanceof

Figure 2.Exampleofare-ratedwallassembly.

Exterior covering

Wall stud

Sill plate

5/8-inch type X

exterior gypsum board

Wood sheathing

Housewrap

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FS No. 7 Exterior Walls HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of3

wallsthathavewoodstudsversusmetalstuds.

Maintainingandremovingcombustibledebris(suchasvegetationandleaves)andrewood

neartheexteriorwallsregularlyreduceabuildingsvulnerabilitytoignitionduringawildre

(seeFactSheet#4,DefensibleSpace).

Effectiveness

Awallassemblywithoneoftherecommendedcoveringsandaminimum1-hourre-resistance

ratingiseffectiveinallFireSeverityZones.

Resources

ASTME119-08aStandardTestMethodsforFireTestsofBuildingConstructionandMaterials.

http://www.astm.org/Standards/E119.ht m.

MaterialsandConstructionMethodsforExteriorWildreExposure:ExteriorWallSidingand

SheathingSFMStandard12-7A-1,2001CaliforniaReferencedStandardCodes(Part12,Title24,C.C.R.).http://www.re.ca.gov/re_prevention/downloads/%20Part_12_CA_SFM_12-

7A-1_Test_Standards.pdf.

http://www.astm.org/Standards/E119.htmhttp://www.astm.org/Standards/E119.htmhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-1_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-1_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-1_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-1_Test_Standards.pdfhttp://www.astm.org/Standards/E119.htm

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FS No. 8 Vents HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of5

VentsHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 8

PurposeToprovideinformationaboutwaystoavoidwindborneembers,convectiveheat,andradiantheat

enteringexteriorventopenings,whichcanleadtotheignitionofinteriorbuildingcomponentsand

contents.Guidancepertainstobothnewandexistingbuildings.

Vent Systems and Vent Openings

Ventscanbedividedintothoseforattics;ventilatedcathedralceilings;crawlspaces;andheating,

ventilation,andairconditioning(HVAC)systems.

Attic and Cathedral Ceiling Vents

Ridge vent acontinuousventinstalledalongthefulllengthoftheroofridge.Ridgevents

allowexltrationofatticair,orinventilatedcathedralceilingsorventilatednailbaseboards,the

exltrationofairfromtheventilationcavityofthecathedralceilingornailbaseboards.Ridge

ventsaremetalorplastic.Someridgeventshaveinternalbafemediatoavoidtheentranceof

wind-drivenrainandsnow.

Soft vent acontinuousorintermittentventinstalledalongasoft.Softventsprovideair

intakeintotheatticorintotheventilationcavityofcathedralceilingsandventilatednailbase

boards.Softventsaremetalorplasticand

oftenhaveascreentopreventinsectentry.

Vinylandmetalsoftsarecommonlyventedby

intermittentlyspaced,perforatedsoftpanels.

Gable-end vent aventlocatedinthegable-

endwall,justbelowtheroofridge.Gable-end

ventsallowairtoowintoandoutofattics.

Gable-endventsnormallyhavelouverblades

toavoidtheentranceofwind-drivenrain

andsnow(seeFigure1).Thistypeofventis

commonlymetalandnormallyhasaninsect

screen.

Through-roof vent aventthatpenetratesthe

rooftoallowexltrationofatticair;alsoknown

asaneyebrowordormervent.Through-roof

vents,includingsheetmetalgoose-necks,arealsoavailableforkitchenorbathroomexhaust

ducts.Through-roofventsaremetal,plastic,orrigidberglass.

Figure 1. Alouveredventopeningcanbeusedfor

gable-endventingorforconnectiontoductwork.

Horizontal louvers can

prevent embers from

entering the ventilation

system

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Page2of5 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 8 Vents

Crawlspace Vents

Crawlspace vent aventinstalledintermittentlythroughthefoundationwallseveralinches

above-grade.Crawlspaceventsallowairtoowintoandoutofthecrawlspace.

HVAC System Vents

Through-roof vent (seeabove).

Wall louvers aventopeningonanexteriorwall(seeFigure1).Walllouversareconnectedto

theHVACductworkwhereairentersorisexhaustedfromthebuilding.Louversarecommonly

metal.Thelouverbladesarenormallyinaxedposition(i.e.,cannotberotated),butsome

havemoveablebladesthatcanberotatedtoclosetheventopening.

Key Issues

Embersandhotgasescanbeblownorpulled

intoventopeningsandenteratticspaces,

crawlspaces,andductwork,leadingtoignitionoftheinteriorofthebuilding(seeFigure2).

Debriscanaccumulateatventopeningsand

igniteduringawildre.

Guidance for New Buildings

All Vents

Specifyandinstallnoncombustiblematerialforallvents.Metalproductsarerecommendedfor

ventsandventashing.

Specifyandinstallcorrosive-resistant,metalmeshscreenswithamaximumopeningof

1/4inchatallventopenings.

Specifyandinstallventopeningswithamaximumnetfreeareaof144squareinches.

Placeallventopeningsatleast10feetfromotherbuildingsorpropertylinestoavoidignition

fromembersandhotgasesfromanadjacentbuildingthathasignited.

Attics (including Cathedral Ceiling and Ventilated Nailbase Boards)

Protectingatticspacesfromwildresisachallengebecauseairisnaturallydrawnintoattics

throughventopenings.Althoughinsectscreenscanpreventtheentryofmanyembers,vent

screensandlouversdonotpreventtheentryofhotgases.Ventsthatallowairtoowintoandout

undernormalconditionsandalsoavoidtheentryofembersandhotgasesinawildrecanbe

providedinthefollowingways:

Gable-end vent .Insteadofusingridgevents,specifyandinstallgable-endventswithspecially

designedmetalshutters.Whenawildrethreatens,theshutterscanbeplacedoverthegable-

endvent.Ahingedshutterthatcanbelatchedinanopenorclosedpositionisrecommended

(seeFigure3).Adetachableshutterdesigncanbeused,butwhentheshuttersareneeded,

Figure 2. Embersorhotgasescanbeblownor

pulledintovents.

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FS No. 8 Vents HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of5

thehomeownermustrememberquickly

wheretheyarestored.Shuttersshouldhave

agasketthatprovidesatightsealbetween

theshutterandgable-endvent.Foramore

conservativeshutter,ashutterwithan

insulatedcoreencapsulatedbymetal(similartoarefrigeratordoor)canbeused.

Whengable-endventsarecombinedwith

softvents,effectiveatticventilationcan

beachievedwhentheatticspaceissimple

andrelativelysmall,suchasasmall,gable-

roofedhouse.Ifthehousehasacomplexroof

areaortheatticistoolargetobeeffectively

ventilatedbygable-endvents,ridgeventsor

through-roofventsshouldbeused.

Ridge vent .Continuousridgeventscanprovideeffectiveventilation,buttypicalridge

ventsarenothighlyre-resistant.Althoughairisnormallyexhaustedthroughridgevents,

hotgasescanentertheridgeventandowintotheattic.Emberscanalsoenterthroughthe

ridgeventiftheventdoesnothaveinternalbafemedia.Typicalridgeventsarethereforenot

recommendedunlesstheatticcongurationorsizerequiresridgeventstoventilatetheattic

effectively.Ifridgeventsareused,metalventswithinternalbafemediaarerecommended,

butduringawildre,theinternalbafe

materialmaymeltandbecomeineffective in

atpreventingembersfromentering.

Soft vent . Aswithridgevents,typicalsoftventsarenothighlyre-resistant,but

becausetheyareanecessaryelementofa

ventedattic,theycannotbeeliminated.To

avoidembersandhotgasesfromentering

thevents,speciallydesignedmetalshutters

overthesoftventopeningsshouldbe

speciedandinstalled.Seetheshutter

recommendationsforgable-endventsabove.

Through-roof vent . Through-roofventsarenot

recommendedforatticventilationbecausethereisnoknowneffectivestrategyfor

avoidingembersandhotgasesfromentering,

otherthanblockingthevent.A1/4--inch

screeniseffectiveatkeepingoutrebrands

andembersthatarelargerthan1/4-inchbut

willnotkeepoutsmallerembersorhotair.

Shutter with

fire-resistant gasket

Shutter latched in

open position

Wall louver vent

Shutter manually latched

in closed position at the

onset of a wildfire

The Unventilated Attic

Themostconservativeapproachto

preventingembersandhotgasesfrom

enteringtheatticistoeliminateattic

ventilation,butunventilatedatticsare

controversial.Althoughallowedbythe

InternationalResidentialCode,provided

theCodescriteriaaremet,unventilated

atticsmaynotcomplywithlocalbuilding

codes.

However,whenunventilatedatticsare

allowedbythebuildingcodeorcode

complianceisnotanissue,andwhenclimaticandinteriorhumidityconditions

(e.g.,noindoorswimmingpools)are

conducivetoanunventilateddesign,

anunventilatedatticisareliableway

topreventembersandhotgasesfrom

enteringtheattic.

Figure 3.Ahingedshutter.

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Page4of5 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 8 Vents

Becauseofvariablereliabilityofblockingtechniquesandthepotentialdangerofhomeowners

fallingfromroofswhileattemptingtoblockvents,blockingisnotrecommended.

Crawlspace Vents

Specifyandinstallspeciallydesignedmetalshuttersovercrawlspaceventopenings.A1/4-inch

meshscreenshouldalsobeinstalledovertheventopening.Seetheshutterrecommendations

forgable-endventsabove.

HVAC System Vents

Wall louvers . Specifyandinstallspeciallydesignedmetalshuttersoverwalllouvers(seethe

shutterrecommendationsforgable-endventsabove)orspecifyandinstallwalllouversthat

haveadjustabletight-ttingbladesthatcanbeclosedwhenawildrethreatens.

Asanadditionalconservativemeasurewitheithershuttersoradjustableblades,specifyand

installredamperswithintheductsimmediatelybehindthewalllouvers.Ifsufcientlyhigh

heatpenetratesbeyondthelouver,theredamperwillautomaticallycloseandpreventhighheatfrompenetratingfarther.

Through-roof vents .Asdiscussedinatticventilation,through-roofventsarenotrecommended.

Ratherthanrunningductworkthroughtheroof,extendtheductworktoanexteriorwallwhere

itcanbettedwithawalllouverandshutter.Ifitisnecessarytopenetratetheroof,however,

installaredamperintheductattheplaneoftheroofassembly.

Guidance for Existing Buildings

Ifthehomehasridgeventsorwalllouversandtheyarenotmetal,replacethemwithmetal

ventsaccordingtotheguidanceprovidedabove.

Ifexistingventopeningsdonothavescreensorifthescreenopeningsarelargerthan

1/4-inch,installmetalscreensaccordingtotheguidanceprovidedabove.

Installshuttersovergable-endvents,softvents,crawlspacevents,andwalllouvers.Ifthe

existingwallorsoftiscombustible,shuttersmaynotbeeffective.Inthiscase,installing

shuttersisprobablycost-effectiveonlyifdoneinconjunctionwithupgradestothewallorsoft.

Considerations

Low-prole,through-roofventshavebeenusedinplaceofsoft/eaveventswithgreatsuccess,

butnoneoftheseproductshavebeentestedatthetimeofthispublication.

Thehomeownershouldperiodicallyhaveaprofessionalremovedebristhathasaccumulated

nearoronventopenings,ventscreens,andlouverblades.

Theamountofvegetationnearventopeningsshouldbelimited(seeFactSheet#4,Defensible

Space).

Tominimizethepossibilitythatembersandhotgaswillbepulledintothehome,theHVAC

system,includingexhaustfans,shouldbeturnedoffwhenawildrethreatens.Atticexhaust

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FS No. 8 Vents HomeBuildersGuidetoConstructioninWildreZones 09/08 Page5of5

fansshouldalsobeshutdown.Atticexhaustfansthatarecontrolledbyathermostatmayneed

tobedeactivatedbytrippingthecircuitbreaker.

Forsoftconstruction,seeFactSheet#6,Eaves,Overhangs,andSofts.

Effectiveness

AllmitigationmeasureslistedinthisFactSheetareeffectiveinallFireSeverityZonesexceptas

notedbelow.

Ifaridgeventisinstalled,theventopeningmaybebreachedduringextremereexposureby

embersorhotgases,whichcouldresultinignitionoftheattic.

Theeffectivenessofshutter-protectedventopeningsisdependentonthedeploymentofthe

shuttersbythehomeownerpriortoreexposure.

Resources

Slack,P.2000.Firewise Construction Design and Materials.ColoradoStateForestService.

UnderEaveSFMStandard12-7A-3,2001CaliforniaReferencedStandardCodes(Part12,Title

24,C.C.R.).Availableatwww.re.ca.gov/re_prevention/downloads/Part_12_CA_SFM_12-

7A-3_Test_Standards.pdf.

http://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-3_Test_Standards.pdf

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FS No. 9 Gutters and Downspouts HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of2

Gutters andDownspouts

Home Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 9

Purpose

Toprovideguidanceaboutinstallingre-resistantguttersanddownspoutstoreducethepotential

fordamagetohomesandotherbuildingsfromwildres.Guidancepertainstobothnewand

existingbuildings.

Key Issues

Debrissuchasbranches,leaves,andpineneedlescan

becometrappedingutters(seeFigure1).Thedebris

canbeignitedbyyingembersorrebrandsduringa

wildre,andtherecanspreadtotheroof.

Guttersanddownspoutsareoftenconstructedof

plastic.Plasticcanmeltwhenexposedtothehigh

temperaturesthatcanoccurduringawildre.

Guidance

Installnoncombustibleleafguardsoverguttersto

preventtheaccumulationofcombustibledebris.Types

ofleafguardsincludemetal-meshscreensandmetal

hoodsthattintothegutter(seeFigure2).

Useguttersanddownspoutsconstructedof

noncombustiblematerialssuchasgalvanizedsteel,

copper,andaluminum.Metalhoodleafguardsare

recommendedbecausetheydonotmeltandare

relativelyeffectiveinkeepingdebrisoutofgutters(see

Figure2).

ConsiderationsIntenseheatfromawildrecandistortnoncombustible

gutters,leafguards,anddownspouts,andtheymayneed

tobereplacedafterawildre.

Someleafguardscanbecomedislodgedovertime,reducingtheireffectiveness.

Figure 2.Leafguardsallowrainwaterintothegutterbutkeepcombustible

debrisout.

Leaf guard

Figure 1. Debrisingutterscanignite

andleadtoignitionoftherooforfascia

board.

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Sometypesofleafguardsdonotpreventalltypesofdebrisfromaccumulatinginthegutter.

Forexample,mesh-typeleafguardsallowpineneedlestoaccumulate.Leafguardsandgutters

shouldthereforebecheckedregularlyanddebrisremovedifnecessary.

Effectiveness

Noncombustiblegutters,leafguards,anddownspoutsareeffectiveinallFireSeverityZones.

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FS No. 10 Windows and Skylights HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of4

Windows andSkylights

Home Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 10

Purpose

Toprovideinformationaboutmeasuresthatcanbetakentoavoidtheignitionofinteriorbuilding

componentsandcontentsduetotheintrusionofwindborneembers,hotgases,andradiantheat

throughwindows,slidingglassdoors,doorvisionpanels,andskylights.Guidancepertainstoboth

newandexistingbuildings.

Key Issues

Glazinginhomesistypicallyvulnerabletowildre

(seeFigure1).(Glazingreferstotheglass,

plastic,orberglass-reinforcedtranslucent

materialinwindows,slidingglassdoors,door

visionpanels,andskylights.)Failedglazingallows

easypassageofembers,hotgases,andradiant

heatintotheinteriorofthebuilding.Glazingis

vulnerabletowildreintwoways:

Flameimpingementandradiantheatcanbe

severeenoughtomeltorbreakmanytypes

ofglazing.Asinglepaneoftypicalresidential

glasscanfailwithin5minutesofexposuretoa

wildre(Slack,2000).

Windbornerebrandscanhavesufcient

momentumtobreakmanytypesofglazing.

Theframesforwindows,slidingglassdoors,and

skylightsareconstructedofmetal,plastic,wood,

oracombinationofthesematerials.Plasticand

woodenframesaresusceptibletofailurefrom

burningormelting(seeFigure2).Iftheframeor

sashfails,theentireglazingmayfallout.

Guidance on New Buildings

Thissectionprovidesguidanceonglazing,frames,

re-ratedassemblies,andexteriorwindowshutters.

Figure 1.Potentialdamagetoawindow

duringawildre.

Embers melt vinyl framesand ignite wooden frames

Radiant heat and windbornefirebrands can shatter windows

and lead to interior damage

Figure 2.Combustibleframing(recenter.

berkeley.edu).

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Glazing

Avarietyofproductsareavailableforglazinginwindows,slidingglassdoors,doorvisionpanels,

andskylights.Glazingcanbeinasingle-ormulti-panedconguration.Therecommendedglazing

productsforhomesinwildrezonesarelaminatedglass,temperedglass,glasswithalow-

emissivity,berglass-reinforcedtranslucentglazing,andinsulatedglazingunits(IGUs).Glazing

productsthatarenotrecommendedareannealedglass,ceramicglass,andplasticglazing.

Recommended

Laminated glass . Laminatedglassprovidesresistancetowindbornerebrands.Ifa

rebrandstrikeswithenoughmomentumtobreaktheglass,theplasticlminthecoreof

theglasswillkeeptheglazingintheframe,allowingthebrokenglasstocontinuetoresist

rebrandimpacts,embers,andhotgases.Iftheplasticlminthecoregetssufcientlyhot,

thepanewilldelaminatewhetherornottheglasshasbeenbroken.Iflaminatedglassis

specied,itshouldeitherbeprotectedbyshutters,asdiscussedbelow,orcombinedwith

temperedglassinanIGU.SeetheinformationonIGUsbelow.

Tempered glass .Temperedglassismoreresistanttoheatandamesthanlaminatedglassorannealedglass(seebelow).Theresistanceoftemperedglasscanbeenhanced

withalow-ecoatingoraproprietaryreectivecoating,asdiscussedbelow.Firebrands

withsufcientmomentumcanbreaktemperedglass.Toavoidbreakage,theglasscanbe

protectedbyshutters,asdiscussedbelow.Anotheralternativeistospecifyandinstallan

IGUwithalaminatedglassinnerpane.

Low-emissivity (low-e) coating . Glasswithalow-ecoatingprovidesahigherlevelof

resistancetoradiantheatthanothertypesofglazingbecausethecoatingreectsradiant

heat,reducingtheprobabilitythattheheatwillbeabletoenterthebuilding.Thecoating

shouldbeontheinnersurfaceoftheexteriorpane.

Proprietary berglass-reinforced translucent glazing .Thisproductisavailableforskylights

andwalls.TheskylightmaterialhasaClassArating.SeeFactSheet#5,Roofs,fora

discussionofthistypeofrating.

Insulated glazing unit. AnIGUconsistsoftwo

orthreepanesofglassthatareseparatedbya

sealedairspace.Double-panedannealedunits

lastabout10minutesinawildre,twiceas

longassingle-panedwindows.Inmanycases,

10minutesislongenoughtoprovideprotection

fromthere.Iftherstpanefails,thesecond

panemuststillbepenetrated(Slack,2000)

(seeFigure3).Laminatedglass,tempered

glass,andglasswithalow-ecoatingcanbe

combinedinvariouswaysintoanIGU.

Two panes of glass with

a layer of air between

The first pane may shatter

within 5 minutes of the

onset of a wildfire

The second pane offers

5 minutes of additional

protection

Figure 3. Double-panedglazing.

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FS No. 10 Windows and Skylights HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of4

NotRecommended

Annealed glass .Annealedglass(alsoknownascommonoatglass)iscommonlyusedin

residentialwindows.Annealedglassisthemostsusceptibletowildresofthevariousglass

typesandisnotrecommendedforhomesinwildrezonesunlessprotectedbyshutters,as

discussedbelow.

Ceramic glass. Thisspecialtyglassiseffectiveatresistingames,butittransmitsradiant

heatreadily.Ifceramicglassisusedforexteriorglazing,heatthatishighenoughto

causeignitioncanbetransmittedintotheinteriorofthebuilding.Ceramicglassisnot

recommendedforhomesinwildrezones.

Plastic glazing. Acrylicandpolycarbonateareoftenusedinskylightsandsometimesin

windows.Becauseplasticglazingcanmeltduringawildre,itisnotrecommendedfor

homesinwildrezones.

Frames

Avarietyofproductsareavailableforwindowandskylightframes.Toavoidwindowfailure,frames

shouldbeconstructedonlyofmetalormetal-cladwood.Woodenandplasticframesshouldnot

beused.

Fire-rated Assemblies

Ifare-ratedwallisspecied,windowsandslidingglassdoorsthatarecommensuratewiththe

wallintermsofthereratingarerecommended.Forexample,awindowwitha1-hourratingis

intendedtobeusedinawallwitha2-hourrating,andadoorwitha3/4-hourratingisintended

tobeusedinawallwitha1-hourrating.However,awindowwithahigherreratingmaybeused.

SeeFactSheet#7,ExteriorWalls,forinformationaboutre-ratedwalls.

Ifare-ratedwallisnotspecied,anIGUwithametalormetal-cladwoodenframeshouldbeused.SeetheinformationonIGUsabove.

Exterior Window Shutters

Exteriorwindowshutterscanprovideprotectionfor

windowsandslidingglassdoorsinawildre.Solid

metalshuttersareunlikelytoigniteormeltandare

thereforerecommendedoverwoodenorplasticshutters

(seeFigure4).Forenhancedprotection,aninsulated

metalshuttercanbedesignedandfabricated.Ifthe

buildingislocatedinawindbornedebrisregionwithinahurricane-proneregion,theshuttershouldmeetthe

windbornedebriscriteriaintheAmericanSocietyof

CivilEngineersstandard,ASCE7-05(2006).Figure 4. Thismetalshutterhastop

andbottomtracksthatarepermanently

anchoredtothewall(FEMA577).

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Guidance on Existing Buildings

Windowsandslidingglassdoors,includingframes,thataresusceptibletodamagefrom

awildreshouldbereplacedwiththecomponentsthatarerecommendedaboveand/or

protectedbyshutters,asrecommendedabove.

Doorvisionpanelsthataresusceptibletodamagefromawildreshouldbereplacedwith

temperedglasswithalow-eorproprietaryreectivecoating,providedthedoorhassufcient

reresistance(seeFactSheet#11,ExteriorDoors).

Skylightswithplasticglazingshouldbereplacedwithoneoftherecommendedtypesof

glazing,asdescribedabove.

Considerations

Shuttersprotectthehomenotonlyfromwildresbutalsofromextremeweather.

Double-panedglassismoreenergyefcientthansingle-panedglass.

Aproprietaryreectivecoatingisavailableforapplicationtotemperedglass.Thecoatingacts

likealow-ecoatinginthatitreectsradiantheat,buttheproprietaryreectivecoatingmaybe

moreeffective.Formoreinformationonthisproductandacomparisonofreratingsofvarious

typesofglassproductsandsizes,seewww.safti.com.

Effectiveness

Windowassemblieswith3/4-hourminimumratingsareeffectiveinallFireSeverityZones.

Metalcladdingonmetalclad-woodframesmaybecomedistortedduringwildreexposureand

requirereplacement.

Temporaryshuttersareeffectiveonlyifthehomeownerhassufcienttimetoputtheshutters

intoplace.

Resources

AmericanSocietyofCivilEngineers.(2006).Minimum Design Loads for Buildings and Other

Structures.ASCE7-05.

CenterforFireResearchandOutreach.UniversityofCalifornia,Berkeley:CollegeofNatural

Resources.http://recenter.berkeley.edu/default.htm.

ExteriorWindowsSFMStandard12-7A-2,2001CaliforniaReferencedStandardCodes(Part12,

Title24,C.C.R.).http://www.re.ca.gov/re_prevention/downloads/Part_12_CA_SFM_12-

7A-2_Test_Standards.pdf.

FEMA.2007.Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds:

Providing Protection to People and Buildings. RiskManagementSeries,FEMA577.

http://www.fema.gov/library/viewRecord.do?id=2739 .

FireRatedGlazingSolution. www.safti.com.

Slack,P.2000.Firewise Construction Design and Materials. ColoradoStateForestService.

http://www.safti.com/http://www.safti.com/http://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-2_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-2_Test_Standards.pdfhttp://www.fema.gov/library/viewRecord.do?id=2739http://www.safti.com/http://www.safti.com/http://www.safti.com/http://www.fema.gov/library/viewRecord.do?id=2739http://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-2_Test_Standards.pdfhttp://www.fire.ca.gov/fire_prevention/downloads/Part_12_CA_SFM_12-7A-2_Test_Standards.pdfhttp://www.safti.com/

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FS No. 11 Exterior Doors HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of3

Exterior DoorsHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 11

PurposeToprovidebasicguidanceonthedesignandconstructionofexteriordoors,includinggarage

doors,onbuildingsinwildrezones.Guidancepertainstobothnewandexistingbuildings.

Key Issues

Exteriordoorsaresubjecttothesame

typesofexposureasexteriorwallsina

wildre(seeFigure1).However,exterior

doorsaretypicallymuchthinnerandless

re-resistantthanexteriorwallsandcanthereforeburnthroughmuchfaster.

Flamesandhotgasescanignite

combustiblematerialsinadooranddoor

frame.

Flamesandhotgasescanpenetrate

openingsbetweenthedoorandframeand

betweenthedoorandthreshold(oroorif

nothresholdexists).

Emberscanbecomelodgedinopenings

betweenthedoorandframeandbetween

thedoorandthreshold(oroorifno

thresholdexists).Emberscanalsobe

blownthroughtheopeningsintothe

interiorofthebuilding.

Flames,convectiveorradiantheat,and

airbornerebrandscanbreakglassina

door.

Exterior Door Characteristicsand Ratings

Typesofexteriordoorsincludesolidentrancedoors,entrancedoorswithglassvisionpanels,

slidingglassdoors,stormdoors,screendoors,garagedoors,andcellardoors.

Solidexteriordoorsaretypicallymadeofwoodormetal.Doorswithasolid,noncombustible

mineralcoreareclassiedasre-rateddoorsandareratedbyUnderwritersLaboratories

(UL)accordingtothelengthoftimetheycanresistre(ULStandard10C)(UL,1998).UL

Figure 1. Typesofexposurethatexteriordoorscanbe

subjecttoinawildre.

Welcom

e

Welcom

e

Embers can become lodged

in openings and separations

Radiant heat can

shatter glass

Radiant heat and embers can ignite combustible

materials and penetrate through openings

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Page2of3 09/08 HomeBuildersGuidetoConstructioninWildreZones FS No. 11 Exterior Doors

classicationsforinteriorandexteriorre-rateddoorsandtheirframesrangefrom3-hourto

20-minuteratings.Exteriorre-rateddoorsareavailablewitharatingof1houror3/4hour.

Thereratingfordoorsisintendedtoequalthree-fourthsofthereratingofthesurroundingwall.

Forexample,adoorwitha1-hourratingisintendedtobeusedinawallwith2-hourrating,and

adoorwitha3/4-hourratingisintendedtobeusedinawallwitha1-hourrating.However,adoor

withahigherreratingmaybeused.

Guidance for New Buildings

Ifare-ratedexteriorwallisspecied(seeFactSheet#7,ExteriorWalls),specifyandinstalla

re-rateddoorandframe.Asexplainedabove,theratingofthedoorandframeshouldbeat

leastthree-fourthsoftheratingofthewall.Inaddition,specifyandinstallre-ratedhardware.

FollowtheguidancepertainingtodoorglassvisionpanelsandglassslidingdoorsinFact

Sheet#10,WindowsandSkylights.

Toavoidembersandhotgasespenetratingtheinteriorofthebuildingbetweenthedoor

andthedoorframe,installadjustableweatherstrippingontheinteriorsideofthedoor

frameandspecifyandinstallanautomaticdoorbottomorthresholdweatherstripping.The

weatherstrippinganddoorbottomshouldbetestedinaccordancewithULStandard10C.

Weatherstrippingisrelativelyinexpensive(seeFigure2).

Garagedoorsaretypicallymadeofwood,aluminum,orsteel

andareinsulatedornon-insulated.Unlikestandardegress/

ingressdoors,garagedoorsarenotnormallytestedforre

resistance(seeFigure3).Toprotectthegaragedoorand

entirebuilding,followtheguidancelistedbelow.

Specifyandinstallinsulated,metalgaragedoors.

Toavoidembersandhotgasespenetratingthegarage,

specifyandinstallweatherstrippingthathasbeentested

inaccordancewithULStandard10Caroundtheentire

garagedoor.

Figure 2.Exampleofadjustable

weatherstripping(FEMA577).

Fire-resistant

weatherstripping

Noncombustible or

fire-resistant trim

Insulated metal door

Figure 3.Agaragedoorwith

noncombustibleandre-resistant

components.

Door

Adjustable

jamb

weatherstrip

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FS No. 11 Exterior Doors HomeBuildersGuidetoConstructioninWildreZones 09/08 Page3of3

Forexteriortrimthatcoverstheopeningbetweenthedoorframeandexteriorwall,specifyand

installnoncombustibleorre-resistantmaterialsuchasre-retardant-treatedwoodorber-

cementboard.

Guidance for Existing Buildings

Addweatherstrippingtodoors,asdescribedabove.

Replacevisionpanelsindoors,ifnecessary,asdescribedinFactSheet#10,Windowsand

Skylights.

Replaceslidingglassdoorsand/orprotectwithshutters,asdescribedinFactSheet#10,

WindowsandSkylights.

Replacewoodengaragedoors,particularlyiftheydonothaveasolidcore.

Replacewoodenegress/ingressdoorswithoutasolidcore,althoughegress/ingressdoorsare

oftenrelativelyre-resistantcomparedtoothercomponentsofthebuildingandthereforenot

normallyahighpriorityforremediation.

Considerations

Metalandmetal-claddoorframescantransmitheatduringare,andtheheatcanignitethe

surroundingexteriorwallifthewallisnotconstructedtore-resistantstandards,asnotedabove.

Formoreinformation,seeFactSheet#7,ExteriorWalls.

Effectiveness

AllmitigationmeasureslistedinthisFactSheetareeffectiveinallFireSeverityZonesexceptas

follows:

GaragedoorsarenotnormallytestedforreresistanceandmaynotprovideeffectivereresistanceinhighFireSeverityZones.

Underveryhighheatorprolongedexposuretoheat,weatherstrippingmaterialcanmeltor

burn,loweringitseffectivenessinpreventingembersandhotgasesfromenteringtheinterior

ofabuilding.

Resources

FEMA.2007.Design Guide for Improving Hospital Safety in Earthquakes, Floods, and High Winds:

Providing Protection to People and Buildings.RiskManagementSeries,FEMA577.http://

www.fema.gov/library/viewRecord.do?id=2739.

SteelDoorInstitute(SDI).2001. Basic Fire Door Requirements. TechnicalDataSeriesSDI

118-01.http://www.steeldoor.org/res/118.pdf).

UnderwritersLaboratory(UL).1998.ULStandard10C,PositivePressureFireTestsofDoor

Assemblies.

http://www.steeldoor.org/res/118.pdfhttp://www.steeldoor.org/res/118.pdf

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FS No. 12 Foundations HomeBuildersGuidetoConstructioninWildreZones 09/08 Page1of4

FoundationsHome Builders Guide to Construction in Wildfre Zones Technical Fact Sheet No. 12

PurposeToprovideguidanceonavoidingtheignitionoffoundationsbywindborneembersandconvective

andradiantheatinwildrezones.Guidancepertainstobothnewandexistingbuildings.

Foundation Designs

Foundationscanbeopenorclosed.Homesnormallyhaveonlyonetypeoffoundation,butsome

haveboth.

Closed Foundation

Inaclosedfoundation,thefoundationwall

extendsfromthefootingtotherstooraround

theperimeterofthebuilding.Thefoundation

wallistypicallyabearingwall.Thebelow-grade

portionistypicallycon