RETROFIT Improvements MakingHomesSafer inDisasters
Hazards
Februar y 2012 Working Draf t w w w.toolbase.org
Purpose•Tocreateacontinuousload-pathfromtherooftothewall
•Toresistupliftforcesfromwind•Toresistlateralforcesfromwindandearthquakes
Benefits•Strengthensconnectionsinwindandseismicevents
Retrofit Opportunity•Roofsheathingreplacement•Soffitreplacement•Residing
IllustrationsRetrofitOption 1:Hurricane clip connecting the truss or rafter to top plates.
SummaryInmanyhomesbuiltbefore1990,rooftrussesorrafterswerefastenedtothewallwithtwoframingnailsangledintotherafterandwallplateinwhatisknownasatoe-nailedconnection.Theconnectionisinadequatetoresisttheforceofhighwindpushingupontheoverhangandsoffit(whichcanactlikeasailtocatchwind).Inhurricaneandgalewindconditions,roofstructuralsupportshavebeenpriedawayfromthewallbytheforceofwind.Installingastrongermechanicalconnectionbetweentheroofframingmembersandthewallwillincreasethecapabilityoftheroofstructuretowithstandtheupliftforcesfromhurricanewindsandlateralforcesfromearthquakes.Steelhardware,suchasisoftenseenonoutdoordecks,canprovidethesecureconnectionrequiredbetweenroofandwallframing.Tiedownhardware,alsoknownashurricaneclips,canbeinstalledforunder$10.Ahousesized40’x30’requiresapproximately42pieces,soprovidingaddedassurancewithtiedownhardwarewouldcostbetween$200and$400.Thiscost,however,assumesdirectandsimpleaccesstothewallandroofframing,whichisnotoftenthecaseinacompletedhouse.But,retrofittingrooftiedownhardwarebecomescosteffectivewhenincludedinthescopeofotherremodelingworksuchasresiding,replacingsoffitandfascia,orreplacingroofsheathingattheoverhang.Consultyourcontractorfortheinclusionofthisandothersafetydetailsthatwilladdvalueandpeaceofmindtoyourplannedhomeimprovementprojects.
Roof-to-Wall AttachmentFloodWind Rain Seismic SnowFire
Option 2:Tie strap connecting the truss or rafter to the wall stud and top plates.
Februar y 2012 Working Draf t w w w.toolbase.org
Potential Damage
Key Steps •Planthisretrofitasapartofalargerhomeimprovementprojecttomaximizecostefficiency,asaccesstothewallandroofframingintersection(frominsideoroutside)isnecessary.
• Inspecttheframingtoensureacontinuousloadpath.• Inspectforexistingtie-downhardwareanddetermineadditionalhardwarerequirements.• Installtie-downhardwarebeforeproceedingwithlargerproject.Hardwareinstallationwillrequireabouttwohours,soitshouldn’tmateriallyaffectthepaceoftheoverallproject.
•Yourcontractormayhaveadditionalideasonhowtoimprovethesafetyofyourhome.•Formoredetailsaboutthisretrofitimprovement,pleaserefertothelistofResourcesinthesectionbelow.
ResourcesFEMA,Home Builder’s Guide to Coastal Constructionhttp://www.fema.gov/library/viewRecord.do?id=2138
Photo:www.fema.gov
