RETROFIT Improvements akin Homes/media/Files/... · braced gable ends are a common cause of major...
Transcript of RETROFIT Improvements akin Homes/media/Files/... · braced gable ends are a common cause of major...
RETROFIT Improvements MakingHomesSafer inDisasters
Hazards
Februar y 2012 Working Draf t w w w.toolbase.org
Additional stud
Lateral bracing
Compression blockingRafter
Truss bottom chord
Lateral bracing (6’ minimum)
Compression blocking
Double top plate
Gable end trussbottom chord
Gable end stud
Purpose•Topreventrooffailurefromhighwinds
Benefits•Preventsrooffailure•Strengthensthebuildingenvelopeagainstpenetrationbywindandwater
Retrofit Opportunity•Thisretrofitcanbeperformedatanytimeiftheatticframingisexposed
•Rooforsidingreplacementproject
IllustrationsRetrofitOption 1:Diagonal bracing
SummaryBecausegableroofspresentalargewallsurfacetotheelementsatthehighestpartofthehousewherewindsarestrongest,gableroofsaremoresusceptibletodamagefromhighwindsthanhiporflatroofs.Ifthegableendisnotadequatelybracedtoresistthewind,thegableendwallcancollapseunderthewind’sforce,leavingtherestoftheroofsusceptibletoupliftandthehouseopentotheelements.Inadequatelybracedgableendsareacommoncauseofmajordamagetostructuresandtheircontentsinstorms.Iftheroofingisbeingreplaced,improvetheattachmentoftheroofsheathingbyinstallingfastenersat4”spacingthroughoutthesheathingforthefirstfourfeetofroofareafromallroofedges.Installfastenersat6”spacingotherwise.Ifthereisanoverhanggreaterthan12”atthegableend(rake),anditisframedasaladderandattachedtothesideofthehouse,itisbesttoremoveit.Itmaybepossible,however,toreinforcetheconnectionbyinstallingalagboltfromtheattic,throughthegableendtopchordandwallsheathing,intothe2x4oftheladderframe.Rakeoverhangsinhighwindareasshouldbeconstructedasoutriggerstiedbackintotheroofsystemfortwicethelengthoftheoverhang,orasfaraspossible,andsecuredattheendwithtiedownhardware(e.g.joisthanger).Gableendswillbesimilarlyconstructedinbothtruss-framedandconventionalrafter-framedroofs,thusaddedbracingdetailswillbesimilarforeitherroofsystem.Rooftrussedsystemswilltypicallyhavepermanentlateralbracinginstalledperpendicularlycrossingthecenterofwebsexceeding8’inlength.Rafterswilltypicallyhavecollartiesandpurlinsinthesameplaneastherafters.Thepermanentlateralbracingofbothsystemsisalsoprovidedbytheroofsheathingandceilingdrywall.Thereareseveral“Do-It-Yourself”approachestogableendbracingforthehandyhomeownerwhoisabletogainaccesstothegableendthroughtheattic,andthecostofmaterialsforthisretrofitisunder$100.Otherwise,consultacontractortoincorporatethisandothersafetyfeaturesintoyournextremodelingproject.
Gable End BracingFloodWind Rain Seismic SnowFire
2x4 Gable bracing
Option 2:Gable end bracing
Februar y 2012 Working Draf t w w w.toolbase.org
Potential Damage
Key Steps •Bracinggablewallsinanaccessibleatticisamoderatelyeasytaskandcanbea“Do-It-Yourself”jobforthenovicewithpatience.
• Inspecttheatticforadequateroofsystemandgableendbracing.• Ifyouareunsurewhetheryourgableendroofisadequatelybraced,haveahomeinspectororlicensedcontractortakealookandreporttoyou.
•Putdownwalkplanksalongthebottomchordsorceilingrafterstopreventdamagetotheceilingbelow.•Yourcontractormayhaveadditionalideasonhowtoimprovethesafetyofyourhome.•Formoredetailsaboutthisretrofitimprovement,pleaserefertothelistofResourcesinthesectionbelow.
ResourcesFEMA,Against the Wind: Protecting Your Home from Hurricane Wind Damagehttp://www.fema.gov/library/viewRecord.do?id=1641FEMA,Home Builder’s Guide to Coastal Constructionhttp://www.fema.gov/library/viewRecord.do;jsessionid=E34B1F94FFFA4B12C81995C6DC000644.Worker2Library?fromSearch=fromsearch&id=2138FloridaDivisionofEmergencyManagement,Hurricane Retrofit Guide: Gable End Bracinghttp://www.floridadisaster.org/hrg/content/roofs/bracing.asp
Photo:NAHBResearchCenter