# Rim joist insulation fire code



## Windows on Wash (Aug 30, 2011)

If it's an inhabited space, foil probably won't meet muster with most code enforcement folks.


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## diyGK (Oct 13, 2009)

So would 1/2" Sheetrock be sufficient?


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## Windows on Wash (Aug 30, 2011)

Yes. Fire rated drywall should be fine.


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## Gary in WA (Mar 11, 2009)

Doesn't require fire-rated (Type X) drywall, regular will work. Also depends on application, see* 4.2; *http://www.icc-es.org/Reports/pdf_files/load_file.cfm?file_type=pdf&file_name=ESR-3089.pdf

Many jurisdictions allow it in a basement without IB, check locally.

Gary


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## Windows on Wash (Aug 30, 2011)

Definitely check with your local guys. 

Code does allow for it in many cases but I have seen plenty of code enforcement (see quote above) try to gig you for it. 

*Code Acceptance*
_The International Residential Code (IRC) allows the exposed_
_use of spray foam at rim joists (i.e., without a 15-minute_
_thermal barrier such as drywall), as long as the thickness is less_
_than 3” (see R314.5.11). High density (closed cell, 2 PCF)_
_spray foams were approved in the 2003 IRC, and low density_
_(open cell, 0.5 PCF) foams were approved in the 2009 IRC, as_
_well as any intermediate densities._


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## Gary in WA (Mar 11, 2009)

My point was you don't need "fire rated = 1hr." drywall for it, regular (15 minute) is fine; http://www.usgdesignstudio.com/wall-selector.asp
I'd be surprised to see them require the "rated" when the rest of the house is all in 15 min.....

Gary


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## Windows on Wash (Aug 30, 2011)

Ah yes. I see your point. 

I would normally figure on fire rated given the know combustible behind it as compared to interior drywall covering framing and fiberglass but you are right that anything is going to be above what is required.


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