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Old 01-09-2012, 11:09 AM   #1
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insulateing rim joist checklist

i like doing things right... once. there are alot of mixed opinions on the subject but i gathered my materials so i can insulate the rim joist in the unfinished part of the basement.

i will be using 1-3/8" thick foil faced rigid foam (dow brand) and will be affixing it to the joists with caulk, then filling in any voids with "great stuff" window type foam and wiping any mess created before its fully cured.

i have about 8' of wall that has a cantilevered rim joist and i will tackle that last. some areas are going to be really tricky because my electrical panel is on that wall. but i think i will try to box in the cantilever part or at least put foam on the back face and bottom face.

do i have to worry about fireproofing or code violations? or is it dependent on where i live. if i called the town building inspector would they be able to tell me?

i appreciate the helpful willing people on here!


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Old 01-09-2012, 11:51 AM   #2
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Of course you need to be concerned about local building codes, and of course your local building inspector is the ONLY place you can get reliable information regarding local building codes. You definitely want to run your plan by them first, in some communities it is necessary to cover the foam with fire rated gypsum (Fire-X wallboard), possibly this is the case where you live.


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Old 01-09-2012, 11:59 AM   #3
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I agree with Daniel, check locally.

The mixed ideas are because the “I” Codes don’t require an ignition/thermal barrier on rim/plates in basements or crawls;

You may not be under those Codes, check locally. It is also possible to show the AHJ the paperwork on foil-faced foam board from Dow to satisfy them.

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