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Author	Comments
kevin smith Posted: Feb 25, 2008 11:28 AM	vapour barrier when you spray the rim of your house or header space, do you have to vapour barrier it or fire proof it?
Posted: Feb 28, 2008 05:11 AM	all foam must be covered with a thermal barrier when applied to habitabal space,,no exceptions.. most foam manufacturers use the 2" of closed cell depth for a vapor permience rating of <1... this is the number needed to be classified a vapor retarder...i shoot 4" to box sills and rim joists for r-25 and the vapor retarder is there with this application... open cell foam is never a vapor retarding membrane till you get out into the 12" or so depths... hope this helps have a nice day dude
Jason Hartkopf Posted: Feb 28, 2008 08:06 AM	I've got the '03 IRC, outdated I know, but R314.2.7 is referenced (and used) around here all the time. Floor rims can be sprayed & left exposed without a vapor barrier. It's got to be 1.2-2# foam, and no more than 3-1/4" thick. Unless something changed in the '06 book.
Posted: Feb 29, 2008 04:44 AM	indeed,,the 06 book reads the same as i remember,,on the rim joists and box sills,, but the headers,,,
Adem Popoola Posted: Feb 29, 2008 09:14 AM	I just had icynene sprayed on my exterior walls and roof rafters in the attic. A mixture of 2x4 and 2x6 framing for the walls. 2x8 for the roof. My contractor says a vapor barrier does not need to be applied over the insulation. He is about to put up drywall. Should I require him to put up a vapor retarder before the drywall. By the way, the house is in Chicago; where we experience the polar extremes of weather patterns.
Mike McGaughey Posted: Apr 10, 2008 08:34 PM	.5# foams are vapor permeable materials. I believe that the IRC requires a vapor barrier to the warm side of permeable foams in DOE climate Zones 5 and 6-I believe Chicago is in zone 5. You will probably be told by the foam manufacturer that the paint used over dry wall will meet the vapor barrier requirement-I'm not so sure I buy that.

Author

Comments

kevin smith

Posted: Feb 25, 2008 11:28 AM

vapour barrier

when you spray the rim of your house or header space, do you have to vapour barrier it or fire proof it?

Posted: Feb 28, 2008 05:11 AM

all foam must be covered with a thermal barrier when applied to habitabal space,,no exceptions..

most foam manufacturers use the 2" of closed cell depth for a vapor permience rating of <1...
this is the number needed to be classified a vapor retarder...i shoot 4" to box sills and rim joists for r-25 and the vapor retarder is there with this application...
open cell foam is never a vapor retarding membrane till you get out into the 12" or so depths...

hope this helps
have a nice day
dude

Jason Hartkopf

Posted: Feb 28, 2008 08:06 AM

I've got the '03 IRC, outdated I know, but R314.2.7 is referenced (and used) around here all the time. Floor rims can be sprayed & left exposed without a vapor barrier. It's got to be 1.2-2# foam, and no more than 3-1/4" thick. Unless something changed in the '06 book.

Posted: Feb 29, 2008 04:44 AM

indeed,,the 06 book reads the same as i remember,,on the rim joists and box sills,,
but the headers,,,

Adem Popoola

Posted: Feb 29, 2008 09:14 AM

I just had icynene sprayed on my exterior walls and roof rafters in the attic. A mixture of 2x4 and 2x6 framing for the walls. 2x8 for the roof. My contractor says a vapor barrier does not need to be applied over the insulation. He is about to put up drywall. Should I require him to put up a vapor retarder before the drywall. By the way, the house is in Chicago; where we experience the polar extremes of weather patterns.

Mike McGaughey

Posted: Apr 10, 2008 08:34 PM

.5# foams are vapor permeable materials. I believe that the IRC requires a vapor barrier to the warm side of permeable foams in DOE climate Zones 5 and 6-I believe Chicago is in zone 5. You will probably be told by the foam manufacturer that the paint used over dry wall will meet the vapor barrier requirement-I'm not so sure I buy that.

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