jmac

What is the latest thinking on putting 1" foam over studs and rafters? The garage I'm turning into an apartment has 2 x 4 walls and 2 x 6 rafters on the North side, 2 x 8 on the South side. I've bought an entry door with a jamb for 2 x 6 thinking I would build out to that with foam and strapping. Watcha think?

inspectorD

Some of it depends on other things, like windows, floor framming and other insulation. The biggest being water entry, with foam, if the water gets trapped in the building, it cannot dry out quickly.
Sounds like a great idea, I have seen it work, and fail.
Read up, www.buildingscience.com, and do a search from there in the information.
Hope this helps , tell us what you come up with and

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AtticCare

Other problems with foam, besides that it is a vapor barrier, and those are a bad idea, is that when you go to side the house it will look like the local wave pool because the foam compresses when you nail on the siding. Insulated wall makes up very little of the avg. envelope of a home, sometimes less than 5%, basically even if they were 8 feet thick, you wouldn't save more than 5% on you enegy bill.