I’ve found a source for free foam-filled door cutouts (eg cutouts from installing lites) and am planning to use them to insulate a portion of my old house. The cutouts are from fiberglass- and steel-skinned foam-core doors. The cutouts are 1 3/4 inches thick and the company that gave them to me claims an R-value of about 15 for that thickness. That seems like a pretty high figure to me, but I’m not an expert. The foam looks like isocyanurate. In any case, I can either pull the skins off the cutouts and just install the foam or I can leave the skins on. Handling just the foam is a lot easier for cutting and fitting. I’m wondering though if leaving the skins on would give me some additional fire protection (I’ll be drywalling over the foam of course). I did a little test with a lighter and was surprised how flammable foam is (I also tried some scraps from two different types of gun foam and it burned even more intensely). Do any of you think the potential benefits of leaving the skins on would outweigh the added work? Thanks!
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Hey, junkhound, it's against
Hey, junkhound, it's against the rules to use more than one ID here!
No. As long as you are drywalling over it, it will have enough protection. What is your vapor barrier situation like where you are adding this new insulation?
I'm not
I'm not junkhound...
Currently there is no vapor barrier. The wall cross section will be (from inside to outside): existing plaster or new drywall, 3.5 inches of this used foam (gaps sealed with gun foam), OSB sheathing, 15# felt, 3/8" thick furring strips, reattached original doug fir clapboard. The felt and furring strips will provide a rain screen (I'm in Seattle).