Sorry – More Poly-Iso Questions
Thinking of using Poly-Iso Foil Foam on BOTH sides of 2×4 stud walls with F’Glass in wall cavities. Marine Zone 4 (Seattle). Spray Foam probably the ultimate but its not DIY friendly and too expensive. Will this work? Regular 1/2″ Drywall over 1″ or 1/2″ Foil Foam, 2×4 studs with Unfaced F’Glass Batts, 1″ Foil Foam Exterior, Tyvek, & Finally LP Smartside 4×9 panel siding.
Reasons for: 1/2″ or 1″ foam on inside is easy to put under drywall using adjustable electric boxes. 1″ foam on outside is good w/o making trim details too much PITA. Reasons against: “Dreaded double vapor barrier”. Won’t the foam on both sides keep the interior from gettiing cold enough to cause condensation? Should I forget the interior foam or do you think its OK in Zone 4?
Is there some other product that could be used on interior? Only thing I can think of is “sound board” which I think is made from cane fiber but it doesn’t do much for sound OR insulation in my experience but would be very “breathable”.
Electric BB heat is just so expensive. Wanting to try to insulate better since replacing all the old single pane windows. Old cellulose (ground up newspaper?) worked great but again its not something that can be DIY.
thanks for opinions/advice.