EXP foam on interior side of shell
Hi folks…we’re planning to layer 1.5″ foam on the inside of our insulation shell, continuous over the studding, with wood backing only at window and door openings and for baseboard. (With minimal thermal breaks, this seems to me to be the simplest way to get a 2X6 wall assembly up close to R-30.) My concern is that the drywall, directly over the foam, may end up being too “soft”, with long screws through the foam allowing for movement of the rock and a bad case of “poppers”. I’m thinking we could go with ceiling density board, and get good pressure on the rock while attaching it to make sure we end up with a solid wall. Anyone out there have any experience or info about this? I haven’t found anything in my back issues that specifically addresses this question; mostly I see that people put 1×4 strapping over the foam. Thanks..earnestly (PS..didn’t make this clear; we’ll be using extruded foam, not expanded)
Edited 6/4/2006 7:47 pm ET by earnest
Replies
I've done drywall over 1" EPS with no problems, but when I use foam thicker than that I usually strap it first. It just seems like a hassle to find the studs through that much foam. XPS is stiffer than EPS, so 1.5" might be ok.
zak
"so it goes"