Improving R-value of 2×4 wall in renovation with interior foam board
Doing a renovation in MA, USA, and I need a little help… There’s a 2×4 wall that needs insulating, and I’m not redoing the exterior of the building. It would be easiest for me to get the wall dense-packed with cellulose, then go over the whole thing with 2″ foil faced foam… but I have a couple questions…
1] Is that legit from a ‘dew point’ perspective.. I mean you want the foam on the outside of an assembly like that, right? Or is that such a winning combination, with such a small amount of humid air moving through it, that one need not worry about condensation?
2] How do you go about drywalling that? Aren’t you supposed to have the drywall tight up against the insulation these days? The easy thing would be to install 1 x 3s over the foam and drywall that. does anyone drywall with 3 1/2″ drywall screws? That sounds insane. But I’ve done crazier things.
3] I frame out a deep wall for the cellulosers to insulate, but I am too lazy.. maybe this would actually be easier than dealing with the foamboard / strapping / drywalling conundrum?
Thanks in advance!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part