Double Stud Wall & Basement Insulation Review – Climate Zone 5A
I’ve read practically every article on this site and many others related to 2×4 double stud walls and moisture. I want to have a wall that is low risk for moisture issues without introducing any more expense and complexity than necessary. The following seems attainable with my budget, and doesn’t seem to cause much builder concern for construction. From exterior to interior:
LP Smartside Siding
1/4 rainscreen composed of either a mesh or furring strips with an insect screen at the bottom
CDX Plywood, seams taped
blown in fiberglass described as a R48 blown in fiberglass system
Membrain on the interior wall
The walls will be about 11 1/2 inches from outside stud edge to interior stud edge. If it helps, the walls will be under a 2′ overhang with a hip roof and no gable. Is this a low risk wall?
Below grade the proposal is for 2″ of foil faced polyiso glued to the basement walls and taped, foil facing inward, plus 2×4 framing with fiberglass batts between the studs, but will the foil faced polyiso provide enough of a moisture barrier to stop the fiberglass batts from getting musty?
No one seems interested in subslab insulation, I’ve been told how it doesn’t matter, it will make my concrete crack, it might make my teeth rot and give me bad breath too from their descriptions. How significant will omitting this detail be? Manual J, Manual S modeling if it is accurate seems to indicate that it won’t make much of a difference, but my reading seems to indicate that it will increase moisture levels in the basement.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part