2-foot concrete stem wall: Interior insulation or not?
14 foot ceiling from slab on grade floor, which will be finished floor with epoxy. In the main outer wall’s wood stud bays, which is above the 2 feet of concrete (stem wall): we are planning to put paperless backed fiberglass insulation. Inside out: kiln dried framing > plywood sheathing > Tyvek House Wrap > Hardie board lap siding.
Question is in regards to the 2 feet in front of the 2 feet of concrete stem wall, which would be in the furred out wall’s stud bays (we only did these furred out walls in the bathroom area that will also have an alcove cast iron tub in between 3 of the walls). The closest info I’ve found is in “How to Insulate a Basement Wall” but it is not exactly the same scenario (as it’s above grade and just a 2 foot concrete stem wall). I’ve read in regards to basements that some experts say do not insulate but also read that insulating the concrete will be better and keep it drier IF done right. 2 thoughts:
1) Do we just leave this furred out inner wall [that’s in front of the concrete stem wall] empty with no insulation and just sheetrock over it? OR
2) Cut squares of rigid foam insulation to insert in each stud bay and adhere from bottom and up 2 feet directly to the concrete?
If we choose option #2, I would have two concerns:
1). Preventing interior air from reaching the concrete (e.g. the hard to access concrete behind the framing sections in those furred out walls) in between each square of rigid foam in each stud bay would be challenging. Would these air gaps in between the rigid foam squares [leaving the concrete exposed to interior air in sections in between insulated chunks] pose the same risks as fiberglass batts does if applied against concrete that leads to mold and rot from interior air condensing on the concrete? If so, I would assume to conclude that it would be better to not insulate in weighing pros/cons.
2) Should my first concern be alleviated, is drywall a risk on the inside of an insulated concrete stem wall? If so, is DensArmor paperless drywall any better?
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