I have some steel stud interior partition walls entering a building (climate zone 4) that has zoned heating/cooling. I wish to handle the insulation properly. There are basically 2 kinds of walls:
A. Walls that divide conditioned space from conditioned space (may be a moderate disparity in temperature based upon zoning).
B. Walls that divide conditioned space from “approximately” conditioned area (ie 45F in the winter season, 85F in the summer season).
With the steel eating up a lot R worth, I figured going thinner on the wall (2.5 ″ where there are not doors and 3 5/8 ″ where doors are present) and including a layer of foam was helpful.
1. Which side of the wall should I put the foam in the 2 situations above? Does it matter?
2. To me, it seemed like 1 ″ of XPS would add substantial R worth (and vapor retarder + air barrier) without making drywall installation too hard. Is that common for interior walls?