Hold on to your hats. We are (still) remodeling a 1950s ranch in Asheville, NC. The home has a stepped down brick (double wythe) foundation with poured footers. We replaced the old basement slab with a 4” insulated/heated slab. We waterproofed everything below grade and installed interior and exterior French drains.

There is an existing intermediate 48”H brick foundation wall with 2×4 framing above separating a finished daylight basement from a conditioned crawlspace. The crawlspace has a rat slab. We intend to insulate the perimeter of the home on the interior with a combination of foam and Rockwool.

The question is, should we insulate this intermediate brick foundation wall and/or the 2×4 wall above it? (The brick begins about 5’ below grade.) I really don’t want to insulate the brick for several reasons: I like the look. I don’t want to lose the space. It’s unclear how much I would gain thermally. And I don’t want to introduce any freeze/thaw issues.