Crawl Space Conversion – GreenBuildingAdvisor

I’m looking at retrofitting the crawl space in my house to add stego crawl vapor barrier to the floor and insulation to the walls, I’m in zone 5 as well.

Currently there are two separate conditions in the crawl space. The main part of the house is unvented, has no vapor barrier on the floor, has no insulation on the CMU stem walls, and no insulation at the rim joists. This space is currently conditioned by a single supply air register.

The second condition is a crawl space that originally appeared to be vented but batt insulation has subsequently been placed in the vents to “plug” them. The floor joists in this space are insulated along with a deteriorating 1″ layer of EPS on the cast in place concrete walls. 

In both instances the stem walls are approximately 24″ tall and the grade is anywhere from 7-14″ below finished floor elevation so the majority of the crawl space is below exterior grade. The exterior wall assembly in both instances working from outside to inside consists of Brick, 1″ Air Gap, 1″ Rigid Insulation, 6″ CMU or CIP Wall. 

I’ve been trying to sort through all of the papers and research out there and trying to come up with the best solution to where to terminate the vapor barrier and how to best insulate the walls. 

Currently I am contemplating insulating the walls and rim joists with 1.5″ xps or eps with fully taped joints and then covered with mineral wool to act as the thermal barrier (i believe there are some products that allow this like rockwool comfortbatt 80 based upon the bulletin i have read). I’ve sketched up what i am thinking in the attached and am hoping to get some feed back as to if i am on the right path. I may be going overkill with the insulation but would rather do that, than underkill.