The conditioned space shared with these knee walls was sweltering in the summer and freezing in the winter due to sharing a wall with an unconditioned attic space. We installed insulation in the wall cavities and covered it with Tyvec to create an air barrier and better insulate the wall. We also installed insulation on the floor of the space to prevent air loss from the room below.
The ground cover in this crawl space was a 6-mil, a similar thickness to a trash bag, it is easily ripped and displaced. Because it is unsealed and has tears, the 6-mil ground cover allows moisture from the earth to affect the crawl space raising the relative humidity, damaging insulation, and causing microbial growth.
After removing the 6-mil, we installed a 20-mil heavy-duty vapor barrier called CleanSpace, and is similar to the thickness of a pool liner. CleanSpace has a built-in Antimicrobial called UltraFresh. When we install the vapor barrier, we overlap and seal all seams, seal the liner to the walls 6-8 inches above outside grade, and wrap and seal all piers. By sealing the CleanSpace at all of these points, we are able to isolate the crawl space from the earth's moisture.
Radiant barrier insulation board installed in room over garage in Sandston, VA home.
Front room over garage with radiant barrier insulation installed.