Crawl Space. DIY spray foam insulation can also be applied in crawl spaces to help prevent air leakage and improve insulation. Rim Joist. Another common place where air leaks occur is the rim joist.

Crawl space insulation will cost between $3,000 and $8,000 with an additional $3 to $7 per square foot for waterproofing, plus a vapor barrier can cost between $2 to $4 per square foot to install.

Close those crawl-space vents to keep cold air out. Older homes in the South were typically built over a crawl space rather than a finished basement. Even today, many homes don't include a ...