Step 3 · Install Vapor Barrier

Lay a heavy-duty vapor barrier material across the entire crawl space floor, overlapping seams by at least 6 inches. Extend the vapor barrier up the foundation walls by at least 6 inches, or to the top of the foundation wall if it's lower. Secure the vapor barrier in place using specialized crawl space tape on the seams and mechanical fasteners like concrete staples or furring strips if necessary, especially on the walls.