Insulate a basement by installing horizontal furring strips at 16-inch intervals, filling the space with a double layer of rigid foam insulation, adding a vapor barrier over the insulation and covering with drywall. Most building codes require covering insulation with drywall to improve fire resistance.
- Install furring strips
Fasten 2-inch-by-2-inch furring strips horizontally on the wall using masonry screws. Attach the strips on 16-inch centers. In most basements, this requires five furring strips.
- Fill the space between strips with foam insulation
Use a utility knife to cut pieces of rigid foam insulation to fit between the strips. The panels should fit tightly to prevent any air leaks. Place a double layer of insulation each space. Use additional masonry screws to hold the insulation in place.
- Install a vapor barrier
Install a standard vapor barrier over the insulation. Overlap any seams in the barrier by a minimum of 6 inches. Attach the vapor barrier to the furring strips, using screws, nails or staples.
- Cover the insulation with drywall
Install 1/2-inch drywall over the walls, attaching it with screws to the furring strips. Most building codes require covering the insulation with drywall to improve fire resistance; however, they do not always require finishing the drywall.