Adding Basement Insulation to a Cinder Block Basement

Adding basement insulation to a basement whose foundation is cinderblock is a virtual necessity if you live in a cold climate. Without this insulation, your basement will be less resistant to the cold outside air. Consequently, you will find that heating your basement can be much more costly than you desire. To avoid this, you will need to add a good insulation to your cinderblock walls. To accomplish this, refer to the following information about insulation installation, materials, and tools you'll need.

Step 1 - Determine the R Value of Insulation You'll Need

Depending on the climate you live in, you will need insulation with thermal resistance rated anywhere from R-3 to R-21. You'll find charts online or at your local home improvement store that will provide this information. Then, compare the various types of insulation available and note which of them offers the R value you'll need. Purchase rigid board insulation with the desired R value.

Step 2 – Install Furring Strips

Determine the total width of all exterior walls on which you'll be adding your insulation. Divide this figure by 16 to determine the number of furring strips you’ll need to attach to your wall. Buy or cut your furring strips to the length you'll need to attach each of them from your basement floor to your ceiling joists. On your cinderblock wall snap a vertical chalk line every 16 inches. Make sure these lines are plumb. Drill holes into one of your furring strips through which you'll insert masonry screws. Hold this furring strip in place against the wall and mark on the wall where each of these holes is located. Using your masonry bit, dill a hole into the wall block where you made your marks. Then, screw masonry screws or concrete screws through the furring strip and into the wall. Do the same for each furring strip.

Step 3 – Cut, Glue, and Caulk Your Insulation Boards

Cut your insulation board to fit between your furring strips. In areas where you find pipes or cable that enter your basement through walls, cut insulation to fit in spaces that are oddly shaped and glue these pieces into place. Apply a ¼ inch bead of adhesive to the wall where your insulation boards will be attached and press your insulation board in place between the furring strips. Fit your cut insulation boards as tight as possible between the furring strips to prevent cold air from entering in these spaces. Glue these strips to the wall using foam insulation adhesive. When they are glued in place, fill with caulk all the spaces between the boards and in those spaces where you glued the odd shaped insulation pieces and the furring strips with caulk.

Step 4 – Install a Vapor Barrier

When your adhesive is dry, cut and attach a plastic sheet to your newly installed insulation. This sheet will act as a vapor barrier to keep out any moisture that might be entering through your walls.