How to Insulate a Cinder Block Wall in Northern Ontario

Power wash the walls to remove dust and dirt. Allow them to dry overnight.

Measure the length and height of each wall so you know how many foam insulation boards you will need to install. The boards will be placed horizontally on the walls.

Apply foam adhesive over the back of the first board with a paint brush. Cover the entire back surface of the board.

Push the board against the bottom corner of the first wall, laying it horizontally against the wall. Press the board firmly against the wall so that the entire board comes into contact with the cinder blocks.

Cover the rest of the bottom edge of the cinder block walls with the foam boards. If you need to cut the boards to fit, hold a straightedge against the board where you want to make the cut, and score the board with a utility knife. Snap the board where you scored it, and cut away any rough edges. Place the boards tightly against each other as you install them.

Place a second course of boards on top of the first course, if needed. Stagger the boards in the second course to prevent the seams between the boards from being aligned with the seams between the boards in the first course.

Place installation tape over the seams between the boards. This prevents leaks from occurring through the seams.