- 1). Measure the area of the walls where the insulation will be installed. Run a tape measure along the base of the walls and add up the total linear feet of each side. Divide that number by two to get the number of sheets that will be needed for installation.
- 2). Inspect the basement wall to make sure there are no gaps or cracks in the wall. Ensure that everything is sealed correctly and ready for installation.
- 3). Line up the first piece of foam board in the corner of the room and stand it up vertically. Run a level along the side to make sure everything is square and plumb. Set the second piece right next to it and push them together so the grooves coming out of each piece are touching.
- 4). Set a one-by-three furring strip into the grooves between the two pieces and screw it into place with masonry screws. Insert a screw every 12 inches up the entire wall.
- 5). Line up the next piece and repeat the process until reaching the end of the first wall. Measure and mark where the final piece will need to be cut and line up a T-square along the mark. Score it with a utility knife and snap it in two. Set it in place on the wall and make sure it fits properly.
- 6). Install the second wall just like the first and continue in the same manner until the entire basement has been completed.
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