Wash the walls off with a power washer. Cleaner walls allow the adhesive to hold better.
Measure and cut the boards to fit on the wall with a utility knife.
Spread Styrofoam adhesive on the back of the first insulation board.
Place the board vertically against the wall in one corner. Press it firmly against the wall to allow the adhesive to get a firm grip on the concrete.
Continue installing foam boards along the bottom of the walls until it's complete.
Measure and cut boards for the second row. You will place these boards horizontally on the wall.
Install the boards in the second row directly above the top of the boards in the first row, using the same technique.
Cover the seams between the adjoining boards with installation tape.