The Best Way to Fasten a Foil-Faced ISO Board to Studs

Attach 1/2-inch plywood to the wooden studs prior to attaching the foam board. The plywood will help strengthen the board and prevent it from breaking. Attach 4-feet by 8-feet exterior plywood using 8 penny nails. Align the plywood vertically along the studs.

Space the nails 16 inches along the plywood to ensure it is securely attached. Pull bent nails from the plywood to prevent damage to the ISO board.

Stagger the foil-faced ISO board over the plywood joints. Attach the board with the foil facing out. Place one felt nail in the bottom of the foam board and align it along the studs so that the felt nails are driven into each stud. Attach the foam board vertically or horizontally. If attaching the board horizontally, stagger the end joints, as well. Hammer the felt nails in gently to prevent damage to the foil face. Space the nails 16 inches apart, as well.

Cover the joints with foil tape. Tape the joints with two rows of tape, overlapping the tap at the ends and sides by 2 inches. Allow the tape to sit for 30 minutes to ensure that it remains attached. Retape the joints with more foil tape is necessary.