Andrew writes from Silver Spring, Maryland: "I inherited a basement covered with 1" thick (R 4.5) foam board glued to the concrete walls without space in between. The basement has always been dry. I know I need to put up drywall over this insulation and it needs to be on furring strips. Can I cut out channels for the furring strips in between panels of the insulation? I thought I could install the furring strips on top of the insulation but I think it will be too deep for the electrical boxes. Can I use 1/2" X 2" furring strips to get around this problem? Or should I just tear down this insulation and start over? Any input appreciated."

Answer: Most foam insulation products can be cut and trimmed. For your information, Owens Corning manufactures a foam product for basement walls that is channeled for furring strips. It is InsulPink® extruded polystyrene foam Insulation. InsulPink insulation has a 7.5 R-value and attaches to a basement wall by means of wood furring strips - no framing is necessary - providing an uninterrupted insulating envelope along the entire wall.