J writes from Rockaway, New Jersey: "Basement wall -- I saw in a home improvement show a method for insulation a basement. They used 2" rigid foam and glued them to the walls. They tuck-taped and glued the seams to bond the pieces together. They didn't use a vapor barrier which was not needed. They framed the walls for drywall over the foam. I like this method but I don't see anyone else doing it this way. What kind of glue could you use?

Basement floor -- They insulated the floor by laying 1" rigid foam and screwed 3/8th plywood using Tapcon® screws into the concrete basement floor. What are your thoughts on this method? I would like to do it this way but I would have to use 1/2" foam. What are your thoughts about this insulation?"

Answer: What you describe is a fairly common method for insulating basement walls. You would need a special non-petroleum-based adhesive that is compatible with extruded polystyrene foam insulation. Owens Corning also manufactures a product for basement walls called InsulPink® insulation. InsulPink insulation is a FOAMULAR® insulation product that is applied using furring strips instead of adhesive.

The floor application you describe is also acceptable.