Ed writes from Middleton, Wisconsin: "I'd like to insulate my basement floor with T&G 1" pink foam, then overlay that with T&G plywood or OSB, then install a finish floor (tile, wood laminate) To keep the floor as thin as possible, with a good R-value, I'd prefer not to fur it out, but rather glue down foam, then glue the underlayment to that. Do I have to drill or drive anchors into the underlayment, or can I just glue it?"

Answer: FOAMULAR® extruded foam insulation is sold as a sheathing product. It is not structural. Be sure to anchor the plywood or OSB into the floor.