Should I put fiberglass batts over foam board?
James writes from Salisbury, North Carolina: “In my basement I have foam board insulation on concrete block walls with 2×4 studs over the foam. Should or can I put fiberglass batts over the foam board to increase the R value? If it is ok should it be faced or unfaced?” Answer: My friends at Owens Corning do not recommend using Fiberglas directly over FOAMULAR® insulation in a basement due to potential moisture problems. If you decide to install insulation anyway because the stud cavities are already in place, we recommend faced insulation with the Kraft paper toward the inside (warm in winter side). The assembly will need to be covered with a 15 minute thermal barrier such as sheetrock.
