Mike writes from Zionsville, Indiana: "I have just removed a flat ceiling and vaulted the room's ceiling to the rafters. I framed a gable wall at each end of the vaulted section (attic on each end). Can I use fanfold on both sides of the gable wall, to protect the kraft-faced insulation, or should I use a house wrap or celotex-type board on the attic side? Also, can I use the fanfold over the thermal layer on the inside of the ceiling?"

Answer: Foamular® extruded polystyrene insulation can be used on the gable end walls of an attic as long as there are no heating elements, furnaces, etc., in the attic. Owens Corning sells fanfold insulation only for use on the exterior of homes under siding. It is not a thermal barrier. We recommend sheet rock for that purpose.