Posted on May 2, 2011 by Scott Gibson
in Q&A Spotlight
Gregg is renovating his 50-year-old house in Wisconsin and trying to devise the best way of insulating exterior walls from the outside. The house was built conventionally, with 2x4 walls, fiberglass batt insulationInsulation, usually of fiberglass or mineral wool and often faced with paper, typically installed between studs in walls and between joists in ceiling cavities. Correct installation is crucial to performance.
, fiberboard sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen.
, and hardboard siding.
He plans to tear off both siding and sheathing and remove the batt insulation, then apply 3 in. of spray polyurethane foam insulation into the stud bays. The existing kraft paper vapor barrier on the interior side of the wall will stay in place.