Although building science has evolved rapidly over the last 40 years, one theme has remained constant: builders are still confused about vapor barriers.
Any energy expert who fields questions from builders will tell you that, year after year, the same questions keep coming up: Does this wall need a vapor barrier? Will foam 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.
trap moisture in my wall? How do I convince my local building inspector that my walls don’t need interior poly?