Which is a weather barrier located on exterior walls?

• A. House wrap
• B. Insulation board
• C. Drywall
• D. Plywood sheathing

Answer: (A)

Weather barriers on exterior walls block liquid water from entering the wall cavity while letting moisture escape. The product that fits this role is house wrap; it’s a permeable membrane installed over the exterior sheathing and beneath the siding to shed bulk water and allow vapor to escape. Insulation board mainly provides thermal resistance, drywall is an interior finish, and plywood sheathing is structural and not designed to act primarily as a moisture barrier.