Which component is placed directly outside the plywood sheathing in the wood frame exterior wall build-up?

Which component is placed directly outside the plywood sheathing in the wood frame exterior wall build-up?

• A. Exterior siding
• B. Building paper
• C. Plywood sheathing
• D. Wood frame

Answer: (B)

The layer that sits directly outside the plywood sheathing is building paper. In a wood-frame exterior wall, the common order from inside to outside is wood framing, plywood (or OSB) sheathing, building paper (or house wrap), then exterior siding. Building paper acts as a weather-resistive barrier, reducing water intrusion and limiting air leakage while still allowing some vapor to escape. Exterior siding goes on top of the building paper, not directly on the plywood. The plywood provides structural strength, while the wood frame is the structural core, so neither is the layer directly outside the sheathing.

The layer that sits directly outside the plywood sheathing is building paper. In a wood-frame exterior wall, the common order from inside to outside is wood framing, plywood (or OSB) sheathing, building paper (or house wrap), then exterior siding. Building paper acts as a weather-resistive barrier, reducing water intrusion and limiting air leakage while still allowing some vapor to escape. Exterior siding goes on top of the building paper, not directly on the plywood. The plywood provides structural strength, while the wood frame is the structural core, so neither is the layer directly outside the sheathing.