A drainage plane is a layer of water-resistant material that completely covers the home’s exterior. When water penetrates the exterior finish, it moves down the drainage plane and back to the exterior. The drainage plane protects sheathing and framing from getting wet and prevents moisture buildup in exterior wall cavities.

In production homebuilding, housewrap is the material of choice for creating the drainage plane on exterior walls. After installing sheathing, wrap the home shingle style with housewrap, starting from the foundation and using only manufacturer recommended fasteners. Extend the housewrap past the wall-to-foundation intersection a minimum of 1″. Overlap all horizontal and vertical seams a minimum of 6″. Tape all vertical seams with construction tape, using the manufacturer’s recommended tape. Ensure that there are no gaps or tears in the housewrap.