Wall Sheathing 101: Choosing the Right Material for Strength and Airtightness What Is Sheathing? Sheathing is a core layer in construction, placed between a building's frame and its exterior finish. It strengthens walls, roofs, and floors, while also helping to manage moisture and improve energy efficiency. The building envelope(/glossary/building-envelope) -- which includes sheathing -- acts as your home's protective shell, keeping temperatures stable, blocking moisture, and ensuring structural stability. If you are comparing sheathing with exterior insulation, use the Wall Assembly Builder(/tools/wall-assembly-builder) to estimate whole-wall R-value and sheathing-plane condensation risk. Structural Support and Load Distribution Sheathing binds the structural frame together, turning individual studs into a unified, rigid system that improves stability. With integrated sheathing, cladding can be attached directly, enhancing the overall strength of the building. In some cases, interior ...