Sheathing
Definition
Sheathing refers to the protective outer layer of boards or panels, typically made of engineered wood like plywood or oriented strand board (OSB), that is fastened to the structural framing of a building's walls, floors, or roof. It serves as a vital structural component by tying framing members together to increase shear strength and provide a stable, uniform nailing base for exterior finishes such as siding, shingles, or masonry veneer. Beyond its structural role, sheathing acts as a secondary barrier against the elements, helping to insulate the structure and protect the interior framework from moisture and wind infiltration. Depending on the application and material used, sheathing can be classified as structural, providing rigidity and load distribution, or non-structural, primarily offering thermal insulation and weather resistance.
Structural & construction notes
Common types of sheathing include wood-based panels like plywood, oriented strand board (OSB), and waferboard, as well as non-wood options such as gypsum, glass mat, cement board, and various foam insulation boards. Specialized engineered systems like ZIP System provide integrated weather barriers, while other varieties include structural fiberboard and magnesium oxide (MGO) boards. Each type is generally categorized as either structural to provide strength and rigidity or non-structural to provide thermal insulation and moisture protection. Common sheathing materials include OSB, plywood, fiberboard, foam board, and gypsum. OSB is the most cost-effective and common choice for modern residential builds, though it is more susceptible to moisture damage than plywood, which offers greater durability and moisture resistance at a higher price point. Premium engineered options like the ZIP System provide superior energy efficiency and moisture protection but carry the highest upfront costs, while non-structural foam boards offer high insulation values but require additional structural support.
Frequently Asked Questions
An educational reference. Project-specific design requires professional guidance.