What is plywood sheathing?

Plywood sheathing is a type of engineered wood product commonly used as an exterior wall covering or roof decking material in construction projects. It consists of thin layers of wood veneer, usually about 3 to 5 layers, that are glued together with the grain of each layer oriented perpendicular to the previous layer. This cross-grain construction gives plywood its strength and dimensional stability.

Plywood sheathing is typically made from softwood species like pine, fir, or cedar, although hardwood plywood is also available for special applications. The wood veneers used in its production are peeled from logs and then dried and graded for quality.

The most common size of plywood sheathing is 4 feet by 8 feet, but it can also be found in larger or smaller dimensions depending on the specific project requirements. Thicknesses can range from 1/4 inch to 3/4 inch, with 1/2 inch being the most commonly used thickness for sheathing applications.

Plywood sheathing is known for its durability, strength, and resistance to warping or splitting. It provides a strong and stable base for siding, roofing, or other exterior finishes. It also offers good insulation properties and helps to protect the building from moisture and weather elements.

Sheathing plywood is manufactured with a specific grade classification system based on its appearance and quality. The most common grades for sheathing are Structural 1 (S1S and S2S) and Exposure 1 (Exterior). Structural-grade plywood is designed to meet specific engineering requirements and is often used in higher-load applications such as roof decking. Exposure-grade plywood, on the other hand, is suitable for use in protected outdoor applications but may not hold up as well to prolonged exposure to the elements.

Overall, plywood sheathing is a versatile, cost-effective, and widely used construction material that provides strength, stability, and protection to the building structure.