Exterior wall sheathing strengthens the wall system, provides a nailing base for the siding, and gives a layer of protection against outside elements. Exterior wall sheathing is either structural or non-structural. Structural exterior wall sheathing ties framing studs together, making the walls resistant to twisting and bending. However, most structural exterior wall sheathings lack insulation value. Non-structural exterior wall sheathing works with the building’s envelope to provide added insulation. Non-structural exterior wall sheathing also prevents intrusion of either water or wind and, in some cases, it acts as a radiant barrier. There are several structural and non-structural exterior wall sheathing options available to home and commercial buildings.
STRUCTURAL EXTERIOR WALL SHEATHING OPTIONS
Structural sheathing gives a home or commercial building integrity and rigidity. It provides a surface for the application of materials, like siding, and helps shield a structure from rain, snow, wind, etc. Five common structural exterior sheathing options include wood-based, gypsum, glass mat, cement board, and Barricade® Thermo-Brace®.
- Wood-based structural sheathing includes plywood, oriented strand board, and waferboard
- Plywood sheathing is made from whole sheets of wood that are cross-laminated, which give the boards strength and stiffness. This helps with expansion and contraction. However, plywood may have weak spots, which can cause core voids in the panels. Plywood is about 15 to 19 percent lighter than OSB. Plywood has good moisture resistance and dries fast.
- Oriented strand board (OSB) is a durable panel sheathing made from hundreds of thin wood strands that are hot pressed onto sheets with a wax and resin adhesive. OSB is available in sizes up to 8 feet wide and 16 foot long. OSB panels are dense and solid throughout the product, with no soft spots. OSB does not breath or redistributed water as well as plywood. OSB is often less expensive than plywood. However, the pricing is more volatile, always changing.
- Waferboard sheathing is a manufactured product made by placing small pieces of wood scraps in a hydraulic press and gluing. Waferboard is far less expensive than plywood; however, it tends to be weaker and less resistant to water than plywood.
- Gypsum based structural sheathing is a panel-type material made of a noncombustible core, primarily gypsum, with a paper surfacing on the long edges, face, and back. It is also known as drywall, wallboard, or plasterboard. Gypsum sheathing is fire-resistant, sound-reducing, durable, economical, and versatile. However, gypsum retains dampness and should not be used on outside walls, in bathrooms and laundry rooms, and other damp areas.
- Glass mat sheathing is like gypsum board but uses a fiberglass barrier instead of a paper material on the outside. Often used for commercial buildings.
- Cement board structural sheathing is Portland cement, reinforced with glass-fiber mesh that creates a sheet that attaches easily to a wall. Cement boards are non-combustible and provide a good base for tile or other masonry products.
- Thermo-Brace is a structural sheathing made from high-quality, long fibers, specially-treated water- and weather-resistant plies that create superior dimensional stability and strength. The advantages of Thermo-Brace are it preserves the integrity of the wall system and creates a tight building envelope. The tight building envelope protects the wall system from water and air infiltration and contributes towards continuous insulation. In fact, all grades of Thermo-Brace have been evaluated and permitted as a water-resistive barrier (WRB) noted in IRC section R703.2 and IBC Section 1404.2.
NON-STRUCTURAL EXTERIOR WALL SHEATHING OPTIONS
Non-structural exterior wall sheathing, also called insulating sheathing, is installed on the exterior wall to add insulation and provide a radiant barrier. Non-structural exterior wall installation of the sheathing is on the exterior or interior side of the structural sheathing. Insulating sheathing comes in various R-values. Examples of non-structural exterior wall sheathing are plastic, foam, cellulose fiber, paper faced and foil faced boards.
Visit Barricade Building Products for more information on exterior wall sheathing.