What Kind Of External Wall Sheathing Is Used?

Exterior wall sheathing is a layer of material attached to the exterior wall framing of a building that provides added strength, insulation, and protection from the elements. It can be either structural or non-structural, depending on the type of sheathing used. Structural sheathing is designed to strengthen the walls of the home or building it’s installed on by tying together the wall studs, increasing their strength and rigidity. Oriented-Strand Board (OSB) is the optimal sheathing choice for most homes. The Exterior Insulation and Finish System (EIFS), also known as synthetic stucco, is a widely used type of sheathing material for exterior walls.

Sheathing works on exterior walls to strengthen walls or provide a base for siding, including both structural and nonstructural sheathing. Common structural exterior sheathing options include wood-based, gypsum, glass mat, cement board, and Barricade® Thermo-Brace®. Other common structural sheathing types include plywood, OSB (oriented strand board), and Huber’s ZIP System® sheathing (OSB coated with a weather-resistant coating).

Plywood, such as CDX or pressure-treated plywood, is commonly used for exterior walls. For most residential structures, OSB or plywood are the most common materials used, while in some commercial wall assemblies, specialized plywood is used. Plywood is an old favorite for exterior sheathing materials due to its versatility and durability.

What is the best sheathing for exterior walls?

Plywood is a popular material for external structural sheathing, consisting of multiple thin layers of wood laid in opposite directions. This creates a more stable and structurally sound sheath for the exterior. Plywood is easy to install, placing it vertically flush with the building’s edge and using 2-inch nails 6 inches apart on the edges and 12 inches apart on the center. It is more dimensionally stable than OSB and does not require spacing between sheets.

To ensure proper installation, start the next row at least 3 stud bays off from the first and mark door and window openings with tick marks. For best installation practices, use house wrap over the plywood before installing the siding.

Can 7/16 OSB span 24 inches?

The International Building Code (IBC) dictates maximum deflection for shingled roofs, which can be l/180 for live plus dead loads or l/240 for live loads only. These maximum deflections can cause a deflection (sag) between the purlins of over 1/8″ under a full design load. However, these loads only occur with a roof covered with snow, making it impossible to see the sag. To ensure proper sheathing, a sheathing with a span rating of at least 32/16, either 15/32″ or 1/2″ thick OSB, is required.

This thickness should prevent any deflection under dead loads only. For roof live loads of 40 psf with a 10 psf dead load, 7/16″ OSB is suitable. For heavier loads, 40/20 rated panels can support 130 psf live load and 48/24 rated panels can support 175 psf. If deflection is a concern, it is essential to opt for a thicker panel before investing in a shingled roof.

What is the sheathing is applied to exterior walls?

Exterior wall sheathing is a crucial component of a building’s structure, providing a protective layer against external elements. It can be structural or non-structural, with structural sheathing tying framing studs together to prevent twisting and bending. However, most structural sheathings lack insulation value. Non-structural sheathing works with the building’s envelope to provide insulation and prevent water or wind intrusion.

There are several options for structural exterior wall sheathing, including wood-based, gypsum, glass mat, cement board, and Barricade® Thermo-Brace®. Plywood sheathing is a popular choice due to its strength and stiffness, but may have weak spots that can cause core voids. Oriented strand board (OSB) is a durable panel sheathing made from hundreds of thin wood strands hot pressed onto sheets with a wax and resin adhesive. OSB panels are dense and solid, but do not breath or redistribute water as well as plywood.

OSB is often less expensive than plywood but has more volatile pricing. Waferboard sheathing is a manufactured product made by placing small pieces of wood scraps in a hydraulic press and gluing. While it is less expensive, it tends to be weaker and less resistant to water.

Does exterior plywood need to be pressure treated?

Outdoor wood should be pressure-treated according to the AWPA, as its use determines the necessary treatment. For indoor or outdoor projects involving humans or pets, extra precautions are necessary. The chemicals in pressure-treated lumber are pesticides, so handling them with the same precautions as hazardous materials is crucial. Wearing gloves and face protection is recommended, as sawdust from cutting the wood can be irritant. Painting exposed wood surfaces with water-repellent finishes, paint, or stain can protect skin if leaning or kneeling on the sides.

Should I use plywood or OSB for exterior walls?

Plywood absorbs moisture quicker than OSB, resulting in quicker drying and swelling when wet. OSB is less forgiving of rain exposure and shows more deformities after a wetting and drying cycle. The durability of a wall depends on its ability to dry, and the materials chosen for wall assembly greatly influence its ability to dry. The vapor permeance of building products is expressed in Nanograms in Canada (NG), and 1 US perm is equal to 57 NG. The Canadian vapour barrier benchmark is 60 NG. For simplicity, perms will be used for comparing OSB and plywood in wall assembly.

Why do builders use OSB instead of plywood?

The debate between plywood and OSB continues, but it is crucial for builders to be aware of potential risks and take steps to avoid them. OSB is more sensitive to moisture than plywood, but its affordability makes it the preferred sheathing for North American builders. When choosing between OSB and plywood, builders must consider factors such as location, weather conditions, subcontractors’ training, product warranty details, and the product’s protection.

OSB manufacturers have introduced new formulations and no-sand guarantees, but most consultants recommend that builders protect OSB from moisture. Proper storage, including rain and snow protection, and vented coverage are required before installation. Buildings should be dried-in as soon as possible to prevent extended exposure to moisture-sensitive materials. If panel saturation is present or early signs of saturation, panels should be inspected to determine if swelling has occurred.

If swelling occurs, a licensed structural engineer should inspect at least a sampling of the sheathing and advise on the appropriate removal and replacement point. If removal is recommended, the cost of replacing a panel due to saturation during construction or prior to installation is less than replacing an OSB panel later.

What thickness of sheathing for exterior walls?

Structural sheathing panels must be made of a minimum of 7/16-inch-thick oriented strand board or 15/32-inch-thick plywood on all sheathable exterior wall surfaces, including areas above and below openings. The minimum length of full-height sheathing on each braced wall line must be at least 20% of the braced wall line length. Full-height sheathing must extend from the bottom to the top of the wall without interruption by openings. Only sheathed, full-height wall sections, uninterrupted by openings, that are 48 inches wide, are counted toward meeting the minimum percentages in Table R603.

9. 2. Structural sheathing must be installed parallel to the stud framing, covering the full vertical height of the wall from the bottom of the bottom track to the top of the top track of each story. Blocking must be 33 mil (0. 84 mm) thick and fastened with No. 8 screws spaced at 6 inches on center to the blocking at the joint. A minimum 48-inch-wide panel should be applied to each end of each exterior wall.

What is more waterproof, OSB or plywood?

Plywood is moisture-resistant but not waterproof, so it’s crucial to seal it when exposed to moisture. On the other hand, OSB (oriented strand board) is more moisture-resistant than plywood but not waterproof. It’s also important to seal OSB if it’s exposed to moisture. Both materials are widely used in construction, DIY projects, and furniture building. To help UK homeowners, builders, and crafters decide which sheet to use, it’s essential to understand their pros and cons.

What type of plywood to use for exterior walls?

Exterior plywood is a versatile material used in various outdoor applications, with the most common being CDX or ACX. These plywoods are marked with an X for their use and construction grade, with A being a premium grade for high-end cabinetry. CDX is a more affordable option with sturdy layers made from veneers, high-density hardwood, or light hardwood. Marine plywood, made from wood without knots, is the highest quality and is used for building boats and marine applications due to its reduced cracking risk.

It is also easier to cut and sand, leaving cleaner edges. Other types of exterior plywood include pressure treated plywood, overlaid plywood, oriented strand board (OSB), and T1-11. Pressure treated plywood is infused with chemicals to increase resistance against mold and mildew, while overlaid plywood has a cleaner finish and better resistance to wear and tear. OSB is an engineered substitute for semi-exposed areas, while T1-11 is commonly used for siding. Overall, exterior plywood offers a wide range of options for outdoor use.

Can I use 7/16 OSB for wall sheathing?

Wood structural sheathing panels should be at least 7/16″ thick, with exceptions for gable end walls. This thickness is crucial for meeting codes and standards requirements and meeting national programs like DOE’s Zero Energy Ready Home program, ENERGY STAR Single-Family New Homes, and Indoor airPLUS. During hurricanes, tornadoes, or high winds, exposed sheathing can lead to structural failures and water damage. Unsealed joints or penetrations can allow rainwater to enter the building, causing severe damage to insulation and drywall.

A fully sheathed plywood or OSB wall, properly connected to the foundation and roof, acts as a strong barrier against persistent forces of hurricanes, tornadoes, and high wind events. Shear walls, composed of braced panels, counter the effects of lateral load on a structure. Proper anchorage prevents laterally racking, displacing, or overturning during high-wind or seismic events.

Can you use 7 16 OSB for exterior walls?

Wood frame exterior and interior walls must be fully sheathed with minimum 7/16-in. wood structural panels, including areas above or below wall openings. Gable end walls must have a minimum of 3/8-in. structural sheathing panels and must be tied to the structure using steel connection plates or straps. Hurricane clips or framing anchors are required on all rafter-to-wall connections. Upper- and lower-story wall sheathing must be nailed to the common rim board.

Intermittent bracing is not allowed on outer walls, and only for interior braced wall lines. Wall sheathing must be nailed to 8d ring shank or 10d nails on 4 inches on center along the edges and 6 inches on center in the field. Structural wood sheathing must be extended to lap the sill plate and nailed to the sill plate using a 4-inch on-center nail pattern along the edges. Shear wall hold-down connectors should be bolted through the stud and water resistive barrier (WRB) installed on the structural sheathing. Proper installation is especially important in hurricane-prone regions and high-wind areas to protect against storm damage.