How Much Sheating Should Be On The Outside Of Walls?

Exterior wall sheathing is a crucial component of any building’s construction, providing added strength, insulation, and protection from external elements. It is designed to strengthen the walls of the home or building it is installed on by tying together the wall studs, increasing their strength and rigidity. The recommended thickness for sheathing on exterior walls can vary depending on factors such as building codes and project requirements. Typically, sheathing thickness ranges from 3/8″ to 7/16″.

Plywood, oriented strand board (OSB), and wafer-board panels should be rated as wall sheathing and chosen appropriately. Panels as thin as 5/16 inch can be used for some applications, but they should be rated as wall sheathing. The International Residential Code specifies 3/8-inch plywood for sheathing walls with a standard stud spacing of 16 inches.

When selecting the thickness of sheathing, consider factors such as building codes, specific project requirements, and the thickness of foam used. For example, plywood sheathing should be at least 1/2 thick to match the sheathing on the walls.

Siding (1/16″ – 1/2″) sheathing (1/2″ – 3/4″) wood framing (5.5″ mostly, 3.5″ in older homes, and sometimes 7.25″ for more insulation) is typically used, while OSB (OSB) is typically 7/16″ thick. Wood framing can vary in thickness, with the 7/16 OSB being 7/16″ thick and the 1/2″ OSB being 15/32″.

What is the best plywood 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.

Is 7/16 OSB good for exterior walls?

The construction of exterior walls should be designed to provide minimum resistance to wind pressures and debris impact, using 7/16-in.-thick OSB wood structural panels attached to wood wall framing. Gable end walls must have structural wall sheathing, such as 3/8-in. plywood or OSB or equivalent, and must be braced. Wood frame exterior walls must be fully sheathed, including areas above or below wall openings, with minimum 7/16-in. Gable end walls must be tied to the structure, with connections made at the top and bottom of the gable end wall.

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, and intermittent bracing is not allowed on outer walls. 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 should be extended to lap the sill plate and nailed to the sill plate using a 4-inch on-center nail pattern along the edges.

What is the minimum thickness of wood boards used as exterior sheathing?

The minimum thickness of wall sheathing for exterior walls is 5/8 inch, with wood boards being the most common type. Wood structural panel sheathing must have an exterior exposure durability classification if used as the exposed finish on the outside of exterior walls. If used elsewhere, it must be of a type manufactured with exterior glue (Exposure 1 or Exterior). Wood structural panel wall sheathing or siding must be capable of resisting wind pressures, as per Section 1609.

Maximum wind speeds for wood structural panel sheathing used to resist wind pressures must be in accordance with Table 2304. 6. 1 for enclosed buildings with a mean roof height not greater than 30 feet (9144 mm) and a topographic factor (K z t) of 1. 0. Panel strength axis must be parallel or perpendicular to supports, with three-ply plywood sheathing applying with panel strength axis perpendicular to supports.

Lateral requirements must be in accordance with Section 2305 or 2308. Wood structural panels with span ratings of wall -16 or wall -24 are permitted as an alternative to panels with a 24/0 span rating.

What thickness of plywood is used for exterior walls?

House frames are made stronger by using plywood to sheath them, providing a surface for siding installation and making the structure stronger. For structures with siding only connected to the plywood sheathing, thicker plywood is required. Standard thickness is ½” thick plywood for walls, but the International Residential Code requires 3/8″ wall sheathing when studs are spaced 16″ apart and siding is attached to the studs.

Local building codes often require 3/8″ plywood for roofing, but using ½” or 5/8″ plywood results in a longer-lasting and safer roof. Thin plywood is often insufficient for roofs, especially in large areas with large spaces between trusses and rafters. Thin plywood also makes it easier for shingles to fly off in high wind situations.

When choosing plywood thicknesses, consider the finished product requirements, such as furniture and construction, and the weather conditions of the building site, especially high winds. It may take only one severe storm to prove the worth of investing in thicker plywood.

What plywood is most common for exterior sheathing?

Exterior plywood sheathing is used on weather-protected building exteriors, typically rated CDX with a C-grade face, D-grade back, and X for weather exposure. It has exterior-rated glue for durability. Plywood underlayment is water-repellent and thicker than normal plywood, suitable for use under hardwood, carpet, tile, and vinyl floor coverings. For a squeak-free floor, look for tongue and groove panels labeled “T and G”.

What is the best wood for exterior sheathing?

Plywood is a stronger and more resistant material compared to OSB, as it is assembled from whole sheets of peeled wood. Diagonal Tongue and Groove sheathing, popular until after World War II, is made from solid wood and provides superior structural support but comes with a higher price tag. Structural Fiberboard, made from recycled wood shredded finely and combined with wax and resin, is cost-effective but not as lightweight as plywood or OSB but offers better resistance against external elements. However, it does not hold fasteners as well as wood.

What size OSB for exterior sheathing?

In the context of residential construction, the use of a rated sheathing panel, such as oriented strand board (OSB) or plywood, with a thickness of 0. 95 cm (or 3/8 in), is a standard practice. This sheathing is comparable to that used for shear wall sections. Nevertheless, it is customary to utilise sheathing thicknesses that exceed the prescribed minimums, a practice colloquially termed as “over-sheathing.”

What is the best sheathing thickness 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.

How thick is exterior grade sheathing?

The majority of residential buildings are constructed with 7/16 or 1/2 inch exterior sheathing on their exterior walls. This may be plywood, fiberboard, OSB, or wood battens, which are more commonly found in older homes.

Is plywood or OSB better for exterior sheathing?

Plywood demonstrates superior performance in the same microclimate when compared to OSB, due to its accelerated drying and enhanced protection properties. Conversely, OSB necessitates a more meticulous drying process, given its reduced capacity to withstand moisture.

Should I run OSB vertical or horizontal?

Most 4×8 OSB panels have nailing lines running both directions on the panel, while 4×9 and larger panels have them running parallel with the long edge. Sheathing can be run horizontally to stiffen the wall assembly in certain conditions, such as high winds. Stud spacing can also be reduced to meet these loads. On balloon framed walls, engineers may call for stud spacing of 12″ o. c. or doubled studs of 16″ o. c., which can be reduced to include LVL or LSL studs.

Staggered seams can deform about 25 less than walls with all joints lined up. Thor Matteson in his book suggests that the framer’s time is better spent on nailing than staggering rows of blocks. However, if a designer requires staggering, it is best to “stagger away” as fully sheathing the wall already creates a stronger wall than needed.