How thick should exterior plywood sheathing be?

The International Residential Code specifies 3/8-inch plywood for sheathing walls with a standard stud spacing of 16 inches, if the siding is nailed to the studs through the sheathing. If the nails penetrate the sheathing, but not the studs, the minimum plywood thickness that the IRC designates is 1/2 inch.

What is the most common thickness of exterior sheathing?

For covering existing siding, 1/2-inch and 3/4-inch thicknesses are commonly used. Standard panels are 2 by 8, 4 by 8, and 4 by 9 feet, although some can be purchased in fan-folded panels that run up to 50 feet long.

What type of plywood do you use for exterior walls?

3. Structural Fiberboard. Plywood and OSB are largely considered the best wall sheathing choices because of their overall abilities to hold fasteners well, create a strong bond between studs, and provide some thermal advantages.

How thick should my wall sheathing be?

The U.S. Department of Energy has determined that 7/16-inch sheathing is the minimum appropriate thickness for structural wall sheathing with an exception for gable end walls, where the minimum thickness is 3/8 inch.

Is 7/16 OSB good for exterior walls?

Wood frame exterior walls must be fully sheathed, including areas above or below wall openings, with minimum 7/16-in. wood structural panels. Interior shear walls must be fully sheathed including areas above or below wall openings with minimum 7/16-in.

OSB vs Plywood Sheathing Choices

What is code for exterior wall sheathing?

1304.13 EXTERIOR WALL SHEATHING. (a) Wooden structural sheathing panels shall be installed on all exterior frame walls.

What size OSB should be on exterior wall?

Exterior walls

Minimum thickness of wall sheathing for use on walls; 3/8" plywood or 5/16" OSB. If you use fibre cement siding, go with 1/2" plywood or 7/16" OSB for the exterior walls.

What thickness of plywood is used for exterior walls?

The International Residential Code specifies 3/8-inch plywood for sheathing walls with a standard stud spacing of 16 inches, if the siding is nailed to the studs through the sheathing. If the nails penetrate the sheathing, but not the studs, the minimum plywood thickness that the IRC designates is 1/2 inch.

Should there be plywood under siding?

The wood that goes under residential siding – exterior sheathing – performs several functions. It adds insulation, waterproofing and structural support for the framing. It also provides a surface on which to nail the siding. The most common sheathing materials include oriented strand board and plywood.

What is the best plywood for exterior use?

Is plywood or OSB better for sheathing?

Industry voices from panel manufacturers or their main trade group—APA – The Engineered Wood Association—say that there's no real difference between the two panels: OSB's and plywood's structural characteristics are equivalent, and they can be used interchangeably.

Can plywood be used as exterior wall?

Plywood is eco-friendly to use

Plywood is one of the greener options when it comes to exterior cladding materials. Manufacturers use less wood to produce a workable ply sheet compared to solid wood.

How thick plywood do I need?

Using ½” thick plywood for walls is standard, although the International Residential Code specifies only 3/8” wall sheathing when studs are spaced 16” apart and the siding is attached to the studs and not just the plywood. For buildings with siding attached only to the sheathing, the IRC requires ½” plywood.

How thick should outside walls be?

Standard ICF external walls need six inches of concrete. However, areas susceptible to high winds require concrete thickness of at least 8 inches.

How thick are residential exterior walls?

External walls are generally 10 to 12 inches wide. Homes that are built with rammed earth or heavy exterior masonry will have thicker walls. There is no limit to how thick an exterior wall can be.

Do you need H clips for wall sheathing?

H-clips are referred to in the APA Guide as “edge support." For the most common roof sheathing in our area, which is 1/2” nominal (7/16” actual) sheathing over trusses or rafters at 24” on center, there is no requirement for H-clips.

Should sheathing be vertical or horizontal?

On roofs and floors, sheathing is installed perpendicular to supports because this is the orientation that results in the strongest roof or floor. Wind loads perpendicular to a wall are similar to floor and roof loads, and installing sheathing horizontally makes walls better at resisting wind pressure.

Should sheathing overlap foundation?

Should sheathing overlap foundation? The advice when installing wall sheathing is to overlap and install flashing, providing a means to direct moisture away from the foundation. Pros often seal the sill when the wall sheathing overlaps the sill plate.

How far down should sheathing go?

The wall sheathing should extend below the rim joist, which is inset on this house to allow for a continuous band of insulation. The wall sheathing below dictates the overhang. It's about 9 inches in this case, and Ben subtracts a quarter inch to allow for inconsistencies.

What is the minimum thickness of roof sheathing?

The minimum requirement for roof sheathing is ⅜” thick. There is no upper limit on how thick your roof substrate is. Thickness allowed depends on how far apart rafters or trusses are spaced and the rating of your roof decking.

How Far Can 3/4 OSB span?

Span is permitted to be 24 inches on center where ³/₄-inch wood strip flooring is installed at right angles to joist. Span is permitted to be 24 inches on center for floors where 1¹/₂ inches of cellular or lightweight concrete is applied over the panels.

Which side faces out on OSB?

Using OSB Safely

When installing in vertical applications such as wall sheathing, you'll want to orient the smooth or stamped side facing out. The smooth side has a better moisture resistance and will ultimately provide better performance against weather.

How thick does plywood need to be for a shed wall?

On the shed walls use exterior rated 1/2 inch plywood for a waterproof finished look, and 3/4 inch CDX plywood on the roof for strength.