roof sheathing thickness

1) Plywood

This sheathing option is considered one of the strongest and more durable options. Typically, they come in 4-foot by 8-foot sheets. Rafters and joints that are spaced further apart will require thicker sheets of plywood to prevent roof sagging.

What size plywood is best for roofing?

5/8-inch plywood is the most common choice for roofing with 24-inch rafter spacing. It’s also the standard for most roof applications because it supports roof loads in most situations.

Is 7/16 OSB OK for roofing?

OSB is the most-used sheathing material for new roofs and roof replacements. You can use 7/16-inch thick OSB sheets without support for areas where the snow load is 30 pounds per square foot because it’s durable and maintains building integrity much longer than other sizes.

What size OSB should be used for roofing?

Typical types of wood used for roof sheathing are oriented strand board, known as OSB, and plywood, the most popular being OSB. Sheets of 7/16-inch thick, with no edge support, can be used in an area where the snow load is 30 pounds per square foot. With edge support and the same snow load, 3/8-inch OSB can be used.

What is better for roof sheathing OSB or CDX?

Although some people will ultimately choose CDX, many experts argue that OSB is better overall for roofing. OSB is far less likely to expand and contract when exposed to humidity and moisture, even though it will take longer to dry. With wrapping, though, it can withstand the elements without issue.

Should there be gaps in roof sheathing?

The recommended maximum gap between roof sheathing boards for low-quality, 3-tab shingles is 1/4-inch. If asphalt shingles are installed over sheathing with gaps exceeding 1/4-inch, over time, these gaps may telegraph through and become visible.

Do you need H clips roof 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.

What type of plywood is used for roof sheathing?

CDX is the grade of plywood most commonly used for roofing (CDX plywood means it is Construction Grade for exterior purposes).

How thick should plywood be for a shed roof?

Plywood thicknesses for roofs start at 3/8” in areas with light load requirements on rafters at 16” centers. Thicknesses of 1/2 to 5/8 inch are common with rafters spaced at 24” centers. For heavy load rated areas, 3/4-inch-thick plywood is recommended, regardless of rafter spacing.

Is it OK to use OSB for roofing?

Both OSB and plywood panels can cut and installed on a roof using conventional roofing equipment. They have similar structural characteristics, and can be used interchangeably.

Which side of OSB goes up on roof?

OSB roof panels should always be installed with the grade stamp facing into the attic and the screened surface (with the nail guide lines) facing up. When the grade stamp is covered by roofing, the building inspector will not be able to confirm that the correct OSB roofing panel was used.

How far should roof sheathing overhang rafter tails?

It is at 45-3/4 in. Measure up the rafter 45-3/4 inch from the cut end of the truss tail and snap a line along the trusses. This indicates the upper edge of the first row of roof sheathing—leaving enough overhang that the subfascia and fascia will tuck neatly underneath when the time comes.

How far should roof sheathing overhang fascia?

The best installation method is to leave a gap between the drip edge and the fascia board, about the width of a finger. The shingles should also overhang the drip edge 3⁄8 to 1/2 an inch.