How Thick Should Roof Sheathing Be

The answer depends mostly on how far apart the rafters are and the roof loads which vary based on the pitch of your roof.

How thick should roof sheathing be.

While many of the roofing shingle courses will land on the 7 1 2 increment there can be entire courses of unsecured shingles that line up on cracks in the shiplap. Wind gusts can then blow these poorly fastened shingles off your roof. Minimum plywood thickness 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. Roof sheathing thickness unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick.

8d ring shank nails should be used instead. You may see 3 8 inch plywood installed as roof sheathing and although it may feel inadequate compared to 1 2 inch plywood installed on rafters spaced 24 inches on center 3 8 inch plywood was at one time considered acceptable in some jurisdictions. Sheathing should be a minimum of 19 32 inch thick. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads.

Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame. In this case plywood should be a minimum of 3 8 inch thick. You need to find a sheathing with a span rating of at least 32 16 which means either 15 32 or 1 2 thick osb. This minimum will only work if the rafters are set 16 inches apart at most and if the roof doesn t have too much load.

Creating a solid substrate. Roof sheathing standard roof sheathing which consists of 4 by 8 sheets of plywood or oriented strand board or osb is 1 2 inch thick and attaches directly to the roof rafters or the roof trusses. With this thickness any deflection under dead loads only the weight of materials only should prove to be imperceptible. Most roofs will be sheathed in plywood at least 3 8 inch thick.

The typical thickness of roof sheathing is about 7 16 inch which is just under 1 2 inch. That s considered to be the minimum. Never attach roof sheathing with staples. The typical thickness range for sheathing is 3 8 to 3 4 inch.