How Thick Roofing Plywood

Plywood is often sold in 1 4 1 2 or 3 4 nominal thicknesses but the actual thickness is often 1 32 thinner.

How thick roofing plywood.

That will suffice on a roof with rafters set 16 inches apart with minimal roof loads. However you may need to consider bolstering the plywood thickness for a roof that has a higher load. Unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick. 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.

Sheathing sizes osb and plywood come in thicknesses ranging from 5 16 to 3 4 inch and the thickness needed for a particular roof depends on several factors including rafter spacing expected load. A 1 2 sheet is actually 15 32 thick. 3 ply is one of the most common types of plywood. Typical types of wood used for roof sheathing are oriented strand board known as osb and plywood the most popular being osb.

That s considered to be the minimum. With edge support and the same snow load 3 8 inch osb can be used. A roof that lays practically flat will have a much heavier load than a steeper roof that allows rain snow and ice to roll right off. It is about 2 to 3 millimeters thick and is generally used indoors since it looks more decorative than thicker plywood boards.

In this case plywood should be a minimum of 3 8 inch thick. A 3 4 sheet is actually 23 32 thick. Loads will vary with the pitch of the roof. 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.

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. That s considered to be the minimum. Because the actual thickness may vary measuring the plywood is the only accurate way to determine its thickness.