How Thick Is Roof Decking

Structural decking also known as roof decking should not be confused with lumber intended for residential and non residential outdoor decks.

How thick is roof decking. 8d ring shank nails should be used instead. Once the spacing hits 24 inches a 5 8 inch thick sheet is more ideal. Osb roof decking thickness 7 16 1 2 or 5 8. 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.

Plywood is made with three or more layers of thin wood glued together with the grain. Many factors affect thickness. Sheathing should be a minimum of 19 32 inch thick. Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame.

The thickness of plywood used for roof decking depends on the roof slope the spacing of. The minimum plywood for roofing plywood is layers of wood. For example a 26 gauge steel panel can range between 0 0179 and 0 0217 inches thick according to a university of north carolina at chapel hill resource. Standard structural decking patterns are 2 nominal tongued and grooved t g and 3 and 4 double t g products available with vee or eased edges to meet discriminating architectural requirements.

If the plywood thickness is less than or the osb less than 7 16 it is going to be weak with the roof rafters spaced the standard 2 on center. An exception to this standard however may occur if you intend to install slate concrete or tile shingles on your roof. Plank sheathing usually 1 6 or 1 8 was used as a roof deck before plywood. Flexural strength can be assumed to be 33ksi unless a new single ply system is contemplated that requires a higher pull out strength.

In this case you can t use a 3 8 inch thick sheet. Never attach roof sheathing with staples. In that case a pullout test device can confirm adequacy. When it s too thin.

Most roofs are spaced at least 20 inches apart. Keep the 16 oc go with 1 2 osb and add an extra clip in each space. The typical thickness range for sheathing is 3 8 to 3 4 inch.