Roof Decking Thickness Osb

Osb panel products give engineers designers specifiers and builders a broad array of choices for use as subfloors combination floors wall and roof sheathing.

Roof decking thickness osb. Common roof sheathing applications and installation recommendations are described in the related publications listed at right. Osb is widely used as roof decking material. With edge support and the same snow load 3 8 inch osb can be used. Osb roof decking thickness 7 16 1 2 or 5 8 currently we space rafters 16 oc and use 7 16 osb with h clips.

Osb comes in 4 by 8 foot sheets as does plywood but the manufacturing process allows the production of longer and wider ones. When this is the case experts recommend a 5 8 inch thick sheet. Correct installation of roof sheathing will ensure the best. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads.

Oriented strand board commonly referred to as osb is a type of engineered lumber similar to particle board formed by adding adhesives and then compressing layers of wood strands. 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. Most roofs will be sheathed in plywood at least 3 8 inch thick. Oriented strand board osb is commonly used as the primary structural sheathing component in residential construction and low rise commercial applications.

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. Keep in mind that the load of the roof still plays a role in the plywood thickness. Typical types of wood used for roof sheathing are oriented strand board known as osb and plywood the most popular being osb. A flatter roof with rafters farther apart may need a thickness of up to inch.

Roof sheathing thickness unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick. We re in dallas so we don t engineer for tremendous live loads for an asphalt shingle and we feel comfortable with 16 oc rafter spacing and 7 16 osb decking. That s considered to be the minimum. A homeowner recently wrote and asked me the following regarding osb roof decking.

Many homes have rafters that are even wider at 24 inches apart and will require a thicker sheet of plywood.