Roof Sheathing Thickness

Loads will vary with the pitch of the roof.

Roof sheathing thickness.

Most roofs will be sheathed in plywood at least 3 8 inch thick. Sheathing should be a minimum of 19 32 inch thick. The typical thickness range for sheathing is 3 8 to 3 4 inch. The minimum thickness of lumber roof sheathing should conform to table 1 below.

That will suffice on a roof with rafters set 16 inches apart with minimal roof loads. 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. Roof sheathing conforming with this table shall be deemed to meet the design criteria of section 2304 7. Roof sheathing thickness unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick.

1 inch 25 4 mm 1 pound per square foot 0 0479 kn m2. Most builder s use 7 16 osb with clips if a heavy roof covering applied or called for on plans. That s considered to be the minimum. Otherwise no clips just be sure to space all edges 1 8 as listed right on the sheathing label which goes down so the inspector can read it from inside it s also the waxed side which is safer.

Uniform load deflection limitations 1 180 of span under live load plus dead load 1 240 under live load only.