Required Thickness Of Roof Sheathing

Many code requirements are not inspected.

Required thickness of roof sheathing.

The most common rafter spacing is 24 inches and 5 8 inch plywood is recommended for that. Roof sheathing conforming to the provisions of table 2304 7 1 2304 7 2 2304 7 3 or 2304 7 5 shall be deemed to meet the requirements of this section. 8d ring shank nails should be used instead. In areas where the average daily temperature in january is 25 f or less solid sheathing is required on the lower section of the roof to support an eaves membrane.

Sheathing should be a minimum of 19 32 inch thick. The eaves membrane should extend into the house 24 inches past the interior face of the outside wall. Unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick. Never attach roof sheathing with staples.

For rafters spaced 20 or more inches apart 1 2 or 5 8 inch plywood is recommended. The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process. If the nails penetrate the sheathing but not the studs the minimum plywood thickness that the irc designates is 1 2 inch. The typical thickness range for sheathing is 3 8 to 3 4 inch.

And for wood structural panel sheathing r803 2 2 allowable spans. 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. That s considered to be the minimum. Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame.

In practice many builders default to 1 2 inch plywood even if they plan. If 8d common nails are specified the nail diameter must be at least 0 131 inch wider than typical 8d pneumatic nails. Wood structural panel roof sheathing shall be bonded by exterior glue. You would go to table r503 2 1 1 1 to determine minimum nominal panel thickness.

Ommended that deformed shank nails be used throughout the entire roof.