Required Thickness Of Roof Sheathing

The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.

Required thickness of roof sheathing.

The most common rafter spacing is 24 inches and 5 8 inch plywood is recommended for that. In practice many builders default to 1 2 inch plywood even if they plan. Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame. 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.

For rafters spaced 20 or more inches apart 1 2 or 5 8 inch plywood is recommended. Ommended that deformed shank nails be used throughout the entire roof. 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.

The eaves membrane should extend into the house 24 inches past the interior face of the outside wall. 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. Screws can be used for typical layout of roof sheathing panels on gable end roof typical layout of roof sheathing panels on hip roof.

According to 2009 irc table r803 1 minimum thickness of lumber roof sheathing. Sheathing should be a minimum of 19 32 inch thick. Unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick. The typical thickness range for sheathing is 3 8 to 3 4 inch.

If the nails penetrate the sheathing but not the studs the minimum plywood thickness that the irc designates is 1 2 inch. 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. Many code requirements are not inspected. And for wood structural panel sheathing r803 2 2 allowable spans.

If 8d common nails are specified the nail diameter must be at least 0 131 inch wider than typical 8d pneumatic nails.