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What is the minimum thickness of OSB for roof sheathing?

Question:

What is the minimum thickness of OSB for roof sheathing?

Answer:

The minimum thickness of wood structural panels, i.e., OSB or plywood, for roof-sheathing applications depends on loading requirements, rafter spacing, and edge support conditions. Refer to the 2003 International Residential Codes (IRC) Table R503.2.1.1(1), or APA Engineered Wood Construction Guide at www.apawood.org for specific requirements for a variety of roof configurations. As an example, in a region with 30 pounds per square foot snow load, and a house with rafter spaced at 24 inches on center, 7/16-inch-thick OSB can be used without edge support or 3/8-inch-thick OSB can be used when edge support is provided by either tongue-and-grove or approved panel clips.