Notice: This site currently shows the 2012/2017 edition of the Ontario Building Code. The current legally effective code is the 2024 edition (O.Reg. 163/24), in effect since January 1, 2025. Confirm current requirements at ontario.ca.
Navigate

The Ontario Building Code | Direction of Installation

9.23.15.3. Direction of installation

(1) Plywood roof sheathing shall be installed with the surface grain at right angles to the roof framing.

(2) OSB roof sheathing conforming to CSA O325, "Construction Sheathing", or to O-1 and O-2 grades as specified in CSA O437.0, "OSB and waferboard", shall be installed with the direction of face orientation at right angles to the roof framing members.

In Plain Language

Roof sheathing must be installed in a specific direction, as set out in this article, maximizing its structural performance across the roof framing.

This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.