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.
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The Ontario Building Code | Material Standards

9.23.15.2. Material Standards

(1) wood-based panels used for roof sheathing shall conform to the requirements of,

(a) CSA O121, "Douglas Fir Plywood",

(b) CSA O151, "Canadian Softwood Plywood",

(c) CSA O153-M, "Poplar Plywood",

(d) CSA O325, "Construction Sheathing", or

(e) CSA O437.0, "OSB and Waferboard".

In Plain Language

Roof sheathing materials must conform to the standards referenced in this article, ensuring the panel or lumber product meets recognized performance criteria.

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.