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 | Joints in Panel-Type Sheathing

9.23.15.4. Joints in panel-Type Sheathing

(1) panel-type sheathing board shall be applied so that joints perpendicular to the roof ridge are staggered where,

(a) the sheathing is applied with the surface grain parallel to the roof ridge, and

(b) the thickness of the sheathing is such that the edges are required to be supported.

(2) A gap of not less than 2 mm shall be left between sheets of plywood, OSB or waferboard.

In Plain Language

Joints in panel-type roof sheathing must be arranged as set out in this article, avoiding weak points where multiple panel edges align.

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.