The Ontario Building Code | Required Flashing at Intersections
9.26.4.1. Required Flashing at Intersections
(1) Except where the omission will not adversely affect adjacent supported or supporting elements, flashing shall be installed at junctions between roofs and,
(a) walls that rise above the roof, and
(b) guards that are connected to the roof by other than pickets or posts.
(2) For the purpose of Sentence (1), roofs shall include platforms that effectively serve as roofs with respect to accumulation or drainage of precipitation.
In Plain Language
Flashing is required at roof intersections, such as where a roof meets a wall or chimney, as set out in this article, protecting these vulnerable transition points from leaks.
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.