The Ontario Building Code | Location of Flashing
9.20.13.3. Location of Flashing
(1) Flashing shall be installed in masonry and masonry veneer walls,
(a) beneath jointed masonry window sills,
(b) over the back and top of parapet walls,
(c) over the heads of glass block panels,
(d) beneath weep holes, and
(e) over the heads of window and door openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings in exterior walls when the vertical distance between the top of a window or door frame and the bottom edge of the eave exceeds one-quarter of the horizontal eave overhang.
(2) Throughwall flashing shall be provided in a masonry veneer wall such that any moisture that accumulates in the air space will be directed to the exterior of the building.
In Plain Language
Flashing must be located at the points set out in this article, generally at wall openings, ledges, and other spots where water could otherwise penetrate.
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.