The Ontario Building Code | Installation of Windows, Doors and Skylights
9.7.6.1. installation of Windows, doors and Skylights
(1) The installation of windows, doors and skylights shall conform to CAN/CSA-A440.4, "window, Door and Skylight installation", except that,
(a) shims used to support windows, doors and skylights are permitted to be of treated plywood, and
(b) protection from precipitation for walls incorporating windows or doors and for roofs incorporating skylights, and the interfaces of these walls with windows or doors and of roofs with skylights, shall conform to Section 9.27.
(2) The installation of manufactured and pre-assembled windows, doors and skylights and the field assembly of manufactured window and door combination units shall conform to the manufacturer’s instructions.
(3) windows, doors and skylights shall be sealed to air barriers and vapour barriers.
In Plain Language
Windows, doors, and skylights must be installed following the manufacturer's instructions and good practice, since even a well-built unit will leak or perform poorly if installed incorrectly.
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.