The Ontario Building Code | Minimizing and Preventing Ingress and Damage
9.27.2.1. Minimizing and Preventing ="http://thehandyforce.com/interior/bathroom-renovations/" title ="Toronto Bathroom renovation inspiration">venting Ingress and Damage
(1) Except where exterior walls are protected from precipitation or where it can be shown that ingress will not adversely affect occupant health or safety, exterior walls shall be designed and constructed to,
(a) minimize the ingress of precipitation into the assembly, and
(b) prevent ingress into interior space.
(2) Except where exterior walls are protected from specific mechanisms of deterioration, such as mechanical impact and ultraviolet radiation, exterior walls shall be designed and constructed to minimize the likelihood of their required performance being reduced to an unacceptable level as a result of those mechanisms.
In Plain Language
Exterior walls must be designed to minimize and prevent water ingress and resulting damage, as set out in this article, forming the overarching performance goal behind the detailed cladding and flashing rules that follow.
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.