The Ontario Building Code | Minimum Protection from Precipitation Ingress
9.27.2.2. Minimum Protection from Precipitation Ingress
(1) exterior walls exposed to precipitation shall be protected against ingress of precipitation with an exterior cladding assembly consisting of a first plane of protection and a second plane of protection where the wall encloses spaces of residential occupancy or spaces that directly serve spaces of residential occupancy.
In Plain Language
Exterior walls must provide a minimum level of protection from precipitation ingress, as set out in this article, establishing the baseline weather-resistance standard.
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.