The Ontario Building Code | Required Protection from Precipitation
18.104.22.168. Required Protection from Precipitation
(1) Except as provided in Sentence (2), where a buildingcomponent or assembly is exposed to precipitation, the component or assembly shall,
(a) minimize ingress of precipitation into the component or assembly, and
(2) Protection from ingress of precipitation is not required where it can be shown that such ingress will not adversely affect any of,
(a) the health or safety of building users,
(b) the intended use of the building, or
(c) the operation of building services.