The Ontario Building Code | Sealing and Drainage
5.6.2.1. Sealing and drainage
(1) Except as provided in Sentence (2), materials, components, assemblies, joints in materials, junctions between components and junctions between assemblies exposed to precipitation shall be,
(a) sealed to prevent ingress of precipitation, or
(b) drained to direct precipitation to the exterior.
(2) Sealing or drainage are not required where it can be shown that the omission of sealing and drainage 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.
In Plain Language
Except in specific cases, materials, components, assemblies, and the joints and junctions between them that are exposed to precipitation must be sealed and designed to drain, preventing water infiltration at these vulnerable connection points.
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.