The Ontario Building Code | General
9.25.5.1. General
(1) Sheet and panel-type materials incorporated into assemblies described in Article 9.25.1.1. shall conform to Article 9.25.5.2. where,
(a) the material has,
(i) an air leakage characteristic less than 0.1 L/(s∙m2) at 75 Pa, and
(ii) a water vapour permeance less than 60 ng/(Pa∙s∙m2) when measured in accordance with ASTM E96 / E96M "water Vapor Transmission of Materials", using the desiccant method (dry cup), and
(b) the intended use of the interior space where the materials are installed will not result in high moisture generation.
(2) Where the intended use of the interior space will result in high moisture generation, the assembly shall be designed according to Part 5.
(3) wood-based sheathing materials not more than 12.5 mm thick and complying with Article 9.23.16.2. need not comply with Sentence (1).
In Plain Language
This article sets out general requirements addressing the interaction between air barriers, vapour barriers, and other envelope components covered in this Subsection.
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.