PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.13.2.2.Dampproofing Materials

(1) Materials installed to provide required dampproofing shall be (a) capable of protecting assemblies against moisture transfer from the ground, (b) compatible with adjoining materials, and (c) resistant to mechanisms of deterioration that may reasonably be expected, given the nature, function and exposure of the materials. (2) Except as otherwise specified in this Section, materials used for exterior dampproofing shall (a) conform to one of the following standards: (i) ASTM D1227 / D1227M, “Standard Specification for Emulsified Asphalt Used as a Protective Coating for Roofing,” Type III, Class I, (ii) ASTM D4479 / D4479M, “Asphalt Roof Coatings - Asbestos-Free,” Type III, (iii) CAN/CGSB-51.34-M, "Vapour Barrier, Polyethylene Sheet for Use in Building Construction," or (iv) CAN/CSA-A123.4, "Asphalt for Constructing Built-Up Roof Coverings and Waterproofing Systems," or (b) have a water vapour permeance of not more than 43 ng/(Pa×s×m 2) when tested in accordance with Procedure A (wet cup) of ASTM E96 / E96M, “Standard Test Methods for Water Vapor Transmission of Materials,” and consist of one of the following material types: (i) a vapour-resistant coating, (ii) a cold-fluid-applied or hot-rubberized bituminous dampproofing membrane, (iii) a liquid-applied or spray-applied asphalt-based emulsion dampproofing, or (iv) a Type III hot-applied asphalt.

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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.