The Ontario Building Code | Vapour Barrier Materials
188.8.131.52. Vapour Barrier Materials
(1) Vapour barriers shall have a permeance not greater than 60 ng/(Pa∙s∙m2), measured in accordance with ASTM E96 / E96M, "water Vapor Transmission of Materials", using the desiccant method (dry cup).
(4) Membrane-typevapour barriers other than polyethylene shall conform to CAN/cgsb-51.33-M, "Vapour Barrier, Sheet, Excluding Polyethylene, for Use in Building Construction".
(5) Where a coating is applied to gypsum board to function as the vapour barrier, the permeance of the coating shall be determined in accordance with CAN/CGSB-1.501-M, "Method for Permeance of Coated Wallboard".
(6) Where insulation functions as the vapour barrier, it shall be sufficiently thick so as to meet the requirement of Sentence (1).