The Ontario Building Code | Insulating Sheathing in Lieu of Sheathing Membrane
9.27.3.4. insulating Sheathing in Lieu of Sheathing Membrane
(1) Where non-wood-based rigid exterior insulating sheathing, or exterior insulating sheathing with an integral sheathing membrane is installed, a separate sheathing membrane is not required.
(2) Where insulating sheathing is installed as provided in Sentence (1),
(a) sheathing panels subject to moisture deterioration shall be sealed at all joints, and
(b) the joints of sheathing panels not subject to moisture deterioration shall be,
(i) sealed at all joints, or
(ii) lapped or tongue and groove, and detailed to ensure drainage of water to the exterior.
In Plain Language
Insulating sheathing may be used in place of a separate sheathing membrane under the conditions set out in this article, provided the insulating product itself meets the necessary water-resistance performance.
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.