The Ontario Building Code | Permitted Openings in Wall and Ceiling Membranes
9.10.5.1. Permitted openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings in Wall and ceiling Membranes
(1) Except as permitted in Sentences (2) and (4), a membrane forming part of an assembly required to have a fire-resistance rating shall not be pierced by openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings into the assembly unless the assembly has been tested and rated for such openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings.
(2) A wall or ceiling membrane forming part of an assembly required to have a fire-resistance rating is permitted to be pierced by openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings for electrical and similar service outlet boxes provided such outlet boxes are tightly fitted.
(3) Where boxes referred to in Sentence (2) are located on both sides of walls required to provide a fire-resistance rating, they shall be offset where necessary to maintain the integrity of the fire separation.
(4) A membrane ceiling forming part of an assembly assigned a fire-resistance rating on the basis of Table 2 of MMAH Supplementary Standard SB-3, "Fire and Sound Resistance of building Assemblies", is permitted to be pierced by openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings leading to ducts within the ceiling space provided the ducts, the amount of openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings and their protection conform to the requirements in MMAH Supplementary Standard SB-2, "Fire Performance Ratings".
9.10.6. Construction Types
In Plain Language
Openings permitted in wall and ceiling membranes that form part of a fire separation are limited as set out in this article, since even small unprotected openings can undermine a fire separation's effectiveness.
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.