The Ontario Building Code | Openings through a Membrane Ceiling
3.1.9.5. Openings through a Membrane Ceiling
(1) A membrane ceiling forming part of an assembly assigned a fire-resistance rating on the basis of MMAH Supplementary Standard SB-2, "Fire Performance Ratings", is permitted to be penetrated by openings leading into ducts within the ceiling space provided,
(a) the ducts are sheet steel, and
(b) the amount of openings and their protection conform to the requirements of MMAH Supplementary Standard SB-2, "Fire Performance Ratings".
(2) Fire stop flapsin ceiling membranes required in Sentence (1) shall conform to CAN/ULC-S112.2, "Fire Test of Ceiling Firestop Flap Assemblies".
In Plain Language
A membrane ceiling with an SB-2-based fire rating can have openings into ceiling-space ducts, provided those ducts are sheet steel and the opening amount/protection meets SB-2's requirements.
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.