The Ontario Building Code | Openings through a Membrane Ceiling
3.1.9.5. openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">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="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings leading into ducts within the ceiling space provided,
(a) the ducts are sheet steel, and
(b) the amount of openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">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.