The Ontario Building Code | Sprinklers in Lieu of Roof Rating
3.2.2.17. Sprinklers in Lieu of Roof Rating
(1) The requirements in Articles 3.2.2.20. to 3.2.2.83. for roof assemblies to have a fire-resistance rating are permitted to be waived provided,
(a) except as provided by Sentence (2), the building is sprinklered,
(b) the sprinkler system in Clause (a) is electrically supervised in conformance with Sentence 3.2.4.10.(3), and
(c) the operation of the sprinkler system in Clause (a) will cause a signal to be transmitted to the fire department in conformance with Sentence 3.2.4.8.(4).
(2) The fire-resistance rating of roof assemblies required by Clause 3.2.2.43A.(2)(b) or 3.2.2.50A.(2)(b) is not permitted to be waived.
In Plain Language
The usual fire-resistance rating requirement for roof assemblies can be waived if the building is sprinklered with an electrically supervised system that signals the fire department on activation, though this waiver doesn't apply to the specific roof rating required under Clause 3.2.2.43A.(2)(b) or 3.2.2.50A.(2)(b).
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.