The Ontario Building Code | Fire Containment in Basements
3.2.1.5. Fire Containment in basements
(1) Except as permitted by Sentences (2) and 3.2.2.15.(3), in a building in which an automatic sprinkler system is not required to be installed by Articles 3.2.2.20. to 3.2.2.83., every basement shall,
(a) be sprinklered, or
(b) be subdivided into fire compartments not more than 600 m2 in area by a fire separation having a fire-resistance rating not less than that required for the floor assembly immediately above the basement.
(2) An open-air storey need not conform to Sentence (1).
In Plain Language
Unless sprinklered elsewhere in the building already covers it, every basement in a building without a required sprinkler system must either be sprinklered itself or divided into fire compartments no larger than 600 m² by a separation matching the floor assembly's rating; open-air storeys are exempt.
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.