The Ontario Building Code | Restricted Use of Horizontal Exits
3.4.1.6. Restricted Use of Horizontal Exits
(1) Except as permitted by Sentence (2), horizontal exits shall not comprise more than one-half of the required number of exits from any floor area.
(2) In a hospital or long-term care home, horizontal exits serving patients’ or residents’ sleeping rooms shall comprise not more than two-thirds of the required number of exitsfrom any floor area.
(3) Where an elementary or secondary school is subdivided by a firewall, a horizontal exitshall not serve as an exit but is permitted to serve as an access to exit.
In Plain Language
Horizontal exits (doors leading to a fire-separated refuge area on the same floor rather than outside) generally can't make up more than half of a floor area's required exits, though hospitals and long-term care homes get more flexibility given the difficulty of moving patients down stairs.
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.