The Ontario Building Code | Exceptions for Major Occupancies
3.2.2.8. Exceptions for Major Occupancies
(1) In a building in which the aggregate area of all major occupancies in a particular Group or Division is not more than 10% of the floor areaof the storey in which they are located, these major occupancies need not be considered as major occupancies for the purposes of this Subsection, provided they are not classified as Group F, Division 1 or 2 occupancies.
Note: On July 1, 2017, Article 3.2.2.8. of Division B of the Regulation is amended by adding the following Sentence: (See: O. Reg. 139/17, s. 17)
(1.1) For the purposes of Sentence (1), a retirement home is deemed to be a separate major occupancy.
(2) A helicopter landing area on the roof of a buildingneed not be considered a major occupancy for purposes of Subsection 3.2.2. where such landing area is not more than 10% of the area of the roof.
In Plain Language
A minor major-occupancy use taking up no more than 10% of a storey's floor area can be disregarded for classification purposes (unless it's a Group F, Division 1 or 2 occupancy), and a 2017 amendment clarifies retirement homes still count as their own separate major occupancy even under this exception.
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.