The Ontario Building Code | Corridors
3.1.13.6. corridors
(1) Except as permitted by Sentences (2) and (3), the flame-spread rating shall be not more than 75 for the interior wall finish of,
(a) a public corridor,
(b) a corridor used by the public in,
(i) an assembly occupancy, or
(ii) a care,care and treatment or detention occupancy,
(c) a corridor serving classrooms, or
(d) a corridor serving sleeping rooms in a care, care and treatment or detention occupancy.
(2) The flame-spread rating limit specified in Sentence (1) does not apply to corridors referred to in Sentence (1) provided the flame-spread rating is not more than,
(a) 25 on the upper half of the wall, and
(b) 150 on the lower half of the wall.
(3) The flame-spread rating limits specified in Sentences (1) and (2) for corridors referred to in Sentence (1) do not apply to a corridor in which the flame-spread rating is not more than 150 provided the floor area is sprinklered.
(4) The flame-spread rating limits specified in Sentences (1) to (3) apply to occupancies in the corridor as well as to the corridor itself.
(5) Except in a floor area that is sprinklered and as permitted in Sentence (6), the interior ceiling finish of corridors and occupanciesreferred to in Sentences (1) and (4) shall have a flame-spread rating not more than 25.
(6) The flame-spread rating limits specified in Sentence (5) do not apply to a corridor in which the flame-spread rating is not more than 150 provided the floor areais sprinklered.
In Plain Language
Interior wall finishes in public corridors, corridors serving certain vulnerable occupancies, or serving classrooms are generally capped at a 75 flame-spread rating, though a two-tier alternative (25 on the upper wall half, 150 on the lower half) is allowed instead, and a further exception applies in specific circumstances.
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.