The Ontario Building Code | Elevators
(1) Except as provided in Sentence (2), where an elevator shaft opens into an interconnected floor space and into storeys that are above such space and that have floor levels more than 18 m above grade, either the elevator doors opening into the interconnected floor spaceor the elevator doors opening into the storeysabove the interconnected floor space shall be protected by vestibules that,
(a) are designed to restrict the passage of contaminated air to the limit described in Sentence 18.104.22.168.(1), and
(b) conform to the requirements of Sentence 22.214.171.124.(3).
(2) Where elevator doors opening into an interconnected floor space are protected by vestibules in conformance with Sentence (1), the elevator doors opening into the lowest storeyof the interconnected floor space need not be protected by such vestibules.