The Ontario Building Code | Rooftop Enclosures
9.10.4.4. Rooftop Enclosures
(1) Rooftop enclosures provided for elevator machinery, stairways and service rooms, used for no purpose other than for service to the building, shall not be considered as a storey in calculating the building height.
9.10.5. Permitted Openings in Wall and Ceiling Assemblies
In Plain Language
Rooftop enclosures, such as stairwell bulkheads or mechanical penthouses, have specific requirements set out in this article addressing their fire safety treatment.
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.