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OBC DIVISION B · PART 3 · SECTION 3.1 — APPLICATION

What is a high building under the Ontario Building Code?

A building is treated as a high building when its top storey floor is more than 36 m above grade for Group A, D, E or F occupancies, or more than 18 m for Group B or C, triggering the additional measures in Subsection 3.2.6.

Code reference
Subsection 3.2.6 applies to buildings whose uppermost floor level exceeds height thresholds above grade, generally 36 m for assembly, business, mercantile and industrial uses and 18 m for care and residential uses, and to certain buildings where large occupant loads are located above the reach of firefighting from outside.
OBC Division B, Article 3.2.6.1.

Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.

What this means in practice

High building status adds significant scope: smoke control measures, a central alarm and control facility, firefighter elevators, voice communication systems and enhanced emergency power. It is a common surprise on mid-rise residential projects, since the 18 m residential threshold can be reached around six or seven storeys depending on floor-to-floor heights and grade. Establish the measurement to the top storey floor early, because designing out or into 3.2.6 materially changes budget and mechanical design.

Plain language

Once a tower gets tall enough that firefighters cannot manage a fire easily from the street, roughly six to seven storeys for apartments, the Code adds extra protections like smoke control, special elevators and a fire command centre in the lobby.

Related questions

Which buildings fall under Part 3 of the Ontario Building Code?How is major occupancy classified under the Ontario Building Code?How are building height and building area determined under the Ontario Building Code?

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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.