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OBC DIVISION B · PART 3 · SECTION 3.1 — APPLICATION

How is major occupancy classified under the Ontario Building Code?

Every building or part of a building is classified into a major occupancy group, from Group A (assembly) through Group G (agricultural), based on its principal use. Classification drives construction type, fire protection and egress requirements.

Code reference
Each building must be classified according to its major occupancy or occupancies, chosen from the occupancy groups and divisions in the Code, based on the actual intended use. Where a use fits more than one description, the building is classified to the group that reflects the principal purpose of the space.
OBC Division B, Subsection 3.1.2.

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

What this means in practice

Occupancy classification is the root input for nearly every Part 3 provision, including the 3.2.2 construction articles, fire alarm triggers and occupant load factors. Common pitfalls include misclassifying restaurants versus takeout retail, treating personal-service uses as mercantile, and missing that subsidiary uses can still be major occupancies. Confirm classification with the authority having jurisdiction early, because reclassifying late can change sprinkler, separation and exiting requirements across the whole design.

Plain language

The Code sorts buildings by what people do inside them, such as gathering, sleeping, working or storing goods. That label decides how fire-safe the construction must be, so getting it right at the start keeps the rest of the design on track.

Related questions

Which buildings fall under Part 3 of the Ontario Building Code?How are building height and building area determined under the Ontario Building Code?What is a high building 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.