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OBC DIVISION B · PART 3 · SECTION 3.4 — EXITS

How many exits does a floor area need under the Ontario Building Code?

Most floor areas in Part 3 buildings need at least two independent exits. A single exit is permitted only for small, low-occupancy floor areas that satisfy strict limits on occupant load, area and travel distance.

Code reference
Every floor area intended for occupancy must be served by at least two exits, except that one exit may serve certain small floor areas where the occupant load, floor area and travel distance fall within tabulated limits that depend on occupancy and sprinklering. Larger occupant loads can require three or more exits.
OBC Division B, Subsection 3.4.2.

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

What this means in practice

The two-exit baseline shapes core design from day one: two stairs, adequately separated, sized for the load. The single-exit allowance is narrow and mainly helps very small buildings and low-rise infill, and Ontario has specific provisions for some small residential buildings, so confirm the exact conditions rather than assuming. Also verify exits from mezzanines, roofs with occupancy, and interconnected floor spaces, which each carry their own exit counts.

Plain language

Almost every floor of a larger building needs two separate ways out, so a single fire can never block escape. Only very small, lightly occupied floors are allowed to rely on one exit.

Related questions

When are two exits required from a floor area in Ontario?How is required exit width calculated under the Ontario Building Code?How far apart must exits be located 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.