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OBC DIVISION B · PART 3 · SECTION 3.4 — EXITS

How far apart must exits be located under the Ontario Building Code?

Where multiple exits are required they must be remote from each other, generally separated by at least one half of the maximum diagonal dimension of the floor area, though the required separation need not exceed 9 m in certain corridor-served layouts.

Code reference
Required exits must be located remotely from one another so a single fire is unlikely to block both. The separation between exits is measured against the floor area diagonal, with a half-diagonal benchmark, and reduced separation is recognized where exits connect through qualifying public corridors or where the building is sprinklered.
OBC Division B, Article 3.4.2.3.

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

What this means in practice

Remoteness is checked on the floor plan by drawing the maximum diagonal of the floor area, then measuring between exit doors or stair enclosures. Scissor stairs in a single shaft raise remoteness questions and need careful separation detailing to count as independent exits. Core-and-shell towers with compact cores often rely on the corridor-connection relaxation, so document the corridor rating and configuration that justifies the measured separation.

Plain language

Two exits close together are really one exit in a fire. The Code makes them stand far apart, roughly half the room's longest diagonal, so smoke or flames at one door still leaves the other reachable.

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 many exits does a floor area need 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.