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OBC DIVISION B · PART 3 · SECTION 3.4 — EXITS

Can an exit pass through a lobby under the Ontario Building Code?

Yes, but only one required exit may lead through a lobby, the lobby floor must be close to grade, travel through the lobby is limited to about 15 m, and the lobby must be separated and finished to restrict fire and combustible content.

Code reference
Not more than one required exit from a floor area may discharge through a lobby, provided the lobby is located essentially at the exit level near grade, travel across the lobby to the exterior is limited in length, the lobby is separated from the remainder of the building consistent with exit protection, and uses within the lobby are restricted to low-hazard functions.
OBC Division B, Article 3.4.4.2.

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

What this means in practice

This allowance is what lets one stair in a typical tower discharge through the ground-floor lobby instead of directly outdoors, saving valuable street frontage. The second stair must still exit directly outside or through an exit passageway. Watch lobby programming: cafes, retail kiosks and furniture groupings can conflict with the hazard restriction, and mail rooms or property management offices opening into the lobby need review. Measure the 15 m across the actual path to the door.

Plain language

One of the building's exit stairs is allowed to empty into the main ground-floor lobby, as long as the front door is a short walk away and the lobby is kept safe. The other stair must lead outside more directly.

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.