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OBC DIVISION B · PART 3 · SECTION 3.4 — EXITS

What is a horizontal exit and when can it be used in Ontario?

A horizontal exit lets occupants pass through a firewall or rated fire separation into a safe area on the same level of an adjacent building or fire compartment. It may substitute for up to half the required exits, with refuge space of about 0.5 m2 per person.

Code reference
Horizontal exits provide egress through a rated separation or firewall into an adjoining fire compartment that offers refuge, with the receiving area sized per person, larger allowances for occupants in wheelchairs or beds, vestibule and door swing requirements at the separation, and a cap on the proportion of required exits that horizontal exits may replace.
OBC Division B, Subsection 3.4.1.

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

What this means in practice

Horizontal exits shine in hospitals, care homes, detention facilities and large connected industrial or heritage buildings where adding stairs is impractical. The receiving compartment must itself have standard exits and enough clear floor area for both populations, and doors typically swing in opposite directions in pairs to serve travel both ways. Confirm the separation achieves the required rating, often 2 h, and coordinate hardware so security needs never compromise egress.

Plain language

Instead of going downstairs, people escape sideways through a heavy fire-rated wall into the safe half of the building next door, then wait or leave calmly from there. Hospitals use this so patients in beds can escape without stairs.

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.