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OBC DIVISION B · PART 3 · SECTION 3.7 — HEALTH REQUIREMENTS

How many washroom fixtures does a building need under the Ontario Building Code?

OBC Subsection 3.7.4 sets minimum water closet counts using tables keyed to occupancy classification and occupant load; assembly, office, industrial, school and residential uses each have their own ratios. Lavatories and permitted urinal substitutions are also regulated.

Code reference
Plumbing facility provisions require water closets for each sex, or universal washrooms in permitted cases, in numbers determined from occupancy-specific tables based on the occupant load of the floor area served. Lavatories must accompany water closets, urinals may substitute for a share of male water closets, and fixtures must be reasonably accessible to the occupants they serve.
OBC Division B, Subsection 3.7.4.

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

What this means in practice

Fixture counts are calculated from the code occupant load, not the expected headcount, so an open-plan office or restaurant can trigger more fixtures than the client anticipates. Establish occupant load, male/female assumptions and any universal washroom substitutions early, and document them in the code summary for the permit set. Watch tenant fit-outs in existing buildings: increasing occupant load often silently increases required fixtures, and adding fixtures late means chasing plumbing stacks across finished space.

Plain language

The code uses tables to decide how many toilets and sinks a building needs, based on what the building is used for and how many people it is designed to hold. A packed restaurant needs far more fixtures than a small office.

Related questions

When is a universal washroom required in an Ontario building?Are drinking fountains required by the Ontario Building Code?What are the medical gas piping requirements in 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.