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What are the requirements for a basement apartment in Ontario?

Last updated: June 2026

Short answer: Legal secondary suites need fire separation from the main unit, compliant egress, minimum ceiling heights, smoke/CO alarms, and municipal approval in addition to OBC compliance.

Detailed explanation

OBC Section 9.10.22 and related provisions address secondary suites in houses. Fire separation, egress, and ceiling height are common upgrade triggers.

Each municipality has zoning and registration rules. A building permit is required for most suite conversions.

Interconnected smoke alarms must alert occupants in both units. Separate HVAC and sound transmission may also apply.

Relevant OBC sections

  • Ontario Building Code

    Section 9.10.22. — Secondary suites

  • Ontario Building Code

    Section 9.5.3. — Ceiling heights

Example scenario

You rent your basement without fire-rated separation or a second exit. A complaint triggers a bylaw inspection — you need permits, separation, and egress upgrades to legalize the suite.

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