Secondary Suite
Basement apartment / accessory dwelling unit
A self-contained second home inside a house or on its lot, with its own kitchen and bathroom, that must meet zoning, building and fire rules.
A secondary suite is a self-contained home inside a house or on the same lot. Common examples are a basement apartment or a unit in a detached garage or garden suite. Ontario's guidance describes a second unit as having its own kitchen, bathroom and sleeping area. Ontario's planning rules call these additional residential units.
In Ontario, the More Homes Built Faster Act, 2022 (Bill 23) created an as-of-right permission for up to three units on many residential lots. That can mean two units in the main house plus one in an accessory building. It applies where homes are allowed in settlement areas with full municipal water and sewer services. Municipalities also cannot impose minimum unit sizes beyond the Building Code.
As-of-right zoning does not mean no permits. You still need a building permit, and the Ontario Building Code sets standards for room sizes, ceiling heights, windows, exits, plumbing and ventilation. The province's guide describes a 30-minute fire separation between units and shared areas. It drops to 15 minutes if the whole house has interconnected smoke alarms. Electrical work needs a separate permit and an Electrical Safety Authority inspection.
Older suites follow different rules. In Ontario, two-unit houses that existed on or before 14 July 1994 are regulated by section 9.8 of the Fire Code. Some municipalities also require suites to be registered or licensed, so ask your local building department. The province says development charges are not collected for a second unit built in an existing house.
A legal suite can add rental income and much-needed housing. An unpermitted one can put occupants at risk and may face municipal enforcement. Before you buy a house with a suite, or count on its rent, confirm it was built with permits. Rules outside Ontario differ by province and city.
Sources
- Ontario.ca: Add a second unit in your house
- Environmental Registry of Ontario 019-6163: Bill 23 Planning Act changes
- City of Toronto: Two-dwelling-unit houses and Fire Code section 9.8
Last reviewed October 16, 2026.
Related terms in Property & Ownership
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General information only, not legal, tax, or financial advice. Rules change and vary by province; confirm the current details with the relevant authority before you rely on them.