What Ontario allows
Since the More Homes Built Faster Act, 2022 (Bill 23), Ontario municipalities must allow up to three residential units on most residential lots with municipal water and sewer. That means a main home plus, for example, a basement apartment and a garden suite, without a rezoning. Some municipalities allow more.
In November 2024, Ontario Regulation 462/24 added province-wide standards for these units. They include a minimum 4.0 m separation between a detached unit and the main house, lot coverage of up to 45%, and no minimum lot size on urban lands. Other zoning rules, the Ontario Building Code and the Fire Code still apply.
Local notes
- Hamilton: allows additional dwelling units, including detached units such as garden suites, on many residential lots, and has been updating its zoning to match the provincial standards.
- Burlington: its February 2025 guidance allows up to three additional units with the main home on serviced urban lots, with at most one in a detached accessory building of up to 80 m². No parking space is needed for the first additional unit, and one each for the second and third.
- Oakville: has allowed up to three units on serviced residential properties since April 2023, and has consulted on allowing a fourth.
Rules change and depend on the exact property, so we confirm the current requirements for your address before design.
What decides whether your property works
- Zoning and lot: setbacks, lot coverage, parking and access to the rear of the lot for a garden suite
- Ceiling height and layout: basements need enough clear height, and ducts and beams can reduce it
- Exits and windows: a safe way out, either a separate entrance or a code-compliant shared exit, and properly sized bedroom windows
- Fire and sound separation: between units, plus interconnected smoke and carbon monoxide alarms
- Services: plumbing, drain capacity, heating and ventilation, and electrical service size
- Moisture and structure: foundation condition, waterproofing, and any underpinning to gain height
The steps
- Feasibility check: zoning, existing conditions and a rough scope
- Design and drawings: floor plans, fire separation details and structural design
- Building permit: submission, municipal review and any revisions
- Construction: with inspections at each required stage
- Final inspection and occupancy: before anyone moves in
Costs and financing
Cost depends mostly on the existing basement, whether you need a new entrance or underpinning, plumbing runs, and finishes. See what affects renovation cost. Financing is available through Financeit, subject to approval; see financing.
General information only, not legal or planning advice. Confirm requirements for your property with your municipality.