Legal Basement Suite Requirements in Ontario, BC and Alberta

A basement suite is legal only when the zoning allows it, a permit covers it and it has passed inspection. The same code items come up in every province: ceiling height, fire separation, linked alarms, a way out and bedroom windows. Check the zoning before any of them, because no amount of code work makes a suite legal on a lot that does not allow one.

What makes a basement suite legal

BC and Alberta call it a secondary suite. Ontario's planning law says additional residential unit, and cities and owners say second unit or basement apartment. Edmonton's definition is a useful test anywhere: the suite has its own living room, kitchen, bedroom and bathroom, and its own entrance, either from a shared indoor landing or straight from outside.

A suite is legal when three things line up: the zoning allows it, permits cover it and it has passed its inspections. Calgary wants a building permit plus separate electrical and plumbing permits, and a development permit where suites are discretionary in the district. Edmonton requires permits for every suite, Vancouver requires one to add a suite to an existing house, and Ottawa requires a building permit even when little or no work is planned, because the change of use has to be reviewed.

On one Edmonton builder's 2026 figures, a legal suite costs $30,000 to $55,000 more than a standard basement development of the same size. A suite built so a relative aged 65 or older, or an adult relative eligible for the disability tax credit, can live with the family may also qualify for the federal multigenerational renovation credit, and the CRA requires that unit to meet local permits, codes and bylaws.

Suite requirements in Ontario, BC and Alberta

Ontario's rules below come from the Fire Code's rules for two-unit houses and the province's second-unit guide, with bedroom windows from the 2024 Ontario code, BC's from the 2024 BC Building Code and the local bulletins that summarize it, and Alberta's from Calgary's suite rules and the province's heating rule.

Ceiling height for a basement suite

Height is the one requirement that drywall and wiring cannot fix. The 1.95 m applies over the required floor area of the rooms and along the path through the suite in Ontario and BC, and the 1.85 m allowance in BC and Calgary covers only the strips under beams and ducts.

Where the basement is too low, underpinning the basement to lower the floor is one way to gain the height, and it is a structural job that needs a building permit. Measure under the main beam and the ducts before paying for drawings.

Fire separation and alarms between the two homes

In Ontario, the Fire Code's rules for houses with two units deem lath and plaster or drywall that was in place on July 14, 1994 to meet a 30-minute rating, and plaster board with a skim coat in place by then to meet 15 minutes, so an older house may already have the rating in its ceilings. A separation in place since then also passes in a house sprinklered to NFPA 13D. For a unit added now under a building permit, the province's guide gives lath and plaster as an example of a 15-minute separation.

BC's 2024 code ties the rating to the alarms, from 15 minutes when every smoke alarm in the house is photo-electric and interconnected to 45 minutes when the units' alarms are not linked. Calgary's suite rules describe the assembly instead: 12.7 mm drywall on the ceiling and both sides of the wall studs, with taped joints, and solid-core doors with self-closers.

Exits, entrances and bedroom windows

Ontario's Fire Code gives a two-unit house without sprinklers three ways to meet the exit rule: a door used only by that unit that opens straight outside to ground level; a shared exit behind a 30-minute separation that does not pass through the other home; or a door through the other unit, backed by an escape window and interconnected smoke alarms. That escape window must open to 0.38 m² with no side under 460 mm, with the sill no more than 900 mm above the floor and 1 m of clear space in a window well.

Cities add their own entrance rules. Calgary requires each home to have at least one exit leading directly outside, Edmonton requires the suite's own entrance from a shared indoor landing or straight from outside, and Ottawa asks for separate access on the ground floor unless the codes allow another way. Bedroom windows follow the same rule as in a finished basement bedroom: an opening of 0.35 m² with no side under 380 mm.

Heating, ventilation and wiring

Heating is where the provinces part ways. Ontario's guide allows a single furnace and shared ducts if duct-type smoke detectors are fitted, and suggests a second furnace to limit odour, smoke and noise passing between the homes.

BC's code accepts a shared system only if it is designed to stop circulating smoke when a duct-type smoke detector trips, and the Central Okanagan's bulletin wants that design and its inspection from a mechanical engineer. Alberta requires independent heating and ventilation for each home: 2 furnaces, or permanent alternate heat with its own ventilation.

Wiring and plumbing carry their own permits. In Ontario, the suite's electrical work takes a separate permit and an Electrical Safety Authority inspection. Calgary lets one electrical panel serve both homes if no branch circuit is shared, and asks for a backflow prevention device on the suite's branch drains.

Zoning: how many units a lot can hold

Ontario's Planning Act stops official plans from prohibiting up to 3 units on a lot of urban residential land: 3 in a detached house, semi or rowhouse, or 2 in the house and 1 in a separate building on the lot. Ontario Regulation 299/19 sets parking at one space per added unit, which can be a tandem space and is not needed where the zoning asks for none for the main home, and lets anyone live in the unit, whether or not they are related to the main home's occupant or own the lot.

BC allows secondary suites or accessory dwelling units in single-family zones across the province, and requires municipalities to permit 3 to 4 units on lots zoned only for single-family or duplex homes inside urban containment boundaries, or anywhere in a municipality of more than 5,000 people that has no such boundary. Alberta leaves the choice to each municipality's land use bylaw.

For a basement suite in Edmonton, the City's 2026 fees are $415 for a development permit and $124.80 to $2,184 for the building permit by construction value, against $403.52 for a new suite's building permit in Calgary, where the suite development permit costs nothing.

Legalizing an existing basement apartment

An existing suite is legalized much as a new one is built: an application with drawings, a review, inspections and upgrades wherever the suite falls short. Richmond, BC, warns that work done without plans or permits may have to be exposed for inspection. In Ontario, the Fire Code's two-unit rules apply to the house as it stands, and the Chief Fire Official can order an Electrical Safety Authority inspection with the fees paid by the owner.