Permits for Basement Apartments in Toronto: What Homeowners Need to Know

With Toronto rents where they are, more homeowners are looking at their basement and seeing a rental unit — or a place for an adult child or aging parent. The City of Toronto allows secondary suites in many houses, but a legal basement apartment is a regulated project with a building permit, inspections and specific safety requirements. Here's what to know before you start.

This article is general information, not legal or code advice. Rules change; confirm details with the City of Toronto, a qualified designer (BCIN holder or architect) and, where relevant, a lawyer and your insurer.

Do you need a permit for a basement apartment?

Yes. The City of Toronto's When Do I Need a Building Permit? page lists "adding a second suite" among basement work that requires a permit, along with structural changes, new or modified plumbing or heating, underpinning and constructing a basement entrance. Even if your basement is already finished, converting it into a separate dwelling unit is a change that needs a permit.

Is my house eligible?

Toronto's zoning by-law permits a secondary suite in a detached house, semi-detached house or townhouse. The City's 2019 amendment to Zoning By-law 569-2013 (By-law 549-2019) set out rules for secondary suites, including a requirement that the suite's interior floor area generally be no more than 45% of the dwelling unit it's in — with an exception allowing a suite in the basement of a one-storey detached house to occupy the whole basement (by-law text). It also limits exterior alterations facing the street, with exceptions for things like a porch or a pedestrian entrance in certain cases.

Toronto has since broadened housing permissions (for example, multiplexes and garden and laneway suites), so the right answer for your lot may have more options than a basement suite alone. A Zoning Certificate or preliminary project review from the City can confirm what's permitted before you invest in drawings.

If you live outside Toronto — Vaughan, Mississauga, Brampton, Markham — each municipality has its own additional residential unit rules and, in some cases, a registration requirement. Check with that city's building department.

What the City asks for in a permit application

According to the City's Secondary Suites application guide, a typical submission includes:

• Site plan — property lines, building locations and setbacks, a zoning summary, parking and driveway areas, landscaping and accessory structures.
• Floor plans for each level — existing and proposed uses, smoke alarm and carbon monoxide alarm locations, plumbing fixtures, structure above.
• Sections — floor, wall and roof assemblies, foundation details, height of exterior grade above the basement floor, floor-to-ceiling heights, stair, guard and handrail details.
• Construction details and notes.
• Applicable forms, submitted through Toronto Building Online Services.

Drawings must be prepared by someone qualified under the Ontario Building Code — typically a designer with a BCIN or an architect. If underpinning is involved, the City may require an engineer's design.

The Building Code issues that drive cost and design

A legal suite is about safety more than finishes. Common issues include:

Fire separation

The suite and the main house must be separated so a fire in one doesn't quickly spread to the other. That affects ceilings, walls, doors between units and sometimes the ductwork.

Smoke and CO alarms

Interconnected smoke alarms and carbon monoxide alarms are typically required. Your designer will specify locations.

Exits and egress

Occupants need a safe way out — a separate entrance or a shared exit meeting code requirements — and bedrooms need windows meeting egress size rules. Creating a new side or rear entrance often means excavation and a new opening in the foundation wall.

Ceiling height

Older Toronto basements are often low. The Code sets minimum ceiling heights for dwelling units; if you're short, lowering the floor (underpinning or bench footings) may be needed, which is a significant structural project. Measure before you plan.

Heating, ventilation and sound

Separate or appropriately separated HVAC, plus ventilation for kitchens and bathrooms. Sound attenuation between units is a quality-of-life issue for everyone.

Electrical

New circuits for a kitchen, and potentially a service upgrade. All electrical work requires an ESA notification by a Licensed Electrical Contractor.

Permit fees and timing

Fees are set by the City's annual fee schedule and are calculated largely per square metre of floor area, with additional charges for new units — check the current schedule on toronto.ca, as it updates each year. Drawings, any zoning review, and potential Committee of Adjustment applications (if your project needs a variance) are separate costs and add time. Build permit review time into your schedule before committing to a rental start date.

What about an existing "basement apartment"?

Many Toronto homes have basement units built years ago without permits. If you're buying such a house — or already own one — it isn't automatically legal. Bringing it into compliance usually means getting a permit for the work and having it inspected, which can reveal deficiencies to fix. Ontario's Fire Code also applies to existing two-unit houses, and Toronto Fire Services can inspect for fire safety. Talk to your insurer too: an unpermitted rental can create coverage problems.

Typical costs

Third-party Toronto guides put a legal secondary suite in a much higher bracket than a standard basement finish. HomeStars lists $90,000 to $140,000 for a legal secondary suite (source); underpinning or major structural work can push costs higher. See our basement finishing costs article for more context.

Step-by-step: from idea to legal suite

1. Confirm eligibility (zoning, house type, lot) and talk to your insurer and, if applicable, your mortgage lender.
2. Measure ceiling height and check for moisture.
3. Hire a qualified designer to prepare permit drawings.
4. Apply for the permit through Toronto Building Online Services.
5. Build with a contractor experienced in suites, with inspections at required stages.
6. Pass final inspection and keep all permit documents — you'll want them at resale and for insurance.
7. Understand landlord obligations under Ontario's Residential Tenancies Act before renting.

Thinking about a basement suite?

Daystar Homes & Construction works with designers and handles the construction side of basement suites across Toronto and the GTA. Talk to us about your suite, or read more about legal basement apartments and basement finishing.

Sources: City of Toronto — "When Do I Need a Building Permit?", "Secondary Suites" application guide, By-law 549-2019; HomeStars Toronto basement cost guide. Information current as of October 2026.