Permitted, inspected, registered basement apartments that pass the first time.
- Feasibility & design
- 1 — 2 weeks
- Permit review
- 4 — 12 weeks
- Construction
- 8 — 14 weeks
- Inspections & registration
- 2 — 4 weeks
The short answer
A legal basement apartment — formally an Additional Residential Unit or second suite — is a self-contained dwelling in a basement that has been built to the Ontario Building Code, approved under a building permit, inspected, and where required registered with the municipality. Under Bill 23 (More Homes Built Faster Act), most detached, semi-detached and townhouse properties in Ontario may add one ARU as-of-right. In 2026 a legal basement apartment in the GTA typically costs $85,000 to $300,000 to build from scratch, or $25,000 to $62,000 to legalise an existing finished basement, and takes four to eight months from permit application to occupancy.
The difference between a finished basement and a legal one is roughly a hundred thousand dollars of resale value and the ability to actually insure and rent it. An unregistered unit can be ordered closed, can void a home insurance claim, and is not counted by lenders as income when you refinance.
The code requirements are not mysterious — they are just unforgiving. Ceiling height, egress, fire separation, sound transmission, interconnected alarms, a compliant separate entrance and an HVAC design that serves two units are all pass-or-fail items. Miss one and you fail inspection.
We handle it end to end: measure the basement against the code before you spend anything, prepare the permit drawings, submit to your municipality, build to the approved set, call every inspection, and hand you the closed permit, the ESA certificate and the registration paperwork at the end.
Code feasibility assessment
Before you spend a dollar we measure ceiling height, window openings, joist depth, panel capacity and lot conditions against the Ontario Building Code and your zoning bylaw, and tell you honestly whether the basement qualifies.
Permit drawings & submission
Floor plans, fire separation details, egress and ventilation schedules prepared and submitted to your municipality, with responses to plan-review comments handled by us.
Separate entrance construction
Side or rear entrances, excavated walk-ups, retaining walls, drainage and a compliant landing and stair. Toronto in particular restricts new front-façade entrances that make a house read as a duplex.
Egress windows & window wells
Cutting and enlarging foundation openings, structural lintels, window wells with proper drainage, and a clear opening that meets the code minimum for escape.
Fire separation & alarms
Rated ceiling and wall assemblies between units, self-closing doors, firestopping at every penetration, and interconnected smoke and carbon monoxide alarms across both dwellings.
Full unit build & registration
Kitchen, bathroom, bedrooms, separate laundry, sound insulation, dedicated HVAC and ventilation, ESA inspection, final building inspection and municipal two-unit registration.
Legal basement pricing depends almost entirely on three things: whether the space is already finished, whether a separate entrance has to be excavated, and whether ceiling height and egress already comply.
Underpinning to gain ceiling height is the single largest cost variable and can add $80,000 or more. We measure your existing height at the lowest duct before quoting so that number is never a surprise.
Legalise an existing finished basement
Bring current build up to code, permit and inspect
Unfinished basement — standard unit
One bedroom, existing entrance, adequate ceiling height
Two-bedroom suite with walk-up
Excavated side entrance, egress windows, full build
Complex build
Underpinning or benching for ceiling height, structural changes
Per square foot — legal suite
Full secondary suite finish standard
Permit drawings (under 800 sq ft)
Plans, submission and plan-review responses
Every one of these is a pass-or-fail inspection item. Your municipality and the current Ontario Building Code are the final authority — we verify each against your specific property during the feasibility assessment.
Brampton requires a Two-Unit Dwelling Registration plus an ESA certificate — renting without them is an offence. Toronto permits second suites as-of-right in most residential zones but restricts new front-façade entrances.
Not seeing your question? Call or text (647) 928-3544 — we answer same day, usually within 2 hours.
A legal basement apartment must meet the Ontario Building Code for a second unit, be built under an approved building permit, pass all inspections, and — in municipalities such as Brampton and Mississauga — be registered with the city. The pass-or-fail items are minimum 1.95 m ceiling height, an egress window with at least 0.35 m² of clear opening, a rated fire separation between units, interconnected smoke and CO alarms, a compliant separate entrance, adequate ventilation, and an ESA electrical certificate.
City of Toronto
York Region
Durham Region
Tell us what you are planning. We come out, measure, and hand you a written line-by-line legal basement quote at no cost.
Same day, usually within 2 hours· Serving the GTA, Hamilton, Guelph & Kitchener