Not a basement refresh — a separate dwelling unit under the Ontario Building Code. Here's what actually drives the cost, and realistic ranges for the four most common starting points.
Set your starting point and finish level, then calculate.
A finished rec room and a legal secondary suite are governed by completely different rules. The suite has to meet the same fire, egress, and life-safety standards as any other independent dwelling unit — that's what most of the budget goes toward, not finishes.
Every bedroom needs a window large enough and low enough to climb through in an emergency — often the single most disruptive (and expensive) line item if the existing windows don't qualify.
The ceiling and shared walls between the suite and the rest of the house need a fire-rated assembly, not just drywall — this is inspected, not optional.
Older Toronto homes often fall short of the minimum finished ceiling height for a legal suite, which can mean underpinning or bench footings — a major cost driver if it applies to you.
Most jurisdictions require two ways out of the unit in a fire — this is usually the entrance plus one qualifying egress window, not two doors.
Not every basement can legally become a suite — ceiling height, lot size, and parking requirements vary by property and by municipality. Start here before spending on drawings.
A designer or architect prepares drawings showing egress, fire separation, and layout, submitted to the city for a building permit.
Framing, plumbing, and electrical inspections happen at set stages — this is where fire separation and egress sizing actually get verified, not just designed.
Once everything passes, the unit is legally occupiable and can be registered as a second dwelling unit with the city.
Provincial and municipal rules for secondary suites have been changing — always confirm current requirements with the City before finalizing a budget or scope.
| Starting point | Typical range | Main cost driver |
|---|---|---|
| Existing walk-out, unfinished | $60,000 – $100,000 | Kitchen/bath rough-in, fire separation |
| Window well, no walk-out | $75,000 – $120,000 | Egress window upgrades, framing |
| No existing egress | $90,000 – $150,000+ | New entrance excavation, structural work |
| Low ceiling height (underpinning needed) | $130,000 – $220,000+ | Underpinning or bench footings |
An unpermitted unit can be occupied, but it isn't legally recognized as a second dwelling unit and may not be insurable or mortgageable as rental income. Most homeowners pursuing this as an income property go the legal route for that reason.
Design and permitting typically take longer than the actual construction — budget several months for drawings and approval before work even starts, then 8–16 weeks of construction depending on scope.
Generally yes, since it's income-producing and legally recognized — but the exact impact depends on your neighbourhood and buyer pool. Talk to a local realtor for a number specific to your street.
Secondary suites aren't a general contractor's everyday job — we match you with GTA contractors who specifically have permit and inspection experience with this exact project type.