How much does a second suite (basement apartment) cost in Toronto?

Declared values for legalizing or building a second suite in Toronto — the permit-visible cost of adding a legal rental unit.

494 permits with a declared value, trailing 36 months. Medians and quartiles only — one outlier can't move them.

We publish a per-square-foot rate only where floor area is what the price actually scales with. For this work the correlation between area and declared value is 0.31 — too weak for a rate to predict your project. Multiplying your floor area by a published $/SF number would produce a confident-looking figure that the underlying permits do not support, so we show the value distribution instead.

• Ceiling height and egress: a second exit or enlarged windows is the usual deal-breaker cost.
• Fire separation and interconnected alarms throughout the whole house.
• Underpinning or bench footings when headroom is short — this alone can double the project.
• Separate HVAC, and whether the electrical service needs upsizing.

Declared construction values on City of Toronto building permits (tier C), trailing 36 months, minimum 12 permits before a guide is published. A declared value is what the applicant stated the work is worth — it can sit below final hard cost, which is exactly why GROUND also publishes awarded contract prices.

Suites created without a permit never appear in this data, so these figures describe the legal path only.

Data: Open Government Licence — Toronto. Recomputed automatically as new permits land; the figures above are current as of October 07, 2026.

Interior fit-outs · New houses · Underpinning · Laneway & garden suites · Additions · Garages