How much does a home addition cost in Toronto?
Toronto addition permits and their declared construction values — rear, side and second-storey additions in one dataset.
The full spread, not an average
| Percentile | Declared value |
|---|---|
| P25 — smaller jobs | $30K |
| Median | $85K |
| P75 — larger jobs | $250K |
| Largest in sample | $130.0M |
893 permits with a declared value, trailing 36 months. Medians and quartiles only — one outlier can't move them.
Why two of these quote differently
- Whether the addition is at grade or a second storey (the latter usually needs the existing structure reinforced).
- Foundation work and how the new roof ties into the old one.
- Servicing capacity — additions often trigger electrical and HVAC upgrades to the whole house.
- Zoning: floor space index and setbacks decide how much you can add before Committee of Adjustment time and cost.
Check it against the record
| Applied | Address | Declared value |
|---|---|---|
| Oct 2026 | 234 WOBURN AVE
Proposal to construct a 1 storey rear addition to existing SFD. |
$100,000 |
| Oct 2026 | 54 WENDOVER RD
Proposed addition (3sqm) to the rear of an existing detached dwelling. |
$10,000 |
| Oct 2026 | 15 SHANDON DR
ENCLOSE EX. CARPORT +ADDITION BETWEEN EX. CARPORT AND REAR GARAGE |
$20,000 |
| Oct 2026 | 120 WELLINGTON ST W
Proposal for temporary vestibule enclosure at the front of the restaurant which will... |
$12,000 |
Where these numbers come from
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.
Data: Open Government Licence — Toronto. Recomputed automatically as new
permits land; the figures above are current as of October 18, 2026.
Pricing a project like this?
The numbers above are the market. For your project specifically — your address, your scope — we'll read the comparables, flag the permits you'll need, and check any quote you've been given against real awarded prices.
Interior fit-outs · New houses · Underpinning · Laneway & garden suites · Garages · Second suites