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 | $90K |
| P75 — larger jobs | $250K |
| Largest in sample | $130.0M |
885 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 | 49 SNOWDON AVE
ONE + TWO STOREY ADDITIONS AT FRONT. NEW COVERED FRONT PORCH |
$250,000 |
| Oct 2026 | 536 ARLINGTON AVE
Proposed basement addition and newly configured rear terrace at the 1st floor. |
$65,000 |
| Oct 2026 | 1998 DANFORTH AVE
Conversion of existing second-floor exterior deck into a secondary unit. |
$75,000 |
| Oct 2026 | 210 AVENUE RD
Proposed a third floor extension |
$35,000 |
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 16, 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.
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