How much does underpinning cost in Toronto?
Underpinning and basement-lowering permits in Toronto, priced from declared construction values.
The full spread, not an average
| Percentile | Declared value |
|---|---|
| P25 — smaller jobs | $50K |
| Median | $100K |
| P75 — larger jobs | $300K |
| Largest in sample | $11.1M |
1,246 permits with a declared value, trailing 36 months. Medians and quartiles only — one outlier can't move them.
Why two of these quote differently
- Linear metres of wall underpinned and the depth of each pin.
- Soil conditions and water table — dewatering and shoring change the job entirely.
- Whether the scope includes a new slab, drainage and waterproofing (it usually does).
- Access: a semi-detached with no side entrance means every bucket comes out through the house.
Check it against the record
| Applied | Address | Declared value |
|---|---|---|
| Aug 2026 | 255 CLINTON ST
Proposal for second storey rear addition, interior alterations, basement underpinning... |
$300,000 |
| Aug 2026 | 325 KENILWORTH AVE
Proposal to lower the existing basement via underpinning, unfinished basement... |
$80,000 |
| Aug 2026 | 176 HOPEDALE AVE
Basement underpinning. |
$60,000 |
| Aug 2026 | 331 MAIN ST
Proposal for basement underpinning, new basement washroom, laundry, bedrooms, and walkout. |
$80,000 |
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.
Underpinning is the most common way a basement second suite becomes legal, so these projects frequently overlap with suite permits.
Data: Open Government Licence — Toronto. Recomputed automatically as new
permits land; the figures above are current as of August 19, 2026.
Interior fit-outs · New houses · Laneway & garden suites · Additions · Garages · Second suites