Basement underpinning in Toronto typically costs $350–$500 per linear foot, or $25,000–$65,000 for a full perimeter on a semi-detached home. OCM Excavation & Construction handles the excavation work on underpinning projects across Toronto, North York, Scarborough, Etobicoke, Mississauga, Vaughan, and Markham. Call 416-317-3090 for a free on-site quote.
What Is Basement Underpinning?
Underpinning is the process of deepening an existing basement by excavating beneath the current foundation footings in small sections. Each section gets excavated, a new footing is poured at the lower level, and the wall above is extended. Repeat around the perimeter until the full basement is lowered.
The result: more headroom. Most Toronto semi-detached and detached homes built before 1980 have basements with 6’6″ or less of clearance. Underpinning typically brings that to 8’0″–9’0″, turning a storage space into a liveable floor.
Basement Underpinning Cost Toronto — 2026 Pricing
The main cost driver is linear footage. Most contractors quote per linear foot of wall underpinned:
- Standard underpinning (bench footing): $350–$450 per linear foot
- Full-depth underpinning (new footing poured to full height): $450–$550 per linear foot
- Waterproofing added at same time: add $80–$150 per linear foot
For a typical Toronto semi-detached with ~100 linear feet of perimeter, expect $35,000–$55,000 total. A detached with 130–150 linear feet runs $45,000–$75,000.
What drives the number beyond linear footage:
- Depth of underpinning — adding 2 feet costs less than adding 4 feet.
- Soil conditions — sandy or unstable soil needs more shoring and slower work.
- Basement access — if equipment can’t get inside, all work is done by hand. Adds time.
- Water table — if you hit water, pump and seal costs go up fast.
- Waterproofing — many homeowners combine underpinning with a full interior waterproofing system while the walls are open.
For a full cost breakdown on excavation in general, see our Toronto excavation cost guide.
How Long Does Underpinning Take?
A standard semi-detached in Toronto takes 6–10 weeks from permits to final inspection:
- Building permit: 3–6 weeks
- Structural engineering drawings: 2–3 weeks (often runs parallel to permit)
- On-site excavation and underpinning: 3–5 weeks depending on soil and depth
- Final concrete cure and inspection: 1–2 weeks
Start the permit early. The on-site work is the fast part.
Benching vs. Full Underpinning
Bench underpinning (also called a concrete bench or false step) widens the base of the footing inward rather than deepening it. It’s cheaper and faster but steals about 18–24 inches of floor space around the perimeter. If your basement is already small, full underpinning gives better results.
Full underpinning digs straight down and pours new footings at full depth. You keep the full floor area. This is what most Toronto homeowners choose for basement apartments and living space conversions.
Permits and Engineering
Every underpinning project in Toronto needs:
- A building permit from the City of Toronto
- Stamped structural engineering drawings
- A Party Wall Agreement with both neighbours on a semi-detached (City of Toronto requirement since 2021)
- Inspections at each stage: footing, framing, drain, final
OCM handles the excavation. Your structural engineer pulls the permit. We coordinate our schedule around the required inspections so there are no delays.
Ready to get a quote for your project?
OCM Excavation serves all of the GTA. We respond same day and provide free, no-obligation estimates.
📞 Call 416-317-3090 Request a Quote →Frequently Asked Questions
Does basement underpinning add home value in Toronto?
Yes. A legal basement apartment in Toronto can add $150,000–$250,000 in appraised value and generate $1,800–$2,500 per month in rental income. Underpinning cost is typically recovered at sale or within 3–5 years of rental income.
Can I live in my house during underpinning?
Usually yes, but the basement is off-limits for the full duration. Dust and noise are significant. Many homeowners arrange temporary accommodation for the 3–5 weeks of active work.
What happens if you hit rock or utilities?
Rock adds breaker time and cost — usually $150–$300 per hour. Utilities require relocation permits and add 1–2 weeks. We do a full Ontario One Call locate before any work and include a contingency clause in contracts for unforeseen subsurface conditions.
Is underpinning the same as waterproofing?
No, but they’re often done together. Underpinning lowers the floor depth; waterproofing stops moisture through the walls. Since underpinning opens up the wall-to-footing joint anyway, doing both at the same time avoids tearing open a finished basement later.
Does OCM do the full underpinning job or just excavation?
We do the excavation portion — soil removal, section-by-section digging, haul-off, and site prep. Concrete forming and pouring is handled by your concrete crew. We coordinate timing so our part and their part don’t overlap. Some homeowners use us as a single-source contractor and we hire the concrete sub.
Ready for an Underpinning Quote?
Call OCM Excavation at 416-317-3090 or request a free estimate online. We do on-site visits with no obligation — usually within 48 hours. Send us your address and the depth you’re targeting.
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2026 Excavation Cost Guide · Richmond Hill · Toronto · Vaughan · Markham
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