Toronto — City of Toronto Building Division
Basement Renovation & Underpinning in Toronto
Under most of old Toronto sits a six-foot-something basement with a rubble or block foundation and a floor that has never been level. We turn those spaces into the most-used level of the house — underpinned to full height, waterproofed from the outside, and finished to the same standard as the floors above.
Underpinning is where Toronto basements are won or lost. Our crews excavate and pour in staged sections under engineering supervision, taking a 6′3″ cellar in a Summerhill semi to a legitimate 9-foot lower level. Bench footings, new slabs with sub-floor insulation, sump and backwater valves — the invisible work is specified in writing before we quote a dollar.
The payoff is real square footage in a city where it costs more than almost anywhere in Canada: a screening room in Lawrence Park, a nanny suite in Bayview Village, or a rental unit near the Danforth that covers a chunk of the mortgage.
- Serving
- Forest Hill · The Bridle Path · Rosedale · Lawrence Park · The Beaches · Summerhill · Bayview Village
- Permits
- City of Toronto Building Division
- Response
- Within 24 hours
- Warranty
- 5-Year workmanship
Why Toronto trusts us below grade
Water rules everything down here. Toronto’s clay soils and hundred-year-old drainage mean we start every basement with exterior waterproofing, weeping tile and drainage-mat assessment — not paint-on promises. Where the City’s Basement Flooding Protection Subsidy applies, we complete the paperwork so you collect up to $3,400 toward backwater valves and sump installation.
We also build legal, not just beautiful. Second suites must meet Ontario Building Code requirements for ceiling height, egress windows, fire separation and sound — and Toronto requires the unit to be registered. Our drawings are prepared by designers who do this weekly, so inspections pass in sequence and your suite is rentable on paper, not just in practice.
Permits for basement work in Toronto
Any underpinning, structural alteration, new plumbing rough-in or second-suite conversion in Toronto needs a building permit from the City of Toronto Building Division; simple finishing without structural or plumbing changes generally does not. Review for a standard basement application usually runs two to three weeks, with underpinning drawings requiring stamped structural engineering.
Second suites bring additional zoning checks — minimum unit sizes, entrance location, parking — and older neighbourhoods like Rosedale can layer heritage considerations onto exterior stair or window changes. We run pre-application zoning reviews first, so surprises appear on paper rather than mid-dig.
Basements we have transformed in Toronto
- Summerhill
Nine-Foot Underpin
A 1911 semi taken from a 6′2″ cellar to a 9-foot lower level with a media lounge, wine room and heated herringbone floors — excavated in 14 engineered stages.
- The Beaches
Garden-Suite-Ready Rental
A registered two-bedroom second suite with separate side entrance, sound-isolated ceilings and its own laundry — appraised rental income of $2,600 per month.
- Forest Hill
Wellness Lower Level
Gym, infrared sauna and steam shower under an existing addition; structural steel let us remove two posts and open a 19-foot training floor.
Client Words — Toronto
“The underpinning schedule scared us until we watched them work — sections dug, poured and inspected like clockwork. Our basement is now the tallest ceiling in the house.”
“Dry through two spring storms that flooded half the street. Worth every dollar of the exterior waterproofing they insisted on.”
Frequently Asked Questions
Service Area — Toronto, Ontario
Start Your Toronto Project
Prefer to talk?
(647) 876-4070Site visits across Toronto within the week. Estimates are fixed-scope and itemized.
More in Toronto
Full Basement Renovation nearby
Building in Toronto?
Tell us what you are planning — we respond within one business day.