Basement Underpinning
in Toronto & the GTA

Basement Underpinning in Toronto: What Homeowners Need to Know

Underpinning means building new footings under the ones your house already stands on. The City of Toronto describes it as increasing the depth of an existing foundation. People do it to get more headroom in the basement, to reinforce a foundation, or to add an entrance below grade.

This guide covers what the City asks for, how the work runs on site, what changes the cost and what to ask before you hire anyone. Manpower Demolition underpins and lowers basements across Toronto and the GTA from our base in Vaughan.

Is Your Basement a Good Candidate?

Underpinning is worth looking at when:

• The ceiling is too low to use. You duck under ducts and beams, and the room only works for storage.
• You want a legal basement unit. Ontario sets a minimum ceiling height for a basement second unit (see below), and a basement can meet it bare and fall short once it’s finished.
• The foundation needs to go deeper or get stronger, for example before a renovation that depends on it. An engineer decides whether underpinning is the right fix.
• You want a separate entrance below grade, such as a walkout or a side door with stairs down.

It may not be the answer when you only need a little height and can give up floor space along the walls (a bench footing can do that), or when the real problem is water coming in. Cracks can have more than one cause, so have them assessed before you choose a fix.

Your Options for a Deeper Basement

Underpinning. The crew digs under the existing footing in short sections and pours a new, deeper footing and wall beneath it, one section at a time, in the order shown on the drawings. You keep the full floor area at the new level.

Bench footing. The old footing stays where it is, and a concrete ledge (the bench) is poured around the inside of the walls at the new floor level. It’s simpler, but the bench takes floor space along every wall it runs. We compare the two in detail in benching vs underpinning.

A mix of both. Some projects underpin the walls where a bedroom or a walkout needs full height and bench the walls that will end up behind storage. The engineer decides wall by wall.

Lowering the slab only. If the existing footings already sit deep enough below the new floor level, the engineer may allow a lower slab without touching the footings. Only the engineer can make that call.

Piles (helical piles, for example) are another way to support a foundation, usually chosen for settlement or poor soil. That’s specialist foundation repair, and it isn’t covered here.

How Much Height Can You Gain?

There’s no standard number. The depth depends on how deep the existing footings sit, the soil, the neighbour’s foundation and what the engineer designs.

What counts is the finished height. Once the new slab, insulation, flooring and a ceiling go in, the clear height shrinks, and ducts and beams take more. Measure from the finished floor to the finished ceiling, not from bare concrete to the joists.

The rule for a legal basement unit. Ontario’s guide to second units says a basement unit can have a ceiling height of 1.95 m (6’ 4¾”) over the entire required floor area, including the route inside the unit to the exit. If a basement apartment is the goal, design the depth around that figure from the start.

Toronto Underpinning Permits, Step by Step

Underpinning needs a building permit in Toronto. Here’s what the City’s residential underpinning guide asks for.

1. Drawings. Drawn to scale, fully dimensioned, signed, dated and submitted as PDFs:

• A survey or site plan with property lines, the building and its distance to the property lines and to the buildings next door.
• A basement or foundation plan showing where you’ll underpin, the support columns and framing above, the stages of work numbered in sequence, and the total linear metres of underpinning.
• Floor plans showing how every space is used, with smoke alarms, carbon monoxide detectors and plumbing fixtures.
• Cross sections showing the footing and wall details, floor-to-ceiling heights, stairs and guards, and how deep the underpinning goes.

2. Who prepares them. A designer registered under the Ontario Building Code (their name, registration number and qualification number go on the drawings) or a Professional Engineer. When an engineer seals the drawings, they also sign the City’s Assumption of Responsibility for Engineering Content form.

3. When an engineer must design and review it on site. The City requires professional design and field review, with a signed Commitment to General Reviews form, when any of these apply:

• The new footing goes below the level of a neighbouring building’s footing and inside the soil’s angle of repose. That’s the steepest slope at which the soil stays stable. Dig inside it next to a neighbour’s footing and their foundation can move too.
• The underpinning is more than 1,200 mm of laterally unsupported height.
• The soil is clay or silt.

4. Testing on every job. Even when an engineer doesn’t have to design the work, the City requires testing and reports by a Professional Engineer during the first and last stages of construction before the work passes inspection.

5. Other forms. The Application to Construct or Demolish, Schedule 1 (designer information), a Tree Declaration if private or City trees could be damaged, and a Rental Renovation Licence Screening Form, which tells the City whether the work also needs a rental renovation licence because the unit is rented.

6. Applying and timing. You apply online through Toronto Building’s submission tool. Underpinning and basement walkouts can go through the City’s Express stream when the house has no more than two units and no active permit for a new house or an addition. An examiner reviews a complete application within 3 days, and the permit is usually issued within one business day after the fee is paid. Missing documents send the application back. Outside the Express stream, a complete application for a house is reviewed within 10 business days.

7. The fee. For 2026 the City charges $12.37 per linear metre of underpinning, with a minimum fee of $214.79. A house about 6 by 12 metres has roughly 36 metres of foundation wall. Underpinning all of it would mean a permit fee of about $445.

Semi-Detached and Row Houses

In a semi or a row house, the neighbour’s footing sits right against yours, so the engineer rule above is likely to apply. The City’s Express stream accepts work that affects a party wall, with extra submission requirements.

Talk to the neighbours before the drawings are final. They will hear and feel the work, and their foundation is part of the design.

How Underpinning Runs on Site

1. Clear out and protect. The basement is emptied, and the finishes, drywall, flooring and old concrete slab come out. That part is demolition, which is our crews’ everyday work: see selective demolition. The rest of the house is sealed off from dust, and the debris is sorted and hauled away.
2. Move what’s in the way. A furnace, water heater, electrical panel or plumbing that sits in the work area may have to be moved or supported. Plan this with your HVAC and plumbing trades before the start date.
3. Dig in stages. Soil comes out, then the sections under the footing are dug one at a time, in the numbered order on the drawings. Each new footing and wall section is poured and left to cure before the section next to it is opened, so two neighbouring sections are never open at the same time.
4. Testing and inspections. The engineer tests and reports during the first and last stages, and the City inspects.
5. Drainage. A new drain runs around the perimeter at the new floor level and leads to a sump pit and pump. A backwater valve may go in at the same time.
6. New floor. The new concrete slab is poured at the lowered level.
7. Clean-up. The site is left clean under our “No Nail Left Behind” promise, ready for the trades who finish the space.

Plan the way out early. Every bucket of soil and broken concrete leaves through a basement window, a door or a new opening, and that route sets the pace of the dig.

Waterproof While the Floor Is Open

With the slab out, everything under it is easy to reach. It’s the natural moment to add a perimeter drain, a sump pump or a backwater valve, and it’s far more work to do later under a finished floor. We do basement waterproofing alongside underpinning, from interior and exterior systems to sump pumps.

Toronto’s Basement Flooding Protection Subsidy. Since 1 May 2026, the City pays up to $6,650 per property for eligible work completed on or after 12 November 2025:

• 80 % of a home plumbing assessment, up to $500.
• 80 % of a backwater valve and alarm, up to $1,600 each (two devices at most).
• 80 % of a sump pump and alarm, up to $2,250, plus up to $300 for a battery backup.
• 80 % of severing and capping the weeping tile connection to the City sewer, up to $400.

You must be the registered owner of a single-family home, duplex, triplex or fourplex in Toronto, your downspouts must be disconnected from the sewer, and you apply within two years of the work. Every contractor and subcontractor who installs the devices needs a valid City of Toronto business licence at the time, and you submit their original invoices. Check your property’s subsidy history with the City (416-338-7668) before you plan around it.

Asbestos and Other Old Materials

Older basements can hold asbestos in pipe wrap, floor tiles or insulation, and lead in old paint. Under Ontario’s Occupational Health and Safety Act, the owner has to find out which designated substances are in the building before the work is tendered. If the survey finds any, they’re removed before the digging starts. See our abatement service.

Can You Stay in the House?

That depends on where your furnace, water heater and laundry sit, and on how much noise and dust your household can live with. Expect the basement to be off limits, noise and vibration while concrete is broken and soil comes out, and short breaks in heat or hot water if equipment has to move.

Toronto allows construction noise Monday to Friday from 7 a.m. to 7 p.m. and Saturday from 9 a.m. to 7 p.m. It isn’t allowed on Sundays or statutory holidays unless the City grants a noise exemption permit.

How Long Does Underpinning Take?

Ask for a written schedule before you sign. These are the things that set it:

• The permit stream: Express (examiner review within 3 days) or the regular house stream (10 business days).
• How many metres of wall you’re underpinning, and how deep.
• The soil, and whether the engineer’s design calls for extra steps.
• How many stages the drawings show, since each section has to cure before the one next to it opens.
• Engineer testing and City inspections.
• Weather, if any digging happens outside, such as a walkout.

Finishing the space (framing, electrical, drywall) is a separate project that starts after the structural work passes inspection.

What Drives the Cost

The biggest factors are how deep you go and how many linear metres of wall get underpinned. After that:

• Clay or silt soil, which brings in professional design and field review.
• A neighbouring footing inside the angle of repose, which needs an engineered design.
• How much soil and concrete has to come out, and how easily it can leave the site.
• A furnace, water heater, panel or plumbing that has to move.
• Drainage and waterproofing: a perimeter drain, sump pump or backwater valve.
• Drawings, site reviews, testing and the City fee.
• Asbestos or lead that has to come out first.
• A walkout or a new entrance.

Compare quotes on the same scope. A quote that leaves out engineering, the permit, drainage or the new slab covers less work, so of course it looks lower. We quote after a site visit, and you get a detailed estimate within 24 to 48 hours of the assessment.

Questions to Ask Any Underpinning Contractor

• Who prepares the drawings, and who is the engineer?
• Who applies for the permit, and through which stream?
• Who pays for the engineer’s site reviews and testing?
• What’s included: strip-out, soil disposal, drainage, sump pump, new slab, waterproofing, clean-up?
• How will the rest of the house be protected from dust?
• What’s the schedule, and in what order will the sections be dug?
• How will the neighbours be informed?

Also call your home insurer before the work starts and ask whether anything about your policy changes during construction.

Common Mistakes

• Starting without a permit. Unpermitted structural work can cause problems when you sell, refinance or insure the house.
• Opening too many sections at once. The numbered sequence is what keeps the house supported while the footings are dug out.
• Forgetting the neighbour, whose foundation is part of your project in a semi or a row house.
• Leaving drainage for later, when it means breaking up a finished floor.
• Measuring the height to the joists instead of to the finished ceiling.

Underpinning Across the GTA

We also underpin basements in Mississauga, Vaughan, Brampton, Oakville and the rest of the GTA. Each city runs its own building permits, so the forms, fees and review times differ from Toronto’s. In Mississauga, for example, permits go through the City’s ePlans portal: see our Mississauga page.

Basement Underpinning Questions

Do I need a permit to underpin my basement in Toronto?

Yes. Underpinning needs a building permit. For a house with up to two units, it can usually go through the City’s Express stream, where an examiner reviews a complete application within 3 days.

Do I need an engineer for underpinning?

Toronto requires engineer testing and reports during the first and last stages of every underpinning job. A full engineered design with site reviews is required when the work goes below a neighbour’s footing inside the angle of repose, when it’s more than 1,200 mm of unsupported height, or when the soil is clay or silt.

How much is the underpinning permit fee in Toronto?

For 2026 the City charges $12.37 per linear metre of underpinning, with a minimum fee of $214.79.

Can I add a basement walkout at the same time?

Yes. A new basement entrance needs a building permit, and Toronto’s guide for basement entrances asks for drawings that show the underpinning beside the entrance with each stage numbered, plus the stairs, landings, guards and handrails. Walkouts and underpinning can go through the City’s Express stream when the house has no more than two units. Digging outside also means calling Ontario One Call (1-800-400-2255) first so buried lines are marked.

How long does basement underpinning take?

It depends on the permit stream, the metres of wall, the depth, the soil, the number of stages and the inspections. Ask for a written schedule before you sign.

Is underpinning worth it?

It is when you need full-height space across the whole floor, for example a legal basement unit, which needs 1.95 m (6’ 4¾”) over its required floor area. If you only need a little height and can give up floor space along the walls, a bench footing may do the job.

Can you underpin a semi-detached or row house?

Yes. Because the neighbour’s footing is right there, expect an engineered design and site reviews. Toronto’s Express stream accepts party wall work with extra submission requirements.

Can I live in my house during underpinning?

It depends on whether your heating, hot water and laundry can keep running or be moved around the work. Either way, expect noise, dust and a basement you can’t use.

What’s the difference between underpinning and benching?

Underpinning builds new footings under the existing foundation and keeps the full floor area. Benching leaves the foundation in place and adds a concrete ledge inside the walls. See benching vs underpinning.

Does Toronto help pay for waterproofing during underpinning?

The Basement Flooding Protection Subsidy pays up to $6,650 per property for a plumbing assessment, backwater valves, a sump pump and battery backup, and weeping tile disconnection, if you meet the City’s conditions.

Do you waterproof basements too?

Yes. Basement waterproofing is one of the services we provide alongside underpinning and crack repair.

How quickly can I get an estimate?

Within 24 to 48 hours after we complete our assessment. Submit a form or call (905) 597-8333.