Underpinning Permits in Toronto: What You Actually Need

Underpinning a basement in Toronto requires a building permit, and the permit will not be issued without stamped structural drawings from a licensed Ontario engineer. Under the City's fee schedule effective January 1, 2026, underpinning is charged at $12.37 per linear metre of wall being underpinned, subject to a minimum building permit fee of $214.79 that applies to all work. For a typical Toronto house that lands between $400 and $900 to the City. Engineering typically adds $1,500 to $2,500.

The part that surprises people is not the cost. It is the wait. The Building Code gives the City 10 days to issue or refuse a permit for a house, and yet real approval runs 6 to 12 weeks. Understanding why those two numbers are both true is the single most useful thing on this page, because the gap between them is almost entirely inside your control.

What the permit package must contain

Stamped structural drawings. Prepared and sealed by a professional engineer licensed in Ontario. This is a design document, not a contractor sketch. It specifies footing depths, section widths and reinforcement.

The underpinning sequence plan. The specific order in which sections are excavated and poured, so the house is continuously supported. This sequence is the engineering, and it is why the work takes weeks rather than days.

Site and structural details showing existing conditions and proposed depths.

Agreement to staged inspections. Inspections happen during the work at defined stages, not only at completion.

The realistic timeline, end to end

Most quotes describe only the 4-6 week middle row. That is not dishonest, it is just the part the contractor controls, but it is why homeowners are repeatedly caught out by the real calendar.

The 10-day rule, and why your permit still takes three months

Ontario's Building Code sets a review window for a complete permit application. The Province's own guidance puts it plainly: the timeframe on a permit application for a house is 10 days, rising to 30 days for something complex like a hospital. Within that window the municipality must either issue the permit or refuse it and give its reasons.

So why does anyone wait three months?

Because the clock only runs on a complete application, and almost nobody submits one the first time. The 10 days is not a queue position. It is a review period that begins when your application meets the criteria set out in the Code, and an application that is missing a drawing, a calculation, or a signature has not started the clock at all. Every round of "please resubmit with X" puts you back at the start.

That reframes the whole problem. The wait is not the City being slow. The wait is the number of times your package goes back and forth, and that number is set by how complete the first submission is.

What actually makes an underpinning application incomplete

These are the recurring gaps that send an underpinning package back, in rough order of how often they come up:

• No sequencing plan, or a generic one. A drawing set that shows the finished condition but not the staged order of excavation and pour is the most common single omission. The sequence is the engineering.
• Depths that do not reconcile with the survey. Proposed underside-of-footing elevations that do not tie to existing grade and existing footing elevations.
• Missing shoring or excavation support details where the depth or the soil condition calls for them.
• Nothing addressing the neighbouring foundation on a semi-detached or row house, where the adjacent structure is affected by the excavation.
• Plumbing not included. Lowering a floor almost always means relocating drains below the new slab, and that is separate permitted work that is easiest to submit together.
• An unsealed drawing set. A drawing prepared by an engineer but not sealed is not a sealed drawing.
• Zoning conflicts surfaced late, most often where the lowered space is intended as a second suite and the proposal runs into a requirement the drawings never addressed.

Every item on that list is knowable before submission. That is the point: the 6-to-12-week reality is mostly a self-inflicted wound, and it is the one part of the timeline a homeowner can genuinely compress.

Semi-detached and row houses: the neighbour problem

On a semi or a row house the foundation you are underpinning is shared with, or immediately adjacent to, someone else's home. That changes the package. The drawings have to address what happens to the neighbouring foundation during excavation, and the sequencing becomes more constrained because you cannot open a section that undermines the party wall.

It also changes the human timeline. Access, notification and, in some cases, agreements with the neighbour sit outside the permit process but block the work just as effectively. Starting that conversation while the drawings are being prepared, rather than after the permit is issued, is what keeps the two tracks from running in series. Our semi-detached underpinning page goes into how the structural side differs.

Why the sequencing rule exists

The house does not stop being supported while its foundation is rebuilt. Underpinning works by excavating alternating sections, typically three to four feet wide, pouring each one, letting it cure, and only then moving to the adjacent section. The undisturbed sections carry the load while their neighbours are open.

Skipping or compressing that sequence is the failure mode that causes settlement, cracking and worse. It is also invisible to a homeowner watching from the top of the stairs, which is precisely why the sequence is specified on stamped drawings and verified by inspection.

What we do and do not do

We coordinate the permit process and work with licensed structural engineers who prepare and seal the drawings. We do not perform structural engineering ourselves and do not hold a professional engineering licence. The engineer's seal comes from the engineer, and their independence is a protection for you, not a formality.

Common questions