Living Through an Underpinning: What Three Months Is Actually Like

Every contractor will tell you underpinning takes four to six weeks. That is the time the crew is on site. The part nobody describes is what your house is like during those weeks, and whether you can stay in it.

Some households can. Some genuinely cannot, and it is far better to know that before signing than in week three. Here is the honest version.

The noise

Underpinning starts by breaking the existing basement slab and then excavating beneath the footing. That is jackhammer work, and it happens most days of the excavation phase.

• It is loud in the way that carries through structure, not just through air. Closing a door upstairs does very little. It comes through the joists.
• It runs on the crew's schedule, typically weekday mornings through mid-afternoon. Toronto's noise by-law restricts construction hours, so evenings and Sundays are generally quiet, but that is small comfort if you work from home.
• It is not constant. There are pour days and cure days that are relatively quiet. But you cannot plan a call around it, because the day it is quiet is not knowable in advance.

If you work from home and take calls, assume you will need somewhere else to do that for several weeks. This is the single most common thing people underestimate.

The dust

Concrete dust is very fine and it finds everything.

A competent crew will hang poly barriers, seal the basement stairwell, run negative air, and keep the work zone contained. Do that and you will still get fine grey dust upstairs. Not a disaster, but a persistent film on horizontal surfaces for the duration.

What actually helps:

• Move anything you care about out of the basement completely, not to one side of it
• Ask for the stairwell to be sealed with a zippered door, not a taped sheet
• Change your furnace filter during and after, and consider a temporary filter over cold air returns in the work zone
• Cover soft furnishings on the ground floor if the stair is open to a living space
• Accept that you will clean afterward. Budget for a deep clean at the end; it is a small line against the project

The soil

A typical whole-basement underpinning removes a large volume of soil, and it has to leave the property.

On a detached house with a driveway and side access, a bin sits outside and a machine or wheelbarrow route handles it. On a downtown semi or row house with no side yard, every wheelbarrow comes out through your house or through the front door. That is slower, more expensive, and considerably more present in your daily life.

Expect a bin on the street or driveway for extended periods, which in some Toronto neighbourhoods requires a permit, and expect the route the soil takes to be protected with hardboard and poly.

The services

Your basement contains the furnace, the water heater, the electrical panel, the water shut-off and often the laundry. All of that has to keep working, or be planned around.

• Furnace and water heater generally stay running. They may need temporary protection or short interruptions when the slab beneath them is worked on.
• Laundry is frequently out of service for part of the project.
• The electrical panel stays live but access to it becomes awkward.
• Plumbing under the slab is usually replaced or rerouted as part of the work, which means planned water shut-offs. Ask for these to be scheduled rather than announced.

The real timeline

This is where the four-to-six-week figure misleads people. That number is the excavation and pouring phase only.

The permit review is the longest single item and it is entirely outside your contractor's control. A contractor who quotes you a total timeline without asking when you plan to submit has not thought about it.

Should you move out?

There is no universal answer, but the pattern is fairly consistent.

Staying usually works when: the house has more than one floor above grade, nobody works from home during the day, there are no infants or shift workers, and the basement stair is behind a door.

Moving out is usually the right call when: someone takes calls from home all day, there is a newborn or a night-shift worker, someone in the house has a respiratory condition, or the house is small enough that the basement stair opens into the main living space.

The middle option most people actually take is staying, and leaving during the day for the six or so weeks of jackhammering. A daytime workspace elsewhere is far cheaper than short-term accommodation and solves most of the problem.

If you do plan to move out, note that the expensive weeks are the excavation phase, not the whole three to six months. You do not need alternative accommodation during permit review.

How to tell the work is being done properly

You do not need to be an engineer to spot the things that matter.

• Sections, not a trench. At no point should a long continuous stretch of foundation be open beneath the footing. Work proceeds in discrete sections in a specified alternating order. If you look down and see one wall fully undermined, stop the work and call the engineer.
• The sequence matches the drawings. You are entitled to a copy of the stamped drawings. The section widths and order are on them.
• Inspections are happening in stages, not just at the end. Ask when each inspection is booked.
• Concrete reaches the underside of the existing footing. Dry packing or an equivalent specified method closes the gap between the new pour and the old footing. That gap is the entire point of the exercise; a section that leaves a void has not done its job.
• Cure time is respected between adjacent sections rather than compressed to hit a date.
• The site gets cleaned each day, which is a decent proxy for how the rest of the work is being done.

What to do before day one

• Empty the basement entirely, including anything on shelves and anything you have not looked at in a decade
• Photograph the basement, the adjoining property if you share a wall, and any existing cracks anywhere in the house, with dates
• Confirm where the bin goes and whether a street permit is needed
• Confirm the working hours in writing
• Tell your neighbours, specifically and in advance, including the expected weeks and the noisy phase
• Arrange a daytime workspace if you work from home
• Confirm dust protection and final cleaning are in the scope
• Ask for the inspection schedule and the stamped drawings

Common questions