Nine Questions That Tell You a Good Underpinning Contractor From a Risky One

Price tells you almost nothing about whether a crew can underpin your house safely. These nine questions do, and the tells are in how fast and how specifically they answer, not in the answers being what you hoped.

Underpinning is the one renovation where the work is buried the day it finishes and you never see it again. You are not buying a kitchen you can inspect. You are buying a process you have to trust. So you interview for the process. Here is the interview.

1. "What section width does your engineer specify, and in what order do you pour?"

Ask this first, because it is the single most revealing question in the trade.

A crew that underpins regularly answers immediately and specifically: a width, usually in the three to four foot range, and a described alternating sequence so the house is never unsupported. Hesitation here is the biggest red flag there is. Someone who has to think about the sequence has not done enough of these, or is not the one who will be on site making the calls.

2. "How many underpinning projects have you finished in the last twelve months?"

Underpinning is not general contracting with a shovel. You want a crew that does this specific work repeatedly, not a renovation company that takes one on between kitchens. There is no magic number, but a specialist will have a ready, specific answer, and a generalist will round vaguely.

3. "Who is your engineer, and can I speak to them?"

The engineer's stamp carries professional liability, and a contractor with a standing engineering relationship names them without hesitation. Vagueness here, or a promise to sort out the engineer later, means the structural design is an afterthought on a structural job. Being able to speak to the engineer before you sign is a reasonable request and a good filter.

4. "Can I see a project you finished more than three years ago?"

Anyone can show you fresh work; fresh concrete always looks good. The proof of underpinning is a basement that is still dry and uncracked after several Toronto freeze-thaw cycles. A confident crew has references from years back and is happy to connect you.

5. "What happens if you hit water or unexpected soil?"

Nobody knows the ground for certain until they dig. The answer you want describes a process: stop, the engineer reviews, a revised approach, a priced change order you approve before work continues. The answer you do not want is a breezy reassurance that it will not happen, or worse, that they will just deal with it. Toronto soil varies street to street, and a mid-dig surprise handled without a paper trail is how budgets and trust both collapse.

6. "Is the permit in your scope, and whose name goes on it?"

Underpinning legally requires a City permit and stamped drawings. Two things to establish:

• A quote with no permit line is not a cheaper quote. It is a quote for work that cannot be legally inspected, and unpermitted structural work surfaces at resale, at insurance-claim time, and when a buyer's lawyer asks for closed permits.
• Whose name is on the permit matters. A permit pulled in your name rather than the contractor's shifts responsibility to you. That is sometimes legitimate, but you should know it is happening, not discover it later.

7. "What is your payment schedule, and will you accept a holdback tied to final inspection?"

Payment should follow progress, not run ahead of it. A healthy structure is a modest deposit, draws tied to completed sections rather than calendar dates, a draw at slab pour, and a holdback of around ten percent released after the final inspection passes.

8. "Is waterproofing in the quote, and what happens if I skip it?"

The foundation is exposed exactly once in the life of the house, during the underpinning. A good contractor raises waterproofing before you do, because they know doing it later means excavating the whole perimeter again at far greater cost. If waterproofing is not mentioned anywhere in the quote, that is not a saving, it is a decision being quietly left to future-you at full price.

9. "What is not included in this number?"

The most useful question you can ask, and the one that separates an honest quote from a low one. Make them say out loud what is excluded: waterproofing, the new slab, permits, engineering, restoration of the landscaping you dig through, the soil contingency. A contractor who itemises the exclusions without flinching is one who has nothing to hide in the gaps. One who says "everything's included" without detail is usually wrong, and you will find the exclusions in week three.

How to use the answers

You are not grading these like a test with right answers. You are listening for speed, specificity and comfort. The good crews answer fast, in detail, and without defensiveness, because they have had these conversations a hundred times. The risky ones hedge, round, and get a little irritated that you are asking.

Put the numbers side by side afterward with the quote comparison scorecard, because once you have normalised the scope, these nine answers are what actually decides who you hand the job to. The cheapest normalised quote from a crew that stumbled on question one is not the cheapest job. It is the most expensive lesson.

Common questions