The surface looks wrong, but the base is the story
A settled patio or a rippled driveway is easy to spot. What is harder to see is whether the contractor standing in front of you understands what caused it. Concrete pavers are durable enough to outlast most of the materials beneath them by decades. When they sink, tip, or separate, the failure is almost always in the granular base, the bedding sand, or the drainage that was supposed to carry water away from both. A contractor who talks first about the pavers has the diagnosis backwards.
Toronto's freeze-thaw cycle is one of the most demanding environments a hardscape base can face. A winter here can move through dozens of freeze and thaw cycles, and each one tests whether the base was compacted correctly, whether the granular material was the right grade, and whether water had somewhere to go before it turned to ice. The contractor you hire should be able to describe that mechanism without prompting, because it is the reason most of the work in this city exists.
This guide covers the questions worth asking, the answers worth trusting, and the signals that tell you to keep looking.
Freeze-thaw experience is not optional in Toronto
A contractor who learned the trade in a milder climate and relocated here is not automatically unqualified, but they need to have adapted. Frost heave in Toronto can lift a poorly prepared base several centimetres in a single winter. The fix is not to relay the pavers on top of the same base. The fix is to understand why the base moved, correct the drainage or compaction that allowed it, and then relay.
Ask any candidate directly: what do you do differently for a base repair in a freeze-thaw climate compared to a simple re-level? A contractor with genuine experience will talk about granular depth, proper compaction in lifts, and making sure water cannot pond against or under the base. They may mention geotextile fabric to separate the sub-base from native soil. They will not say the answer is a thicker layer of bedding sand.
If you are not sure what caused your surface to move, the post on why interlock sinks walks through the three most common mechanisms before you pick up the phone.
Ask about base compaction before anything else
Compaction is where most shortcuts happen, because the results are invisible until the following spring. A properly built granular base is placed and compacted in lifts, typically no deeper than about 100 mm at a time, with a plate compactor making multiple passes. Skipping lifts, using the wrong granular material, or compacting once at the end rather than in stages all produce a base that looks fine on installation day and begins to move within a year or two.
A contractor doing base repair on an existing surface faces an additional challenge: they are working in a confined area, often bordered by structures or plantings, and they need to achieve the same compaction quality as a new installation. Ask how they handle that. Ask what equipment they bring. A plate compactor should be on the list. Hand tamping alone is not sufficient for anything beyond a very small patch.
- What granular material do you use for the sub-base, and what depth do you specify?
- How many lifts do you compact, and what equipment do you use?
- Do you use a geotextile fabric between the sub-base and native soil?
- How do you handle drainage before you close the surface back up?
- What do you do if you find soft or unstable soil below the existing base?
These are not trick questions. A contractor who has done this work in Toronto for more than a couple of seasons will answer them without hesitation.
A good contractor measures before quoting
The scope of an interlock repair is not obvious from a photograph or a quick walk across the surface. Settlement spreads. What looks like a 1.5-metre problem at the low point often has another metre or two of compromised base extending in each direction. A contractor who quotes without a string line or a level is guessing, and that guess tends to grow into a change order once the pavers come up.
Toronto Interlock Repair uses a string line to measure the extent of any settled area before a number is put on paper. That step takes ten minutes and changes the accuracy of the quote significantly. Ask any contractor you are evaluating how they determine where the repair begins and ends. If the answer is visual inspection alone, that is worth noting.
Honest scoping also means telling you when the work is not worth doing yet. A settled area smaller than roughly a square metre, with no trip hazard and no water pooling against a structure, is rarely worth a call-out on its own. A contractor who pushes for immediate action on a surface that has years left in it is not working in your interest.
For a sense of what repair work typically costs before you start collecting quotes, the re-levelling cost page breaks down what moves the number.
Drainage and edge restraint: the two things often skipped
Most recurring interlock problems in Toronto trace back to one of two omissions: water arriving where it should not, or a perimeter with no edge restraint holding the field together. A contractor who repairs the settled area without addressing either one is handing you the same job in three years.
Edge restraint is the plastic or metal spike edging that runs along the perimeter of an interlock surface and keeps the border course from spreading outward under load. When it is absent or has pulled free, the field loses its confinement and pavers begin to migrate. Edge restraint repair is often a small addition to a re-levelling job, but it changes the longevity of the repair considerably.
Drainage is the larger conversation. If water is pooling on or against your surface, the grade may need correction, a channel drain may need to be added, or the swale directing water away from the area may have silted up. Ask any contractor whether they check the grade as part of their assessment. If they do not, pooling water will continue to wash fines out of the base and the cycle repeats. The pooling water page covers the most common causes if you want to understand what you are looking at before the conversation.
Before you sign: practical checks that matter
Once you have had the technical conversation and the quote is in front of you, a few practical checks are worth completing before you commit.
- Confirm the contractor carries liability insurance and can provide a certificate. Hardscape work involves excavation, and excavation carries risk.
- Ask whether they will contact Ontario One Call before any digging begins. This is a legal requirement in Ontario, not a courtesy. A contractor who is unfamiliar with the process is not set up to work safely on your property.
- Ask for a written scope of work, not just a total price. The document should describe what comes up, what goes back, what base work is included, and how the joints will be finished.
- Ask how joint sand is handled at the end of the job. Polymeric sand applied correctly locks the joints and resists washout. Applied incorrectly or over a damp surface, it fails within a season. Polymeric sand is a finishing step that matters as much as the base work beneath it.
- Get at least two quotes. Not because the lowest number wins, but because the conversation with a second contractor often reveals something the first one did not mention.
If the surface you are evaluating includes a retaining wall, the hiring conversation gets a layer more complex. Most municipalities set a threshold near a metre, above which a wall becomes an engineered structure requiring drawings and potentially a permit. Your municipal building department sets that threshold, not the province. A contractor quoting wall work should know to ask about height and should not tell you a permit is definitely not required. The wall rebuilding page covers when that conversation becomes necessary.
Toronto Interlock Repair works across the city and the surrounding area. The frequently asked questions page covers the questions that come up most often before a job starts, and the contact page is the right place to start if you want a scope and quote for your surface.
The short version: hire for the base, not the surface
The contractor who earns the work is the one who talks about what is under your pavers before they talk about the pavers themselves. They will ask about drainage. They will use a level or a string line before they quote. They will mention Ontario One Call if excavation is involved. They will tell you if the surface has years left in it rather than pushing for a repair it does not need yet.
Concrete pavers are not the problem. They almost never are. The base beneath them, the water moving through it, and the edge holding it together are where the work happens. A contractor who understands that is worth the time it takes to find them.
If you want to understand more about what a repair involves before the first conversation, the re-levelling service page and the repair cost overview are good places to start.