Why interlock fails between November and April
Most of the interlock that fails in the GTA does not fail in summer. It fails between late November and the second week of April, and you only see it in the spring when the ground finishes moving for the year.
The mechanism is freeze-thaw and water. Toronto’s native soil is mostly clay and silty clay, which holds a lot of water and shrinks-and-swells more than sandy soils when it freezes. When water in the sub-base freezes, it expands by about 9 percent, lifting whatever is sitting on top of it. When the ice melts, the lifted material does not go all the way back down — sand washes sideways, fines migrate, water pockets form, and a paver that was perfectly level in October can be sitting half an inch higher (or lower) than its neighbour by April. Repeat that for 100 freeze-thaw cycles and the cumulative damage looks like waves, sunken corners, edges that no longer line up, and joints that gulp water every time it rains.
The damage is rarely uniform. You will usually see one or two zones — the apron near the garage, the low corner that drains the rest of the driveway, the strip along a downspout discharge — that took the brunt of it while the rest of the surface looks fine. That uneven failure pattern matters because it changes what you actually need to do about it.
The four common spring failure modes you’ll see this week
Spring driveway walks fall into four buckets and each one has a different fix.
The first is joint failure. Joints are washed out, polymeric sand has cracked or sunk well below the chamfer, weeds and ants are establishing, and the surface looks tired but the paver elevations are still mostly correct. This is the easiest fix and the one most homeowners over-pay for. The companion topic GTA Polymeric Sand Refresh Spring 2026: When Interlock Joints Need Topping Up, How It’s Done Right, and Real Costs covers the joint refresh in detail.
The second is localized settling. A small zone — usually less than 50 square feet — has dropped below the surrounding pavers. Often this is over a utility trench (gas line, water service, abandoned downspout drain) where the original installer did not properly compact the trench backfill, or where a downspout discharge has slowly washed fines out of the sub-base for years. The fix here is a partial lift and relay over a re-prepped section.
The third is frost heave. Pavers are sitting noticeably higher than the surrounding surface, often along the edges or near the structure where the slab transitions to drier soil under the foundation. Heave usually unwinds at least partially through the summer, but if pavers are still sitting proud by mid-June you have either a base that is too shallow for the freeze depth or trapped water that never had a way out. The fix may be cosmetic if the heave settles back down, but if it persists you are looking at a partial lift with drainage correction.
The fourth is base failure. The pavers themselves are intact, but the surface is wavy across a large area, edges have rotated outward, and you can hear the pavers chatter as you walk on them. This is what happens when the original 12-inch compacted granular base was actually six inches of dumped pea gravel, or when the original installer skipped the geotextile separator over clay subgrade. Base failure is not repairable in place — it requires a full lift and rebuild of the affected section, and at that point the conversation is whether to do the whole driveway or just the failed half.
Distinguishing surface fixes from base failures
The single most common spring quote pattern in the GTA is a contractor walking the driveway, pointing at sunken pavers, and quoting a full lift-and-relay when what is actually needed is a 60-square-foot partial. The reverse also happens — a homeowner pays for joint sand and a few reset pavers, and is back to the same problem in two years because the underlying base was the issue.
The diagnostic that separates them is simple but underused: probe the joints with a long screwdriver in three or four spots across the failed zone. If the screwdriver bottoms out at less than 8 inches of resistance, the base is too thin and you have a base problem regardless of what the surface looks like. If it bottoms out at 12 inches or more of solid compacted granular, you have a surface problem and a partial relay will hold.
Walk the surface barefoot or in soft shoes. Live unevenness you can feel through your feet is meaningful — pavers that pop or rock under weight are sitting on voids, which means either the bedding sand is gone (relay) or the granular base has migrated (base rebuild). Cosmetic unevenness you can only see at low sun angles is usually a relay candidate.
Look at the joints themselves. Joint width that has stretched from the original 1/8 inch to 3/8 inch or more across multiple joints in a row is a sign that the pavers have rotated outward — that is base failure or edge restraint failure, not a surface fix.
Real spring 2026 GTA repair costs
Numbers below are for a typical Toronto-area residential driveway, in the 400 to 700 square foot range, with reasonable access. Heritage neighbourhoods with limited side access, or driveways with retaining walls and stairs, will sit at the upper end of these bands.
Joint refresh only, polymeric sand replacement on the full surface, no paver removal: $700 to $1,800 for a single-car driveway, $1,400 to $3,200 for a double-car. The wide range reflects whether the surface is pre-cleaned (pressure-washing alone is $300 to $600) and whether old polymeric is dug out properly or just topped over.
Localized lift and relay, less than 50 square feet, no base rebuild: $500 to $1,800 for the affected zone, depending on how clean the lift is and whether matching pavers are available. Expect $30 to $45 per square foot for partial relays — higher than new install per-foot because the labour is not amortized over a large area.
Partial lift with base rebuild, 50 to 200 square feet of sub-base re-excavated and re-compacted: $1,800 to $5,500. This is the sweet-spot fix for most localized settling and trench-related failures. The cost driver is excavation and disposal of the failed base, not the re-laying of the pavers themselves.
Full driveway lift and relay, all pavers picked up, base rebuilt, pavers re-laid with new bedding sand and new polymeric: $9 to $14 per square foot for the typical GTA driveway when the existing pavers are reusable. Roughly 35 to 50 percent of new-install pricing. This is the right call when more than a third of the surface is failing and the existing pavers are still in good shape.
Edge restraint replacement (Snap-Edge or equivalent steel/aluminum spike-down) on a perimeter that has rotated outward: $9 to $16 per linear foot, almost always packaged with a partial relay because removing the perimeter pavers is required.
Individual paver replacement for cracked or stained units: $35 to $90 per stone if the contractor is already on site for other work, $150 to $300 minimum trip charge if they are not.
For comparison: a brand-new GTA interlock driveway runs roughly $24 to $45 per square foot for a fully engineered installation with the proper 12 to 14 inches of compacted granular base, geotextile separator, 1 inch of coarse angular bedding sand, and polymeric sand joints. The Pickering driveway case study at Interlock Driveway Installed in Pickering: 12-inch Base, Unilock Beacon Hill, Full Cost and 2-Year Update walks through the spec for a real install.
The base re-prep nobody mentions in repair quotes
When a quote comes in for a partial lift with base rebuild and the contractor has not asked you about the soil conditions, drainage, or what you saw underneath the pavers when they were lifted, treat that as a yellow flag. The reason a section settled in the first place is the part of the job that needs the most attention.
A proper base re-prep on a partial lift looks like this. The pavers come up and are stacked on a clean tarp in the same orientation pattern they came out so they can go back in matched. The bedding sand is fully removed — not just brushed off the granular base, removed. Failed granular is excavated to the depth of the original specification, which in Ontario for a driveway should be 10 to 12 inches of compacted Granular A or a Granular B / Granular A combination. If the original installer used trench fill or pit-run as the base, that comes out and gets replaced with proper road-grade granular. A geotextile separator goes on the clay subgrade if the original install missed it — without that separator, fines from the clay migrate up into the granular every freeze-thaw cycle until the base loses its compaction.
The base goes back in lifts of 3 to 4 inches and gets compacted between each lift with a plate compactor — a single pass at the end of a 12-inch dump does not compact the lower portion, and that is exactly how soft spots get baked into a “rebuilt” section. New 1-inch coarse angular bedding sand goes on top, screeded flat, and the pavers are re-laid in the original pattern. New polymeric goes in the joints, edge restraints get reinstalled or replaced.
A contractor who quotes a partial relay without specifying granular depth, compaction lifts, or geotextile is selling you the appearance of a fix.
Spring 2026 GTA contractor red flags
The reno-economy in the GTA has been busy this spring and the door-knocker pattern is heavy. A few things that usually mean walk away.
A spring quote that arrives on the same day a contractor knocks on your door, with no questions about how long the driveway has been settling and no probe-test of the existing base. The walk-up sales pattern peaks in April and May and is very rarely the right contractor.
A quote that lumps “full driveway repair” into a single line item without breaking out base rebuild square footage, paver count, polymeric sand brand, edge restraint type, and disposal fees. You cannot compare two quotes that are not itemized the same way, and you cannot enforce the spec at the end of the job.
A quote that is significantly cheaper than the rest because the contractor is “already in the area” or “has leftover material from another job.” Leftover material usually means a different paver run with a different colour batch, and the colour mismatch will be visible from the street for the next 25 years.
A contractor who refuses to put the base specification in writing. The whole point of a real repair is the base. If the spec is not in the contract, the spec is whatever they decide to do that day.
A contractor who proposes a polymeric sand topcoat over a joint that still has functional polymeric below the surface. That is not how polymeric chemistry works — fresh polymeric needs to bond to clean granular sand below it, not to the cured top of the existing joint, or it will lift off in sheets within two seasons.
When to repair vs when to just replace
Repair makes sense when the existing pavers are 80 percent intact, the base is salvageable in most of the area, and the colour is not so faded that a partial relay will look like a patchwork. Most GTA driveways under 15 years old fall in this band.
Replacement makes sense when more than half the surface needs base rebuild, when the original install used a paver line that has been discontinued (relay matching is impossible), or when the homeowner is already going to be re-grading the property for drainage or adding a side walkway. Replacement is also the right call when the existing paver thickness is 60mm — that is a pedestrian-grade thickness used by some early-2000s budget installs and it is not built to handle modern vehicle weights, especially with full-size SUVs and EV curb weights.
A full replacement on an 18-year-old driveway that still has 60mm pavers is not a repair conversation, it is a re-spec conversation. The right answer is 80mm vehicular-grade pavers, a 12-inch Granular A/B base, geotextile, and a real edge restraint. That puts the new install in the 25-to-30-year range with normal maintenance.
Bottom line
If your interlock driveway is sitting unevenly this spring, the diagnostic comes before the quote. Walk it, probe the joints with a screwdriver, look at how the failure is distributed, and figure out whether you have a joint problem, a localized settling problem, or a base failure. The right fix and the right cost follow from that.
Quotes for partial lift-and-relay should specify base granular depth, compaction lifts, geotextile, polymeric sand brand, and edge restraint type. Quotes that do not are quoting cosmetics, not repair. Spring is the right time to make this decision — get the lift-and-relay done before mid-July when contractors get into peak install season and pricing climbs.
Track $RENO earnings on this topic — top contributors at the homeowner-and-trades intersection are tier-up candidates. If you have an interlock driveway that survived this winter (or one that did not), the case study and photo posts that come back from these threads are the highest-signal $RENO earners on the forum. Welcome to $RENO — Quests, Rewards, Leaderboard is the starting point. Link a Solana wallet on signup to claim earnings when on-chain settlement opens.
LF Builders has been repairing and installing interlock driveways across the GTA for over 50 years — request a quote at lfbuilders.ca. LF Builders supports Samm Simon’s 251 km charity run for cancer research.