A sunken slab doesn’t happen overnight. It’s usually the end result of months, sometimes years, of soil movement happening quietly underneath your feet. Then one day you notice the step down at your garage entry is deeper than it used to be, or your patio has started pooling water instead of draining it away. That gap between the slab and the ground below is the real story, and it’s exactly what concrete lifting is built to fix.
If you’ve searched around Edmonton or Calgary for a way to deal with a settled walkway, driveway, or garage floor without tearing everything out, you’ve probably run into two competing ideas: mudjacking (pumping a cement-based slurry under the slab) and polyurethane foam lifting. Poly-Mor works with the polyurethane method, and for good reason. It’s faster, lighter, and far less disruptive to your property. You can read the full rundown on our slab lifting service page, but this article walks through the mechanics of how it actually works and why it’s become the go-to fix for concrete slab lifting across Alberta.
Concrete itself rarely fails on its own. What fails is the ground underneath it. Freeze-thaw cycles are the biggest culprit in this part of the country. Water gets into the soil beneath a slab, freezes, expands, and pushes things around. When it thaws, the soil doesn’t always settle back the way it started. Add in poor compaction during original construction, tree roots pulling moisture from the soil, or a leaking downspout dumping water in one spot for years, and you get voids. Air pockets. Loose, unsupported ground under a slab that used to be fully supported.
Once that support disappears, gravity does the rest. The slab doesn’t crack because it’s weak. It cracks or tilts because it’s resting on nothing.
The process is more precise than people expect. A technician drills a series of small holes, usually around the diameter of a coin, through the sunken sections of the slab. Through those holes, a two-component polyurethane resin gets injected under pressure. The two parts react chemically the moment they mix, expanding within seconds and filling the voids beneath the slab.
As the foam expands, it does two things at once. It fills the empty space where soil used to be, and it applies gentle upward pressure that raises the slab back toward its original position. Technicians control this closely, watching the slab in real time and adjusting injection points until the panel is level again. The holes get patched, and in most cases the area is ready for foot traffic within an hour or two.
Compare that to mudjacking, where a heavy slurry mix is pumped in through larger holes. It works, but it adds significant weight to already-compromised soil, takes days to cure fully, and leaves bigger holes to patch. Polyurethane foam, by contrast, weighs only a few pounds per cubic foot. It’s not adding a new load problem while solving the old one.
Take a fairly typical scenario: a homeowner in a mature Edmonton neighbourhood notices their front walkway has dropped almost two inches at one joint, right where it meets the driveway. It’s been like that for a couple of winters, and the trip hazard is starting to worry them, especially with grandkids visiting. They’d assumed the whole walkway would need to be torn out and repoured, a job that means dust, saw-cutting, disposal costs, and at least a few days without a usable path to the front door.
Instead, a lifting technician comes out, checks the panel with a straightedge and level, and confirms the slab itself is still structurally sound. It’s just sitting on a void. The team drills a handful of small entry points, injects the foam, and watches the panel rise back to grade in real time. Two hours later, the walkway is level, the holes are patched, and the family can walk on it that same afternoon. No dumpster in the driveway, no jackhammer noise for a week.
Concrete lifting works well when the slab itself is intact but has settled, sunk, or tilted due to soil loss underneath. Driveways, sidewalks, patios, garage floors, and pool decks are common candidates. Poly-Mor also handles concrete pad lifting for utility pads, equipment slabs, and other flatwork that’s settled unevenly.
It’s not the right fix for a slab that’s severely cracked, crumbling, or structurally compromised beyond the settlement issue. In those cases, replacement may genuinely be the better long-term answer, and a straightforward assessment will tell you which category your slab falls into before any work starts.
A proper evaluation involves checking the slab’s condition, measuring how much it has settled, and probing to understand where the voids sit underneath. From there, a technician can tell you roughly how many injection points the job will need and what kind of timeline you’re looking at. Most residential lifting jobs, driveways, walkways, small patios, wrap up in a single day.
Cost varies depending on the size of the slab, how much settlement needs to be corrected, and site access. It’s worth getting a site-specific quote rather than relying on a generic per-square-foot number, since soil conditions in older Edmonton and Calgary neighbourhoods can differ block to block.
If a slab on your property has settled, dropped at a joint, or started holding water where it never used to, it’s worth having someone look at it before the problem gets worse. A quick call to discuss the site and what you’re seeing is the easiest way to find out whether concrete lifting is the right next step for your property.
Most residential jobs, like a driveway or walkway panel, take a few hours from injection to a walkable surface. Larger areas or multiple panels may take a full day. Curing to full strength happens quickly, so the slab is usable the same day in most cases.
The injection holes are small, roughly the size of a coin, and get patched with a matching concrete-based filler once the lifting is complete. They’re noticeable up close at first but blend in over time as the patch weathers alongside the rest of the slab.
It works well on slabs that are intact but have settled due to soil voids underneath, including driveways, sidewalks, patios, and garage floors. Severely cracked or structurally damaged slabs may need a different approach, which an on-site assessment can confirm.
Polyurethane foam is far lighter than the cement slurry used in mudjacking, so it doesn’t add stress to already weak soil. It also cures in minutes rather than days and requires smaller holes, which means less mess and faster return to normal use.
Lifting fills the void that caused the settlement, which addresses the immediate cause. Ongoing factors like drainage, grading, and soil conditions still matter, and a technician can flag any drainage issues nearby that could contribute to future movement.
