Why Sunken Concrete Sidewalks in Minnesota Don't Need to Be Replaced
Polyjacking lifts and levels sunken concrete slabs faster than mudjacking — without tearing out a single panel. Most homeowners don't know this option exists until they've already paid for a full replacement they didn't need.
We got a call last spring from a homeowner in Lakeville. She'd already had two contractors out to look at her front sidewalk — three panels that had dropped nearly two inches toward the house, with a lip at the joints that her husband had tripped over twice. Both contractors told her the same thing: tear it out and pour new. She was quoted between $4,200 and $5,800. Before she signed anything, her neighbor told her to call us first.
We were on-site within a few days. Forty-five minutes after we started drilling, all three panels were level. She paid less than a third of the lowest replacement quote.
That call isn't unusual. A significant portion of the concrete leveling jobs we do come from homeowners who were told replacement was their only option — when the slab itself was structurally sound the whole time. The problem was never the concrete. It was the soil underneath it.
In Minnesota, freeze-thaw cycles do something replacement can't fix on its own: they keep moving the ground. Clay-heavy soils in the Twin Cities metro expand when wet and contract when they dry out. Over time, voids open up beneath slabs, and without support, the concrete follows gravity. Pouring a new slab on that same unstable base starts the clock over — it doesn't address what caused the settling in the first place.
Polyjacking fills those voids. We drill small holes through the existing slab, inject a high-density expanding polyurethane foam, and the foam expands to fill the void and lift the panel back to grade. The foam cures in about 15 minutes. The concrete is walkable the same day.
What We See in the Field
Roughly 70% of the sunken sidewalk panels we evaluate are good candidates for polyjacking — the concrete itself is intact, the problem is entirely below the surface
The average polyjacking job on a residential sidewalk takes between 45 minutes and 2 hours from setup to cleanup
Replacement costs in the Minneapolis-St. Paul area typically run 3 to 4 times more than polyjacking for the same linear footage
We've lifted panels that had dropped more than 3 inches and returned them to within ¼ inch of original grade
Voids beneath sidewalk slabs in clay-heavy metro soils are often larger than they appear — a 1-inch surface drop can mean a 4 to 6-inch void at the center of the slab
How to Know If Your Sidewalk Qualifies
The contractors most likely to recommend replacement without mentioning polyjacking are the ones who don't offer it — not because it's the wrong call, but because it's not in their toolkit. That's worth knowing before you get a quote.
Here's what actually determines whether a slab can be lifted versus replaced:
Check the condition of the concrete itself. If the panel is cracked into multiple pieces, severely spalled, or crumbling at the edges, replacement may be the right call. But if the slab is intact — even if it's old — polyjacking is almost always a viable option. Age alone doesn't disqualify a slab.
Look at the gap and the direction of the drop. Panels that have settled away from the house, toward a tree, or along a seam are typically void-related — exactly what polyjacking addresses. If one edge dropped but the opposite edge didn't move, that's a strong indicator the soil shifted beneath one side.
Ask any contractor specifically why replacement is necessary. A legitimate answer involves the condition of the concrete. "It's old" or "it'll just settle again" aren't complete answers — the foam we use is hydro-insensitive and doesn't wash away or compress over time the way gravel base material can. We're straightforward with homeowners when a slab genuinely needs to go. We've lost jobs by telling people they didn't need what they called about. That honesty is what brings them back.
FAQ
How long does polyjacking last? The polyurethane foam we inject is lightweight, waterproof, and doesn't break down over time the way soil or gravel fill can. In stable soil conditions, a properly done polyjacking job holds for decades. In areas with significant tree root activity or ongoing drainage issues, the underlying cause needs to be addressed — but the foam itself isn't the weak link. We've revisited jobs from several years back in the metro and found the lift holding within a fraction of an inch of where we left it.
Will the drill holes show after the job is done? The holes we drill are about the size of a dime — typically 5/8 of an inch. Once we fill and patch them, they're visible if you're looking for them, but they blend into normal concrete texture reasonably well. On older or weathered concrete, they're barely noticeable. We're honest that it's not invisible — but most homeowners tell us they stop seeing them within a week.
Is polyjacking safe near my foundation? Yes, when done correctly. We control the injection volume and pressure throughout the lift, which prevents over-expansion against adjacent structures. We've worked within inches of foundations, garage slabs, and basement window wells without issue. What matters is experience — we monitor the lift continuously and stop when the panel reaches grade, not when the foam runs out.
My sidewalk has been sunken for years. Is it too late? Not necessarily. We've lifted slabs that had been settled for five or more years. The longer a void sits unfilled, the more likely it is that surrounding soil has shifted further — but the slab itself doesn't become un-liftable just from time. The honest answer is that some long-neglected slabs have developed secondary cracking from years of flex and load. We'll tell you that upfront during the evaluation rather than starting a job we can't finish cleanly.
How does polyjacking compare to mudjacking? Mudjacking uses a cement and soil slurry to fill voids and lift slabs. It works, but the material is heavy — which adds load to already compromised soil — and it can wash out or compress over time. The polyurethane foam we use weighs a fraction of the mudjacking slurry, cures faster, and doesn't introduce water into the void during injection. In Minnesota's freeze-thaw environment, keeping moisture out from under slabs matters. That's one of the main reasons we use poly over mud.
The Cost of Leaving It
A two-inch trip hazard on a front sidewalk isn't a cosmetic problem — it's a liability. In Minnesota, property owners can be held responsible for injuries on their sidewalks, including the public-facing strip between the curb and their front walk. Beyond the legal exposure, settled panels that drain toward a foundation contribute to water intrusion over time. Every winter that passes with an unlevel slab is another freeze-thaw cycle working against the void beneath it.
BCR has been lifting sunken concrete across the Twin Cities metro for years. If you've got a sidewalk, driveway apron, or patio that's dropped and you've been told replacement is your only option, we'd rather give you a second opinion than have you spend money you don't need to. Reach out and we'll take a look — no pressure, just a straight answer
