The Best Way to Repair a Sinking Garage Apron in Minnesota
For most Minnesota homeowners, polyjacking is the best method to repair a sinking garage apron — it lifts the settled slab back to grade in under two hours, without demolition, without a curing wait, and at a fraction of what concrete replacement costs. The key is confirming the slab itself is structurally sound before committing to any repair method.
A homeowner in Lakeville called us in late April, right after the ground had fully thawed. Her garage apron had dropped about an inch and a half on the left side — gradual enough that she'd gotten used to it, until her husband backed the truck over it and noticed the thud. She'd already talked to a concrete contractor who quoted $3,800 to remove and repour. What she didn't know was that the concrete itself was in good shape. The problem was underneath it.
That scenario plays out every spring across the Twin Cities. The freeze-thaw cycle that defines Minnesota winters doesn't just damage surfaces — it works on the soil beneath them. Clay-heavy subsoils absorb moisture, expand when frozen, contract when they thaw, and over years of cycling, they create voids beneath concrete slabs that have nowhere to go but down. The slab doesn't crack first. It settles first. And a settled slab sitting over a void is a completely different problem than a slab that's deteriorating — it just doesn't look different from the driveway.
Polyjacking addresses the actual cause. High-density polyurethane foam is injected through small ports drilled into the slab, expands to fill the void beneath, and lifts the panel back to its original elevation. The foam cures in roughly 15 minutes. The Lakeville apron was driveable the same afternoon.
Why Minnesota's Climate Makes This Problem So Common
Garage aprons settle faster and more frequently in this region than most homeowners expect, and the reason is almost always the same: soil movement beneath the slab driven by years of freeze-thaw cycling.
Minnesota's clay soils hold water. In winter, that moisture freezes and the ground heaves upward. When it thaws in spring, the soil contracts — and it doesn't always return to exactly where it was. Over several cycles, small gaps accumulate into voids. Add in the weight of vehicles driving over the apron daily, and the settlement accelerates.
What makes garage aprons particularly vulnerable is their position: they transition between the heated garage slab and the exterior grade, two surfaces that move differently through the season. That joint is almost always where settlement starts. A gap at the garage door threshold or a visible slope away from the building is usually the first sign.
How to Tell If Polyjacking Is the Right Fix
Not every sinking garage apron is a polyjacking candidate, and we'll say so when it isn't. Here's what we look at before recommending a repair method:
Check the slab for structural damage, not just position. Polyjacking lifts a slab — it doesn't repair cracked or deteriorated concrete. If the apron is crumbling at the edges, cracked through in multiple places, or heaving from tree root pressure rather than soil settlement, the slab itself may need to be replaced. We've turned jobs down for this reason, and it's the right call.
Look at how the slab is sitting, not just how far it's dropped. A slab that's settled evenly — dropped uniformly across the panel — is usually a straightforward void fill. A slab that's tilted, broken into sections, or sitting unevenly across the joint line may have a more complex void pattern underneath that requires a careful evaluation before quoting.
Don't wait until spring to call. In Minnesota, every winter adds another freeze-thaw cycle to an existing void. Voids grow. The larger the void, the more material is needed to fill it, and the higher the job cost. A slab that's a good candidate in April may be a borderline candidate two winters later if the settlement continues. We've had customers tell us they noticed the drop two years ago and figured it wasn't urgent — by the time we evaluated, the void had widened significantly.
What We See on These Jobs
The majority of sinking garage aprons we evaluate in the Twin Cities are good polyjacking candidates — the concrete is intact, the problem is entirely in the soil below
Most garage apron jobs take 60–90 minutes on-site from setup to cleanup
Voids beneath aprons are routinely larger than the surface settlement suggests — a one-inch drop at the surface can indicate a void several inches deep across a wide footprint
Roughly 1 in 4 jobs we look at involves some slab deterioration that makes polyjacking the wrong call — we're straightforward about that because overselling a repair that won't hold isn't a business model
Spring is our busiest evaluation window, but fall is actually a better time to address the problem — soils are more stable after summer, and you're not racing the next freeze cycle
Common Questions About Garage Apron Repair in Minnesota
What causes a garage apron to sink in Minnesota?
The primary cause is soil movement beneath the slab driven by freeze-thaw cycling. Minnesota's clay-heavy soils absorb moisture, freeze and expand in winter, and contract when they thaw — and over years of cycling, small gaps beneath the slab compound into voids. Vehicle traffic accelerates the process. The concrete itself is often intact; the ground underneath is what's moved. That distinction matters a lot when choosing between repair and replacement.
Is polyjacking better than mudjacking for a garage apron?
For most garage apron repairs in this region, yes. Mudjacking fills voids with a cement-and-soil slurry that's heavier than the foam, takes longer to cure, and is more susceptible to washing out when water gets beneath the slab — which is a real concern at a garage apron where runoff and snowmelt are constant. Polyurethane foam is waterproof, cures in minutes, and doesn't add significant load to the soil below. In Minnesota's climate, those differences are meaningful. We're straightforward about that because mudjacking isn't always wrong — but for aprons near foundations and high-moisture areas, poly holds up better.
How long does a polyjacked garage apron last?
On a stable substrate with the void fully filled, polyjacked slabs hold well for many years. The foam itself doesn't degrade, doesn't wash out, and doesn't compress under vehicle weight. What we can't guarantee is whether ongoing soil movement creates new voids over time — especially in areas with drainage issues or significant clay content. If the same apron settles again five years later, it's usually a new void forming, not the foam failing.
Can you polyjack a garage apron in the spring right after the ground thaws?
Yes, and spring is when we get the most calls. One thing worth knowing: if you're evaluating in early spring, the ground is still stabilizing from the thaw. In most cases that doesn't affect the repair — the foam fills the existing void and the job holds. But if the soil directly beneath is still saturated and actively shifting, we may recommend waiting a few weeks for it to settle before injecting. We flag that when we see it.
What does garage apron polyjacking cost in the Twin Cities?
Most single-panel garage apron jobs run $500–$900, depending on the size of the panel and the extent of the void beneath it. Larger aprons or jobs with multiple settlement points cost more, but the comparison to full concrete replacement — which typically runs $3,000–$5,000 or more for the same area — still holds significantly in favor of polyjacking when the slab is sound.
A Sinking Apron Doesn't Fix Itself Through Another Winter
Left alone, a void beneath a garage apron grows with every freeze-thaw cycle. What starts as a one-inch settlement becomes a two-inch drop, a widening void, and eventually a slab that's moved far enough to affect the garage door threshold, the floor transition, or the foundation grade. At that point the repair window narrows and replacement becomes more likely — not because the concrete failed, but because the underlying problem was ignored long enough to make lifting it impractical.
Benchmark Concrete Raising evaluates and repairs sinking garage aprons across the Twin Cities using polyurethane foam injection. If you're not sure whether your apron is a lift candidate or a replacement situation, that's a question we can answer on-site — and we'll tell you the honest answer either way.
