Concrete Raising and Leveling
Sunken Concrete? Raise It Back to Grade.
Concrete raising lifts a sunken slab back to its original grade instead of tearing it out and pouring a new one. Benchmark injects expanding polyurethane foam through small holes in the concrete, filling the void underneath and returning the slab to level. Most jobs finish in a single visit, the surface is usable the same day, and it costs 50 to 70 percent less than replacement. We work throughout the Twin Cities metro from our shop in Burnsville.
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What You Need to Know
- Concrete raising, concrete leveling, concrete lifting, polyjacking, and slab jacking all describe the same basic service: lifting a settled slab rather than replacing it.
- Polyurethane foam raising costs 50 to 70 percent less than tearing out and repouring the same concrete.
- The foam cures in roughly 15 minutes, so a driveway or sidewalk is usable the same day rather than after a week of curing.
- Slabs sink because the soil beneath them moved, not because the concrete failed, which is why lifting the slab and filling the void is a real fix rather than a patch.
- Raising only works if the slab is structurally sound. Concrete that is crumbling or broken into loose pieces has nothing solid left to lift and needs replacement instead.
- Benchmark uses polyurethane foam rather than mudjacking slurry, which matters in Minnesota because foam does not absorb water or wash out through freeze-thaw cycles.
The Basics
What Is Concrete Raising, and Why Does Concrete Sink?
Concrete raising is the process of lifting a sunken concrete slab back to its original position by filling the empty space that opened up beneath it. The slab you already own goes back where it belongs. Nothing gets demolished, hauled away, or repoured.
Concrete sinks because of what happens under it, not in it. The Twin Cities metro sits on clay-heavy soils that swell when they take on water and shrink when they dry out. Minnesota's freeze-thaw cycle drives that movement hard every single winter. Add water runoff eroding soil from beneath a slab, or ground that was never properly compacted before the concrete was poured, and voids open up. The slab has nothing holding it, so it settles into the gap.
That distinction matters for one practical reason: if the concrete itself is still sound, replacing it does not solve anything the void was causing. Filling the void does.
The Method
How Concrete Leveling Works, Step by Step
Polyjacking, also called foam jacking or polyurethane concrete raising, is the method Benchmark uses on every job. Here is the entire process:
- We evaluate the slab on site and confirm the concrete is sound enough to lift.
- Holes roughly the diameter of a dime are drilled through the slab at points chosen to control the lift.
- High-density polyurethane foam is injected beneath the concrete. It expands, finds and fills the void, and raises the slab back to grade.
- We check the slab against level, patch the injection holes, and clean up.
The foam cures in about 15 minutes. Most residential jobs are finished in a few hours, and you can drive or walk on the surface the same day. There is no demolition debris, no equipment tearing up the yard, and no week of waiting for new concrete to cure.
Foam vs. Mud
Polyurethane Foam Compared to Mudjacking
Mudjacking is the older approach. It pumps a cement and soil slurry under the slab to push it up. It works, and it is still offered by plenty of contractors. But for Minnesota residential concrete, polyurethane foam has clear advantages, and the weight difference is the one that matters most.
| Polyurethane Foam | Mudjacking | |
|---|---|---|
| Weight added | About 2 lbs per cubic foot | Over 100 lbs per cubic foot |
| Hole size | Roughly the diameter of a dime | Typically 1 to 2 inches |
| Cure time | About 15 minutes | Can require days before full use |
| Water resistance | Does not absorb water or wash out | Slurry can erode or wash away over time |
| Freeze-thaw | Holds through Minnesota winters | More vulnerable to seasonal breakdown |
The weight comparison is the heart of it. The soil under a sunken slab has already demonstrated it cannot carry a load. Mudjacking answers that by adding hundreds of pounds of wet slurry on top of it. Foam adds almost nothing, which is why it holds up better on ground that has already failed once.
Cost
What Concrete Raising Costs, and What Moves the Number
Concrete raising typically runs 50 to 70 percent less than tearing out and replacing the same concrete. We do not publish a flat price, because slabs are not standard and a quote that ignores the details is a quote that changes later. What we can tell you is exactly what determines the number:
- How many slabs need lifting, since one settled panel and a whole driveway are different jobs.
- How far the concrete has settled, because a deeper drop means a larger void and more foam.
- The size of the void underneath, which is not always obvious from the surface.
- How accessible the area is for our equipment and hose runs.
- Whether an underlying drainage problem needs to be addressed so the slab does not settle again.
Estimates are free and done on site throughout the Twin Cities metro. If we look at the job and conclude replacement is the better call, we will tell you that instead.
What We Raise
Same Method, Every Surface
Concrete raising works on essentially any flat slab that has settled. These are the surfaces we are called out for most often across the metro:
We also raise garage floors, basement floors, steps, and interior slabs. If your concrete is sitting lower than it used to, it is worth a look.
The Honest Limit
When Raising Is Not the Right Answer
Concrete raising is not a universal fix, and we would rather say so up front than show up and disappoint you. Lifting works when the slab is structurally intact. If the concrete is crumbling, spalled through, or broken into loose pieces, there is nothing solid left to raise and replacement is the honest recommendation.
The same is true when settlement is a symptom of something larger. A slab that keeps sinking because water is being routed under it will keep sinking after it is lifted unless the drainage gets corrected. We will point that out during the estimate rather than after the invoice.
In our experience most homeowners who have already been quoted for full replacement do not actually need it. But some do, and we do not take jobs we cannot do well.
Common Questions
Concrete Raising and Leveling: FAQ
What is concrete raising?
Concrete raising is the process of lifting a sunken concrete slab back to its original grade instead of tearing it out and pouring a new one. Benchmark does this by injecting expanding polyurethane foam through small holes in the slab. The foam fills the void underneath and raises the concrete back into position. The same service is also called concrete leveling, concrete lifting, polyjacking, and slab jacking.
How does concrete leveling work?
A technician drills holes roughly the diameter of a dime through the sunken slab, then injects high-density polyurethane foam beneath it. The foam expands, fills the void that caused the slab to settle, and lifts the concrete back to grade. The holes are patched and the surface is usable the same day. The foam cures in about 15 minutes.
What does concrete raising cost?
Concrete raising typically costs 50 to 70 percent less than tearing out and replacing the same concrete. Final pricing depends on how many slabs need lifting, how far they have settled, how large the void underneath is, and how accessible the area is. We provide free on-site estimates. Call 952-295-0500 or request a quote online.
Is polyjacking better than mudjacking?
For most Minnesota residential work, yes. Polyurethane foam weighs about 2 pounds per cubic foot compared to over 100 pounds for mudjacking slurry, so it adds almost no weight to soil that has already proven unstable. Foam is also moisture-resistant and does not wash out or compress over time, and it cures in about 15 minutes rather than requiring days.
How long does concrete raising last?
Polyurethane foam does not absorb water, compress, or erode the way mudjacking slurry can, which is why it holds through Minnesota freeze-thaw cycles year after year. The foam itself does not break down. If the surrounding soil continues to move for an unrelated reason, such as an ongoing drainage problem, that issue needs to be corrected separately.
When is concrete raising not the right fix?
Concrete raising works when the slab itself is structurally sound. If the concrete is badly crumbling, spalled through, or broken into multiple loose pieces, there is nothing solid left to lift and replacement is the honest answer. We evaluate every job on site before committing to it.
The Bottom Line
Lift the Concrete You Already Own
If your concrete is sound but sitting low, replacement is rarely necessary. Concrete raising addresses the actual cause, which is the empty space under the slab, in a single visit and at a fraction of what a tear-out costs. The concrete you already paid for stays in the ground.
We provide free estimates throughout the Twin Cities metro. Call 952-295-0500 or request a quote online to get started.
