Lifting a sunken slab instead of replacing it
Walk a few Aurora blocks after a wet spring and you'll see it. A sidewalk panel sitting an inch lower than its neighbor. A driveway slab that tilts toward the garage. A patio that now drains straight at the back door. The concrete itself is usually fine. It's the ground under it that gave up.
Here's what we find when we dig beside one of these slabs. Clay that swelled and shrank for years, a void the size of a cooler under one corner, and a slab bridging the gap with nothing holding it up. Water gets in, softens the clay, and carries fines away. The panel drops. Then it keeps dropping, a little more with every freeze.
Concrete leveling fixes that without a jackhammer. We drill small holes through the slab, pump material underneath, and lift the panel back to grade while it fills the void. That's the whole idea. It can be mudjacking, which uses a cement-based slurry, or foam jacking, which uses polyurethane. Mudjacking runs $4 to $8 per sq ft. Foam jacking runs $7 to $15 per sq ft. Both cost well under replacement when the slab is still in one piece. When it isn't, we'll tell you straight and quote a new pour instead.
Should you level it now, or can it wait?
A sunken slab is a trip hazard first and a drainage problem second. Here's how we sort the urgent ones from the ones you can watch.
Call soon if you see
- A sidewalk or driveway edge that sits higher than the next panel, enough to catch a toe, a stroller wheel, or a shovel
- A slab that slopes toward the garage, foundation, or a window well so water runs the wrong way
- A panel that thumps or rocks when you step on the low corner
- A visible gap under the slab edge where you can see dark soil or daylight
Usually safe to watch
- A panel that dropped a quarter inch and has stayed there for a year
- Slight settling at an old expansion joint where nothing drains toward the house
- A patio that sank a little but still sheds water away from the foundation
Common reasons concrete sinks in Aurora
Clay that shrinks and washes out
Expansive clay swells when it's wet and shrinks when it dries. Over a few seasons the slab loses its support, and sandy fill under it can slump into the gap. Leveling restores the support. Fixing the water that caused it matters just as much, which is why we look at downspouts and grading before we quote.
Sunken sidewalk panels and trip hazards
A one-inch lip between panels is the classic one. Leveling is usually the cheapest way to fix it, and it's the first thing we check before suggesting a tear-out on sidewalks and walkways. If the panel is cracked in several pieces, lifting it won't hold. Replacement will.
Driveway panels that settled at the garage
The first panel or two by the garage tends to drop because of backfill around the foundation that never fully compacted. A lift can fix the slope and stop water from running into the garage door. If the whole driveway is cracked and scaling, a lift only fixes the elevation. Our driveway replacement work is the better call for that.
Mudjacking: heavy, low-cost, and proven
Mudjacking has been around for decades. We drill holes about 1.5 to 2 inches across, usually every few feet in a grid, then pump a cement-based slurry of soil, cement, and water under the slab. The slurry fills the void and pushes the panel up. When the slab reaches grade, we stop, patch the holes, and clean up.
The slurry is heavy. That is both its strength and its limit. On a firm base it works great, and it's the cheaper option, running $4 to $8 per sq ft. A single sunken sidewalk section is often a minimum-charge job, typically $350 to $650. But all that weight sits on top of the same clay that already let the slab down. On soft or wet soil, the extra load can push the slab down again over time.
The holes are bigger, which shows on decorative or colored slabs. Walk on it the same day, drive on it after about a day.
When mudjacking is the right call
- Sidewalks, driveways, and garage aprons on reasonably firm ground
- Large areas where cost per square foot decides the job
- Slabs where small patched holes won't bother you
Foam jacking: light, clean, and quick
Foam jacking, sometimes called polyjacking or foam leveling, uses a high-density polyurethane foam instead of slurry. The holes are about 5/8 inch, roughly the size of a dime. The foam goes in as a liquid, expands, fills voids and gaps, and lifts the slab as it hardens.
It adds very little weight, which is why we reach for it when soil is soft, when the void is deep, or when the slab is a heavier structure like a garage floor or a patio by the foundation. It cures fast. Most slabs can take foot traffic within minutes and vehicles shortly after. It costs more, typically $7 to $15 per sq ft. Lifting two sunken driveway panels, about 200 sq ft, usually lands around $1,400 to $3,000.
Foam doesn't wash out like soil-based fill, which helps over wet clay.
When foam jacking is the right call
- Slabs over soft or wet clay where added weight would be a problem
- Patios, steps, and garage floors where small holes keep the finish looking good
- Jobs where you need to use the surface again quickly
Not sure which fits your slab? Our side-by-side guide, mudjacking vs foam jacking in Aurora, goes through both.
When neither one is the right fix
We'd rather tell you no than take your money for a lift that won't last. Leveling doesn't work when:
- The slab is badly broken. A panel cracked into several pieces can't hold a lift. It'll shift again the first time the ground moves. Replace it.
- A washout is still active. If a broken gutter line, a leaking sprinkler, or a runoff path is still sending water under the slab, any fill is temporary. Fix the water first.
- Drainage is the real problem. If the yard pitches toward the slab and the slab is sinking because of it, lifting changes the elevation but not the cause. We'll talk about regrading or a drain before we pump anything.
- The base is gone, not just thin. If the slab is sitting on a big void with no support at the edges, the cost of fill can approach the cost of a new pour.
In those cases we'll quote a replacement instead.
How a concrete lift goes
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Inspect the slab and the surroundings
We check how far each panel dropped, where water goes, what's under the edges, and whether the slab is solid enough to lift. You get a written price and a recommendation, mudjacking or foam, or neither.
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Mark and drill the holes
We lay out the holes to lift evenly, then drill through the slab. Mudjacking holes run about 1.5 to 2 inches. Foam holes are about 5/8 inch.
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Pump and lift in stages
We pump a little at a time and watch the slab rise with a level and a string line. Lifting slowly keeps the slab from cracking. We stop when it matches the next panel and the slope drains away from the house.
What affects the price of concrete leveling
Mudjacking typically runs $4 to $8 per sq ft and foam jacking runs $7 to $15 per sq ft. Several things push a quote up or down.
- Size of the area
Bigger areas cost less per square foot. A single panel usually falls under a minimum job charge, since we still bring the pump and crew.
- How far it needs to lift
A half-inch lift uses far less material than a three-inch lift over a deep void. Voids you can't see until you start drilling are the biggest cost swing.
If the lift isn't going to hold, replacement pricing is on our driveway replacement and sidewalk pages.
Leveling through Aurora’s seasons
Winter
Frozen ground makes lifting harder, and slurry can freeze before it sets. We do some winter work, but most leveling waits for the ground to thaw. Foam is less fussy about cold than slurry.
Spring
Spring is when sunken slabs show up. The clay is wet, the slab has dropped, and the schedule fills fast. We like to let saturated soil drain a bit before we lift.
Summer
Summer is a good window. Dry ground, long days, and quick cure times. Check for dry clay shrinkage gaps under slabs after a hot stretch.
Fall
Fall is the time to get slabs back to grade before the first freeze, so water drains off them instead of sitting in a low spot and freezing. Seal the joints after the lift.
Aurora soil, HOAs, and the city sidewalk
Expansive clay
Clay is why most Aurora slabs settle in the first place. It swells when wet and shrinks when dry, and water can carry fines out from under a slab. Leveling fixes the gap. Managing water around the slab is what keeps it from coming back.
City of Aurora sidewalks
The city maintains the public sidewalk, curb, and gutter, and property owners maintain their driveways and aprons. The city's concrete repair policy lets owners have the city repair damaged right-of-way concrete or hire a private contractor, and private work in the right-of-way must meet city specs and needs a permit. The city also rates sidewalk displacement as low under 3/8 inch, moderate 3/8 to 3/4 inch, and severe over 3/4 inch. Confirm current rules with Aurora Public Works before you hire anyone.
Concrete Leveling and Mudjacking FAQs
What is the difference between mudjacking and foam jacking?
Mudjacking pumps a heavy cement slurry through holes about 1.5 to 2 inches wide. Foam jacking injects lightweight polyurethane through holes about 5/8 inch wide. Mudjacking costs less. Foam weighs less, cures faster, and leaves smaller patches. Our comparison guide has the full breakdown.
How much does concrete leveling cost in Aurora?
Mudjacking typically runs $4 to $8 per sq ft and foam jacking runs $7 to $15 per sq ft. One sunken sidewalk section is often a minimum job, usually $350 to $650. Lifting two driveway panels with foam, about 200 sq ft, usually runs $1,400 to $3,000.
Will the slab sink again?
It can, if the cause is still there. A lift fills the void, but water that keeps washing soil out will make a new one. That is why we check downspouts, sprinklers, and grading first. Foam resists washout better than slurry.
Can you level a cracked slab?
Sometimes. A slab with one or two clean cracks can usually be lifted in one piece. A slab broken into many pieces won't hold a lift and should be replaced. We'll tell you which you have after we look at it.
How long until I can use the slab after leveling?
Foam jacking is ready for foot traffic within minutes and for cars shortly after. Mudjacking is fine to walk on the same day, and we usually ask you to keep vehicles off for about a day.
Will the holes show after leveling?
Yes, a little. We patch every hole with cement mortar so the patches sit flush with the slab. They show as small gray circles. Foam holes are about 5/8 inch across, and mudjacking holes run about 1.5 to 2 inches.