What sinking concrete usually looks like
Settled slabs tend to show up in predictable places around an Omaha home.
- A driveway section that has dropped, leaving a lip at a joint or at the garage apron
- A sidewalk panel that rocks when you step on it, or tilts toward the house
- Patio slabs that have shifted unevenly, sometimes pulling away from the house
- Concrete steps that have dropped or separated from the foundation
- A garage floor that has sunk in the middle or along one edge
Sometimes the change is gradual enough that homeowners do not notice it until a guest trips, or until they really look at it. Other times a slab drops noticeably after a heavy rain or a hard freeze.
Why concrete settles in Omaha
The soil here is a big part of the story. Omaha sits on loess, a fine wind-blown silt, with clay-rich subsoils beneath. The city's own engineers have noted that loess can be easily carried away by water, leaving behind gaps underground. When water moves through or under a slab, it can carry fine soil particles with it. Over time, that leaves voids. The slab, no longer fully supported, settles into them.
A few local conditions make this more likely:
- Omaha averages about 135 days a year with overnight lows at or below freezing. Frost heave can lift and shift slabs through the winter, and when the ground thaws, slabs do not always settle back where they started.
- Omaha city crews have reported more than 400 ground cave-ins a year since 2021, mostly where aging pipes and fine soil meet. Nebraska's State Geologist is clear that Omaha is not heading for giant sinkholes, but eroding loess does create underground voids that can affect slabs over time.
- Poorly compacted fill soil under a new driveway or patio is another common cause. If the base was not well prepared when the slab was poured, it may settle as that fill compacts over the years.
Mudjacking, foam leveling, and replacement: what a contractor may suggest
Concrete leveling generally comes down to three options. A contractor will look at the condition of the slab, the size of the void, and the soil before recommending one.
Mudjacking, also called slabjacking, involves drilling small holes through the slab and pumping a slurry of soil, cement, and water underneath. The material fills the void and lifts the slab back toward its original position. It has been used for decades and works well when the slab itself is in reasonable condition.
Foam leveling uses a similar process but injects an expanding polyurethane foam instead of slurry. The foam is lighter than slurry, which some contractors prefer in certain soil conditions, and it cures quickly. It can also cost more.
Replacement means breaking out the old slab and pouring new concrete. This makes sense when a slab is badly cracked, too thin, or too deteriorated to be worth lifting. Concrete leveling of any kind only works if the slab is structurally sound enough to lift in one piece.
What affects the cost
Concrete leveling costs depend on how many slabs need attention, how much they have settled, how large the void underneath is, which method the contractor uses, and how accessible the area is. Replacement is almost always more expensive than lifting, when lifting is an option. There is no honest way to give a number without someone looking at the specific slab.
How to choose a contractor
Nebraska requires contractors to register with the Nebraska Department of Labor. You can search by name, city, or ZIP at dol.nebraska.gov. Also check the BBB of the Midwest Plains, based in Omaha.
When you talk to a contractor, ask:
- What is causing the slab to sink, and will the same problem affect the repair over time?
- Are you recommending mudjacking, foam, or replacement, and why?
- What does the work include, and is there a written warranty?
- Will you pull any required permits?
Get everything in writing before work starts.
Frequently asked questions
How do I know if my slab can be lifted or needs to be replaced?
A contractor will assess the condition of the concrete itself. If it is badly cracked, crumbling, or too thin, lifting may not be possible. If the slab is structurally sound and the problem is just a void underneath, concrete leveling is usually worth considering.
Does frost cause permanent damage to concrete slabs?
Frost heave can move slabs, but the slabs often settle back close to their original position when the ground thaws. The concern is when the slab settles into a void that was created by eroding soil, because then it does not come back up on its own. That is when leveling or replacement becomes necessary.
Is mudjacking a permanent fix?
No concrete leveling method comes with a guarantee that the slab will never move again. The underlying soil conditions that caused the settling in the first place do not disappear. A good contractor will be honest about this and explain what, if anything, can be done to reduce the chance of future settling.
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