Concrete Leveling & Slab Lifting
How foam and mudjacking raise sunken flatwork for a fraction of replacement, what makes a slab a candidate, and the plain line that a settling house slab is a different trade.
By the Georgetown Concrete Guide editorial team · Updated July 17, 2026
Leveling is the fix people skip past on the way to a replacement they may not need. A driveway, walk, or patio that has sunk but is still in one piece can often be raised back to grade for a fraction of the cost of tearing it out. The slab is fine; the ground under one part of it gave way, and lifting sets the concrete back where it belongs.
What makes a slab a candidate
The test is simple: is the concrete sound but sunken, or broken? A slab that dropped as a whole, or tilted at one end, with the concrete itself still solid, is an ideal candidate. A slab that has cracked into pieces, spalled through, or crumbled at the edges is not, because lifting shattered concrete only rearranges the pieces. In that case the replacement comparison is the honest read.
Edges and corners are the usual candidates, since a slab most often drops where its support is thinnest: along a driveway approach, at the leading edge of a patio, or where a walk meets a step. A slab that sits low evenly across its whole area is sometimes a grading question rather than a lifting one, and worth a second look before anyone pumps material under it.
Why the void matters more than the slab
Under a sunken slab is a void, the empty space where supporting soil used to be. Leveling fills that void and raises the concrete, but the more important question is why the void formed. Settlement of loose fill, a downpour washing fines out from under an edge, or a plumbing leak each leaves a slab sitting over air. If the cause keeps working, the slab drops again, so a good crew wants to understand the void before filling it.
Foam or mudjacking
| Polyurethane foam | Mudjacking | |
|---|---|---|
| Material | Expanding polymer | Cement slurry |
| Access holes | Small ports | Larger holes |
| Weight added | Light | Heavier |
| Cure time | Minutes | Longer |
| Cost per hole | More | Less |
Published industry cost data puts flatwork leveling between $800 and $3,500, well under the cost of a comparable repour. Foam costs more per hole but adds little weight to ground that may already be moving and resists washout, which is why it has become the common choice on Central Texas soil. Sunken slabs on a walkway or a settled porch are the everyday candidates, and the cost guide breaks down how crews price a lift by the slab and the void rather than by the hour.
Questions homeowners ask
Most flatwork lifts are a same day job, often just a few hours. The crew drills small ports through the slab, pumps foam or a cement slurry underneath to fill the void and raise the concrete, then patches the holes. Foam cures in minutes, so you can usually use a lifted walk or drive almost right away, which is a big part of its appeal over a repour.
Both fill the void and raise the slab; they differ in material. Mudjacking pumps a heavier cement slurry through larger holes and costs less. Polyurethane foam is lighter, goes in through smaller ports, resists washout, and adds little weight to soil that may already be moving. Foam costs more per hole but often lasts longer on Central Texas ground.
It depends far more on what caused the sink than on the lift itself. If a plumbing leak or bad drainage washed out the base, the slab drops again unless that source is fixed. If the void came from a one time settlement, a good lift can hold for years. Any honest crew treats the cause, not just the symptom, before quoting the raise.
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