What concrete leveling covers
Concrete leveling lifts settled flatwork: driveways, walkways, sidewalks, patios, steps and landings, garage floors, and pool decks. Expanding polyurethane foam is injected through small ports, fills the void beneath the slab, and raises it in controlled stages.
It is flatwork, not foundation work. The distinction is worth repeating because it drives both scope and price, and because the two get conflated regularly in sales conversations. If the slab in question is carrying your house, that is slab foundation repair, and it is a different job handled by our structural foundation repair team in Nashville.
Why slabs settle around Nashville
Poorly compacted fill. Where a slab was poured over fill that was never properly compacted, consolidation continues afterwards, and it rarely happens evenly.
Soil washout. Water entering through joints and cracks carries fines away over time. This is the most common cause we find, and the one most likely to recur if nothing changes.
Tree roots. Roots displace slabs upward and, when removed or decayed, leave voids behind.
Consolidation over time. Ordinary soil settlement under load, particularly on a driveway that carries vehicles.
Erosion at edges. Concentrated runoff at a downspout or roof valley undermines a slab edge and works inward.
How the lift works
Small ports are drilled through the slab at planned locations. Two-component polyurethane is injected, expands, and first fills the void beneath. Once the void is filled and the foam meets resistance, continued injection generates lift.
That is the reason the process is staged and monitored. Elevation is watched throughout, and injection stops when the target is reached. Over-lifting is not reversible, and a slab pushed too far cracks.
Once the lift is complete, ports are patched. Joints are sealed where useful, which limits the water entry that caused the washout in the first place. Because the foam cures quickly, most residential surfaces return to service the same day.
Foam versus mudjacking
Mudjacking pumps a cementitious slurry through larger holes to raise a slab. It works, and it has been used for decades.
The practical differences: foam is lightweight, so it does not add significant load to soil that already failed to support the slab, and it uses smaller ports, which are less visible afterwards. Mudjacking is heavier and needs more cure time before the surface can be used.
Neither material addresses the reason the void formed. Longevity in both cases depends on whether the water story gets corrected. Our guide on polyurethane foam versus mudjacking goes through the comparison in full.
When we recommend replacement instead
Lifting works on slabs that can move as a unit. When a slab has broken into many small pieces, is crumbling or spalling through its thickness, is too thin to handle the lift, or has deteriorated from years of freeze-thaw and de-icing salts, lifting it produces a raised broken slab rather than a repaired surface.
We say so in those cases. Our guide on concrete leveling versus replacement covers where the line sits.
Address the cause, not just the symptom
A settled slab is evidence that something underneath changed. If washout caused it, the same water will cause it again unless something changes.
That is why joint sealing goes in most of our leveling scopes, and why we look at nearby downspouts, grading, and runoff paths while we are there. Where the water story is significant, drainage correction belongs alongside the lift rather than three years after it.
What drives the cost
Square footage of slab being lifted. Lift height and the volume of void beneath, since foam is consumed by volume. Number of injection ports and access to the work area. Whether joint sealing is included. Whether drainage correction is needed. Slab thickness, reinforcement, and general condition.
For eligible slabs, leveling is typically well below replacement cost and considerably faster, which is the practical reason to have it assessed before assuming a slab has to come out.
