Services
Concrete leveling
A slab has dropped and now sits lower than the concrete next to it.
Concrete leveling raises a slab that has sunk, by filling the space underneath it until the slab lifts back toward where it started. The concrete itself is not replaced. Small holes are drilled through the slab, material is pumped through them under pressure, and the slab rises as the space below fills.
It exists because most settled flatwork is not worn out. A driveway panel that has dropped an inch is usually perfectly good concrete sitting on ground that moved. Replacing it means demolishing something that still works in order to fix the ground underneath — which lifting can often do without the demolition.
The catch is that lifting only addresses height. It does not repair concrete, and it does not stop whatever moved the ground in the first place. Both of those matter when deciding whether it is the right answer.
What actually happens under a settled slab
Concrete flatwork is poured on prepared ground. When that ground loses volume, the slab loses support and follows it down. The loss happens for ordinary reasons: fill that was never fully compacted continuing to settle, water washing fines out from under an edge, a poorly directed downspout running under a corner for years, soil shrinking in a dry spell, or a utility trench backfill consolidating.
The result is a gap between the concrete and the ground — a void. Sometimes the slab bridges it and sounds hollow underfoot. Sometimes it cracks and drops into it. Either way, the concrete is a symptom and the ground is the cause.
The two methods, in plain terms
There are two mainstream ways to fill that space. Polyurethane foam injection — often called polyjacking or foam jacking — pumps a two-part polymer through small holes; it expands in place and lifts. Mudjacking, also called slabjacking, pumps a cementitious slurry of sand, cement and water through larger holes to do the same job.
They lift the same slab for different reasons and at different costs. Foam is light, cures in minutes, and uses holes around the diameter of a pencil. Slurry is heavy, much cheaper per unit of material, cures over hours, and uses holes roughly the size of a quarter or larger.
- Foam adds very little weight to ground that has already proven it cannot hold weight well.
- Slurry is a proven, long-established method and usually the lower-cost option on large areas.
- Foam's small holes are easier to make visually unobtrusive; slurry's larger holes are patched and remain visible on close inspection.
- Neither method repairs cracks, changes the concrete's thickness, or adds reinforcement.
What leveling does not do
Lifting restores height. It does not restore concrete. A slab that comes up cracked goes back down cracked, and a slab that was crumbling before it was lifted is crumbling concrete at a new elevation.
It also does not fix drainage. If a downspout has been discharging under the corner of a driveway for six years, lifting the driveway resets the height and leaves the downspout doing exactly what it was doing. The settlement usually returns. Any contractor who does not raise this before quoting is worth asking about it directly.
How long a lift lasts
Honestly: it depends almost entirely on whether the cause was addressed. Where a slab settled because of a one-off — a trench backfill consolidating, construction fill finishing its settlement — a lift can hold for many years. Where water is still moving soil, it holds until the water has moved enough soil again.
Warranties in this trade vary widely and often exclude further settlement of the underlying soil, which is precisely the thing most likely to happen. Read what the warranty covers rather than how long it runs.
When leveling is worth evaluating
- The slab has dropped but is still essentially in one piece.
- The problem is height — a trip hazard, a step at a joint, water running the wrong way — rather than the condition of the concrete.
- The cause of the settlement is identifiable and fixable, or has clearly finished.
- The concrete is otherwise sound: no crumbling, no widespread deep cracking, no exposed and rusting reinforcement.
- Replacing it would mean demolishing concrete that is doing its job apart from its elevation.
When leveling is the wrong tool
- The slab has broken into several pieces. Lifting assumes the slab moves as a unit; pieces move independently and can break further.
- The concrete is crumbling, badly spalled through its depth, or soft.
- The ground is still actively moving, and nothing is being done about why.
- The problem is a structural one — foundation walls, footings, bowing basement walls. That is a different trade and a different assessment.
- The slab needs to end up somewhere it never was. Lifting returns concrete toward its original position; it does not redesign a layout or correct a slope that was wrong from the day it was poured.
Alternatives worth pricing
- Replacement, where the concrete itself is finished rather than simply low.
- Grinding a trip hazard down, where the only issue is a small offset at one joint and appearance is not a concern.
- Doing nothing yet, where the settlement is old, stable and cosmetic — a legitimate answer that a good contractor will sometimes give you.
What moves the price
We do not publish national dollar figures. A single average applied across every site, method and market gives you a confident-looking benchmark that is wrong for your job in an unknown direction. What does transfer between jobs is the structure of the price:
- The number of holes and the volume of material needed, which follows from how big the void is — not from the slab's surface area alone.
- Which method is used; foam and slurry price very differently per job.
- Access for equipment, and how far material has to be run.
- How much lift is required, and whether the slab has to come up evenly across several panels.
- Whether drainage or grading work is bundled in.
Local quotes decide actual pricing. If you want to compare two of them properly, the quote comparison guide covers how.
What to ask a contractor
- What do you think caused this settlement, and what stops it happening again?
- Foam or slurry here, and why that one for this slab?
- How much lift do you expect to achieve, and what will the joints and edges look like afterwards?
- What happens if the slab cracks during the lift — who carries that?
- What exactly does the warranty cover, and does it exclude further soil settlement?
- Is there anything about drainage or grading you would want changed first?
Common questions
Is leveling always cheaper than replacing the concrete?
Usually, but not always, and not by a fixed proportion. Lifting avoids demolition, disposal and a new pour, which is where most of replacement's cost sits. But a job needing a large volume of material under several panels can close that gap, and if the concrete then needs replacing in three years anyway, the cheaper job was the more expensive decision. Price both when it is a genuine choice.
Will the holes be visible afterwards?
Yes, on close inspection. They are patched, and foam's smaller holes are less obvious than slurry's, but patched concrete does not colour-match aged concrete exactly. On a driveway most people stop noticing within a season. If appearance is a priority, ask to see finished work rather than photographs taken on the day.
Can I drive on it afterwards?
Timing depends on the method and the contractor's specification, and it is a fair question to ask before booking rather than after. Foam systems generally return to service quickly; slurry needs longer to cure. Get the actual answer for your job in writing.
The slab is hollow-sounding but hasn't dropped. Is that a problem?
It means there is space under it, which is worth knowing about, but a void alone is not an emergency. Unsupported concrete is more likely to crack under load, so it is reasonable to have it looked at — particularly under a driveway that carries vehicles. It is not a reason to be alarmed.
Work it out, or judge the quote
Project cost planner
Where your project sits relative to other residential concrete work, and what will actually move your quotes.
Open it →Repair or replace tool
Ten questions about what you can see, and the options your answers rule out.
Open it →Contractor Vetting Standard
Fourteen checkpoints, a red-flag list and a printable interview checklist.
Open it →Related guides
Polyjacking (foam injection)
Polyurethane foam injection: light, fast-curing, small holes — and more expensive per unit of material.
Read more →Mudjacking (slabjacking)
Cementitious slurry lifting: long-established, cost-effective on volume, heavier, with larger patched holes.
Read more →Sunken concrete
A slab that now sits lower than it should — almost always a ground problem, not a concrete problem.
Read more →Voids under concrete
Space beneath a slab — often before anything has visibly dropped.
Read more →What drives leveling cost
Why lifting is priced by the void rather than by the slab, and what makes two quotes differ.
Read more →Leveling vs replacement
When lifting is the smart economy and when it is a deposit on a job you will still do.
Read more →