What slab jacking actually does
Slab jacking lifts a sunken concrete slab by filling the gap underneath it until the pressure of the material raises the concrete back to grade. That is the whole mechanism, and it explains both the appeal and the limits. You keep the existing slab — its color, its finish, its edges against everything around it — and the work is measured in hours at $3 – $6 per square foot for cement slurry, or $5 – $25 per square foot for polyurethane foam.
It applies where a slab dropped into a void while the concrete itself stayed sound: a driveway panel over soil that eroded beside a downspout, a patio over backfill that consolidated, a garage or basement floor section that settled away from the walls.
The lift, step by step
| Step | What happens | Typical | What the operator is watching |
|---|---|---|---|
| 1. Lay out the drill pattern | Grid across the panel | 3 – 8 holes | Where the slab sits lowest and how far the void extends |
| 2. Drill through the slab | 1 – 2 in. holes | Foam: about 5/8 in. | Rotary hammer or core bit, staying clear of rebar and utilities |
| 3. Probe the void | Rod through a hole | Per hole | How deep the gap runs, and whether it is soil or open air |
| 4. Pump material in | Low, steady pressure | Lowest hole first | Material appearing at the next hole means that pocket is full |
| 5. Watch for the lift | About 1/8 in. at a time | Level or string line | The slab edge rising against a fixed reference outside the panel |
| 6. Stop at first movement | Immediately | Per hole | Over-pumping cracks the panel from underneath |
| 7. Patch and cure | Matching grout | Same visit | Slurry cures in hours; foam is walk-on in minutes |
Source: Process sequence and hole dimensions follow published concrete lifting installer procedures for cement slurry and two-part polyurethane systems, cross-checked against manufacturer application guidance. Hole counts assume standard residential slab panel dimensions. · Last reviewed July 30, 2026 · Reference data · How we compile these figures
The drill pattern is a design decision rather than a routine. The operator reads which end of the panel dropped furthest, estimates how far the void reaches, and lays out holes so material spreads across the whole gap rather than piling under one spot. A standard driveway panel takes three to eight holes, generally two to six feet apart, set back from edges and joints so pressure builds under the panel rather than against a free corner.
Hole size is where the two methods separate visibly. Mudjacking needs roughly 1 – 2 inch holes because cement slurry is a heavy, coarse material that has to be pumped through a wide hose. Polyurethane foam goes in through a port of about 5/8 inch, since it arrives as a thin two-part liquid and expands after it is in place. On a decorative or stamped surface, that difference in patch visibility matters as much as the price does.
Pumping starts at the lowest hole and works outward, and the operator watches for two signals: material appearing at the adjacent hole, which says that pocket is full, and the first sign of the slab lifting. Judging the lift is the skilled part — the crew sets a level, a laser or a taut string line referenced to something outside the panel, watches the slab edge against it, and stops pumping as soon as movement begins. The panel comes up in increments of roughly an eighth of an inch, moving between holes so it rises evenly rather than tilting.
Over-pumping is the failure mode worth knowing about, because it damages a slab that arrived intact: pressure under one point while the rest of the panel still bears on soil bends the concrete against itself and cracks it from underneath. An operator who stops early and returns to a hole is doing the job correctly.
Holes are then filled with a grout mixed to match the slab. On a driveway or sidewalk the patches fade into the surface within a season; on a bare interior floor or a colored slab they stay visible as a row of circles, worth picturing before you agree to the pattern. Slurry needs a few hours before foot traffic and a day or two before you park on it. Foam is walk-on in about fifteen minutes.
What to expect on the day
- The crew arrives with a pump rig on a trailer. Clear the panel and give them a path for hoses from the truck to the work.
- They measure and mark. Expect a straightedge or string across the panel and paint marks where the holes will go. This is when to ask how much lift they expect to achieve.
- Drilling, roughly ten minutes. Loud, dusty, and much shorter than people expect.
- Pumping and watching, one to two hours. Slow and undramatic. The slab moves in increments you have to look carefully to see.
- Patching, and a walk-around. Ask them to show you the reference line and the height difference against it before the rig leaves.
- Back in service. Hours for slurry, minutes to a day for foam. Take dated photos before and after, with a straightedge in frame.
A typical residential panel is a two-to-four-hour visit start to finish. A whole driveway takes most of a day. None of it requires you to leave the house.
What the lift costs
| Option | Typical cost | Unit | What you are buying |
|---|---|---|---|
| Mudjacking (cement slurry) | $3 – $6 | per sq ft | Larger holes, cures in hours, adds real weight to the soil |
| Polyurethane foam jacking | $5 – $25 | per sq ft | Small holes, cures in minutes, adds almost no load |
| Typical slab section | $700 – $2,100 | per section | Driveway panel, patio or walkway of ordinary size |
| Whole driveway | $3,000 – $6,000 | per driveway | Panel count and total square footage lifted |
| Replacing the concrete instead | 2 – 3× the lift | per section | Demolition, new pour, cure time and a color mismatch |
| Grinding a trip-hazard lip | $100 – $300 | per lip | Solves the safety problem without lifting anything |
| Correcting the water that caused it | $100 – $600 | per project | Downspout routing and regrading. The repair that lasts |
Source: Compiled from 2025–2026 concrete lifting contractor pricing datasets and polyurethane installer rate sheets, normalized to installed cost including drilling, material, lift and hole patching. Replacement multiple reflects typical demolition, disposal and new pour pricing for the same area. · Last reviewed July 30, 2026 · Reference data · How we compile these figures
The first two rows are the whole method choice in summary: slurry is cheaper and heavier, foam costs more and weighs a fraction as much, which matters on soil that already demonstrated it could not carry what was above it. The full comparison, with weight, hole size, cure time and service life side by side, is on mudjacking cost. One practical note that applies to both: nearly every company has a minimum charge, so bundling all your sunken flatwork into a single visit is the easiest saving in this category.
What slab jacking cannot do, and when to spend nothing
Slab jacking fills a void. It does nothing about whatever created the void, and that is the honest limitation of the method rather than a criticism of it. Where a downspout discharges beside the driveway, an irrigation line leaks, or a broken drain washes soil out from under a patio, the gap reopens and the slab follows it down again. Correcting the water costs $100 – $600, and doing it alongside the lift is what turns a five-year repair into a much longer one.
Several versions of this problem also deserve no contractor at all. A drop under about half an inch with no trip hazard is a cosmetic condition on flatwork that carries none of your house — watching it for a season costs nothing and tells you whether it is still moving. A single raised lip is a grinding job at $100 – $300 that removes the hazard in under an hour. And settling that is currently active is worth pausing on: lifting a slab over soil that is still washing out means paying twice, so find the water first and let the ground settle before booking the lift.
One boundary is worth naming clearly. Slab jacking is flatwork repair, and it has nothing to do with foundation settlement. Where the house itself is dropping rather than the concrete beside it, the repair is underpinning at $1,250 – $3,100 per pier, and it starts with an independent structural engineer at $450 – $600 rather than a lifting crew. That distinction is set out in slab foundation repair cost.
When replacing the concrete beats lifting it
On a sound slab, lifting wins comfortably. It costs roughly a third to a half of replacement — replacement runs about two to three times the price of a lift for the same area — finishes in hours instead of days, and leaves no fresh gray panel sitting in the middle of a weathered driveway.
Replacement becomes the right answer when the concrete has failed as a material, because a lift depends entirely on the slab behaving as one rigid piece. Look for crumbling or scaling across the surface, spalling with rust staining that says the reinforcement is corroding, a panel broken into several loose pieces that would move independently under pressure, or edges you can break away by hand. Concrete in that condition comes apart when pressure arrives underneath it, and a contractor who recommends replacing it is giving you accurate advice.
The gray area is a slab with a couple of clean cracks and otherwise sound concrete. That often lifts as two or three pieces, with the operator managing each side of the crack, so ask a lifting company directly rather than assuming replacement. Where a contractor recommends replacing a slab that looks intact to you, the useful question is specific: what about this concrete makes it unable to be lifted.
Where to go next
- Mudjacking cost — priced per square foot, with the full foam comparison.
- Slab foundation repair cost — lifting against underpinning, by problem.
- Underpinning cost — per-pier pricing for genuine house settlement.
- House leveling cost — what releveling a whole house costs.
- Foundation repair cost — every repair type, itemized.