Mudjacking - lifting slabs with cementitious slurry

What is mudjacking?

Mudjacking (slab jacking with slurry) lifts sunken concrete by drilling ports through the slab and pumping a cement-based mix into the void beneath until the panel rises back toward grade. The material is heavier and the holes are larger than foam injection. It has decades of field use on sidewalks, driveways and pads where mass is acceptable and access for slurry equipment is good.

Signs you need mudjacking

• A driveway, sidewalk, patio or garage apron panel sits low at a joint or corner
• You can see a void or hear a hollow area under a still-intact slab
• Water ponds on a panel that used to drain, or drains toward a building
• A trip lip has formed between two otherwise solid sections
• You prefer a cementitious fill under a thick outdoor slab rather than polymer foam
• A previous thin patch on the surface keeps failing because the slab is still low

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How mudjacking actually works

1. 1

   Confirm the slab is worth lifting

   Mudjacking needs concrete that still acts as a panel. Wide structural cracks into many pieces, severe spalling, or reinforcement exposed and rotting are replacement candidates. Lifting rubble creates level rubble.

   Watch forA mudjacking quote on a slab that should be demoed. If the surface is failing, height is not the main problem.

2. 2

   Find why it settled

   Washout from downspouts, poorly compacted trenches, organic soil rot-out and plumbing leaks under slabs all create voids. The slurry fills the void; it does not stop active erosion. Water management has to be part of the plan.

   Watch forLift-only proposals next to a downspout that still dumps at the edge. Expect a return visit in a few seasons.

3. 3

   Drill ports and mix slurry

   Holes are typically larger than foam ports - often in the range used for traditional mudjacking equipment - arranged so the panel can be raised evenly. The slurry is a pumpable cementitious mix; exact recipes vary by contractor and soil conditions.

   Watch forRandom holes with no lift sequence. One-corner pumping cracks slabs that would have survived staged lifting.

4. 4

   Pump, watch, and stop at grade

   Material is injected while the crew watches joints and elevations against a reference. The slab should rise gradually. Overlift creates a new trip hazard the other way.

   Watch forNo laser, string line or fixed reference. "Looks about right" is how overlift happens.

5. 5

   Patch ports and control traffic

   Holes are filled and finished flush. Because the fill is cementitious and heavy, cure and traffic rules depend on the mix and weather. Ask when vehicles or heavy point loads may return.

   Watch forSame-afternoon truck traffic promised without a cure basis. Early loads punch into soft subbase even if the surface looks hard.

6. 6

   Address the water path

   Regrade edges, extend downspouts, seal open joints that feed water under the slab. Mudjacking without drainage work is often a temporary cosmetic.

   Watch forJoint sealing sold as optional when open joints are clearly feeding the void you just filled.

7. 7

   Compare quotes on scope, not slurry brand names

   Two mudjacking bids can look similar until you compare whether drainage corrections, joint sealing, traffic protection and re-visit terms are included. The cheap number is often a lift-only line that leaves the failure mode untouched.

   Watch forMaterial volume estimates that seem wildly different for the same panel without explanation of void size assumptions.

What does mudjacking cost?

Mudjacking is usually priced by square footage lifted or by hole count and material volume. It is often less than full replacement of the same panel and can undercut foam on some large, simple outdoor slabs - though access, thickness and void size move the number. Compare written scopes, not method brand names alone.

See the full mudjacking cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →