Mudjacking vs Polyjacking: Which Lifting Method?
Updated June 2026
Both mudjacking and polyjacking lift a sunken slab back to grade by filling the void underneath, so you keep the concrete you already have instead of tearing it out. Mudjacking pumps a heavy sand and cement slurry through larger holes and suits big slabs on a solid base. Polyjacking injects a light, waterproof polyurethane foam through small holes and suits weak or wet ground where weight is a concern. Either one beats replacement when the slab itself is sound and only the base settled. The honest way to know which fits is a free site visit and a written quote.
A driveway slab that has dropped at one corner, a garage floor that slopes the wrong way, a walkway panel that now traps a puddle. The first instinct is to break it out and pour a new one. Most of the time you do not have to. If the concrete is still sound and the ground under it settled, the slab can be lifted back to where it belongs without replacement. The two ways to do that are mudjacking and polyjacking, and they suit different slabs. This guide walks through how each one works and how to tell which is right for yours.
How concrete lifting works at all
Both methods solve the same problem the same basic way. When a slab sinks, the concrete itself is usually fine. The base under it is what failed. Soil washed out, settled, or was never compacted properly, and the slab dropped into the empty space. Lifting puts the support back.
The crew drills holes through the slab, pumps material into the void underneath, and the pressure of that fill raises the slab back to grade. Then the holes get patched. That is the whole idea behind every name you see for it: mudjacking, slabjacking, polyjacking, concrete leveling, concrete lifting. The difference between the two main methods is what gets pumped in, and that one difference drives everything else, the hole size, the weight, the cure time, and the kind of job each one suits.
Mudjacking, the proven workhorse
Mudjacking, also called slabjacking, is the original method and still the right call on a lot of jobs. The crew drills holes through the slab, pumps a sand and cement slurry underneath, and the pressure raises the slab. The slurry hardens into a solid fill that carries the load.
It earns its place for a few reasons. The method is proven, it has lifted slabs for decades, and the slurry is a dense, strong fill once it sets. It does well under large, heavy slabs where the base below is solid, because there is no concern about the weight of the fill on good ground.
What you trade is worth knowing plainly. The slurry is heavy, which is fine over a solid base but adds load where the base is already weak. The access holes are larger, so the patches are more visible afterward. And because the fill goes in wet, the slab usually needs a day or two to set before it takes full traffic. On poor or shifting soil, a heavy slurry fill can settle again over time if the ground keeps moving under it. For a big driveway, a shed pad, or a walkway on decent ground, mudjacking is often the sensible, dependable choice.
Polyjacking, the lighter foam method
Polyjacking uses an expanding polyurethane foam instead of slurry. The crew drills much smaller holes, injects the foam, and it expands in place to fill the void and lift the slab. It is the newer method and it earns its keep in specific conditions.
The foam is light, so it will not pile more weight onto a base that is already struggling. That is its biggest advantage on weak or questionable soil. It does not absorb water, so it will not wash out where moisture caused the problem in the first place. The lift is precise, because the foam can be controlled to raise a slab gradually and evenly, which matters on a floor or any slab where level really counts. The holes are small, so the patches barely show. And the foam cures in minutes, so the slab usually takes traffic the same day.
The trade is cost. Polyjacking costs more than mudjacking. On the right slab, where the base is weak or wet, where precision matters, or where the area has to reopen fast, the foam is worth it.
Mudjacking vs polyjacking, side by side
| Factor | Mudjacking (slabjacking) | Polyjacking (foam) |
|---|---|---|
| Fill material | Sand and cement slurry | Expanding polyurethane foam |
| Weight on the base | Heavy | Light |
| Hole size | Larger | Smaller |
| Lift precision | Good for general leveling | Precise, controlled |
| Water resistance | Can wash out in wet ground | Does not absorb water |
| Back in service | A day or two | Same day |
| Best fit | Large slab on a solid base | Weak or wet base, precision lifts |
| Cost | More affordable | Higher |
Neither column is the right answer for every slab. The slurry suits a solid base where the slab is large and the weight is no concern. The foam suits a weak or wet base, a slab where the lift has to be exact, or a job that has to be back in use right away. A good contractor reads the slab and the ground and tells you which fits, instead of selling one method for every driveway.
When lifting beats replacement
This is the question that decides whether you are even in a lifting conversation. When a slab sinks, the concrete usually is not the problem, the base under it is. The slab above is often still perfectly good.
Replacement throws that good concrete away. You pay to break the slab out, haul it off, rebuild the base, pour a new slab, and lose the use of the area for days while it cures. Lifting keeps the slab you already have and just puts the support back under it. That is why lifting a sound slab back to grade comes in well under the cost of tear-out and repour. So the first question on any slab is not which method, it is whether your slab is a lift candidate at all. If it is, you have likely saved most of the job already.
When to replace instead
Lifting is not always the honest answer, and this is where a real contractor earns the site visit. The test is whether the slab is still sound as a single piece.
A slab that is intact, or has only a hairline crack or two, sitting on a base that washed out or settled, is a textbook lift. The concrete is fine. Put the support back and it is good for years. That is the common case for driveways, garage floors, walkways, patios, and porch slabs across Southern Ontario.
The flip side is the slab that has failed as a unit. Concrete cracked into several pieces, badly spalled across the surface, or crumbling at the edges cannot be lifted as one piece, because raising it would just grind the broken sections against each other. That slab is a replacement, and a contractor who tries to lift it anyway is wasting your money. A sound slab on a failed base is a lift. A broken slab is a replacement.
What each job involves on site
Both methods follow the same shape on the day, so you know what to expect. The crew checks that the slab is a lift candidate, marks the hole pattern, and drills. Mudjacking holes are larger and spaced for the slurry to spread; polyjacking holes are small and tidy. Then the fill goes in, slurry pumped under pressure or foam injected and left to expand, and the slab rises back to grade as the void packs out. The crew watches the level the whole way and stops at grade. Last, the holes get patched flush.
There is one more part of an honest job that has nothing to do with the fill. If water is what carried the soil away, the fix has to deal with the drainage too, the downspout discharging in the same spot, the grading that sends runoff at the slab, the eavestrough that leaks beside a footing. Fill the void without fixing the water and the slab settles again. Solving the cause is part of doing the lift right.
Cure, return to use, and Ontario freeze-thaw
The cure difference is one of the clearest reasons to pick one method over the other. Mudjacking slurry is wet when it goes in and needs time to set, so the slab usually waits a day or two before it takes full traffic. Polyjacking foam cures in minutes, so a driveway or garage floor is often back in service the same day. If the area cannot be out of use for long, that gap decides it.
Freeze-thaw is the Ontario backdrop to all of this. Our soil holds water, that water freezes and thaws through the winter, and the cycle keeps shifting the ground and opening voids under slabs. It is a big reason slabs sink here in the first place, and it is why the drainage fix matters so much. Waterproof foam has the edge in wet ground because it will not wash out as the soil keeps moving, while a slurry fill on a base that stays wet can settle again. On dry, solid ground, neither cares much about the cycle once the void is properly filled.
Getting a real answer for your slab
There is no way to settle this down the phone, because the whole question is whether your slab is sound and which method the soil calls for, and only someone looking at it can tell you. A fair quote names whether the slab is a lift candidate or a replacement, which method fits and why, and whether the drainage that caused the settling needs attention.
The honest way to get that answer is a free site visit and a written quote that holds. If your slab is sound, lifting almost always beats replacement, and you keep the concrete you already paid for. Union-certified crews do the work, the quote you sign is the bill you get, and a lifetime warranty on labour stands behind it. Tell us where the slab is and what it is doing, and we will come take a look.
What is the difference between mudjacking and polyjacking?
Both lift a sunken slab by pumping material under it through holes, but the material is different. Mudjacking uses a sand and cement slurry, sometimes called slabjacking. The fill is heavy, the holes are larger, and the slab usually needs a day or two before it takes traffic. Polyjacking uses an expanding polyurethane foam. The holes are smaller, the foam is light so it does not load a weak base further, it does not absorb water, and the slab usually takes traffic the same day. Which one fits depends on the slab and the ground under it.
Is mudjacking or polyjacking better?
Neither is better for every job, and a contractor who pushes one method for everything is selling, not solving. Mudjacking suits a large slab on a solid base where the heavier fill is no problem. Polyjacking suits a weak or wet base, a slab where the lift has to be precise, or a job that has to be back in use right away, because the foam is light, waterproof, and cures fast. A crew that reads the slab and the soil first tells you which fits yours.
Should I lift my slab or replace it?
If the slab is sound as one piece and only the base under it settled, lifting is almost always the call, because you keep the original concrete and skip the tear-out. Lifting stops making sense when the slab itself has failed. Concrete cracked into several pieces, badly spalled, or crumbling at the edges cannot be raised as one unit, so replacement is the honest answer. The short version: a sound slab on a failed base is a lift, a broken slab is a replacement.
How long does concrete lifting last?
It lasts as long as the new support under the slab holds, which is usually a long time when the void is filled properly and the cause of the settling is fixed. Both the mudjacking slurry and the polyurethane foam fill the empty space and carry the load. Foam does not absorb water and will not wash out, which is why it is often chosen where moisture caused the sinking in the first place. Lifting is a real repair when the slab is still good, not a temporary patch.
How long before I can use the slab after it is lifted?
It depends on the method. Mudjacking uses a wet slurry that needs time to set, so the slab usually waits a day or two before it takes full traffic. Polyjacking foam cures in minutes, so a driveway or floor lifted with foam is usually back in service the same day. If a job has to reopen fast, that cure difference is often the deciding factor between the two methods.
Does freeze-thaw affect a lifted slab in Ontario?
It does, and it is part of why slabs sink here in the first place. Southern Ontario soil holds water, that water freezes and thaws through the winter, and the cycle opens voids under slabs as the ground shifts and washes out. A proper lift fills that void and, where water is the cause, addresses the drainage so the slab does not settle again. Waterproof foam has an edge in wet ground because it will not break down or wash out the way it sometimes can where moisture keeps moving soil.