Concrete leveling · Comparison

Foam Leveling vs. Mudjacking

The short answer

Foam lifting and mudjacking both raise sunken concrete by filling the space underneath it. Foam uses a lightweight, waterproof polyurethane through 5/8-inch holes and is usable the same day; mudjacking pumps a heavy cement slurry through larger holes and usually costs less upfront. Foam generally lasts longer because it doesn't erode or add weight.

By Rob Diederich, owner · Updated October 2026

Side by side

	Polyurethane foam	Mudjacking
Material	Two-part polyurethane foam	Cement, sand and soil or limestone slurry
Weight added under the slab	A few lbs per cubic foot	Roughly 100 lbs per cubic foot or more
Hole size	About 5/8 inch	About 1-1/2 to 2 inches
Usable again	Same day	Usually after a day or more
Water	Waterproof, won't wash out	Can erode where water flows under the slab
Fine control	Very fine, stops when the slab hits the line	Good, but heavier and slower to react
Cost	Higher per pound of material	Usually the lowest upfront

Where foam wins

On soils that already failed. Heavy slurry adds load to the same weak soil that caused the problem; foam barely adds any.
Where water is the cause. Foam doesn't wash out the way slurry and soil can.
Where looks matter. Small holes on a front walk or patio are far less noticeable.
When you need it back fast, like a driveway or a business entrance.

When mudjacking can make sense

Mudjacking is a legitimate method. If you're filling a very large void under a slab that won't see much water, and budget is the deciding factor, slurry can be the cheaper way to do it. Ask any contractor what material they're using and what the warranty covers; a vague answer is a warning sign.

Can foam go where mudjacking was done before?

Usually, yes. If a slab was mudjacked years ago and has settled again, foam can be injected around or through the old material. The old large holes get patched too.

Questions

Common questions

Which lasts longer, foam or mudjacking?

Foam generally lasts longer. Polyurethane doesn't absorb water or wash out, and it adds very little weight to the soil. Mudjacking slurry is heavy and can erode where water flows under the slab, which is why mudjacked slabs sometimes settle again.

Which costs less, foam or mudjacking?

Mudjacking is usually cheaper upfront because the material is inexpensive. Foam costs more per job but tends to last longer and needs smaller holes, so the cost over the life of the slab is often similar or lower.

Why are foam holes smaller than mudjacking holes?

Foam goes in as a thin liquid and expands after it's under the slab, so it fits through a 5/8-inch port. Mudjacking slurry is thick and has to be pumped through holes around 1-1/2 to 2 inches wide.

Does mudjacking wash out?

It can. Slurry is cement mixed with sand or soil, and where water runs under the slab it can erode over time. That's one of the common reasons mudjacked slabs drop again.

Keep reading

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