Foam vs. Mudjacking: How Concrete Lifting Works

What concrete lifting is

Up front: the Oregon and Wisconsin reports below look at highway and bridge-approach slabs, not houses, so read their details as a description of the methods only, not as findings about house foundations. Concrete lifting raises a settled slab from below. A 2002 Oregon Department of Transportation research report describes the conventional approach for raising in-place concrete slabs as pressure-injecting grout under the slab, and studies polyurethane injection as the alternative (Oregon DOT, Injected Polyurethane Slab Jacking, Final Report SPR 306-261, 2002, state transportation research report, checked 2026-10-19).

Mudjacking (slurry or grout jacking)

In the Oregon report's description, holes 2 to 3 inches across are drilled through the concrete to the base soil, grout goes in through them, injection pressure controls how much the slab rises, and the grout generally fills voids only near each hole (Oregon DOT report, checked 2026-10-19). A Wisconsin Department of Transportation study calls mud-jacking a grouting process that brings slabs back to near-original levels, with grout filling voids in the subgrade through two- to three-inch access holes that then have to be filled (WisDOT, Evaluation of the URETEK Method of Pavement Lifting, 2007, state transportation research report, checked 2026-10-19).

Foam lifting (polyurethane)

The Oregon report outlines one foam process: holes about 16 mm (0.63 inch) across are drilled through the pavement, and two liquid chemical components are injected at the same time. They react at once into a rigid polyurethane foam whose volume is several times that of the liquids, and that expansion lifts the slab; the rate of injection controls the rise (Oregon DOT report, checked 2026-10-19). The FPA adds that once the injections are done, the lifted part of the slab sits on the foam (FPA-RC-01-0, §2.2, checked 2026-10-19).

Foam vs. mudjacking side by side

Neither source names a winner, and neither do we.

Concrete jacking vs. a structural foundation repair

On a house slab, the FPA's repair committee lists both methods with a pointed warning: each is a shallow repair system affected by active moving soil, so if the soil moisture changes, the slab can move again (FPA-RC-01-0, §2.1 and §2.2, checked 2026-10-19). Systems meant to reach below that moving soil, such as drilled piers, pressed piles and helical piers, are compared on our helical piers page; slab foundation repair covers the wider job, and our page on house leveling covers lifting a whole house.

Cost

We don't quote lifting prices here. Any figure we publish lives on the foundation repair cost page, credited to whoever published it.

Questions to ask before anyone lifts your concrete

The FPA's failure lists point to broken sewer or water pipes, poor drainage and trees (FPA-RC-01-0, cited above). Ask whether the work needs a city permit, and who pulls it. The FTC's advice is "Get multiple estimates," and it lists "Scammers ask you to get any required building permits" among the signs of a home improvement scam (FTC home improvement scam guide, checked 2026-10-20). For contract questions, ask an attorney. See also concrete leveling and who evaluates a foundation.

Compare foundation repair options

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When quote requests open, the contractor we refer you to will pay us for each referral; you pay us nothing. We're not a contractor.

Related: Signs of foundation problems · Slab foundation repair · Helical piers · Foundation inspection · Home