Yes, expanding foam (also known as polyurethane foam) can lift concrete. This approach, called polyjacking, involves injecting the foam rather than concrete slurry to fill voids and raise the concrete slab back into place. It’s often faster and requires smaller drill holes than traditional mudjacking, though it may come at a higher cost. Some contractors also prefer polyjacking over mudjacking for more damaged and delicate slabs.

A good slump height really depends on the project, but there is a use for nearly all slump levels. For example, low slumps are best in projects that require structure, such as curbs and roads. High slumps often require additional reinforcement, but they flow more freely into hard-to-reach spaces.

There is no real alternative to underpinning, although mudjacking and polyjacking are other repair methods that can add support from underneath your foundation. Rather than placing supportive piers under your structure, these involve pumping a material under your slab to lift a sunken section back into its original position. Polyjacking, in particular, is sometimes a suitable solution for stabilization issues under slab foundations, but underpinning is often accepted as the best and most permanent solution.

Most states and municipalities don’t require concrete mudjacking companies to carry a specific license, but they usually need to have a general contractor’s license, and they should be fully insured. The only exception is if the mudjacking company provides foundation repairs as well, or if it offers mudjacking for home foundations. In that case, they will typically need a foundation repair contractor’s license. You can check state requirements and then use Angi’s license lookup tool to confirm that a company is properly licensed to provide mudjacking services in your area.