High-density foam is polyurethane formulated with more material per cubic foot, giving it greater compressive strength for lifting and supporting heavier slabs and higher loads.
In depth
Foam density is measured in pounds per cubic foot (PCF), and higher density generally means higher strength. Lower-density residential foams handle patios, walkways, and light floors, while high-density formulations are used for commercial slabs, machine bases, heavy traffic, and infrastructure. Selecting the right density for the load is what makes a repair last.
Even high-density lifting foam remains far lighter than mudjacking slurry, so it adds strength without meaningfully increasing the weight the subgrade must carry.
How Acme applies it. Acme’s lineup spans densities: RR-201 (2.5 to 2.99 lb/ft3) for residential work, RR-401 (4.0 to 4.5 lb/ft3, about 121 PSI) as its everyday commercial foam, and RR-601 (6.0 to 6.5 lb/ft3, about 292 PSI) for extra-heavy infrastructure such as the I-294 Tollway.
Related terms: Foam Density, Compressive Strength, Polyurethane Foam, Slab Lifting
Frequently asked questions
Is higher-density foam always better?
No, it is matched to the load. High-density foam is used for heavy slabs and infrastructure, while lighter foam is ideal and more economical for residential flatwork.
Does high-density foam add a lot of weight?
Not compared with mudjacking. Even at 6+ lb/ft3 it is a small fraction of the 100+ lb/ft3 of slurry, so it strengthens support without overloading the soil.