Slab Jacking Lifts Sunken Concrete Back to Level Without Full Replacement

Polyurethane foam concrete lifting (also called polyjacking or foam jacking) is the modern replacement for traditional mudjacking. Where mudjacking injects a heavy cement-sand slurry that adds weight and can wash out over time, this method uses a two-component polyurethane foam that is injected as a liquid, expands to fill the void completely, and cures into a rigid, waterproof cellular structure that permanently supports the slab from beneath. At Ground Up Foundation Repair, we use polyurethane foam lifting for driveways, sidewalks, pool decks, patios, garage floors, and interior concrete slabs that have settled due to soil voids, erosion, or inadequate compaction. The foam is injected through 5/8-inch holes drilled through the slab at strategic locations. Once injected, the foam reaches working expansion within seconds and lifts the slab to the target level within minutes. Injection ports are patched with concrete caulk and the surface is ready for use immediately, no cure time required. Polyurethane foam is waterproof, does not wash out, does not add meaningful structural load, and does not compress further under normal loading conditions.

Foam injection for concrete void filling is a targeted, preventive application of polyurethane foam used to fill sub-slab voids before they cause visible settlement or slab failure. While polyjacking uses foam to actively lift an already-settled slab, void-filling foam injection is used where ground-penetrating radar or hollow-tap surveys have located a void beneath a slab that is still at grade. By filling the void while the slab is still level, we prevent the sudden drop that occurs when remaining support fails. This application is common beneath garage floors, interior concrete slabs, warehouse floors, and any flatwork area where a hollow sound is detected during inspection. The injection process is nearly identical to polyjacking: small holes are drilled through the slab, foam is injected to fill the void, and holes are patched. Because the slab is not being raised, the process requires precise foam volume control to fill the void without over-lifting.

Concrete joint sealing is the process of filling and sealing the planned control joints, expansion joints, and construction joints in concrete flatwork to prevent water, debris, and vegetation from entering beneath the slab. Every concrete driveway, patio, and sidewalk has joints, either cut into the slab at installation to control cracking, or formed between pours on different days. These joints are intentional features of the slab, but they must be maintained. When joint sealant deteriorates, cracks, or was never installed in the first place, the open joint becomes a direct pathway for water to enter and erode the soil beneath the concrete. In Middle Tennessee, with roughly 47 inches of annual rainfall and expansive red clay soils that are easily destabilized by water, open concrete joints are one of the primary drivers of the slab settlement and cracking that Ground Up is called to repair. Sealing joints proactively, or resealing them when deteriorated, is the most cost-effective maintenance a homeowner can perform to extend the life of their concrete.

Mudjacking, also called slabjacking or pressure grouting, is the traditional method of lifting settled concrete slabs. It works by pumping a slurry mixture of water, soil, and cement beneath the slab through holes drilled in the concrete. As the slurry fills voids and builds pressure, it lifts the slab. Mudjacking has been used for concrete lifting since the 1930s and is widely available across the country. However, it has significant limitations compared to modern polyurethane foam lifting methods. Ground Up Foundation Repair primarily uses polyurethane foam lifting for concrete lifting in Middle Tennessee because of its superior weight-to-strength ratio, faster cure time, and longer-term stability. We explain mudjacking honestly so homeowners can make informed decisions about their concrete repair options.

NexusPro is a professional-grade, flexible polyurethane joint and crack sealant engineered for concrete flatwork. Unlike rigid fillers and hardware-store caulks that crack and debond with the first seasonal freeze-thaw or thermal expansion cycle, NexusPro remains elastic after curing, it flexes with the concrete rather than fighting it. This flexibility is especially valuable in Middle Tennessee's climate, where concrete surfaces experience wide temperature swings between winter freezes and summer heat, and where red clay soil movement causes slabs to shift slightly across every wet and dry season. NexusPro is also UV-resistant, meaning it does not degrade, yellow, or become brittle from sun exposure, a critical property for outdoor applications in Tennessee's sunny summers. Ground Up uses NexusPro to seal control joints, expansion joints, random cracks, and the joints between adjacent slabs on driveways, patios, pool decks, sidewalks, and garage floors.

This polyurethane foam is a two-component, high-density system used to lift and stabilize sunken concrete slabs. Developed specifically for slab lifting applications, it expands when its two components mix beneath the concrete, filling voids and gently raising the slab back to its original position. Because the cured foam weighs only about 2 lbs per cubic foot, compared to the 100+ lbs per cubic foot of traditional mudjacking slurry, it adds virtually no load to the soil beneath the slab. This lightweight property is one of the key reasons foam-lifted slabs are far less likely to re-settle than slabs lifted by mudjacking. Ground Up Foundation Repair uses polyurethane foam lifting across Middle Tennessee for driveways, patios, garage floors, sidewalks, pool decks, and other residential concrete flatwork.