Open Concrete Joints Are Channels for Water. Seal Them Before They Cause Settlement

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.

Ground Up uses 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, this sealant 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. The sealant 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 seals control joints, expansion joints, random cracks, and the joints between adjacent slabs on driveways, patios, pool decks, sidewalks, and garage floors.

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.

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.

Concrete slab replacement is the last-resort solution when a slab is too severely damaged, shattered, or deteriorated to be lifted and restored. While Ground Up Foundation Repair prioritizes concrete lifting with polyurethane foam as a faster, less expensive, and less disruptive solution for most settled concrete, there are situations where the slab itself has failed beyond repair, where cracks have proliferated through the full depth of the concrete, where sections have broken into multiple displaced pieces, or where severe spalling has compromised the structural integrity of the slab. In these cases, full removal and replacement is the only path to a safe, durable concrete surface. The key difference in how Ground Up approaches replacement is our focus on proper sub-base preparation: addressing the soil conditions that caused the original failure so that the new slab does not repeat the same settlement cycle.