Slab Jacking: Lifting and Leveling Sunken Concrete Slabs

A concrete slab is only as steady as the soil under it. When that soil settles, erodes, or washes out, the slab loses support and begins to sink, crack, or tilt.

The reason varies by region. In the Sandhills around Fayetteville and Pinehurst, loose sandy soils can erode and leave voids beneath a slab. In the Piedmont, water moving through clay can carry fine material away and leave gaps, and in coastal areas saturated soils can compress over time. Soil that was not compacted well during construction is another common cause.

The result is the same: an unsupported slab that drops. Inside a home, that can show up as cracks running across the floor, and on a tiled floor as tile and grout that split along one line.

Slab jacking, also called slab lifting and leveling, restores support without removing and repouring the concrete. We drill small ports, then pump material beneath the slab to fill the voids and raise it back toward its proper elevation.

The material is a polyurethane foam that expands as it cures. Lifting a slab back toward level can close gaps that opened as it settled, reduce trip hazards, and keep water from pooling toward a sloping slab.

A cement slurry, used in mudjacking, is a heavier, denser fill. Polyurethane foam is lighter, cures quickly, resists water, and adds less weight to the soil beneath the slab, which can matter where that soil is weak. HydroHelp911 lifts slabs with polyurethane foam.

Where the problem is loose soil, grout injected into the loose soil can fill and pack it so the ground gives steadier support. We look at the slab, the soil, and the access before recommending a repair.

Slab lifting is not the answer when the concrete is badly broken apart, or when the soil beneath it is still failing. If a slab keeps dropping because the soil below keeps settling, slab piers set in firmer soil may be the better fit, because they carry the weight of the slab down past the layer that moves.

Where the house itself is settling, the repair moves to repairing the slab foundation itself, and we check for signs such as one corner of the house dropping. Every slab repair begins with a free inspection of slab and soil, and we will tell you whether lifting is the right approach.