Slab Lifting in Chattanooga, TN - Foam Injection vs Mudjacking

Mudjacking involves pumping a slurry of cement, water, and soil beneath the sunken slab through drilled holes. It is effective and has been used for decades, but the slurry is heavy - adding weight to the same soil that caused the problem. In clay soils, the additional weight can accelerate re-settlement within a few years. Polyurethane foam injection uses a two-part expanding foam that is lighter, sets in 15 minutes rather than 24 hours, and creates a more durable lift in expansive clay environments.

For interior slab lifting - floors inside the home that have sunk due to clay shrinkage or plumbing leaks - polyurethane foam is the preferred method because it requires smaller holes (5/8 inch vs 1.5 inch for mudjacking) and causes minimal disruption. Exterior concrete can use either method depending on budget and the underlying soil conditions. Chattanooga Foundation Repair Co. uses polyurethane foam for interior slab work and can advise on the best approach for exterior applications after inspecting the affected area.

Slab Foundation Repair in Chattanooga: Causes and Solutions

Post-tension and conventional slab foundations in Chattanooga face specific challenges from expansive clay soils. Slabs crack when differential movement occurs - when one part of the slab rises due to clay heave while another settles, or when the entire slab settles unevenly due to soil consolidation or erosion beneath it. Hamilton County's combination of clay soil and seasonal rainfall variability creates above-average risk for both heave and settlement in slab-on-grade construction.

Slab heave - upward movement driven by swelling clay - is most common in areas with poor drainage where soil beneath the slab stays consistently moist. Slab settlement occurs due to soil consolidation under heavy loads, erosion through plumbing leaks beneath the slab, or long-term drying and shrinkage of clay soils. Both conditions can produce similar symptoms - cracked walls, sticking doors, uneven floors - but require different repair approaches.

For slab settlement due to voids or soil loss, polyurethane foam injection is often the most effective approach. Small ports are drilled through the slab, foam is pumped beneath, and the slab rises back toward level as the foam expands and fills voids. The process is minimally invasive and can be completed in hours for most residential applications. For cases requiring bearing support to bedrock, slab piers provide a permanent solution.

Slab repair in Chattanooga requires accurate diagnosis of whether you are dealing with heave, settlement, or both - and in which zones of the slab. Our free inspections include elevation measurements across the slab to map movement patterns and determine the right repair strategy.