Slab Lifting in Chattanooga, TN — Foam Injection vs Mudjacking

Sunken concrete slabs — driveways, patios, sidewalks, garage floors — are a common problem in Chattanooga's clay-heavy soils. When the clay beneath a slab dries and shrinks, it creates a void that causes the slab to sink and crack. Two primary repair methods exist: mudjacking (also called slabjacking) and polyurethane foam injection. Understanding the difference helps homeowners choose the right solution.

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.