Mudjacking in Chattanooga

How Mudjacking Works

Mudjacking, sometimes called slabjacking or concrete pressure grouting, is one of the oldest slab-lifting techniques still in regular use. The procedure starts with the installer drilling a series of holes through the settled slab, typically 1.5 to 2 inches in diameter and spaced 4 to 6 feet apart in a grid pattern. A pump then forces a cement-based slurry through these holes into the space beneath the slab.

As the slurry enters, it first fills any voids that have formed beneath the concrete (from soil erosion, settling fill, or compaction over time). Once voids are full, continued pumping builds hydraulic pressure that lifts the slab. The installer monitors elevation across the slab using a string line or laser level and adds slurry progressively to bring the slab uniformly back to grade. When the slab is at the target elevation, the drilled holes are patched with mortar or concrete colored to roughly match the original slab.

Slurry composition

Traditional mudjacking slurry is a mixture of portland cement, water, sand, and sometimes clay or fly ash as a filler. The mix is engineered to flow under pressure but cure to a stable, load-bearing mass. Cured slurry has a density of roughly 100 pounds per cubic foot, which is significantly heavier than the polyurethane foam used in the foam-leveling alternative method.

When to Pick Mudjacking

Mudjacking is the right method when four conditions are met:

1. Exterior concrete. Driveways, sidewalks, patios, pool decks, and concrete steps are textbook mudjacking applications.
2. Supporting soil can carry the added weight. Because the slurry is heavy, the soil below must support both the original slab and the new fill weight. Loose fill or organic soils that compress under load may not.
3. Lift precision under half an inch is not required. Mudjacking can hit within roughly a half-inch of target elevation. For precise lifts (matching adjacent fixed slabs to a quarter inch), foam leveling is more controllable.
4. Cost is a factor. Mudjacking is the lowest-cost slab-lifting method per area.

Mudjacking vs Polyurethane Foam Leveling

Decision rule: pick mudjacking when the slab is exterior and the supporting soil is firm. Pick polyurethane foam leveling when soil is compressible, when the access holes need to be smaller, when cure time matters, or when the precision requirement is tighter than half an inch.

Project Timeline and Cure

Most residential mudjacking projects are single-day jobs:

• 2 to 6 hours of on-site work for typical residential slab sizes
• Foot traffic is fine within hours of completion
• Vehicle traffic must wait 24 to 48 hours for full cure
• Rain during the cure window can wash out unstable slurry and is the main weather concern

Cost

Per Bob Vila’s May 2024 cost guide, mudjacking runs $500 to $1,300 per area, with most residential single-area projects falling near the middle of the range. Per-square-foot pricing is roughly $3 to $6 depending on slab thickness, lift height, and access. See the foundation repair cost guide for full method comparison.