How Concrete Leveling Works
Mudjacking (Slab Jacking)
Mudjacking pumps a cement slurry mixture (typically cement, sand, and water) through small holes drilled in the slab. The slurry fills voids beneath the slab and lifts it as pressure builds. The holes are patched after the slurry is injected.
- Hole size: 1.5-2 inch diameter
- Injection material: Cement slurry (weight approximately 100 lbs/cubic foot)
- Cure time: 24-48 hours before full use
- Best for: Voids under stable soil; garage floors, driveways, walkways, steps
Polyurethane Foam Injection
Foam injection uses expanding polyurethane resin through smaller holes (5/8 inch). The foam expands to fill voids and lift the slab. It weighs much less than slurry (2 lbs/cubic foot vs. 100 lbs) and cures in minutes.
- Hole size: 5/8 inch diameter (barely visible when patched)
- Injection material: Two-part polyurethane resin
- Cure time: 15-30 minutes
- Best for: Interior slabs, areas where adding weight to soil is a concern, smaller voids
How Foundation Repair (Piering) Works
Foundation pier installation addresses the soil stability problem at depth. Piers are driven past the problem soil layer to competent bearing - rock, dense natural soil, or soil that doesn’t move with moisture changes.
The existing slab is supported by the piers rather than by the problem soil beneath it. The foundation is then lifted using hydraulic jacks acting through the installed pier brackets.
This is a fundamentally different intervention - it doesn’t fill a void; it bypasses the problem soil entirely.
Decision Guide
| Factor | Use Concrete Leveling | Use Foundation Repair |
|---|---|---|
| Soil type | Stable (sand, gravel, organic fill) | Expansive clay, loose fill |
| Settlement cause | Void formed by erosion or decomposition | Soil bearing capacity loss |
| Settlement amount | Minor (< 2 inches, localized) | Significant or widespread |
| Settlement status | Static (not recurring) | Active or recurring |
| Area affected | Isolated slab sections | Home’s structural floor |
| Soil quality at depth | Competent | Soft, loose, or expansive |
| Budget priority | Lower cost solution | Long-term stability |
Warning Signs That Leveling Alone Won’t Work
- The area has previously been mudjacked and settled again
- You’re in a high-clay-soil region (Texas, Oklahoma, Colorado)
- The settling is affecting multiple rooms or the entire perimeter
- There are accompanying structural symptoms (sticking doors, cracking walls)
- A contractor has documented expansive or unstable soil conditions at the site
If any of these apply, concrete leveling is likely to be a temporary fix. The cost difference between mudjacking now and adding the piering cost later is often greater than just doing the piering correctly the first time.
Cost Comparison
| Solution | Typical Residential Cost | Durability on Stable Soil | Durability on Problem Soil |
|---|---|---|---|
| Mudjacking | $500-$2,500 | Long-lasting | 1-5 years |
| Foam injection | $500-$2,500 | Long-lasting | 1-5 years |
| Helical/push piers (full project) | $8,000-$25,000 | 25-50+ years | 25-50+ years |
| Piers + foam hybrid | $5,000-$15,000 | Long-lasting | Long-lasting |
For garage floors, driveways, and walkways in stable-soil areas, concrete leveling is an excellent, cost-effective solution. For a home’s structural floor slab on problem soil, piering is the appropriate long-term approach.