What Is Concrete Leveling?
Concrete leveling is a repair method that lifts settled slabs back into their original position by injecting material beneath the concrete. Instead of demolishing and repouring — which is expensive, time-consuming, and messy — leveling fills the voids beneath the slab and raises it from below.
Two methods are commonly used: mudjacking (also called slab jacking or stone slurry grout leveling) and polyurethane foam injection. Both are proven, cost-effective alternatives to full replacement.
Signs You May Need Concrete Leveling
- Sunken or sinking slabs — sections of your driveway, sidewalk, or patio have dropped below their original level
- Uneven surfaces — adjacent slabs sit at different elevations, creating lips or steps
- Trip hazards — even a half-inch elevation difference can cause someone to stumble
- Pooling water — settled concrete creates low spots where rainwater collects instead of draining away
- Gaps beneath slabs — visible voids under the concrete where soil has eroded or settled
- Cracking — settlement stress causes cracks as the slab shifts and bends
How Concrete Leveling Works
The process is straightforward and typically completed in a few hours for residential projects:
- Inspection — The area is assessed to determine the cause of settlement, the extent of the drop, and the best leveling method for the situation.
- Drill access holes — Small holes (5/8 inch for polyurethane foam, 1-2 inches for mudjacking) are drilled through the sunken slab.
- Inject material — Mudjacking slurry or polyurethane foam is pumped beneath the slab, filling voids and gradually raising the concrete.
- Lift and level — The slab is raised to the desired elevation with controlled pressure for precise results.
- Patch and clean up — Access holes are patched with concrete or grout, the area is cleaned, and the surface is ready for use.
With polyurethane foam, the surface is typically ready for foot traffic within 15 minutes. Mudjacking usually requires 24-48 hours before the surface can handle heavy loads.
Concrete Leveling Methods
Mudjacking
Mudjacking pumps a slurry of pulverized limestone and cement beneath the slab through 1-2 inch holes. The dense fill compacts the soil and lifts the concrete. It's cost-effective for larger areas and provides solid, heavy support. Learn more about mudjacking →
Polyurethane Foam Injection
Polyurethane foam injection uses expanding geo-foam pumped through smaller 5/8-inch holes. The foam expands to fill voids and lift the slab with precision. It's lightweight, hydrophobic, and sets in 15 minutes. Learn more about polyurethane foam →
Not sure which method is right for your project? See our detailed mudjacking vs. polyurethane foam comparison.
Common Applications
- Driveway leveling — sunken or sloping driveways
- Sidewalk leveling — uneven walkways and trip hazards
- Patio leveling — settled patios and pool decks
- Garage floor leveling — sinking garage slabs
- Steps and stoops — settled entryway concrete
- Commercial slabs — warehouse floors, parking lots, ADA ramps
Cost Factors
The cost of concrete leveling depends on several factors, including the size of the area, the amount of settlement, the leveling method chosen, site accessibility, and the number of slabs involved. In general, concrete leveling costs 50-70% less than full replacement.
For a detailed breakdown of pricing factors, see our concrete leveling cost guide.
How Long Does Concrete Leveling Last?
When done correctly, concrete leveling is a long-lasting repair. The material injected beneath the slab fills voids and provides stable support. However, no repair is truly permanent if the underlying cause of settlement — such as poor drainage or soil erosion — is not addressed. Results last longest when drainage issues are corrected as part of the project.
Minnesota's freeze-thaw cycles are the primary cause of concrete settlement in the Minneapolis area. Understanding why concrete sinks in Minnesota can help you prevent future problems.
Frequently Asked Questions
Most settled concrete can be leveled if the slab is structurally sound. If the concrete is severely cracked, crumbling, or spalling, replacement may be the better option. An on-site assessment can determine which approach makes sense for your situation.
Most residential projects are completed in 2-4 hours. Polyurethane foam sets in 15 minutes, so the surface is usable the same day. Mudjacking typically requires 24-48 hours before heavy use.
Access holes are patched with concrete or grout that matches the surrounding surface as closely as possible. Polyurethane foam uses smaller holes (5/8 inch) that are less noticeable. While the patches won't be invisible, they are typically subtle.
Leveling lifts the slab and can close some cracks by realigning the pieces. However, existing cracks may still need to be sealed separately to prevent water infiltration. Crack sealing is often done as part of the leveling project.