What Causes an Uneven Concrete Driveway and How Do You Fix It?

An uneven concrete driveway can develop when the soil beneath it settles, tree roots push against the slab, or frost heave forces the concrete upward. Before choosing a repair, it’s important to understand what caused the movement and assess the condition of the slab. Some sound, settled slabs may be suitable for concrete raising, while severely damaged concrete may need a different solution. This guide covers common causes of uneven driveways and the repair options to consider.

Is the Uneven Slab Higher or Lower Than the Rest?

Compare the uneven slab’s height with an adjacent section that appears stable. If it sits below that section, it may have settled. If its edge sticks up above it, something may have pushed it from below. The cause matters when deciding between concrete raising and resurfacing, so have a contractor assess height differences that you cannot confidently explain.

A straight board laid across the joint can help show a difference in height, though it can’t confirm why the slab moved or which repair it needs.

Why Does Part of a Concrete Driveway Sink?

The University of Wisconsin Extension guidance on concrete slabs notes that poorly compacted soil beneath a slab can settle over time and cause the slab to fail early. The same guidance explains that if expansive soil is too wet when a slab is placed, later drying and shrinkage may leave parts of the slab unsupported.

As Pavement Interactive notes, rain and snowmelt can carry surface water into pavement through cracks, joints and nearby unpaved areas. 

If the concrete is still in good condition, raising it may be an option for a sunken driveway. Our guide to leveling a sunken driveway explains how the process works and what it actually  involves.

What Pushes a Driveway Slab Up?

Tree roots are one cause. Iowa State University Extension explains that roots grow under pavement and push sections up as they thicken, and it names driveways along with sidewalks.

Another cause is frost heave, which occurs when ice forms in frost-susceptible soil and pushes the pavement upward. It requires suitable soil, freezing temperatures and available water. When that ice melts, the soil can stay saturated and lose bearing capacity for a while. The University of Wisconsin guidance on concrete slabs recommends draining water away from slabs to help reduce frost heave problems. Check downspouts and runoff when assessing the cause, but don’t assume drainage alone will correct a slab that has already risen. 

How Do You Fix an Uneven Concrete Driveway?

The right repair starts with understanding what caused the driveway to become uneven and checking the condition of the concrete. Use the table below to identify possible causes and repairs to discuss with a contractor.

What You See	Likely Cause	What Addresses It
One slab sits lower than its neighbors and is still in one piece	Possible settlement or loss of support	Slab lifting may be suitable if the slab is sound and the contractor confirms the underlying conditions can be addressed
A slab edge sticks up near a tree	Possible root-related movement	Have the slab and nearby roots assessed; the appropriate repair depends on the cause and the slab’s condition
A slab rises in freezing weather	Possible frost heave	Have the cause assessed and ask whether drainage changes or slab repair are appropriate
The slab is badly cracked	Damage to the slab itself	May be too damaged to lift; ask about other options
The driveway is blacktop or gravel	Not a concrete slab	Replacement or reinstallation

Iowa State University Extension’s guidance on managing trees near sidewalks describes several options for root-lifted sidewalks:

• Grinding or shaving: Removing part of a raised surface can reduce a trip hazard, but it is a temporary measure because the roots may continue growing.

• Patching: Asphalt or concrete patches can create a smoother transition between uneven sections, though they do not stop root growth.

• Rebuilding over the roots: A replacement sidewalk can be designed to slope over the roots, with suitable support beneath it.

  
  

These examples apply specifically to sidewalks. A contractor should assess whether a similar approach is suitable for a driveway, considering the slab’s condition, vehicle loads and nearby tree roots.

What Should You Note Before Getting an Estimate?

Before requesting an estimate, make a note of the following details: 

• Which slabs sit low and which stick up, compared with a section that appears stable

• Any trees close to raised sections

• Where rain and snowmelt run off the driveway, and whether joints or edges are open

• Whether each problem slab is in one piece or badly cracked

• Whether the driveway is concrete, blacktop or gravel

We offer free estimates across York, Harrisburg, Lancaster, Hanover and Gettysburg, PA. Bring your notes to the estimate so we can assess the affected areas,  the likely cause of movement and suitable repair options.

When Is Concrete Driveway Repair a Lift, and When Is It Something Else?

For some settled slabs, lifting involves injecting material beneath the concrete to fill voids and raise the slab. Missouri DOT’s guidance for settled bridge approach slabs describes pumping material through drilled holes to fill voids and raise settled concrete. That guidance covers bridge approach slabs, not driveways, so a driveway contractor should assess the right method for each job.We, at Lift It PRO, handle driveway concrete leveling by injecting polyurethane foam as a liquid that sets into rigid foam beneath the slab. The two-year warranty applies only to concrete that is at least 10 years old. To maintain warranty coverage, homeowners must seal repaired seams or backfill exposed edges and direct downspouts away from the slab.

Solid concrete slabs can be raised, but gravel and blacktop can’t and need replacing or reinstalling. A badly cracked slab may be too damaged to lift; our post on what slab leveling can fix in cracked concrete covers that and explains what leveling can address