Can Concrete Slab Leveling Fix Cracks, Uneven Areas, and Sinking?

Concrete slab leveling can correct uneven or sunken concrete by filling voids beneath the slab and raising it, provided the slab is suitable for lifting. It can raise a dropped section toward the level of adjacent concrete, depending on the slab's condition and the site. Leveling does not seal cracks, so any necessary crack or joint sealing is a separate step after lifting.But knowing what slab leveling can do is only part of the picture. Before lifting a cracked or sinking driveway, you need to understand what is happening beneath the concrete, what will physically change when the slab is raised, and whether the slab can be safely lifted.  This guide explains what concrete leveling can and cannot fix, what may happen to existing cracks during the lift, and what problems can return if drainage or soil movement is left unaddressed. With local experience serving homeowners across Lancaster, York, Harrisburg and surrounding areas, at Lift It PRO, we look at the condition of the slab and the ground beneath it before treating a sinking section as a simple leveling job. 

What Does Concrete Slab Leveling Actually Fix?

Concrete slab leveling corrects an uneven slab by changing the foundation it rests on. Polyurethane foam is injected beneath the slab, where it fills voids and helps raise the concrete. This approach can address sunken sidewalk sections, settled driveway slabs, and patio panels sitting lower than adjacent concrete, provided the slabs are suitable for lifting.

Slabs can settle when the supporting soil changes, erodes, or no longer provides adequate support. Changes in soil moisture can contribute to settlement. Poor drainage and inadequately compacted backfill can also contribute.

The polyurethane foam we use goes in as a liquid and sets as a rigid foam. HMI reports that polyurethane foam weighs 2–4 pounds per cubic foot, compared with more than 100 pounds per cubic foot for traditional mudjacking material. HMI describes typical injection holes of 5/8 inch for polyurethane foam and 1–2 inches for traditional mudjacking. Our guide on filling a void under a concrete slab covers washed-out gaps.

Can Slab Leveling Fix Cracks?

Concrete slab leveling can correct a height difference caused by slab movement, but it does not repair the crack itself. If the concrete is badly cracked or crumbling, it may not be suitable for lifting. Have the slab assessed before choosing between leveling, crack repair, and replacement.

Leveling works from beneath the slab; it does not repair existing spalling (flaking), chipping, or surface wear. The location and pattern of the crack can also help show whether the slab has moved or whether the damage is mainly at the surface. Cracks with significant movement, loose sections, or widespread deterioration may require a different repair approach. 

Is One Side Of The Crack Higher?

Look at the crack from the side. Cracks caused by soil settling or heaving usually have one side higher than the other, according to InterNACHI. InterNACHI describes shrinkage cracks as generally lacking vertical displacement, and it cites the Portland Cement Association, which names restraint to shrinkage as the most common cause of concrete cracking. Crack appearance alone does not confirm the cause.

A height difference across a crack can indicate slab movement. Have the cause and the slab's condition assessed before deciding whether lifting is suitable.

What Happens To Cracks During A Lift?

Some existing cracks may become more noticeable during lifting, and new cracks can also develop as the slab moves. Appropriate caulking can help limit water entry and reduce the risk of further crack enlargement, but it does not correct the underlying cause of cracking.

After the work is complete, we ask homeowners to caulk suitable joints and seams or backfill exposed edges where needed. We recommend silicone-based, self-leveling caulk for suitable joints. Choose a caulk suited to the joint and follow the product directions.

What Leveling Can And Can't Fix

Problem	Can leveling fix it?	What else it needs
Sunken or settled slab	Often, if suitable	Drainage that keeps water out
Panel lower than its neighbor	Often, if suitable	Caulk along the joint
Crack with one side higher	Potentially: lifting may reduce the height difference	Sealing the crack
Flat hairline crack	No	Sealing, if appropriate for the crack
Badly cracked or crumbling slab	Often not	Possibly replacement
Spalling, chipping or wear	No	Separate surface repair
Dips poured into the slab	Not completely	Surface stays as poured
Pavers on sand or gravel, blacktop	No	Resetting or replacement

Is Concrete Leveling A Permanent Fix For A Sinking Slab?

Concrete leveling can provide a lasting repair when the slab is suitable for lifting and the underlying causes of settlement are addressed. However, the slab may settle again if water continues to erode the supporting soil.

Preventing water from going under the slab is key to preserving the repair. Recommended maintenance includes caulking suitable joints, backfilling exposed edges where needed, and directing downspouts away from the concrete and foundation to help limit water intrusion.

Where the slab is still sound, leveling can cost about half as much as replacement, and the surface can be ready to use once the work is complete. Get a project-specific estimate to understand the cost for your slab and when you can safely use the surface again. 

When Sinking in Lancaster County Points to Something Bigger 

Pennsylvania DCNR explains that karst commonly occurs over limestone and dolostone bedrock and can be associated with sinkholes. Water can flush open drainage paths in that rock, creating a sinkhole. A 1990 Pennsylvania Geological Survey report mapped Lancaster County's carbonate bedrock areas with a history or risk of sinkholes.

Slab lifting works on the soil right under the concrete. If the surrounding ground continues to subside or a depression grows, seek an appropriate geologic or engineering assessment before arranging slab lifting.

What To Check Before Having A Cracked Or Sinking Slab Assessed

Before you contact us, take a few notes about the concrete and the area around it. This can help us understand what may be causing the problem and whether leveling may be suitable.

• Whether one side of each crack sits higher than the other

• Where rainwater from nearby downspouts ends up

• Whether the slab is in one piece, a few pieces, or crumbling

• The concrete's approximate age

Our two-year warranty applies only to concrete that is at least 10 years old. Required maintenance, including appropriate caulking or backfilling, is also a warranty condition. Ask us for the full warranty terms before scheduling the work.

We lift sidewalks, driveways, patios, pool decks, and garage and basement floors across York, Harrisburg, Lancaster, Hanover, Gettysburg and surrounding areas. If you’re dealing with a cracked or sinking slab, you can learn more about your options through our concrete repair in Lancaster page or our concrete leveling in Lancaster, PA page.