Concrete Leveling With Polyurethane Foam: Four Kinds of Jobs

Gloved hand holding a foam injection gun over a small drilled hole in a sunken concrete sidewalk panel, the neighboring panel sitting an inch higher

Polyurethane Foam Lifting (Polyjacking)

The installer drills small holes through the low panel and injects a two-part polyurethane under it. The foam expands, fills the gap and pushes the slab back up. It adds very little weight to soil that has already given way once, which counts for a lot on the swelling clay most Topeka houses sit on. Lifting foams are rated by density and strength: one manufacturer's two lifting grades weigh 2.75 to 5 pounds per cubic foot and test at 50 to 100 psi before they're confined under a slab.

Slab	Foam lifting cost
Front steps (about 40 sq ft)	$320 to $1,000
Sidewalk section (100 sq ft)	$800 to $2,500
Patio or porch slab (150 sq ft)	$1,200 to $3,800
Whole driveway (450 sq ft)	$3,600 to $11,300

Cutaway view of a concrete patio slab with a washed-out gap of clay soil beneath one edge, gray foam filling the void

Void Filling and Soil Stabilization Under Slabs

Some slabs haven't dropped much yet. The soil has washed out from under one edge, and the slab rocks when you step on it or has a gap opening along the side. Foam pumped into the void fills it without lifting much. Cost guides list soil stabilization at $500 to $2,000 as an add-on and drainage fixes at $500 to $2,000 or more. Don't skip the drainage. A downspout emptying beside the slab will carry the new support away the same way it carried off the old.

Unfinished basement floor with a cracked, sunken section near a block wall, a row of small drilled holes and a long level laid across the low spot

Basement and Interior Floor Slabs

Foam goes in through small holes and the floor is usable almost at once, which suits garage and basement floors. Cost guides put an 800 sq ft basement floor at $6,400 to $20,000 and a full 360 sq ft garage floor at $2,880 to $9,000. A sunken floor is not always the whole story, though. If the walls are cracking or the house itself is out of level, the floor is a symptom, and the fix is slab foundation repair or piers. Any job that drills through a basement floor is also a sensible time to think about radon testing.

Concrete driveway control joint freshly filled with gray flexible sealant after the panels were lifted level, a caulk gun resting on the slab

Sealing Joints and Cracks After a Lift

A lift closes the trip edge at the joint, but the joint is still open to rain. Sealing it, along with any cracks, keeps water from washing out the soil under the panel again.

Sealing: $1 to $3 a square foot
Crack filling: $50 to $800 per crack

Ask whether sealing is in the lifting price or a separate line. Cracks in a basement wall are a different job; see foundation crack repair.

Laser level on a tripod in an unfinished basement, a gloved hand holding a measuring rod and a stair-step crack in the block wall behind

Why Topeka homeowners and property owners call Topeka Expert Foundation Repair

The call and the inspection request cost you nothing
Your details go to one Topeka contractor, never a lead list
Ask for piers, anchors and price on paper before any digging
Method explained first: piers, anchors, straps or mudjacking

Concrete Leveling Cost: What Changes the Number

Size changes the unit price most. One cost guide puts a 50 sq ft repair at $20 or more a square foot and a 500 sq ft job closer to $12. Minimum charges make one sunken step cost nearly as much as three, so get every low panel on the same visit. Depth matters too: a slab that dropped 1 to 2 inches takes less foam than one that dropped 4 to 6. Tight spots behind landscaping or between houses can add 20% to 50% to labor.

Compare against replacement before you sign. New concrete runs about $6 to $15 a square foot, so on a big slab foam isn't always cheaper. You're paying for speed and for keeping the concrete you have: the surface is usable within the hour instead of a week of demolition and curing. One cost guide expects a foam lift to last 10 to 15 years or more.

Foam Concrete Leveling: When It's the Wrong Fix

The slab is broken up
Concrete that's cracked into pieces or crumbling gets torn out and poured new.
Water is still running at it
Lift a panel next to a downspout that empties onto it and you'll be lifting it again. The basement waterproofing page covers grading and downspouts.
The house is moving, not just the walk
Doors sticking all year and wall cracks point to the foundation, which foam under a sidewalk won't touch.
One small panel on a tight budget
Cement slurry costs less per square foot; it's heavier and cures slower.

See mudjacking for the cement-slurry method and how its price stacks up against foam.

Concrete Leveling in Topeka, KS