Before you pay anyone to lift a slab, go outside with a straight board and a few minutes. What you find tells you whether concrete leveling will work, whether a grinder will do it for less, or whether the panel has to come out. A lot of concrete that looks like a mudjacking job in Plainfield turns out to need one of the other two, and it is better to know that before any holes are drilled.
Can Your Sunken Slab Be Lifted? A Four-Point Check
1. Is it still one piece?
Lay the board across the panel. If it sits flat, or the panel is tipped but straight, it can usually be lifted as a unit. If the board rocks over a crack in the middle and the two halves sit at different angles, you are lifting pieces, not a slab.
2. Did it drop, or did something push it up?
A sunken panel sits lower than its neighbors or has pulled away from the house. A heaved one sits higher, usually near a tree. Leveling only raises concrete. It cannot push a slab back down.
3. Where does the water go?
Look for a downspout that empties at the edge of the slab, a gap along the foundation, or a puddle that sits after rain. Whatever carried the soil away will keep doing it under a lifted slab unless it gets fixed too.
4. Is it still moving?
A gap that is wider than last year, soil washing out from under an edge, or a hollow sound when you tap near the low corner all mean the void is still growing. Lifting works best once you know why it sank.
| What you found | Usual fix |
|---|---|
| One-piece panel that sank or tipped toward the house | Lift it: mudjacking or foam |
| A small lip at one joint, panels otherwise flat | Grind the lip flush |
| Panel pushed up by a tree root | Replace the panel and deal with the root |
| Panel cracked through, crumbling or in pieces | Cut it out and pour a new section |
| Soil still washing out from the edge | Fix the water first, then lift |
| Slab rose over the winter | Wait for the thaw and look again |
Mudjacking vs. Polyurethane Foam Lifting
Both methods are slab jacking: holes go through the concrete, material is pumped into the empty space underneath, and the pressure raises the panel. The difference is what goes under it.
| Mudjacking (slurry) | Polyurethane foam | |
|---|---|---|
| What is pumped | A cement-based slurry | A two-part foam that expands as it cures |
| Holes | Larger | Smaller |
| Weight added under the slab | Heavy | Light |
| Back in use | Usually the next day | Usually sooner, once the foam cures |
| Cost | Generally lower per job | Generally higher per job |
Slurry is the older method and the cheaper one, and for a driveway panel that dropped over firm ground it does the job. Its weight is the trade-off: on soft, wet soil you are adding a heavy load to the same ground that let the slab sink. Foam weighs little, goes in through smaller holes, and cures fast, which helps on soft ground and on surfaces where the patches will show. Slurry can also wash out over time if water keeps running under the slab. Foam holds up better to that, but no fill survives a downspout pointed at it forever.
The estimate should name the method and say why it fits your slab. If someone offers only one method, ask how they decide when it is the wrong one.
What Concrete Leveling Can Fix
Concrete is poured in panels separated by joints, and each panel settles on its own. That is what makes concrete lifting possible: one panel can be raised back to meet the ones that stayed put.
Driveway Panels That Dropped at the Garage
The classic case. The panel at the garage door sits on fill placed against the foundation after the house went up, and that fill keeps settling. The panel tips down, a step forms at the garage threshold, and meltwater runs toward the door. Lifting restores the step-free edge and the slope away from the garage. If the slab inside the garage has dropped too, our garage floor repair page covers lifting the floor itself.
Sidewalk Trip Hazards
A front walk panel that dropped below its neighbor leaves an edge that catches toes and snow shovels. If the low panel is whole, sidewalk leveling brings it back flush. If the high panel is the problem, lifting the low one only makes a different edge, so check which side moved before deciding.
Patios and Stoops Pulling Away from the House
Same backfill, same story: the slab next to the foundation sinks, tilts toward the house, and opens a gap at the wall where water runs straight down along the basement. Lifting it back and sealing the gap sends the water out to the yard again. A stoop with steps is heavier and its shape matters, so not every stoop is a good lifting candidate.
Pool Deck Panels
Deck panels that settle away from the pool edge can often be lifted. Point out the pool plumbing and any deck drains before work starts, so the holes and the pumping stay clear of them. On a decorative or stamped deck, ask about patch color first, because the holes will show.
Why Slabs Sink Around Plainfield
Most of the village's housing went up in the 1990s and 2000s, so a lot of driveways, walks and patios here are 20 to 25 winters old. Sinking here usually traces back to a few causes:
- Backfill against the foundation. The soil pushed back against a new basement wall is loose, and it settles for years. Slabs poured over it at the garage, the stoop and the patio door go down with it.
- Clay that holds water. Much of Will County sits on clay soils that hold water and move with the seasons. USDA's soil survey maps poorly drained Will silty clay loam in parts of the Plainfield area. Wet clay softens, then shrinks as it dries, and the slab follows it.
- Water carrying the base away. Other parts of the area sit on fast-draining gravelly outwash, with some of the county's shallowest groundwater in it. A downspout or sump line dumping at the edge of a slab can carry fine base material out from under it over a few seasons.
- Frost. The Will County building code puts the frost line at 42 inches. A slab sits far above that, so winter frost can lift a panel and spring can set it back down in a new place. That is movement, not a void, and it is why a slab that rose in January should be judged in May.
Lifting fills the void. It does not change the soil or the water. Extending a downspout, regrading a low spot, or sealing the gap at the house is often part of a lift that lasts.
When Slab Jacking Is the Wrong Fix
Every one of these is a job we could take and get paid for. We would rather tell you up front:
- The panel is broken into pieces.Each piece lifts at its own angle, and the cracks between them open up. A badly broken panel needs to be cut out and repoured. Our concrete repair page covers section replacement.
- A root pushed it up.Leveling cannot lower concrete, and lifting the panels around a heaved one just spreads the problem. The heaved panel comes out and the root gets dealt with.
- The soil is still washing out.Lift a slab over an active washout and the new void opens under the fill. Fix the water first.
- It moved with the frost.A panel that rose in winter may settle back on its own in spring. Wait for the thaw before deciding.
- The surface is the problem, not the height.Lifting does nothing for flaking, pitting or a crumbling top layer.
- Most of the slab has sunk in many places.At some point you are paying to lift a driveway that needs to be replaced anyway. See concrete driveways for what replacement involves.
- The house is the thing settling.Cracked foundation walls, sticking doors and sloping floors inside are foundation repair, a different trade with different equipment. We do not do that work.
Lifting also carries a small risk of its own. Raising an old slab puts stress on it, and an existing crack can open a bit or a new one can form during the lift. Lifting slowly and watching the panel keeps that risk low, but it is never zero.
