Here's the call we get most often, usually in March or April: "My driveway's cracked and the house is only twelve years old. Is the foundation moving?"
Almost always, no. And the reason is worth understanding, because it changes what you should spend money on.
Your house has footings. Your driveway doesn't.
When a builder puts a house up, the footings go down to ground that will carry it. That's the whole point of a footing. Your driveway gets poured on whatever's at the surface, with nothing underneath it but what the developer left behind.
So when the driveway cracks and the house is fine, that difference is usually the entire explanation. The slab is following ground that's still moving. The house isn't, because it's sitting on something that isn't.
Two things move the ground around here
1. Loess that got wet
All of eastern Nebraska sits under loess, a deep layer of wind-blown silt left behind at the end of the last ice age. It's fine stuff to build on while it's dry. It'll even stand up in a near-vertical cut, which is why the road banks around here look the way they do.
The problem is what happens when it gets thoroughly soaked. A good chunk of loess's strength comes from a weak natural bonding between the silt grains, and water breaks that down. Loess that gets saturated under load can consolidate, and anything sitting on it goes along for the ride.
Which is why, nine times out of ten, when we're looking at a settled slab we're really looking at a drainage problem. A downspout that's been dumping at the edge of the driveway for six years. A sprinkler zone aimed wrong. A grade that sends roof water under the slab instead of away from it. The concrete gets blamed and the gutter did it.
2. Fill that never got compacted
Nearly every subdivision built around Lincoln in the last thirty years, plus the growth in Waverly, Hickman, Bennet and Eagle, sits on ground that was cut, filled and graded during development. Farm ground gets stripped, the high spots get cut, the low spots get filled, and the whole site gets shaped to drain.
Done right, that fill goes in in controlled lifts and gets compacted and tested, and it behaves fine. Done in a hurry in October to close a plat before winter, it keeps consolidating for years afterward.
The signature is pretty recognizable: a crack running diagonally out from a corner of the garage apron, or a joint where one side has dropped a visible step. If that's what you're looking at, the concrete didn't fail. It reported.
So which one do I have?
You can get a decent idea standing in your own driveway.
| What you see | Usually means |
|---|---|
| Hairline cracks, no height change across them | Normal shrinkage. Cosmetic. Seal it and move on. |
| Crack with one side higher than the other | Something moved underneath, and it'll keep moving until the cause is fixed. |
| Diagonal crack from the garage corner | Classic fill settlement on a newer lot. |
| A low spot that ponds after rain | Settlement, and the ponding makes it worse every season. |
| Surface is sandy or flaking everywhere | Scaling. Different problem, usually a mix with no air entrainment plus salt. |
| Slab tipping back toward the house | Backfill settlement. Fix this one sooner, it's routing water at your foundation. |
What it costs to deal with
This is the part people are usually surprised by, because the cheapest fix is often the right one.
- Fix the drainage first. Extending a downspout properly might cost you an afternoon. If water getting under the slab is the cause, nothing else you do matters until that's handled.
- Route and seal a stable crack. Roughly $300 to $1,000 depending on how much of it there is. Keeps water out, which is what makes cracks widen.
- Lift a settled slab. Usually $600 to $2,500. If the concrete itself is sound and it's just dropped, filling the void and bringing it back to grade is a fraction of replacing it.
- Replace a panel or two. $450 to $1,400 a panel. Good when the failure is in one spot.
- Replace the driveway. $5,000 to $10,000 for a typical two-car. Right answer when it's broken into pieces or the surface is gone across the whole thing.
The thing to watch out for
If the cause was uncompacted fill and somebody replaces the concrete without over-excavating and re-compacting that base, you will get the same crack on the same line inside about a decade. We've torn out eight-year-old driveways that replaced twelve-year-old driveways that cracked for the identical reason.
So before anyone quotes you a slab, somebody should be digging a test hole and finding out what's actually under there. It takes twenty minutes and it's the difference between buying a driveway once and buying it twice.
When it really is the foundation
Occasionally it is, and we'll say so. Signs that it's a house problem and not a flatwork problem: doors and windows that have started sticking, cracks in drywall running diagonally from door corners, visible step cracks in the foundation wall itself, or a floor that's noticeably out of level. That's a structural engineer's question, not a concrete contractor's, and we'd rather point you at one than sell you flatwork you don't need.
Quick answers
Is a cracked driveway an emergency?
Usually not. A flat hairline crack can wait until it's convenient. Three things are worth moving on sooner: a crack with a height difference across it, because something is still moving; concrete tipping back toward the house, because it's sending water at your foundation; and a trip edge on a public walk you're responsible for.
Can you just fill the crack?
If the slab is otherwise sound and the crack is stable, yes, and routing and sealing it is the right fix. It keeps water out, and water is what turns a hairline crack into a half-inch one. If the slab is moving, filling the crack just hides the symptom for a season.
Why is there a crack right in the middle of a brand new slab?
Concrete shrinks as it cures, so some cracking is coming no matter what. That's what control joints are for: they give it a weak line to crack along, straight and tidy, usually down inside the saw cut where you barely see it. A crack across the middle of a new slab means the joints were spaced too far apart, cut too shallow, or cut too late.
Got concrete that needs work?
Tell us what you're looking at and we'll tell you what it needs, what it costs, and when we could get to it.