Can I seal driveway cracks myself?

Level cracks and open joints, yes. A tube of flexible concrete sealant, some closed-cell backer rod, and a dry day above 40°F handle most of them. Call for help when one side has dropped or the edges are crumbling.

Should I seal hairline cracks in my driveway?

You don't have to. Thin, level, stable hairlines are usually cosmetic. Seal them if water collects there, or just photograph them and check again next spring.

When should I plan on resealing?

Walk the driveway every spring after the snow is gone. A good flexible sealant in a clean, properly prepared joint commonly goes several years, often up to about a decade, depending on the product, sun, and how much the slab moves. Redo any bead that has split or pulled away from a side.

There's a lip at one crack. Can I just caulk it?

You can, but the lip will still be there for toes and plow blades, and so will the hollow under the low side. Lift that slab even with its neighbor first, then seal the crack.

The crack I filled with patch last fall broke loose. Why?

Patch is rigid and the driveway isn't. The slab shrinks in the cold and grows in the heat, so a hard filler in a crack that moves breaks loose, often by the first spring. Save patch for broken edges and holes.

Can you lift and seal my driveway in the same visit?

In most cases, yes. We lift the settled slabs first, patch the holes, then seal the cracks and joints once everything sits level.

Driveway Crack Repair: The Right Fix for Each Type of Crack

8 min read

You notice it when the snow finally melts. A crack that was a pencil line last fall is now wide enough to grow weeds. The joint by the garage has a lip that catches the snowblower. And the apron at the street looks like it lost a fight with the plow.

Most driveway cracks aren't an emergency. But in northeast Wisconsin, water plus January is what turns small cracks into big ones. Here's how to figure out what you've got and what it needs.

Why Wisconsin Driveways Crack

All concrete cracks eventually. That's what the control joints (the straight grooves cut across the slab) are for: they give it a planned place to crack. The stuff that makes cracks worse is more local:

Freeze-thaw. Water gets into a crack, freezes, expands, and pries the crack wider. We go through that cycle many times between November and April.
Spring snowmelt. Snow piled along the driveway edge melts into the soil under the slab. Soft, wet soil lets slabs settle, and settled slabs crack and tip.
Road salt and deicers. Salt doesn't cause cracks by itself, but deicers make freeze-thaw damage worse and speed up surface flaking and edge breakdown.
Plows and snowblowers. A raised slab edge or a sealant bead left sticking up gets caught and chipped every winter.
Downspouts and sump discharge dumping onto or next to the driveway, washing out the base.

Sort Your Crack in 60 Seconds

Grab a tape measure and a coin. Look at each crack and ask two questions: How wide is it? and Is one side higher than the other?

Crack type	How to spot it	Right fix	DIY or pro?
Hairline	Thinner than a credit card, both sides level, not growing	Leave it, or seal it to keep water out	DIY
Open crack, level	You can slide a coin in, both sides even	Clean, backer rod if needed, flexible sealant	DIY
Control or expansion joint, open	The planned grooves or gaps, old filler missing or caulk failed	Clean out, backer rod, flexible sealant	DIY, or pro for long runs
Offset crack or joint	One side is lower, you can feel a lip with your toe	Lift the low slab level, then seal	Pro: lift + seal
Slab tipped toward garage or house	Water runs back toward the building	Lift to restore drainage, then seal the joints	Pro: lift + seal
Wide, crumbling, or spalled	Edges breaking off, chunks loose, surface flaking	Patch the damage or replace the section	Pro, usually a concrete contractor
Map cracking or broken into pieces	Spider-web cracks across a panel, or a slab in several loose chunks	Usually replacement of that section	Concrete contractor

Not sure which one you've got? Our guide to concrete crack types goes deeper on what causes each.

Hairline Cracks: Usually Leave Them

Thin cracks with level sides are cosmetic in most cases. Concrete shrinks as it cures, and a few hairlines are normal, especially on a driveway that's a few years old.

You have two reasonable options:

Leave it and watch it. Snap a photo with a coin for scale. If it looks the same next spring, it's fine.
Seal it. If it's in a spot where water sits, a thin bead of flexible sealant keeps water from getting in. Hairlines usually don't need backer rod.

Don't skim concrete patch over it. A thin rigid layer tends to flake off within a winter or two.

If your driveway is less than a year or two old and already cracking, see why new concrete cracks.

Open Cracks and Joints: Flexible Sealant

This is the most common repair, and most homeowners can do it themselves. Cracks and joints that open and close with the seasons need a sealant that stretches with them.

The short version:

1Wait for the right weather. Most concrete sealants call for at least 40°F and a dry, frost-free surface. In Green Bay that's roughly late spring through early fall.
2Clean it out completely: old caulk, rotted filler strip, sand, weeds, dust.
3Push in closed-cell backer rod on anything about 1/4" wide or wider, so the sealant ends up about half as deep as the joint is wide.
4Fill with a flexible sealant rated for concrete joints and traffic. Self-leveling for flat joints, gun-grade for slopes.
5Leave it slightly below the surface so plows, shovels, and tires don't catch it.
6Keep cars off until the label says it's ready for traffic. That can be a few days, and longer in cool weather.

We cover sealant types and backer rod sizing in best concrete crack caulk, and cracks beyond the driveway in how to fix concrete cracks.

Thinking about mortar or a bag of patch instead? Picture a slab that shrinks every January and grows every July, with a hard plug wedged in the middle. The plug loses: it lets go along one side, or a new crack opens right next to it, and it can take a chip of slab edge with it.

Offset Cracks: It's a Settled Slab, Not a Crack Problem

If one side of a crack or joint sits lower than the other, you're not looking at a crack problem. You're looking at a settled slab. The soil underneath compressed or washed out, and the slab dropped.

Caulking an offset crack leaves the trip edge, the void underneath, and the drainage problem in place, and the bead sits right where a plow blade can catch it.

The right order:

1Lift the low slab. We drill a few 5/8" holes (about the size of a dime) and inject high-density structural polyurethane foam. It fills the void under the slab, then raises it in small, controlled increments until it's level with its neighbor.
2Patch the holes.
3Seal the crack or joint now that both sides are even, so water stops getting under the slab and washing out the base again.

You can walk on it right away and drive on it the same day after the lift, then stay off the fresh sealant as long as its label says. That's why we usually do both in one visit: the lift fixes the position, and the sealing protects it.

Common spots for this on a Wisconsin driveway:

The slab at the garage door, which often drops and tips back toward the garage
The slab next to the house or front walk, sitting on loose foundation backfill
Slabs near downspouts or where the sump discharges
The last slab before the apron, where plows pile snow every winter

Learn more about how lifting works on our concrete lifting page.

3D render of a driveway with one slab sunk at the garage, before and after foam lifting — after — The sunken slab by the garage comes back up level with its neighbors, the puddle is gone, the holes are patched and the garage joint is sealed. Drag the slider.

3D render of a driveway with one slab sunk at the garage, before and after foam lifting — before — The sunken slab by the garage comes back up level with its neighbors, the puddle is gone, the holes are patched and the garage joint is sealed. Drag the slider.

Wide, Crumbling, or Broken Concrete: Patch or Replace

Some cracks are past the point of sealant or lifting. Be honest with yourself here:

Edges crumbling or chunks breaking out. A sealant has nothing solid to stick to. A concrete contractor can patch spalled edges with a repair mortar made for that.
Surface flaking off (scaling or spalling). That's a surface problem, not a crack problem. See concrete spalling causes.
A slab broken into several loose pieces or covered in spider-web cracking. Lifting can raise a slab, but it can't glue a shattered one back together. That section usually needs replacing.

We don't do patching or replacement, and we'll tell you from the photos if that's what you need. If only one or two sections are shot and the rest have just settled, replacing the bad ones and lifting the rest can save a full tear-out. Our concrete replacement questions article can help you weigh it.

The Street Apron: Check Before Anyone Touches It

The apron (the section between the sidewalk or curb and the street) takes the worst of it: plow blades, salt spray, heavy trucks swinging wide, and runoff from the street.

Before you repair, lift, or replace it, check who controls it. In many communities the apron sits in the public right-of-way. In Green Bay, for example, the city treats aprons, sidewalks, and curbs as right-of-way, where work requires a permit from Public Works and resurfacing is limited to contractors licensed and bonded with the city. Other towns and villages have their own rules. One call to your public works department settles it.

Winter Habits That Keep Cracks From Coming Back

Seal joints before winter, while it's still warm enough for the sealant to cure.
Keep the sealant recessed so plows and snowblowers skate over it.
Go easy on deicers. Never use ammonium nitrate or ammonium sulfate (sometimes found in fertilizers) as a deicer; concrete industry guidance warns they attack concrete fast. Skip deicers entirely the first winter on new concrete. Shovel early so you need less salt.
Don't pile snow where it melts straight under a slab edge.
Move downspouts and sump discharge away from the driveway.
Walk your joints every spring. Reseal anything that's split or pulled away before it becomes a lifting job.