How to Repair Cracks in a Concrete Driveway (DIY Guide)

Concrete driveways crack. It's not a question of if — it's when. Freeze-thaw cycles, tree roots, settling, and time all conspire against the slab. The good news: 95 percent of driveway cracks are perfectly DIY-fixable in an afternoon for under 50 dollars.

The trick is matching the product to the crack size. Use the wrong filler, and you'll be back out there next year doing it again.

Why Repair Cracks at All?

A cracked driveway looks bad, but the bigger problem is water. Water seeps into the crack, freezes, expands, and widens the crack every winter. Once water reaches the soil under the slab, you can get washouts that lift and break sections of concrete — a far more expensive repair.

Sealing cracks early is what makes a driveway last 50 years instead of 25.

What You'll Need

• A wire brush for cleaning out the crack
• A shop vacuum or stiff broom
• Garden hose with pressure nozzle
• Crack repair product based on size (see below)
• A concrete margin trowel or putty knife
• Heavy-duty work gloves
• For wide cracks: foam backer rod

Match the Product to the Crack

This is where most DIY driveway repairs go wrong. The wrong product won't bond, won't flex with the slab, and pops out within a year.

Hairline cracks (under 1/8 inch wide)

Use a polyurethane concrete crack sealer in a caulking tube. Self-leveling versions work best on horizontal surfaces.

Medium cracks (1/8 inch to 1/2 inch wide)

Use a self-leveling concrete crack filler. It pours into the crack and levels itself flat.

Wide cracks (over 1/2 inch wide)

Stuff a foam backer rod into the crack first, then fill with trowel-grade concrete patching compound. The backer rod gives the patch something to bond to and prevents you from filling 4 inches deep with material.

Major cracks (over 1 inch wide, or sections heaving)

Pull and replace that section. Patches over 1 inch wide rarely hold long-term. If the slab is broken into pieces or shifting, you're in pro territory.

Step 1: Pick the Right Day

Concrete repair products need a dry surface and 24 to 48 hours of dry weather to cure. Check the forecast. Spring afternoons in the 50 to 80F range are ideal.

Don't repair concrete in direct sun on a hot day — it cures too fast and cracks again.

Step 2: Clean the Crack Thoroughly

This is the step that determines whether the repair lasts 1 year or 10. Filler bonds to clean concrete, not dirt.

• Brush the crack out with a wire brush
• Vacuum or sweep all debris out
• Hose the crack out with a strong stream of water (a pressure washer works great here, but isn't required)
• Let the crack dry completely — at least 24 hours of dry weather

If the crack has plant roots or grass, dig them out fully. Anything organic in the crack will rot and create a void under the patch.

Step 3 (For Hairline Cracks): Apply Crack Sealer

Cut the tube tip at a 30-degree angle, slightly smaller than the crack width. Load it in a caulking gun.

Run a slow steady bead along the crack, keeping the tip just inside the crack opening. Smooth it with a wet finger or a foam smoothing tool.

Let cure 24 hours. Some sealers will accept foot traffic in 4 hours but not vehicle traffic.

Step 4 (For Medium Cracks): Pour Self-Leveling Filler

Self-leveling fillers do the work for you. Pour from the bottle directly into the crack, slightly overfilling. The filler settles into the crack and levels itself.

If the crack is deep (more than an inch), fill in two passes — first pass settles overnight, second pass tops it off.

Don't try to spread it with a trowel. It's designed to flow on its own.

Step 5 (For Wide Cracks): Backer Rod + Patch

Push foam backer rod into the crack with a screwdriver until it sits about 1/4 inch below the surface. The backer rod size should be slightly larger than the crack width — that lets it compress and stay in place.

Trowel concrete patching compound on top, slightly overfilling. Smooth with a wet trowel. Then dampen the surface lightly and cover with plastic sheeting for 24 hours — slow curing prevents new cracks.

Step 6: Cure and Seal

After the patch has cured (check product instructions, usually 24 to 72 hours), apply a concrete sealer to the entire driveway. A silane/siloxane water repellent sealer is the longest-lasting option. It penetrates the surface instead of just coating it, so it doesn't peel or fade.

Sealing the whole driveway every 3 to 5 years is the single most important thing you can do to prevent future cracks.

Common Mistakes That Make Crack Repairs Fail

• Filling damp cracks. Filler can't bond to wet concrete. Wait until it's been dry for 48 hours.
• Skipping the cleanout. Loose dirt in the crack is the most common cause of failed patches.
• Using regular caulk or cheap concrete patch. It won't flex with the slab. Polyurethane sealer or vinyl-fortified concrete patch is what you need.
• Filling deep cracks without backer rod. Concrete patch shrinks as it cures. A 4-inch deep patch shrinks dramatically and pulls away from the sides.

Frequently Asked Questions

How long does a concrete crack repair last?

Done correctly with the right product, 5 to 10 years. With sealing every few years on top, the patch can outlast the surrounding concrete. Quick caulk-style repairs without proper cleanout typically last 1 to 2 years.

Should I repair driveway cracks before or after sealing?

Always before. Sealer alone won't bridge a crack. Repair first, let cure, then seal the whole driveway.

Why are large parts of my driveway cracking everywhere?

That's a sign of foundation problems — usually poor base prep when the driveway was poured, washouts under the slab, or tree roots. Fix the underlying issue (often by hiring a contractor for slab jacking or replacement) rather than just patching.

Can I drive on a freshly repaired crack?

Walk traffic in 4 hours, vehicle traffic in 24 to 72 hours depending on the product. Always check the label.

Final Thoughts

Crack repair on concrete is one of the highest-ROI DIY jobs in home maintenance. An afternoon and 30 dollars worth of materials adds years to a driveway. Do it the first season you see cracks — they only get worse with time.