How to fix expansion joint damage in a driveway

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Introduction

Expansion joints are an important part of any concrete driveway. They’re the narrow gaps filled with flexible material that allow concrete to expand and contract with temperature changes. Without them, your driveway would crack under pressure. Over time, however, these joints can deteriorate—filler material wears away, water seeps in, weeds grow, and the edges of the concrete may crumble.

Tired of seeing weeds or crumbling gaps where your expansion joints used to be? This guide will show you exactly how to fix expansion joint damage in a driveway and restore both function and appearance.

Why Expansion Joint Repair Matters

Expansion joint damage may seem minor, but it leads to major issues if ignored.

  • Prevents water damage: Open joints allow rain to seep under slabs, eroding the base.
  • Stops weed growth: Empty joints create a perfect environment for weeds to sprout.
  • Maintains driveway integrity: Without joints, cracks spread across the surface.
  • Boosts curb appeal: Clean, filled joints make the driveway look sharp and maintained.
  • Extends lifespan: Repairing joints prevents costly replacement later.

Just like sealing a driveway protects from UV rays, keeping joints repaired ensures your driveway withstands seasonal shifts.

Step-by-Step Guide to Fixing Expansion Joint Damage

1. Inspect the Joints

Begin by checking all joints in your driveway.

  • Look for missing filler, weeds, or debris inside the gaps.
  • Check edges of the slabs for chips or cracks.
  • Mark damaged areas that need repair.

Pro Tip: If most of the filler is worn away, plan to replace all joints for consistency.

2. Clean Out the Expansion Joints

Preparation is the most important step.

  • Use a screwdriver, putty knife, or joint rake to remove old filler.
  • Pull out weeds and roots completely.
  • Vacuum or blow out dust and loose debris with a shop vac or leaf blower.

Safety Note: Wear gloves and goggles to protect against flying debris.

3. Wash and Dry the Area

Moisture or dirt prevents new filler from adhering.

  • Rinse joints with a garden hose or pressure washer.
  • Let the concrete dry completely—at least 24 hours in warm weather.
  • For faster drying, use a leaf blower.

4. Repair Crumbled Edges (If Needed)

If the concrete edges around joints are damaged:

  • Chisel away loose pieces.
  • Apply a concrete patching compound with a trowel.
  • Smooth the surface level with the slab edge.
  • Allow patch to cure before proceeding.

5. Add a Backer Rod (Optional for Deep Joints)

For joints deeper than ½ inch, use foam backer rods.

  • Cut rods to size and press them into the joint.
  • Leave space on top (about ¼ inch) for sealant.
  • This saves material and ensures proper flexibility.

6. Apply New Joint Filler or Sealant

Now it’s time to restore the joint’s flexibility.

  • Use a high-quality polyurethane or self-leveling joint sealant.
  • Cut the tube tip at a 45-degree angle.
  • Apply steady pressure and fill the joint evenly.
  • Smooth the top with a caulking tool or putty knife for a neat finish.

Pro Tip: For a clean line, apply painter’s tape along the slab edges before sealing.

7. Let the Sealant Cure

Curing ensures long-lasting protection.

  • Allow at least 24–48 hours before driving on it (check product instructions).
  • Protect from rain during curing—cover with plastic if needed.
  • Avoid foot traffic until fully set.

8. Maintain the Joints

Once repaired, keep joints in good condition.

  • Inspect annually for cracks or gaps.
  • Reapply sealant as needed (usually every 3–5 years).
  • Keep debris and weeds out with regular cleaning.

Common Mistakes to Avoid

  1. Leaving old filler in place: Weak filler prevents new material from bonding.
    Solution: Always clean out joints fully before repair.
  2. Skipping drying time: Moisture breaks down sealant quickly.
    Solution: Ensure joints are completely dry before sealing.
  3. Using the wrong sealant: Silicone and acrylic crack under driveway stress.
    Solution: Use polyurethane or self-leveling concrete joint sealants.
  4. Not adding a backer rod: Filling deep joints entirely with sealant wastes material and causes cracking.
    Solution: Use backer rods for joints deeper than ½ inch.
  5. Overfilling joints: Sealant should be flush with the slab, not bulging.
    Solution: Smooth with a trowel for a neat, level finish.

Extra Driveway Tips & Hacks

  • DIY Weed Prevention: After cleaning but before sealing, sprinkle a little vinegar in joints to kill hidden roots.
  • Seasonal Check: Inspect joints in spring after freeze-thaw cycles.
  • Long-Term Protection: Seal the entire driveway every few years to complement joint repairs.
  • Aesthetic Upgrade: Use colored sealant that matches your driveway for a professional look.

Want more help? Check out our guide on how to repair cracks in a concrete driveway for additional repair techniques.

Conclusion

Expansion joint damage may look small, but it can cause major driveway issues if left unchecked. By cleaning out joints, repairing edges, adding backer rods, and sealing with the right material, you’ll restore both function and appearance.

A few hours of work now will save you thousands in future repairs and keep your driveway strong, safe, and sharp-looking for years. Make joint repair part of your driveway maintenance routine to protect your investment.