Fixing an Uneven Concrete Slab

Concrete surfaces are designed for durability, but settling and erosion inevitably lead to dips, cracks, and uneven patches. When a slab begins to tilt or sink, it creates a trip hazard and traps standing water, which accelerates further decay. Taking action early prevents the concrete from cracking completely through or damaging the foundation of adjacent structures. Restoring a level surface is less about heavy demolition and more about precise preparation and layering. Done well, your repair will blend into the existing slab and withstand the expansion and contraction cycles of the seasons. The key is in the cleaning—if the new material doesn't bond perfectly to the old, it will eventually flake away and leave you back at square one.

  1. Strip Away All Debris. Scrub the uneven area with a stiff wire brush to remove moss, loose debris, and flaking concrete. Use a pressure washer or a stiff broom and water to clear away all dust, as bonding agents cannot adhere to dirty surfaces.
  2. Open the Pores. Apply a concrete etching solution to open up the pores of the slab. This ensures the new patching material locks into the existing concrete rather than just sitting on top of it.
  3. Bridge the Gap. Paint a thin coat of concrete bonding agent over the sunken area using a masonry brush. This liquid glue acts as a bridge between the old slab and your new leveling compound.
  4. Mix to Perfect Consistency. Follow the manufacturer's ratio to mix the self-leveling compound in a large plastic bucket using a drill and mixing paddle. Mix until it reaches a smooth, pourable consistency similar to thick pancake batter.
  5. Let Gravity Level It. Pour the mixture into the center of the depression and use a long screed board or a flat trowel to spread it toward the edges. Let gravity do the work to level the compound, making only minor adjustments to ensure the edges feather out smoothly.
  6. Protect and Patience. Cover the wet patch with plastic sheeting if the temperature is high or if it is a windy day to slow down the drying process. Allow at least 24 to 48 hours before walking on or sealing the patch.