How to Repair Cracks in a Garage Floor

Concrete is durable, but it isn't indestructible. Over time, shifts in the ground, temperature fluctuations, and the weight of your vehicles will inevitably lead to cracking. Ignoring these fissures is a mistake; moisture will seep in, freeze, and expand, turning a hairline crack into a crumbling, unsightly gap that compromises the integrity of the entire slab. Repairing your garage floor is a straightforward process that restores the seal of your concrete and prevents further degradation. When done correctly, the patch will be level with the floor and capable of handling the heavy traffic of a daily-driver. Focus on thorough preparation, as a patch will only adhere as well as the surface beneath it.

Open and Clear the Crack. Use a hammer and cold chisel to open the crack into a slight V-shape, ensuring the edges are at least 1/4 inch wide. Vacuum out all loose debris, dust, and gravel from the channel.
Scrub Every Surface Clean. Scrub the inside of the crack with a stiff wire brush to remove any lingering moss, grease, or loose concrete particles. Use a shop vacuum one final time to ensure the channel is bone dry and pristine.
Prime for Perfect Bond. Apply a thin coat of concrete bonding adhesive along the interior walls of the crack. This ensures the filler bonds to the existing concrete rather than just sitting inside it.
Fill Bottom Up Completely. Load your chosen concrete filler into a caulking gun and fill the crack from the bottom up. Overfill it slightly to account for minor settling as the material cures.
Level and Match the Texture. Use a masonry trowel to level the filler with the surface of the surrounding floor. If the floor has a broom-brushed finish, lightly drag an old paintbrush or a stiff broom across the wet filler to mimic the texture.
Wait for Complete Cure. Allow the patch to cure according to the product instructions, usually 24 to 48 hours. Keep foot and vehicle traffic completely off the repaired area until the material is fully set.