If the cement in your garage floor has cracked, the imperfection may not just look unsightly, but can also cause a safety hazard and eventually lead to greater problems if not repaired correctly. Investigating the cause of the crack and using the right technique to address it, however, involves only a simple do-it-yourself project.
Consider the Underlying Cause
Before attempting the repair job, consider the underlying cause of the crack to prevent future damage. There is little point repairing the crack if the floor is going to open up again in a couple of months’ time. For example, large trees near your garage may have roots that reach under the floor, disturbing the cement and causing it to crack.
Another possible cause of a crack can be standing water. Water is a powerful force, and if it is allowed to freeze, the resulting ice expands and widens any tiny crack it has seeped into, accelerating damage to a concrete floor. Another possibility is a poorly constructed foundation. If the garage is not standing on a sound foundation, the structure as a whole could be at risk, and the cement garage floor crack could be an early warning sign of deeper problems.
Clean the Area to Assess the Damage
To assess the damage, sweep the garage floor and remove any debris and loose cement with a wire brush. If your cement garage floor is stained with oil or grease, clean it with a solution of Trisodium Phosphate (TSP) and water, mixed in quantities suggested in the manufacturer’s instructions. Take care to protect your eyes and skin if you use this product.
Repairing Small Cracks
To repair a small crack in a cement garage floor, use regular cement. Mix the powder with water to form a paste (about the same consistency as toothpaste). Apply this to the crack with a putty knife, and smooth the surface off to be level with the rest of the floor. Let the repaired area dry a little, then cover it with a plastic sheet or tarpaulin. If the cement dries too quickly, it risks cracking again, so sprinkle the area with a few drops of water every day until the surface is perfect.
Repairing Larger Cracks
If the crack in your cement garage floor is bigger than a hairline, you will need a more advanced product–latex cement. This product is ideal because it expands and contracts with the temperature and humidity, and won't lead to further problems. Latex cement comes in straightforward kits that are easy for the do-it-yourselfer to apply. Simply mix the latex and cement together, then apply in layers to the crack, leaving a few minutes in between each layer if necessary. Finish the job as you would any normal cement by leveling it to the rest of the floor.