Repair Concrete Cracks

There are some simple methods to repair concrete cracks. The method you choose depends on the severity of the crack, whether it's indoor or outdoor, and any painting or staining you may want to do afterwords.

You should know that not all cracks need to be repaired. All concrete is guaranteed to crack sooner or later. That's why contractors put those grooves (control joints) across the surface of concrete. Those grooves are meant to intentionally weaken the concrete in that particular spot to give the concrete a "suggested" place to crack. This makes the cracks alot less noticable. In most cases these cracks don't become a problem if there is a proper subgrade in which water can pass through so that water doesn't stand in the cracks.

More often than not repairs to minor cracks are more unsightly than the crack itself. Cracks 1/8 inch or less in width can usually be left alone without further damage resulting assuming you have a proper subgrade. If the crack gets larger or you see the concrete chipping away along the crack, you should address it and do some repairs. Repairing concrete cracks, however, won't always solve the problem if the concrete isn't structually sound. If a crack has quickly opened more than 1/4 inch or there is vertical displacement (one side of the crack is higher than the other), you should consult a contractor for structural problems and solutions.

Methods to Repair Concrete Cracks:

For small cracks, use a wire brush to remove any loose debris and rinse thoroughly with water. Allow crack to dry completely. Use concrete or mortar repair or epoxy crack filler in a caulking tube and fill the crack. Force the material down inside the crack with a thin object like a putty knife. Then smooth out the surface with a trowell or your finger.

For large cracks, clean, rinse and let it dry. Then mix a batch of concrete patching material according to label instructions. Fill the crack with the patching and stuff it down inside. Then smooth out the surface with a trowell.

When the patching begins to harden, scrape off excess down the sides of the crack and smooth out the repair with a soft, wet brush.

Tips:

Repair concrete cracks when the temperature is above 50 degrees and overnight temperatures are not expected to drop below freezing the next few nights.

Don't do repairs when it's too hot or too windy. The material will dry out too fast resulting in a weak repair. If this is unavoidable, then put plastic over it or shade it.

After you repair concrete cracks, it's always a good idea to put a coat of concrete sealer over the area to help prevent water seapage.

If your repairs are a darker color than the surrounding concrete, try rubbing it with a flat stone. This will turn it white making it less noticable.

If you plan to acid stain, be sure the caulk or patching used for any repairs contains cement or cementitious material. If not the acid won't react and the repairs will be left uncolored.

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Repair Concrete Cracks