How To Repair a Concrete Sidewalk: Concrete Crack Repairs

Use These Patching and Caulking Tips to Fix Concrete Sidewalks


A damaged sidewalk can really detract from the curb appeal of your home. Fortunately, fixing a sidewalk is within the do-it-yourself abilities of many homeowners prepared to pick up some concrete repair materials and tools and follow these directions!  

(You can also find concrete restoration tips and tricks that will help you repair anything from a sidewalk to a patio border like a pro.)

  1. Determine what type of damage you're dealing with. Some is easy to repair and some isn't. Most types of sidewalk cracks are easy to fix. Big sections that have heaved and broken into pieces are not easy to fix, and will probably require the services of a professional.
  2. Determine why the damage occurred. There are two main reasons that sidewalks crack. The first one is lack of control joints, or an insufficient number of control joints. Control joints are those lines that run across a sidewalk every few feet. Yes, they do actually serve a purpose. Concrete tends to expand and contract with the air and ground temperatures. Control joints do not prevent this from happening, but they do minimize the damage that occurs by giving the concrete a very small bit of space in which to expand. In addition, any cracks that do occur will tend to be along the control joints, and will not be as severe as they would otherwise. The second reason that sidewalks crack is because tree roots have invaded the space underneath. As the roots grow, they tunnel through the base and push the concrete up, which causes cracking.
  3. Remedy the cause of the damage. If the damage is caused by lack of control joints, use a concrete saw to cut lines across your sidewalk every two or three feet. Do not cut all the way through the concrete - your control joints should be only a half-inch deep or slightly less. Remember, always wear the proper protective equipment when using a concrete saw, including hand and eye protection. If the damage is caused by invasive tree roots, dig out all around the offending roots and remove them with a pruning saw. Depending on the size of the tree, this has the potential to stunt the growth of the tree, or possibly even kill it, so if you're really attached to that eighty-year-old oak, you may want to learn to live with your sidewalk damage! After you have removed all potentially damaging tree roots, you may want to insert a sheet of metal into the ground vertically along the sidewalk to prevent the roots from regrowing. Fill the area back in with the dirt that you removed, along with additional dirt if necessary.
  4. Decide on an appropriate material for your concrete repairs. The type of material that you will use to repair your sidewalk depends mainly on how large the crack is. For tiny cracks (less than a half-inch wide), you can use concrete grout. Slightly larger ones can readily be fixed with caulk, and the largest ones (an inch or wider) will need to be repaired with concrete patching compound.
  5. How to use concrete grout. Concrete grout can be found at any home improvement store in small cylinders. The first step is to thoroughly clean the crack and surrounding area so that the grout can bond effectively with the concrete. Next, wet the surface and interior of the crack to promote better bonding. The final step is to apply very thin layers of concrete grout in the crack until it is filled slightly above sidewalk level. You want to overfill the crack a bit because the grout will shrink as it dries. Applying it in layers is important because if you apply it all at once, it's likely to be squeezed right back out when the ground freezes and thaws. It is not necessary to wait for it to dry between applications.
  6. How to use caulk. These tips will help you use caulk for concrete crack repairs. The caulk that is used for sidewalk repair is similar to the kind used to seal windows for the winter. Prepare the sidewalk just as you would for concrete grout, then snip off the plastic tip of the caulking gun. Inserting the caulk into the crack will be easiest if you can make the opening in the gun approximately the same width as your crack. Apply it to the interior of the crack in thin layers until it is level with the sidewalk surface. As with grout, you do not need to wait for the caulk to dry between layers.
  7. How to use concrete patching compound. Concrete patching compound is basically concrete. This is the material that professionals use for sidewalk repair. You will need to clean the area around your sidewalk crack, then prepare it to be patched. Since patching compound is typically used with larger cracks, it's a good idea to excavate the crack a bit. Okay, so you're thinking, "I'm supposed to make the crack bigger?" Well, in a word - yes. You want to make the bottom of the crack slightly wider than the top. This prevents the patching compound from being pushed out when those pesky cold temperatures cause the concrete to contract. If you have prepared the crack properly, a cross-section of it would resemble an inverted V. Next, prepare the patching compound. This usually involves mixing a powder with water and stirring it vigorously. It will dry very quickly, so prepare only a small amount at one time. Wet the crack and the area around it with a garden hose, but don't flood it. Using a trowel, push the compound in, a little bit at a time. Continue in this manner until the crack is filled. If necessary, smooth the surface of the patch by wetting your trowel a bit and sweeping it back and forth across the patching compound.

The key to successfully patching your concrete sidewalks is to apply the patching material in small amounts. If you get in too much of a hurry, the grout, caulk, or patching compound will crack. Then you'll have a situation in which your sidewalk crack has cracks! Now that you know how to repair damage, take your time, do it right, and hopefully, you won't be back out there repeating the process any time soon!


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