Driveway Crack Repair: The Complete Guide
Posted by Dale Pease - October 9, 2019, 3:34 PM
When is it important to address those cracks and open expansion joints in your concrete driveway? The short answer is ASAP, but it can be a bit more complicated than that. And there are definitely things to keep in mind if you want to make sure it is done right and will last.
Concrete Driveway Crack Repair
Stopping water from flowing under your concrete is probably the most important thing you can do to keep your driveway from sinking and becoming out of level. Caulking the joints and cracks is the best way to stop this from happening.
Even expansion joints in your concrete driveway should be caulked. They can be the biggest culprit of water under your slabs.
Notice how the caulking is slightly lower than the concrete slab around it. This protects the caulk from wear and tear of people walking and driving over it.
In this guide, you will learn the steps that can, and should, be taken to help extend the life of your concrete and keep your home safe and beautiful for years to come. These include the types of caulk to use, as well as best practices for getting those concrete driveway cracks repaired and long-lasting.
Concrete Driveway Crack Repair Basics
Concrete driveway crack repair is not all that different than any other concrete crack repair, except for one big difference; the size of the cracks. Because driveway slabs are normally much bigger than sidewalks and other concrete areas, the cracks can be longer, and oftentimes wider.
When we talk about concrete driveway crack repair, we are typically talking about two processes. The first is concrete leveling, and the second is caulking (and sometimes grinding) the crack.
We discuss concrete leveling in-depth on other pages of this site (here's a detailed guide on what is involved in concrete leveling) but for our purposes, we first want to get any slabs that are out of level from each other back into alignment. This involves a process of pumping some material under the lower slab and gently lifting it until it is the same level as the slabs around it. This could involve intact slabs that have sunk at expansion joints or slabs that have broken and partially sunk on one side of the crack. Depending on how out of level your driveway is, this could be simply moving one slab, or it could involve lifting and leveling nearly every slab in the driveway.
Once the slabs are leveled with each other, then the cracks or expansion joints are filled with a flexible caulk to keep water from flowing under the slab. This is the primary purpose of concrete driveway crack repair. If water is flowing under your driveway, it is only a matter of time before the slabs will begin to sink. This is precisely why we always recommend caulking the cracks and joints after we level your concrete slabs.
How to Caulk Your Concrete Driveway Cracks
With the right tools, material, and patience, caulking your concrete driveway cracks is something you can do yourself. In the end, you may want to hire an experienced professional (discussed more below) but if you're the handy, do-it-yourself type then this might be a project you can tackle as a weekend project.
Tools & Material Needed For Concrete Crack Repair:
- Caulk - We recommend a flexible polyurethane caulk. You can find either self-leveling or non-sag caulk that is specifically made for joint and crack sealing. Two brands we use are Chemlink and Sika.
- Caulk Gun - You'll need a caulk gun that will hold the size caulk tubes you buy.
- Backer Rod - If you have larger expansion joints, you will often want to buy a roll of backer rod to fill in the gaps between the joints before you caulk. This can save you a ton of money by limiting the amount of caulk needed to fill the joint.
- Spray Bottle - Using a spray bottle filled with soapy water can help smooth out the caulk. Especially important if you use non-sag caulk.
- Dry sand - Definitely optional, but sometimes used to help visually blend the caulk in with your concrete.
Self-leveling vs. non-sag caulk
First, a brief discussion about the differences between self-leveling and non-sag caulk. Self-leveling is just what it sounds like. It is a thinner material and will flow to fill up the gap between your concrete slabs nicely. It finishes with a nice surface and doesn't require any smoothing afterward. However, self-leveling caulk can run out through the ends of a crack, or through any gaps underneath where you caulk. So you must make sure you've got a pretty well-sealed area for the caulk before you put it down. It cannot be used on any vertical surface either. Typically, if your job is larger, self-leveling caulk is the way to go as it doesn't require smoothing.
Non-sag caulk is a bit thicker, and will generally stay in place once you put it down. This can sometimes be used as a "dam" at the end of cracks that you then fill in with self-leveling caulk. It can also be used to fill cracks that go vertically (like cracks that might go from a driveway to a pored concrete curb.) Because this caulk is thicker, it requires smoothing after application. This can best be accomplished by spraying the still-wet caulk with soapy water and running a finger along the caulk to smooth it out. It's a good idea to wear gloves to keep the caulk off your skin. Non-sag caulk is best if you only have a small amount of caulking to do.
Step by Step Guide for Concrete Driveway Crack Caulking.
- Before applying the caulk, make sure all the expansion joints, or cracks, are free of debris and cleaned. A power washer is helpful during this time. Make sure the concrete is dry before proceeding to the next step.
- If the crack to be caulked is more than about 1/2" wide, and an inch deep, then we recommend using a backer rod. Backer rod is a similar material as a pool noodle (and you can actually use pool noodles if you don't mind cutting them up to fit.) You'll want to make sure the backer rod you choose is slightly larger in diameter than the crack is wide so that it will fit snugly in the crack. Also, when inserting the backer rod, you'll want to make sure it is installed at least a 1/2" below the surface of the concrete, to give room for the caulk. If you're unable to buy backer rod and don't have any pool noodles available, you can also use playground sand for this. Pour the sand into the crack until all the holes are filled. Tapping the concrete with a 2x4 can help settle the sand into all the voids. Like the backer rod, leave the sand at least 1/2" below the surface of the concrete.
- Once the backer rod is installed, or the crack is small enough to not need it, it's time to lay down your caulk. If you're using self-leveling, be sure you've sealed off the ends of the crack. Again, it's not a bad idea to buy at least one tube of non-sag in the same color, so you can seal off the ends of the crack before you use the self-leveling. Either way, be sure to lay a nice bead of caulk all the way along the crack. Be sure to not use too much, so that it is mounding up higher than the surface of the concrete, or too little so it leaves gaps that water can get through. It's actually best to keep it slightly lower than the concrete surface (as indicated in the illustration.)
- If you are using non-sag, then after you put your caulk down be sure to smooth it out with soapy water. You'll want to do this right away before the caulk has a chance to set up. Again, a pair of disposable gloves is a good idea here.
- Sometimes, depending on the color of your caulk and concrete, we will take some sand and throw it down on the caulk to give it a little texture and help it match the concrete. You'll want to do this while the concrete is wet as well.
- Finally, follow the directions on the caulk as to how long it takes to set up. You'll want to keep anyone from walking over it, or driving on it until it's fully set.
DIY vs. Experienced Caulking Pros
While fixing your concrete driveway cracks is sometimes a project you can undertake yourself, there may be times when you want to consider hiring a professional.
First, if you need to level the concrete slabs, before fixing the cracks, it is definitely time to call in the pros. This isn't something you want to attempt on your own. It takes special equipment, and significant expertise to lift concrete back into place correctly.
Second, getting caulk to lay down smoothly, and look the way you want it to is a skill in and of itself. Professionals do this day in and day out. So if the visual results of your caulking job is a priority, then it might be worth it to spend the extra amount to hire the experts. Not to mention the time it will take to purchase the right materials and get the job done. If it's something you just don't want to mess with, then give us a call.