Driveway Crack Repair: The Complete Guide

With the right tools, material, and patience, caulking your concrete driveway cracks is something you can do yourself.

Concrete Driveway Crack Repair Basics

Because driveway slabs are normally much bigger than sidewalks and other concrete areas, the cracks can be longer, and oftentimes wider, than other repairs.

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.

Concrete Leveling

When caulking concrete cracks, we first want to get any slabs that are out of level from each other back into alignment. The concrete leveling process involves pumping material under the lower slab and gently lifting it until it is at 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.

Concrete Caulking

Once the slabs are leveled, 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.

Tools & Materials Needed For Concrete Crack Repair

1. 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.

2. Caulk Gun

You'll need a caulk gun that will hold the size of the caulk tubes you purchase.

3. 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.

4. Spray Bottle

Using a spray bottle filled with soapy water can help smooth out the caulk. Especially important if you use non-sag caulk.

5. Dry Sand

Definitely optional, but sometimes used to help visually blend the caulk in with your concrete.

Self-leveling vs. Non-sag caulk

Self-leveling Caulk

Self-leveling caulk 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

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.

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

1. Clean Area

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.

2. Install Backer Rod

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 to 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.

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.

 

4. Smooth Caulk

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.

5. Add Sand

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.

6. Let the Caulk Set

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 the 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 are a priority, then it might be worth it to spend the extra amount to hire the experts.

A-1 For Concrete Caulking

Here at A-1 Concrete Leveling, we've been perfecting the art of concrete repair and protection for over thirty years. In addition to performing concrete leveling repairs, we also specialize in concrete caulking, cleaning, and sealing.

If you have gaps and cracks in your concrete that need to be filled and you're not keen on trying the DIY method mentioned in this article, click the link below to request a free onsite cost estimate with one of the A-1 concrete experts!