You should address cracks and open expansion joints in your concrete driveway as soon as possible, but the issue is a little more complicated than that. If you want to make sure it is done correctly and will last, there are definitely some important things to keep in mind.
Here’s what you need to know to ensure that your concrete lasts longer in your home, caulk types to use, and what to do to repair those cracks the right way.
It Is All About Caulking
Caulking joints and cracks is the best way to stop water from flowing under your concrete and causing your driveway to sink and become out of level.
Even your concrete driveway’s expansion joints need caulking. They are often the source of water under the slabs.
Concrete Driveway Crack Repair Basics
Repairing cracks in concrete driveways is little different from any other concrete crack repair, except for one key difference: crack size. The cracks can be much wider and longer when it comes to driveways and other similar areas, as a result of larger slabs compared to sidewalks.
When we talk about concrete driveway crack repair, we are typically talking about two processes. Concrete leveling is the first step, and then caulking (and sometimes grinding) the crack is the second.
The topic of concrete leveling is discussed here, but for our purposes, we need to get any slabs that are not level from each other back into alignment. The lower slab is lifted gently until it reaches the same level as the slabs around it. This involves pumping some material under the lower slab. Occasionally, intact slabs may sink slightly at expansion joints or, in some cases, partially sink along a crack.
Your driveway may require only moving one slab or the whole driveway may need to be lifted and leveled. You should never attempt to do this on your own. It takes specialized equipment, and considerable expertise to lift concrete into place correctly – so it is quickly moving out of the realm of DIY.
The cracks and expansion joints between the slabs are filled with flexible caulk to keep water from flowing beneath the slabs once they are leveled.
Concrete driveway crack repair is primarily meant to stop water flow under concrete. When this occurs, the slabs of concrete will begin to sink. Because of this, it is always recommend to caulk the joints and cracks in your concrete slabs after leveling them.
How To Caulk Your Concrete Driveway Cracks
You can caulk your concrete driveway cracks with the right tools, materials, and patience. It may be worthwhile to hire an experienced professional, but if you are handy and like to DIY, then this might be one for a weekend project.
Tools & Material Needed For Concrete Crack Repair:
- Caulk – A flexible polyurethane caulk such as Chemlink and Sika is suitable for crack sealing as well as for self-leveling joints.
- Caulk Gun – You need a gun of the right size to hold the caulking tubes you’ll be using.
- Backer Rod – A roll of backer rod can be used to fill gaps between expansion joints before caulking in order to allow you to save money by using less caulk. Take this approach if your joints are bigger than 1 inch thick.
- Spray Bottle – The use of a spray bottle with soapy water helps the caulk go on smooth. Especially useful if you are using non-sag caulk.
- Dry sand – Definitely optional, but often used for blending purposes so the caulk will match the concrete better.
Self-leveling vs. non-sag caulk
Let’s start with a quick comparison of non-sag caulk and self-leveling caulk.
Self-leveling is a thin and flowy material that fills in the spaces between your concrete slabs nicely. You do not have to smooth it out afterwards, but the caulk can run out through the ends of cracks, or through any gaps beneath where you caulk. So you must make sure the caulk is put down on a well-sealed surface. It cannot be used on vertical surfaces either. A self-leveling caulk is the way to go if your job is larger as it does not require any smoothing.
Non-sagging caulk is thicker, and tends to stay put once applied. This can sometimes be used in order to block off the ends cracks before applying self-leveling caulk to keep it contained.
A crack that goes vertically like one that goes from a driveway to a poured curb can also be filled. Since it’s thicker, it needs to be smoothed after being applied. Smooth the caulk best by spraying it with soapy water and then running your finger along it. Wear gloves while working with caulk to protect your skin. Caulk that does not sag is ideal if there is not much caulking to do.
Step by Step Guide for Concrete Driveway Crack Caulking.
Laying caulk smoothly, and having it look the way you envision it is a skill. You need to proceed carefully to get it right. If you’re unsure, maybe call a professional. If you want to give it a go, here are the steps:
- Clean all expansion joints and cracks before caulking them. A power washer will come in useful for this. Just make sure everything is dry before proceeding to the next step.
- In case the crack is more than about 1/2 inch in width and 1 inch in depth, a backer rod should be used. Think of a backer rod as a mini pool noodle. It is made from similar material. If the crack is wide, the backer rod diameter you choose must be a bit larger than the crack itself. Also, while installing a backer rod, keep in mind that it must be installed about a 1/2 inch below the concrete surface, so it leaves some space for the actual caulk. Another approach is to use playground sand for this instead of the backer rod. Getting the sand into the cracks can be done by tapping with a 2×4 until all the voids are filled. Just like with the backer rod, have the sand at least 1/2″ below the surface of the concrete so you can caulk on top of the sand.
- Once the backer rod has been installed or the smaller cracks don’t require it, caulk will need to be applied. Before you use self-leveling, seal off the ends of the crack with non-sag. It’s a good idea to have a tube or two of a non-sag in the right color so you can seal off the ends of the crack. Be sure to use enough caulk along the crack, but not so much that it becomes higher than the concrete, or too little that it leaves gaps where water can get through. It is recommended to keep it slightly below the concrete surface.
- Make sure that you smooth out the caulk after putting it down, if it is a non-sag blend. Don’t wait. Now is the time to do it before the caulk sets up. Again, disposable gloves are a great idea here.
- We sometimes use sand to add texture to your caulk and help it match the concrete color. The concrete needs to be wet when you do this.
- Finally, follow the caulk’s directions about how long it takes to set, and don’t walk or drive on it until it is fully set up.