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Concrete Expansion Joints

Concrete expansion joints are important for your sidewalk or driveway.

Keeping your joints watertight will prevent moisture from seeping under concrete pads and causing them to heave or sink. This post shares how to accomplish this task.

The purpose of a concrete expansion joint is to allow the pads to expand and contract (get bigger and smaller) with temperature & humidity changes.

If you’ve got kids think of the expansion joint as yourself and the concrete pads as your children – queue memory of standing between two kids as they try to tear each other apart. Well, this is how I feel sometimes with my daughters (is it bad if I view myself as an expansion joint that buffers arguments about clothes, food, and hair?).

Good news!!

Protecting and repairing a concrete expansion joint is super easy. And it’s far cheaper to do this weekend project than it is to hire a contractor to replace a severely damaged concrete driveway or sidewalk.

Here are the supplies you’ll need

This supply list may sound intimidating because of the angle grinder.

But what better time to begin using one of these awesome tools, and they can be very affordable.

So let’s get started and seal your concrete expansion joint so it’s protected from the effects of weather!


Removing Old Material from a Concrete Expansion Joint 

Concrete expansion joints are also known as isolation joints.

Like I said in the intro these joints allow concrete pads to expand and contract during freeze-thaw cycles.

Without a concrete expansion joint, your sidewalk or driveway would crack.

If you look at the expansion joints between your concrete you might see black felt or old sealant.

Old sealant and worn-out felt need to be removed.

Concrete Expansion Joints-Remove old sealant

When I called Sika, the company that makes the self-leveling sealant for this kind of project, they told me to use a utility knife to remove old material and clean off any remaining residue with acetone. If you do this step, make sure the Acetone flash dries (Sika said to wait about 1 hour).

You could give this utility knife technique a try. But I found that the people who owned our house applied a layer of new sealant over an old layer. And I had a true hot mess because both sealants were pulling away from the concrete.

If you’re in the same predicament, using an angle grinder with a standard cutting wheel or diamond blade is the way to go.

Sure, neighbors might think you’re a bit crazy. But they also will think twice about sending their kids over for fundraisers (which could be a good thing).

Concrete Expansion Joints-Angle grinders help remove old sealant

Yes, the angle grinder is an extra purchase but you can get one cheaper than a pair of running shoes.

In my example, I had to cut through two layers of old sealant. The angle grinder cutting wheel had to penetrate about 1/2 to 1 inch down through the sealant layers. You should also remove any old foam backer rod that is beneath the sealant (I’ll explain what this is in the next section).

The concrete joint doesn’t have to be perfectly clean for the new sealant. And old sealant that’s left behind after you use the angle grinder will be pretty well adhered to the concrete and won’t interfere with the new sealant’s bonding capacity.

Loose sealant on the edge of the expansion joint can be scraped off with your utility knife.

This step is perhaps the most important one. It’s definitely the most time-consuming.

Make sure you wear safety glasses and protective gloves since the cutting wheel sparks a bit when it occasionally touches the concrete.

Here’s a short video to give you an idea of what needs to be done to remove old sealant from a concrete expansion joint.

Prepping Your Concrete Expansion Joint for Sealant

If you’re as nerdy as me when it comes to remodeling you may have wondered what the heck that rubber stuff is between concrete pads or walkways.

It’s okay if you’ve never had this thought, this means you’re normal and the rest of us DIYers are at risk of tripping over ourselves while pondering such questions.

The stuff that looks like rubber is a self-leveling sealant. The brand you can find at the local store here in the states is called Sikaflex Self-Leveling Sealant.

Concrete Expansion Joints-Sikaflex is self leveling sealant

Sikaflex can be used to seal horizontal expansion joints. It’s a great product because it remains permanently flexible, dries quickly, sticks to anything, is self-leveling, and highly resistant to weather conditions.

You should apply Sikaflex when the temperature is between 40F-100F. The ideal temperature is in the middle of this range because the joint will be less likely to be fully contracted or expanded.

Sikaflex will be tack-free in 1 to 2 hours and fully cured in 3 to 5 days.

I didn’t drive on it for 5 days. Who wants tires tracks of sealant on their driveway (not me and I certainly don’t want to explain this to my wife). Also, make sure rain isn’t in the forecast for 24 hours.

After removing all the old sealant use a vacuum or wet/dry vac to suck up any debris from your concrete joints.

Then use a closed-cell foam backer rod in between the joints.

Concrete Expansion Joints-Backer rod needs to be placed in joints before sealant

Foam backer rods act to fill in space between concrete joints so you don’t need to use a ton of self-leveling sealant.

Here’s a BIG TIP: the diameter of the backer rod should be 1/8 inch larger than the width of your concrete expansion joint.

This will ensure a water-tight seal.

Concrete Expansion Joints-Add closed cell backer rods to joints before sealant

Push the backer rod down into the joint with your hand. The depth of the joint should be a minimum of 1/4 inch and a maximum of 1/2 inch below the concrete pads. This means the backer rod should be this far below the concrete pad surface.

If your joint is wider than the backer rod you can twist two strands together like a rope.

Here’s a Second BIG TIP: double-check the backer rod sits beneath the surface of the concrete pad.

Otherwise, you’ll have a little hump that develops when you apply the sealant. And yes, I’m speaking from experience ๐Ÿ™

By the way, the backer rod can be found in the same section as the concrete supplies at the hardware store.

Keep Your Concrete Expansion Joint Watertight and Crack Resistant with Sikaflex Sealant

Gather all your old socks and a few worn-out T-shirts.

You’ll need them as rags (don’t whine about using your old Pink Floyd concert shirt, nobody thinks you’re cool if you wear it to the mall in 2000 whatever. Hey, I love Pink Floyd but seriously, if you’re reading this you’re probably old enough to know they aren’t touring anytime soon).

Sikaflex self-leveling sealant comes in two size tubes. The large tube is 29 fluid ounces and the small tube is 10 fluid ounces.

If you have a huge concrete expansion joint to fill I highly recommend the 29 fl oz tube. You’ll have to buy a large caulking gun but this will save you a ton of time.

Concrete Expansion Joints-29 oz tubes of Sikaflex require a large caulking gun

Here’s a Third BIG TIP:

Think about how many tubes you need then BUY twice as many.

Again, talking from experience here. It’s so much easier to buy a ton of sealant then return what you don’t use.

With the backer rod in place, you can cut the Sikaflex tube so that it will make a 1/4 inch bead. You might be tempted to cut the tube bigger but don’t.

Once the sealant starts flowing it can be hard to stop and a bigger bead means you’ll have to work faster. Not to mention, but I will anyway, the huge potential mess you might have. Visualize sealant on your pants, hands, shoes, hair…..

Pierce the seal inside the tube with an old wire hanger, the kind you get from the dry cleaners.

Place the tube in your caulking gun and pretend you’re Dirty Harry. Just kidding. This step is unnecessary and only meant to make you feel cool (which you are of course).

Squeeze the Sikaflex sealant into the concrete expansion joint and allow it to flow & self-level itself. Add more Sikaflex where it’s needed.


Your concrete expansion joint is now watertight and way more unlikely to crack.

In case you’re more into watching than reading here’s a video showing you what to expect when using Sikaflex

What’s Next

Our tutorial on stone patio care is also super helpful – you’ll save a ton of time cleaning with our tips!

If you’re doing a bathroom remodel and need help, join one of our online courses – they’ll make your bathroom renovation much easier!

Let me know if you have any questions and I’ll do my best to help.

Thanks as always for reading, watching, and being part of our awesome community.



Concrete Expansion Joints

  1. Jeanne K. Briscoe says:

    You have so many good tips. I need the joints redone in my driveway as well as a long walkway and patio made of flagstone. Do I need a concrete company for this or who? Athens, Ga.

    1. Hi Jeanne, you could hire a mason, contractor with concrete experience or do it yourself ๐Ÿ™‚

      It’s really not that hard to do. Certainly there is a time element because the old sealant or felt needs to be removed if worn out. But the application of the new sealant is as easy as caulking.

  2. Jennifer @ Decorated Chaos says:

    Awesome post/tutorial. My house is 65+ years old and in need of of this!

    Thanks for sharing! (I just pinned to my DIY Pinterest board)


    1. Thanks Jennifer, glad it was helpful and I appreciate your pin because that helps others see this project is pretty easy.

      You and I are in the same boat (caring for an older home) and sometimes it springs a leak or two or three!! LOL.

      Hope you have a great day ๐Ÿ™‚

  3. Pam Oleson says:

    When our concrete steps were poured a few years ago, the contractor did not put an expandable joint between the bottom step and the concrete sidewalk slab. Can I use the grinder to create a joint and follow these directions. There is a crack between the step and slab.

    1. Hi Pam, you could try to do that but it’s a lot of work. The best option would be to use a crack filler to seal the crack.

      This will stop water or ice from penetrating the concrete. Here’s a tip, measure the width of the crack and find a concrete crack filler that can accommodate that dimension.

      For example, if the widest point in your crack is 1/4 inch wide then use a filler that states it can fill a 1/4 inch or larger crack.

      Hope this helps ๐Ÿ™‚

      1. Pam Oleson says:

        Thanks. I’ll give it a try when it warms up (I live in MN).

        1. Definitely let me know how it goes Pam ๐Ÿ™‚

  4. Ryan says:

    Wow this really great Jeff. I have been looking on the web for an easy to follow guide on properly fixing concrete joints. I have a weed problem as well and have been removing them from the cracks which leaves a little gap. Also I’m sure most people know this but going to Home Depot and renting tools is also a good way to keep the cost down if you are only going to use the tool once.

    Thanks for providing this. I’m definitely going to check out your other guides!

    1. Thanks Ryan for the reminder about renting tools. Another option is to look for refurbished items on Amazon.

      I picked up a great tile saw this way.

      You can also get good tool deals on Craigslist!!

      Glad the post helped you out. Hope you’re having a fantastic day ๐Ÿ™‚

  5. Ryan says:

    Wow this is really great Jeff. I have been looking on the web for an easy to follow guide on properly fixing concrete joints. I have a weed problem as well and have been removing them from the cracks which leaves a little gap. Also I’m sure most people know this but going to Home Depot and renting tools is also a good way to keep the cost down if you are only going to use the tool once.

    Thanks for providing this. I’m definitely going to check out your other guides!

    1. Thanks Ryan for the reminder about renting tools. Another option is to look for refurbished items on Amazon.

      I picked up a great tile saw this way.

      You can also get good tool deals on Craigslist!!

      Glad the post helped you out. Hope you’re having a fantastic day ๐Ÿ™‚

  6. Jackie says:

    Thanks for this post!

    I went to Sika’s website and see MANY self-leveling sealants…..which one should I get for the concrete joints?

    1. Thanks Jackie!!

      You need Sikaflex Self-Leveling Sealant. I bought it at Home Depot in the building materials aisle. It’s next to all the concrete supplies. Hope this helps.

      1. Oops, here’s a link with a picture of the product. You’ll need to click on Sikaflex Self-Leveling Sealant then the photo will be on the right after you click on Show Details.

  7. Geneva says:

    My sidewalks and driveway here in Houston has a piece f wood as an expansion “joint”. These are getting old and the wood is decaying. Do I just pull it out and use this sealant? Wonder why they used wood?

    1. Geneva, the wood acts as an expansion and contraction joint. It helps prevent the concrete from cracking. You could remove the wood and replace it with a similar type if wood or use foam backer rod along with Sikaflex.

      Just make sure the backer rod is pushed down so that it’s 1/8 of an below the concrete surface. Then apply Sikafkex according to the instructions.

      1. Geneva says:

        Thank you! I do have cracks, and actually, all the driveways in my neighborhood are sinking slowly (no rebar used by home builder), I’ve already poured a new proper 1/2 portion of it because my sink level had dropped so much. Really pathetic. I’m going to follow your guide and replace the wood. I’m also going to look for a good sealant/concrete repair material to try and stop the long linear cracks I see as well. Thank you!


        1. Geneva, if you learn a new skill while replacing the wood please let me know!! I love discovering new ideas and adding to my tool box of knowledge ๐Ÿ™‚

  8. Ed says:

    Great video Jeff! Thanks for all the great advice.
    I’m also wondering about the control joints located between pads (those grooves that “encourage” cracks to occur there vs. in the pad themselves). Is it advisable to seal these as well, and to use backer rod + sealant to fill up the groove such that it is level with the remaining pad?
    Or is it better just to seal the actual crack itself and leave the groove profile intact?

    1. Great question Ed. Honestly, I’m not sure what to do with concrete control joints. One thing’s for sure, I wouldn’t backfill them with backer rod. Just leave them the way they are. But what should be done with a crack that gets wider within the control joint itself? If it were me, I’d fill in the crack just enough to seal it (with something like SikaFlex which can be bough at home stores). But I wouldn’t fill up the control joint. Let me know if you feel like this isn’t a great answer. Isolation joints and control joints are a bit different in their makeup. And as such, need to be treated differently too.



      1. Daryl Gilbert says:

        My daughter’s home in North Carolina is three years old. The home is on a hill so the driveway has a decline down to the street. There are channels (maybe called sore joints, definitely not expansion joints) that have cracks in them (both directions, up/down and across). When it rains, sand rises up through the cracks and settles at the bottom of the driveway. The builder has filled the cracks twice with a caulk type product. One month after each application of caulk, the caulk cracks then allows sand to escape again. Any suggestions?

        1. Hi Daryl, do you know if the builder used a product like SikaFlex? Not all joint fillers are made the same and I like this product because of its elasticity and ability to flex with the concrete. That said, you’d have to remove all the old filler to ensure the SikaFlex would stick to the joints. Just make sure that your joints can accept SikaFlex Self-Leveling sealant based on the directions. Here’s the link to the site

          Hope this helps a bit.

  9. Geneva says:


    Was in my local Ace hardware store and they had cut to whatever length you need rubber expansion joint tubing that you press down and tightly fit in the space. Have you heard of this?

    I have a picture of it if you are interested.


    1. Hi Geneva,

      I’ve never heard of this option but that’s pretty cool. Maybe is a local thing. However, if it’s not this would be wonderful to let people know about since sometimes you only need a few feet. Totally send me a picture. My email address is [email protected].


  10. David Kapral says:

    Hi Jeff. this is a good DIY procedure! I am in the middle of doing this job on my driveway and can add a couple of things based on hard experience:

    1. the best reason for installing backer rod is so the self leveling sealant doesn’t ooze through the void. When it does, there will be bubbles that look like grey acne in the job and sections will sink and look quite ugly. This can lead to “3 point bonding” & a failed job.

    2. Dam up the ends if the joint is even slightly sloped. Self Leveling sealant will ooze out of either end. Tape will work as a dam on clean surfaces.

    3. Sealant Engineering Co. offers an adhesive backer rod (“Seafoam”) in various widths and thicknesses that works well in shallow joints. It helps prevent the backer rod from floating up, making unsightly humps. Sealant Engineering offers “Low Modulus” silicone products that are supposed to be free of the UV problems on polyurethane (hardening, cracking). I’ll be trying it.

    4. Sealant Eng also has 1/4″ triangular, adhesive backed backer rod for use at the driveway / foundation junction. This is supposed to give the joint flexibility if reg backer rod can’t be used. I will let you know.

    1. Hi David,

      Like I said in our emails you have a TON of fantastic tips. Please let me know how this project works out for you so that we can feature in on DIY Success Stories. Driveways and sidewalks can be super expensive to repair. And if these products can help us homeowners save money and time then they are well worth the money.



  11. Dave Anderson says:

    I just did my expansion joints with backer road and Sikaflex. Prep was the big job. Now I am looking at the “control joints” which of course have cracks in them. They look kind of dumb with the nice grey sikaflex expansion joints. So I was wondering about sweeping some loose sand into the cracks in the joints and adding sikafex without backer which would not work as the joints are not that wide or deep. Any thoughts? Sikaflex is too thin and would probably run thru the un-stoppered (sand filled) cracks.

    1. Hey Dave,

      I spoke with another friend about this exact issue. It’s good that there are cracks in the control joint because that indicates they’re doing their job (keeping the cracks confined to the joint and not the concrete pad). Prep indeed stinks for expansion joints.

      Does the sand fill in the small cracks within the control joint?

      This fix also is more aesthetic than anything. I’ve noticed several instances where control joints are simply left alone and the expansion joint is filled in with something like SikaFlex. It sounds like you’d prefer the joints to kind of “match” each other (I totally understand your preference because I’d probably want the same look). However, if the project is a pain in the butt then maybe living with the control joints the way they are isn’t too bad.

      Before you do anything give Sika’s technical service department a call and ask them for their opinion. They are AWESOME and won’t steer you wrong. Here’s the number 248-577-0020

      Ask them about your sand idea. I’d think that would work and you could always test it out on a small section of the control joint (like 12 inches). That way, if it didn’t work and the SikaFlex ran through you wouldn’t have to remove a ton of it. Hope this helps a bit.


      1. Dave Anderson says:

        Thanks for the reply. I understand about the purpose of control joints…to crack where you want it to! And it has. Not large cracks. I have one long center joint with the Sikaflex and two lateral ones (one at the garage and one on the pads (10). It looks really nice now. No caverns and no weeds! But like you said it is the aesthetics of those unfilled control joints that bother me. It would probably only take one or two big tube of Sikaflex to fill them as they are only 1/2-5/8″ deep “V” grooves cut with a tool when wet and having a smoothed border. You know the look. I was going to ask my neighbor about the idea of the control joints…he is the chief PA Dot bridge engineer for W. PA and he works with this sort of stuff on a big scale. He did his driveway 5 years ago and it appears he did the control joints too. I will call Sikaflex on Monday. I filled one with sane and swept most of it away. There is also a concrete crack filler at HD with a squeeze bottle that does fill cracks I think) but it may be too runny as well. I need 1/16 backer rod (LOL) so maybe I could use wet spaghetti! My daughter is an Architect and she specifies backer rod all the time but doesn’t ever recall 1/16. Thanks for writing back so quick. I’m waiting the 5 days now to drive over the joints. To help you visualize my driveway is 22 X 50″ Long, two lanes and 5 panels on each side.

        1. Hi Dave,

          Whew, your driveway is a big boy!! Let me know what you decide to do because I’d love to know. I think that you’ll end up with a great looking result that will last. Make sure to take several pics and send them to me, I should post your project so that other homeowners will know what to do with a similar scenario!!


  12. Tim Lawrence says:

    Jeff, I need to re-do my driveway expansion joints. However, my driveway has a decent slope to it. Just how “self levelling” is the Sika product? Will it simply run down the expansion joint to the street?

    1. Hey Tim,

      Thanks for your question, I got a similar one recently from another friend and have the same issue myself.

      Sika makes a product called Concrete Fix that doesn’t have the same sagging issues as their SikaFlex Self-Leveling product. Now, I haven’t used it yet and will probably call their tech line to make sure it’s okay. But the product details on their site say the Concrete Fix is meant for this kind of project. Hope this helps a bit. Let me know.


    2. DaveAnderson says:

      Sikaflex SL (self leveling) is like pancake batter. Apply a big bead between two slabs of concrete and you will have a nice flat shiny surface in a few minutes. You need to dam up the ends of the joint to contain the sealant. I think if you apply it at the top of a sloped driveway you will have a puddle at the bottom in no time. I think they make a thicker formula that might need tooled.

      1. Hey Dave,

        That thicker formula might just be Sika Concrete Fix. But like I said to Tim, I’d like to call Sika and ask them if it can be used for this specific purpose. Have you ever used it?


        1. Tim Lawrence says:

          Thanks for the replies gents. I guess the question for Sika is going to be along the lines of whether it is elastic enough?
          If there isn’t a product that will not work well on slopes, would my only option be the extruded ribbon type products like “Trim-a-Slab”


          1. Hey Tim,

            I called Sika today and asked them about our sloped driveway issue. They said the Sika Concrete Fix would be a good option since it isn’t as elastic as SikaFlex Self-Leveling sealant and that it can be tooled with a plastic putty knife or spoon.

            So, this looks to be a viable course of action. Admittedly, I haven’t tried it yet but will. I’ll probably buy the smallest tube and give it a shot. Let me know if you try it ๐Ÿ˜€


          2. Tim Lawrence says:

            Thanks for the update Jeff. I think I’ll have to go visit Lowes/HD and check it out.

  13. kim says:

    concrete pool patio – expansion joints. dirt and debris stuck in buff/off-white wet caulking. is there a way to remove it from the finished/hardened caulk or will it need to re-done?

    1. Hey Kim,

      Great question. Have you already tried to clean the caulk with soap and water? If so, I’d give Wet & Forget a try. It’s a surfactant that you spray onto outdoor surfaces. Water, wind, and sun activate it to clean over time (like 2-3 months). You may have to apply it a few times but I’ve had great success using it on patios & siding. Hope this helps.


  14. Keith Himmel says:


    My story is a long one. I purchased my home in 1991. I have approx. 1400 sq ft of patio and a 24,000 gallon pool. We originally had Astro turf(yuk). We replaced it and the wooden expansion joints. The EJ’s were replaced with PVC and looked great at first but after a couple of years started to fail by sinking and holding dirt. My EJs go all the way down to the earth. Some are normal size some have grown wider and deeper. I thought about the SLAB GASKET material but there’s no “One size fits all”. SO I’m trying the SL QuikCrete product and it seems like I will probably need and 18 wheeler load. Are there larger diameter backer rod material? In my case it would bigger the better.

    Can you give a guy some direction?

    Thanks in advance,

    Keith Himmel

    1. Hey Keith,

      Thanks for your question. Sounds like you have an awesome outdoor setup.

      I believe you can get 3/4 inch wide backer rod. But if that’s too small the directions on the package say you can twist two pieces together to get a larger diameter. You could also call Quikrete’s tech support line. I’ve also had good luck with calling Sika for advice.

      Hope this helps a bit. Let me know.


  15. Josh says:

    Hey Jeff, Instead of using Foam backer rods could you use sand to fill up the hole? the gap between my garage and driveway is about 1/2″ wide so and its deep. (I have plenty of sand on hand if its OK to use.


    1. Hi Josh,

      You can get 3/4 inch foam backer rod and it should fit pretty tight in your gap. It’s not that expensive and will work better than sand. Hope this helps



  16. Jesus says:

    Hi Jeff,

    Great post!

    What if a day after using sikafelx SL I realize I need to apply another layer for a better leveling? Do I apply it right away (24 hours after first application) or do I wait 5 days until it cures?

    1. Hi Jesus,

      Good question. I don’t know the answer and would hate to steer you in the wrong direction. You should give Sika a call and ask their technical support department. Let me know what you find out because I’m curious myself.



      1. Jesus says:

        Just called them. They only work Monday through Friday. I want to get it done this weekend so I guess I’ll take my chances ๐Ÿ™‚

  17. Steven John says:

    I like your video representations for the SIKA concrete sealant but would prefer black. Do they have a choice for black or do you have any other product recommended with the black color?

    1. Hi Steven,

      I don’t know if Sika makes black. This would be a good option since the black would hide stains and whatnot. I’d have to do some research to see if black is offered in other brands. Let me know what you find if you get a solution first.


  18. Toni says:

    Hi Jeff,

    I have an expansion joint where my garage ends and driveway begins (and I can’t wait to follow your instructions to fix) and then I have another between the side of the driveway (concrete) and the RV pad (asphalt). Do I use the same material to seal the joints between these two different materials? I really want to do something because I currently have grass/weeds growing in the expansion joint. Toni

    1. Good questions, you may want to look into Sika’s Sikaflex Concrete Fix since you can use it with materials that have different coefficients of expansion. This might be a good option for your problems and I think you can buy it at either Lowe’s or Home Depot. I attached product info for this product in the P.S. in this post.

      Let me know what you think.


  19. Tina says:

    Very informative! The joint in my driveway varies and is over an inch. Is there width limit to this method? Also it has been pretty wide for quite a while. Is there a good way to remove the dirt and the weeds growing in there?

    1. Hi Tina,

      Our joints are over an inch as well. Make sure to read the label on the product that you decide to use. I do know that SikaFlex has specific instructions on depth and width.

      As far as the dirt & weeds, you could spray the weeds with a weed killer or vinegar first. Let them die off then remove them with a string trimmer. That’s probably the quickest way. Hope this helps.

  20. wabi says:

    First of all, I would like to thank you for posting this valuable resource. I’m a kind of person who wants to learn with any opportunity I have, and to learn especially on construction fields every single day.
    Thank you.

    1. Glad to help any time Wabi, thanks for coming by ๐Ÿ™‚

  21. Durai Thavamani says:

    Dear Sir,
    I am in middle of resealing the concrete slab pavement. The damaged sealant were removed and I am stuck now due to rain and cannot pour the new sealant. Guide me of how to protect the existing joints from seepage of rain water that will harm the slab

    1. Hi Durai,

      I’m not sure what sealant you’re using. You’ll likely have to wait for the rain to stop before applying any product. You can always call the maker of the sealant and ask them for advice. I’m sure they’ll be helpful.

  22. Bagya says:

    can I apply sand over sikaflex so it blends with the existing driveway?

    1. Hi Bagya, wish I knew the answer to this but don’t. You should call Sika’s technical service line and as them their thoughts. They’re normally very nice and helpful.

      Please let me know what you find out since others might be thinking the same thing.

    2. Tyler Sinclair says:

      Good stuff, great blog, photos, video and all made it really easy to understand!

      1. Thanks Tyler. Hope it all helps you. Let me know if you have any questions.

  23. Mike says:

    Can I use sika concrete sealer at the base of my concrete foundation wall meets concrete sidewalk

    1. Hey Mike, great question. I’m not sure. You’d have to call Sika and explain your situation to them.

      Call the technical service line. They were pretty cool to me ๐Ÿ™‚

  24. Chris says:

    Jeff, would it be better to leave the wood “expansion joints” in place of using the backer rods?
    Will the Sika sealant fill in the gaps around it?

    1. Sika will definitely fill any gaps Chris. Just make sure the wood is below the concrete.

      I’ve never tried this so it might be worth it to call Sika and get their opinion.

  25. Thom Bouis says:

    Trim-A- Slab is a better product, easier to install and longer lasting. Search Trim-A-Slab on eBay for best deal.

    1. Thanks Thom, it looks like a really cool product.

      I do like the concept and ease of use. Especially if the joint is fairly even.

      If anyone is interested here’s the link to Trim-A-Slab’s site

      1. Mike says:

        That stuff really doesn’t work well. It pops up and you have to constantly push it back down.

        1. You can get a tighter fit by combining two pieces, almost like a hair braid. But you’re right, it’s not perfect.

  26. Kat says:

    Hey Jeff! Great tutorial, big fan of DIY and just starting to get into house stuff and you are very thorough! Will definitely subscribe ๐Ÿ™‚

    I have a sort of dumb rookie question that I seem to not be able to find on the Sika PDFs about the product (so I will apologize ahead of time) but what exactly is the dry time for Sika Cement Fix?

    We just used this to seal some cracks in the shower and some members of the family have been itching to shower now! It’s been about 28 hours now and I read somewhere that it needs 72 if we are planning to paint (we are not). Is that enough time?

    1. Thanks Kat, I love DIY too. You’ve got a buddy in me ๐Ÿ™‚

      I’m not sure about the cure time for Sika Cement Fix. But call the Sika technical service line and see what they say.

      They’ve always been great at answering my questions. I’d hate to give you the wrong advice and ruin your DIY project.

      Let me know what they say.

  27. Steve says:

    To obtain a more textured and incognito appearance is it possible to sprinkle sand to the surface after caulking and if so how soon afterwards should this be done.

    1. I don’t see why you couldn’t Steve. I’d wait until the caulking is tacky so that the sand will stay on the surface.

      I’ve never done this before so keep me posted ๐Ÿ™‚

  28. Sherry says:

    Hi Jeff,
    I’ve read about the width between the slabs, but I’m wondering about the depth? The depth seems very deep between the slabs on my driveway, I can can put my finger all the way down to the dirt. Is this normal? Also, any advice for directing the water away from the garage? The water pools at the entrance because of poor workmanship and it’s getting worse every year. I don’t have much to spend so any cheap ideas will help.

    1. You can use foam backer rod Sherry to fill the depth. I’d just get a backer rod that’s a bit wider than your gaps. That way you only have to place the backer rod so that it’s maybe 1/8 to 1/4 of an inch below your slabs. Then you can fill in the gap using Sika Flex self leveling sealant.

      I don’t know the answer to the pooling issue. You could put in a skirt drain that runs the length of the garage but that requires some work & money ๐Ÿ™

      Maybe someone else has a better suggestion. Darn workmanship, it can be good or bad.

  29. xaire says:

    Jeff: Great information! You may want to add the information that if the backer rod is twisted to fill the joint the mastic is going to leak around the openings on the outside of the twists. Use a cheap caulking to prefill the openings, wait a few minutes for the caulking to set. I wasted about 3 tubes of mastic for first hand experience. Good ol’ hindsight.

    1. Thanks Xaire, that’s a great idea. I’m sure this will save us all a ton of money by using less self leveling sealant.

      You’re awesome!!

  30. Brian says:

    If this has been mentioned already, sorry, but would also have a bucket if fine sand and spread it over the caulking as you go, makes it look a ton nicer when finished. Sweep or blow the excess sand into the yard after 24 hours.

    1. Thanks Brian, that’s a great tip. I can already envision it looking a lot better ๐Ÿ™‚

  31. 127001er says:

    Another tip: apply wide masking tape along either side of the crack or expansion joint, and at the ends of the work area. This will help to maintain a professional finish and assist with cleanup of any sealant that overflows during application.

    1. Great suggestion ๐Ÿ˜€

  32. John says:

    I have a basement which is below ground level 1 metre, my concrete slab and the masonry walls are waterproof but the water is coming up between expansion joint which is between masonry wall and concrete slab is there a product that can stop a tiny puddle of water surfacing on my concrete slab when I get heavy rains?
    Kind regards John

    1. Hey John, sorry to hear about your water issues.

      This may sound obvious but are your downspouts clogged? If so, you may need to clean them out.

      Another issue might be your downspouts becoming disconnected from the underground drains.

      In which case you’d have to reattach them or just reroute the downspouts so that they drain 4-5 feet away from the foundation.

  33. Mary says:

    Love your advice and want to get started but used the level whereby some of the driveway concrete is higher than the garage slab and some spots are lower. Will this cause water to run into garage after I use the filler?

    1. It’s hard for me to say Mary.

      You could try to fill the expansion joint with the backer rod and then spray water on it with a hose. This might give you a good idea of how the water will travel before you fill the joint with the sealant.

  34. Jim says:


    I can’t use Self Leveling sealant because the joint has a slight incline. What would you suggest for sealing inclined joints?

    1. Hey Jim, I have the same issue.

      And it’s not perfect but if you live in an area that gets cooler you could wait until the temperature drops enough whereby the sealant becomes less watery.

      I’m going to try this myself.

      You could also apply duck tape to either side of the joint so that any spillage won’t get on the cement.

      Maybe a call to Sika will reveal a product that’s better on inclines.

    2. Joe says:

      Sikaflex works on slightly inclined surfaces like my typical suburban tract home driveway. I just did mine and there was no pooling at the bottom. Start at the top and work your way down, using slightly less sealant as you get near the bottom.

      1. Thanks Joe for you tip. This question does come up a lot about the pooling action. So any additional advice on the issue is fantastic.

  35. krithika says:

    Very informative post and video for a dummy like me!
    Our home has a small gap between the home and the concrete patio through out the perimeter where the patio meets the home. Do you suggest I can seal it the way you have suggested to prevent water intrusions?

    1. Self leveling sealant is a great way to go Krithika because it allows your patio to expand and contract.

      I think this would be a good solution for you.

  36. Scott says:

    Yep, I’ve done this. and it’s a P.I.T.A. LOL.

    1. For real Scott, it’s no fun at all.

      And I have to do it again!!!

  37. Noah says:

    I’m looking to complete this project on my driveway, but I’d also like to use a densifier/waterproofer on it. Any recommendations on which should come first?


    1. Hey Noah, that’s a great question and I’m not sure. Here’s what you can do though. When you figure out the products you’ll be using give the technical support lines a call. I bet they’ve gotten this question and will be able to help you out.

      Please, if you don’t mind, let me know what you figure out because some of our members will be curious too ๐Ÿ˜€

  38. Rachel says:

    Hi Jeff…I read your article & all comments. You’re so cute! I priced all this stuff out 4 yrs. ago and it was too expensive for me to do my old 75yr old driveway…so I know it would cost even more now. My solution was to buy black asphalt patch in pourable jug and pour that in my humungous expansion joint gaps which are in some places close to 2 inches wide and VERY deep. I pulled out all the old rotted wood where I could.

    I haven’t done this project yet but what do you think about using the material? I can’t afford $400 for foam rod & copious amount of tube sealant. Besides since my concrete is so old & beat up the cost for those items seems silly.

    Let me know what you think Jeff! I bought the jugs when they were on sale….if it works the whole double drive will have cost me about $25 tops to repair the joints!

    Rachel the HandyWoman

  39. nelson rhodes says:

    I used sealant you recommended about a year ago. it is now lifting out of the joint along with sand. it seems water is getting under the concrete. what can I do about this problem.

    1. Thanks Nelson for letting me know. The most important part of applying self-leveling sealant is to remove all the old material before putting down the new sealant. Otherwise, the new sealant will not adhere correctly.

      I know this firsthand because the prior applied self-leveling sealant directly on top of the old material. Now I’m in the same predicament as you!

      So my suggestion is to remove all the old material/new material and start over. Use an angle grinder to cut out the old material and mineral spirits to clean off the concrete. Then apply the new self-leveling sealant.

  40. AW says:

    I really like your concrete joint sealer DIY and how it contains both written and video instructions. We are buying a 50 year old home where the garage floor has settled several inches and is grading toward the foundation. The concrete slab itself is in good shape without lots of cracks so on its own doesn’t need to be replaced right away. There is a seam between the garage floor and the foundation as the garage floor is not part of the main footprint. I was wondering if as a temporary solution (for a few years until the slab would need to be replaced) sealing this seam would work to prevent moisture from seeping into the seam with the foundation. Where we live it gets snowy in the winter and all that moisture ends up falling off our cars onto the garage floor… Thanks for your advice!

  41. Joan says:

    2 x 4 wooden forms, expansion joints or plywood forms, Maybe they are all the same, really don’t know. But they were left in the concrete in the garage of my south carolina home. I am now smelling mildew. i think it’s coming from this wood thats stuck in the cement thats all around the the edging of concrete. This is upsetting me very much. I believe when i lived in N Y this wood was always removed from the cement when the job was done. Is the same thing done in a garage as you are explaining for driveway fixings. Thanks

  42. Roxanne says:

    Hi Jeff,
    We have a large concrete patio that runs the full width of the back of our house. I m wondering if your guidance re replacing expansion joints applies here as well. The slab has pulled away from the foundation leaving a gap of about an inch. Any advice would be most appreciated!

  43. Pat says:

    Hi Jeff, we live in Canada where our winters are usually below zero. We have a concrete patio where no expansion rubber sealant was applied where it meets the foundation. We’ve had it repaired every few years because the concrete continuously cracks and leaves large gaps. Also the patio meets concrete steps going to the basement which were experiencing the same problem. What do you recommend?

  44. Barbara says:

    Thank you Jeff for your explanation of repairing concrete driveway expansion joints with Sika. I have one joint that is wide, so my contractor twisted the backer rod as you explained, but there is one problem. Where it is twisted in some areas the Sika being so thin rain down between small openings! Do you have any suggestions what to use to block these small openings before applying more Sika?

  45. April says:

    Hi Jeff! My husband and I have just purchased our first home, exciting stuff! The driveway has old wooden expansion joints that need to be replaced. They’re rotted and a trip hazard. The problem is that the space is huge! Almost 3 inches wide and pretty deep. Any ideas on what we could use to fix them? Would backer rod and sealant work or just replacing with wood be a better option?
    Thanks in advance!

  46. Ed says:

    Hey Jeff, I just used the self-leveling sealant in the expansion joints of my driveway. Part of the driveway is on a slight slope, causing more sealant to move down the joint toward the bottom of the slope before curing. The results, some of the sealant cured in a bead above the surface of the driveway. In fact, there’s a half-dollar size pool of cured sealant at the bottom of the slope. Do I need to do anything with the sealant that cure in the joint with a bead above the driveway surface, or will the seal remain in tack with cars tires rolling over it? Thank you.

  47. Teddy says:

    Hi Jeff,
    This is a question that relates but not sure if you can give me your opinion. I have 1 inch expansion joints that mostly are filled with weeds and some rotting wood. I want to cover the patio with slate tile and am wondering if expansion and contraction will be the much of a concern. Do I still need to fill it with what you have recommended. By the way, excellent presentation and comments. I am excited to check out some of the other info here as I have tons of projects to do.

  48. P. Duffy says:

    I just bought a house that has a 5,500 sq ft concrete driveway. The slabs are 10’x13′ each and there are about 40 of them! It looks like a airport runway! I live in NH where it gets pretty cold in the winter. The slabs do not have anything between them and yet I don’t have any cracks- am I looking for trouble by filling them in?

  49. Jo says:

    Jeff, we did our driveway joints with the backer rods and the self leveling sealant as recommended. My husband wants more sealant on one of the joints (the first one he did). Can you put a second layer of sealant over the first layer? We do have the room to do so in the joint. I can’t find any answers on the Sika website. Thanks. Great job with your information.

  50. Geoffrey says:

    This is good stuff!!

    I am about to embark on replacing the concrete joint for my back patio here in TX. The previous sealant was absolutely gone, with not a trace left. The foam was hardened and very brittle. I have already scraped everything out, and have found my joint is at least 4 inches DEEP! The rebar is visible at about 1.5 inches down. So how do I take up this space?? I feel backer rod/sealant would sag overtime if I didn’t put something in to take up the empty space.


  51. Lou says:

    Sikaflex is a great product for expansion joint repairs. However, I spoke with a friend who owns a concrete business and he warns that if you use Sikaflex self leveling on a driveway that has any more than a 2% grade with a continuous joint running perpendicular from the building to the road, you’ll end up with a blob at the lower end and very little material at the higher end. Do you have any ideas on how to avoid the blob?

  52. Melinda says:

    Good morning, I’m looking for something along these lines to fill in the spaces of my flagstone patio. Will this stuff work, if not do you have any other suggestions? I don’t want a sand or anything, I’d like something that will fill in the spaces between the stones and attach to them to keep bugs and weeds out. Any help would be great, thank you.

  53. Angie LaRoque says:

    Hi Jeff,
    The problem I have is my side patio, that buts up to my house is pulling away from the house and I have a big gap there and water is get down the side of my foundation. How would I approach this? The same way you would repair a driveway joint; with backer rod and self leveling sealant? A fast response would be appreciated since winter is right around the corner. Thank you so much! Angie

    1. I would approach it the same way Angie.

      If that gap is super wide you can combine two pieces of backer rod together.

      You want that backer rod tight against the house and pad, that way you won’t be using excess sealant.

      And you can dam the edges of the gap so that sealant doesn’t ooze out of the joint.

      Make sure to follow the directions on the Self-Leveling sealant ๐Ÿ˜€

  54. Bob says:


    I may need to remove some self-leveling caulk because I put sand in the gaps.

    Then I figured that sand will not be compressed when the concrete gets hot and so the concrete will crack.

    A good strong leaf blower will blow the sand out.

    But I will have to remove the DAP 3.0 self-leveling concrete caulk I put on top of backer rod.

    What kind of cutting wheel do you use with an angle grinder? I’m not sure exactly what a cutting wheel is.


  55. Aaron says:

    So, I listened to a guy at Lowes’s who suggested spray foam to create a base instead of the foam backer. That seemed to be fine, but he also suggested a black neoprene sealant that I believe was designed for asphalt. I thought it was odd, but thought perhaps the product was just black. Well, I went back today and realized that it is not the self leveling caulk I had requested. My question is, now that I have the black neoprene sealant down, is it fine to put the self leveling caulk on top of it?

  56. Mohamed Sayed says:

    Man…thanks for such a description for beginners like us.. you are awesome that while going through your notes we wished that everyone could describe each single point for easy grasping to the one who reads…it’s awesome …hats off my friend…

  57. Mike Whaley says:

    does the product become firm? I can picture my kids poking sticks in it or something?

    1. It does Mike, more of a flexible sealant but still very firm

  58. Jeff says:

    I just recently had a new concrete driveway poured in July of 2015. Very satisfied with everything….until a few weeks ago. After some heavy rains, followed by snow, and brutal temperatures, I started noticing that the expansion joint between the new driveway and existing garage floor was 1/2″-1″ higher along the total expanse. What was once a smooth transition into my garage is no longer. Is this the result of heaving and will it gradually return as the temperatures warm? I’m reluctant to drive my truck into my garage for fear that it may crack. Only wish I would have been informed by the contractor that this would happen and the possibilities that are out there to resolve this issue. Any advice? Greatly appreciated and many thanks!

    1. Oh man Jeff, yah that shouldn’t be happening. Calling the contractor is your best bet. That and taking several pictures.

      They should have warrantied their job for some period of time, do you recall the contract stipulations?

      1. Jeff says:

        Thanks for your prompt response, Jeff. I felt I did my homework on the contractor that I hired (I had 3 other estimates from others), and based on recommendations from individuals and visually inspecting his work, I based my decision on those factors. Looking over my contract, all it basically says is that he will “prep, form, and pour 4″ thick concrete and 6″ thick at the end of driveway w/ limestone mix, wire mesh, broom finish, cured, and cut. A penetrating sealer will be applied after 30 days of curing time.” (which was done). I see nothing as far as a warranty. I think I’ll get my camera ready and fire off some pics! Thanks, Jeff!

        1. Oh man, sorry to hear that Jeff.

          Yah, take some pics. Let me know how it goes.

          They should uphold their workmanship but sometimes that’s not a given!

          1. Jeff says:

            I called the contractor and had him come out and inspect the expansion joint. Believe it or not, we had a warm spell for awhile and it is now back to level with the existing garage floor! He said it was probably nothing more than moisture getting in, freezing, and causing it to “heave.” He said he will be out this spring to resolve the issue with some sealant. Thanks for your help, Jeff!

          2. Whew, good to hear your contractor came back Jeff. That’s a good sign. Let me know how it goes this spring and what fixes they make.

  59. Karl says:

    Have you ever used the Quikrete version of the self leveling sealant? I would like to first use Styrofoam material to fill in the gaps kind of like backer rod material but Styrofoam. Ever here of this, will it work possibly? Also after installing the sealant how long before I can sprinkle sand on top to give a finished look?

    Thanks for the advice:)

  60. Colin says:


    You’ve created a great resource here which has clearly been useful for many people. My question is about the longevity of this solution. How long can I expect for the Sikaflex to last before I would have to do it again?

    Also, traditionally the method of choice for expansion joints has been to use wood hammered into the gaps. What do you see as the pros and cons of wood versus sealant?



    1. Colin says:

      OK, so I took the plunge and went with the backer rod/sealant method over wood. Overall, it will cost more but it will give me a more even look due to the self leveling compound as opposed to the wood which would have to be cut due to the variances in depth due to tree roots and muck that can not be removed from the joint cracks.

      I would definitely endorse Jeff’s big tip of ensuring that your backer rod is snug. If it is at all loose at any point, the sealant will leak through and you will be left with holes in your sealant where water will get through. Even if the crack is evenly 5/8″ across and you use a 7/8″ backer rod but you have sections where there are chips making it greater than 5/8″, this will be the weak areas.

      A situation I ran into is where the joint was wider than the largest diameter backer rod. I am going to experiment with two methods. Jeff suggested twisting two backer rods together but it seems to me that this does not make it uniform when inserting into the joint. Instead, I am going to use the largest diameter I can find and then an additional backer rod that will give me enough width to provide the additional 1/8″ that I need to fill the joint. Because the backer rod is tubular, they tend to roll away from each other when you insert it into the joint. Instead, I am considering cutting part of the backer rod so that it is flat(ish). Perhaps, I might cut both and have the flat ends butted against the sides of the joint. I recognize that I will probably need to account for the loss of material and therefore go with two larger diameter backer rods.

  61. Kimo says:

    Just came across your website. I’ve been wondering how to water seal the expansion joints in my concrete driveway. Your site gave me all the information I need to attempt this DIY project which I plan to do shortly. Will let you know how it’s going. Still recovering from rotator cuff surgery so it’ll be a month or two before I get started.

  62. Joel Thornton says:

    Jeff, I have another question about sand…my expansion joint is about 5 inches deep. Can I fill the first 4 or so inches with sand, then backer rod on top of that, then finish off with Sika? Or should I just use the backer rod and leave the space empty below it? Thanks!

  63. Angela Beauchamp says:

    Hi Jeff. My expansion cracks have never been filled so I didn’t have any caulk debris that needed to be removed. I did however remove weeds where I noticed the expansion cracks to be about an inch wide and the dirt inside it goes down VERY deep. Should I get a very deep and wide backer rod or some other “filler” to fill this crack before I apply the Sika SLS? Thank you!

    1. Thanks Angela for your question. I’d recommend getting backer rod and filling in the joint with it such that the foam is slightly below the concrete. You can even twist two pieces of foam together if you can’t find some that’s wide enough to fill the gap. You want the foam to be pretty tight against the sides of the expansion joint so that the SikaFlex won’t ooze below it. Hope this helps.

  64. Amanda says:

    Hi Jeff!!

    This post is a life saver! I have been working on the driveway of my boyfriend’s rental house since spring. Just now getting all the weeds up and heading toward the phase of getting the dirt and old sealant (among other things) out of there. I am a DIY newbie but it’s all fun to me.
    As far as the driveway, the expansion joints are one thing, but there are also cracks of varying depth and width. Some meet the joints and just end at the side of the driveway. My main question is… should I fill these cracks with concrete or sealant? And if concrete, should I fill the expansion joints first or the cracks?
    One last question- what is the best material to dam the ends of the joints with?

    Thank you so much for this resource!

    1. Thanks Amanda and congrats to you helping with the DIY, always good to learn new stuff. I’d fill the minor cracks with crack filler. Sakrete and Quikrete make great options. The crack filler is better than concrete as it will expand and contract with the weather. If you need to damn the sides of the joints you can use anything that makes sense, even clay or old wood will work fine.

  65. Robert says:

    Here’s some things I learned as a first time Sikaflex SL user as they pertain to my project. I hope you can learn from my mistakes and successes. My intent is to share and not sound preachy:
    Spend plenty of time prepping your project. It took hours and hours to dig out old expansion joint materials, weeds, dirt, etc. but it was worth it when it was time to pour.
    Measure the width and length of all the spaces you need to fill and purchase several sizes of backer rod. The hardware stores carry the narrow widths. I bought 100โ€˜ rolls up to 1 1/4″ on eBay.
    Something didn’t feel good about having a void under the backer rod, even if it was tight against the sides so I pulled it out and filled in the space with sand and leveled it out so the backer rod sat on the sand. I poured in dry sand and wetted it before putting the backer rod on to get rid of the air pockets. Don’t know if this is necessary but didn’t want any air pockets figuring in later. Maybe the air pockets are helpful though with winter heaving?
    As mentioned in the original article, keep the top of backer rod below the surface. If you don’t, it will leave a hump when the pouring is done. I read online that backer rod has gas in it which will release and weaken its integrity if cut so I did not trim the top of it as another poster did.
    Leave the backer rod in for a few days before pouring the sealant. Mine contracted six inches over the span of a two stall garage opening. I learned this after I laid the backer rod, got my project interrupted, and got back to it days later. I’m glad that happened instead of it moving around with wet the sealant on it trying to set. My neighbor poured his right away. His ends were not secure and when he woke up the next morning it looked like the Loch Ness Monster was breaking the surface. The ends were sticking out four inches. His said some naughty words and has a LOT of work ahead of him.
    After the backer rod is in, I brushed a medium layer of sand over it to fill in any unseen air holes. I learned this the hard way on my first experimental try. The sealant found a hole and ran and ran down it. I wetted the sand with a spray bottle immediately prior to adding sealant.
    Dam the ends. I used whatever fit the area. A snip of backer rod, a piece of cardboard, a strip of duct tape.
    On some places I could not get the old material out of the gap in places and backer rod would simply not fill the gap so I stuffed different diameters of rope in as filler. It looks fine after a week. Fingers crossed for the long term.
    I did mine in the fall and leaves galore found the wet sealant. So did bits of grass, dust, sand, dirt. This would be a great indoor project.
    Find a neighbor and share the costs. Home Depot sells SikaFlex at a discount by the case (can’t remember if there are 10 or 12 of the large tubes). When we bought, it was about $10 vs. $12 per tube.
    Get the right color. They had tan and gray when we bought and you have to look at the color strip on the package. Tan was less expensive for some reason.
    Do your project during the day when people are at work. EVERY neighbor who has this project ahead of them (which is every neighbor) will stop and want an explanation. Every neighbor. It’s great to meet the neighbors if they don’t mind you continuing to work while you visit. If you do decide to take them up on their offer to “do theirs next”, bid it out per hour, not per job. It takes way longer than expected.
    I took plenty of rags and paper towels but did not get the proper cleaning solvent. It does not wash off with water. Not off your concrete and not off your hands.
    Getting tools out one by one as I used them, here’s a list ahead of time that I used at least once and are in the pile: buckets for sand and debris, scoops, brush, broom, gloves, tape measure, yard stick, needle nose pliers (pulling out leaves from wet sealant), putty knife, box cutter, scissors, painters tape, paper towels, rags, screwdrivers for digging, rope, spray bottle with water, backer rod, case of sealant, large size caulking gun, towel for relief for knees on concrete, shop vac, headphones, patience.

  66. Jack Riegel says:

    Hi Jeff-

    Thanks for all of the great info. Would this process still be appropriate for a house gap between my foundation and attached walkway? In some parts, there are some large deep gaps developing. Old caulk (almost tar looking?) has pulled away in the past which I’ll need to remove. Could I fill deep gaps with course sand/fine rock then use backer rod and self leveling caulk on top?

  67. Bill says:

    Hey Jeff, I just a new patio poured about 45 days ago (12×15). My old one would heave as the temps became frigid in the winter. The contractor installed rebar & cut expansion joints. Would be wise to caulk the joints? Or is it not necessary? Thanks…

  68. Lisa says:

    Hi. Great info, thanks! I am trying to fix a problem made worse after hiring 2nd concrete contractor to redo section of driveway meeting garage floor. 2nd guy used 2×4 treated wood as isolation joint where garage walls meet driveway. Wood too high &some concrete below wood, causing more heaving and damage to siding and garage wrap. I have removed wood and chiseled out most of problematic concrete. The problem is that the joint width is about 3 1/4″!! Depth is about 6″. It is a 1-car garage so that each joint length is less than 1 foot each. Should I sandwich together foam expansion joint material to fill this space??? Thanks.

  69. Ross says:

    Thanks for posting. FYI, acetone will go through nitrile gloves, so if using these to protect against the acetone, then you’d want to consider butyl rubber gloves.

  70. John Lasker says:

    Do you answer directly? This posting is great reading but I skipped to the end to send this question. I have used the Sika product and backer products on my driveway and while it looks and seems to take care of the problem, it doesn’t seem to be a long term solution. It’s been about 4 years since I did the work and now it is weathering and showing gaps again. I think I need to remove and replace every bit that once looked nice. Has anyone else reported this?

    1. I’ve experienced similar problems John, it’s mostly due to the fact that nothing is permanent. Four years is pretty good. Concrete is always moving, just slowly. And if you have bad weather, like in Pittsburgh, that expansion and contraction is constant. This in turn applies pressure to the expansion joints and that’s what causes the Sika to pull away. Sorry to say there’s not really anything that’ll last for more than a few years.

  71. Ali says:

    Thanks a lot. Excellent step by step instructions. Made me project so fast and easy.

  72. David Loving says:

    Jeff, can you post or email me the link to Amazon for the preferred tile cutter blade you reference in your written outline? Or, email me the blade model number? The Amazon link for this blade is incorrect; it takes you to the cutter itself. Thanks for the tip…just want to get the best stuff!!!

  73. Mike says:

    Jeff, this is nice of you sharing your experience with others. This is what I am looking for since I am newbie on this kind of stuff. I will use your guide to do mine. May the good bless with you and your family.

  74. Pam says:

    I don’t see my problem addressed anywhere. I believe the contractor hired by our builder was a little lazy. The wooden boards in our driveway’s expansion joints appear to be part of the forms built prior to the concrete being poured. As you know, these forms don’t always fully contain the concrete as some inevitably oozes under the boards before it hardens. My husband and I were trying to pull one of the boards out because it had popped up on one end. We couldn’t get it to budge so I took a long thin knife and probed trying to find out why it wouldn’t move and found several sections of 2 to 3 inches in width of what felt like concrete about half way up the board. In other words, I could only probe 2 to 3 inches deep instead of 4 or more. How do we break the concrete loose from the board so we can remove the board and replace it with a foam backer rod and self-leveling sealant?

  75. Linda Gisler says:

    Jeff, you are so helpful. I have a long double wide driveway and spent most of yesterday digging weeds out of the joints. The sealant is all gone over the entire driveway. The joints are all empty except for soil. Do I just clean it well and then put the foam in the joint on top of the soil? Also I have cracks in another area. These are not joints. Can I use the same sealant in these cracks and do I use the foam too? Some cracks are wider than others . I’m a 76 yr old widow and so excited to start this project. I’m tired of pulling weeds all summer.

  76. Sue says:

    Hi Jeff, thank you for the information here. I have a wobbling 2’x 2′ concrete slab that has a water cap on it. It is located on the sidewalk in front of my house. Will placing backer rod in between joints before adding Sikaflex Self-leveling sealant stop this wobbling? Thank you!

  77. Rina says:

    Hi Jeff,

    Does this method apply for expansion joints on walls of 2 storey building?


  78. Tony says:

    I’m am in Houston. It’s July 10, 2017. It’s raining off and on interrupting my work. I have done the first layer awaiting to put on the final application. Should I be worried that mother nature will ruin my work? Please send an email reply.

  79. Mark says:

    I have a huge concrete patio on top of my 2 car garage. We have always had a water leakage problem from the expansion seams of the concrete which creates a very damp wet garage.. not a useable storage area! Would this be of good use in this case to stop the water from leaking into garage?

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  81. Sherry says:

    This is very helpful, thank you!! Are the directions and sealant recommended the same for expansion joints surrounding a pool? Also, I am a newbie doing this by myself. Is there any harm in removing the old caulk ahead of time (a few days) and adding the caulk and backer rod later on? Not sure I can do it all in one day. Thanks!!

  82. Naomi Prosky says:

    how do i know if my separations are expansion joints or concrete control joints? From the way you are describing this project I think it is for me but I don’t know how to tell what type of openings i have.

  83. Michael O'Hara says:

    Here is a tip. A much better way to remove the old sealant is with a multi-tool and a regular old scraping blade attachment. It cuts through the old sealant like a hot knife through butter. A grinder is a bit of overkill I think.

  84. Robert says:

    I have a problem with a group (6) of tiles coming off because of contraction. I had it repair several times and I had it!! They are located on my patio, I do not want to remove all the tiles in the patio because it will cost a fortune. After watching your video I thought applying that special product in between the tiles in that area will repair the contraction problem. Please advise. Thank you

  85. Dean says:

    Hello Jeff,
    Thanks for the very informative post. I love your easy, interesting and thorough writing style that includes everything you need to know for each step. As I read the post, I could visualize similar projects I have done and recall what I did, or similarly, what I afterwards realized I should have done as you capture in your details. I love all the tips, especially the simple yet useful ones like “use an old wire hanger” to piece the tube – how many times have I raided the closet for a hanger to so just that. Thanks

    1. Thanks Dean for your kind words. Really appreciate it. Always feel free to ask any question or add your own tips!!

  86. Brian says:

    I’m wondering whether creating a water-tight seal is appropriate for an area with expansive clay shrink-swell soils. Foundations often crack during hot summers and droughts because the soil contracts when the moisture dries up; they return to normal after a big rain. It seems that we would actually want water to penetrate the joints of the driveway and sidewalks to encourage constant moisture levels and keep things level. Would a permeable filler material (like wood or felt) be better in this situation?

  87. Frank B says:

    What happens when your “self-leveling sealant” doesn’t self-level? I did my patio joint last fall in warm weather, and when down, it looked like I had squeezed a big tube of toothpaste – a continuous row of humps that never flattened. Was I supposed to use some kind of tool, like a putty knife, to level it? Since the sealant is very new, can I go back this spring and add more (there’s room) and use a tool to level it?

  88. John McGarvey says:

    I have weeds growing out of the expansion joints in my driveway and was going to buy a tool for this but I thought they were too expensive. Then I thought about an old rusty pole pruning saw blade I had, so I made a handle for it and bolted it through the holes in the blade and it really rips the weeds and roots out of the crack, then I apply weed killer and then seal it up ! The idea you gave me about the closed cell backing rod and the sika flex self leveling sealant is the answer to the final weedings ! Thank You.

  89. John McGarvey says:

    That is all I have to say !

  90. Amy says:

    Thank you for the information and videos. My driveway was poured sometime in the ’50’s and has never been resealed. There are a few areas where the foam backer or some other type of filler/sealer remains but it is mostly gone and not the seams have sandy dirt and grow grass and other weeds. I have removed the plant matter and am wondering if, when I clean it out deep enough, the foam backer can sit directly on the dirt and will this system keep the grass and weed from growing back. Thanks.

  91. Rich Prilliman says:

    Hi Jeff… How long does it need to cure before driving on and what precautions do I need to do while curing?

  92. Gary lackey says:

    Iโ€™m going to Epoxy my garage floor with Armorseal 1000 before I seal the expansion joints. I believe my expansion joints are just saw cuts. I do not need Backer rods. After feeling the joint with silka do a smooth over it with a Joint knife?

  93. Camy Botezatu says:

    I just got my driveway repaired, I have 4 new concrete slabs.
    After the job was done, I noticed that there is no expansion joint between the slabs, there is only a crack line. My husband wants to rent a grinder and make the joints himself. I called the contractor back and he said he knows better, that this way he is protecting against water intrusion. I am not sure what needs to be done, please advise.
    Thank you so much!!!!!

  94. Dan says:

    As an added note, advise the do it yourselfers to also invest in a comfortable pair of knee pads. You know yourself, we aren’t getting any younger and doing this job, I guarantee they’ll be kneeling more than a few times and the knee pads will help immensly.

  95. Suresh says:

    Very detailed, Informative.

  96. Carolyn says:

    Great info! I purchased the same self leveling sealant but I am having an issue with finding backer rod that works. My garage control joints are about 5/8″ and are not very deep at all. I have some old 1/2″ backer rod and it fits but sticks out on top causing the issue that you had and there is no room for any sealant. Suggestions?

  97. Wendy says:

    What if your driveway is slanted. What type of sika product would you use. I have hairline cracks in those grooves between the concrete. Grass is growing. I’m in the process of killing the grass. Should I use backer rod and sealant or just sealant. Thanks

  98. jeanne says:

    We just had a new 18×60 ft. concrete driveway installed. 1. They poured in two sections at 28 ft. and 32 ft. Do we need to seal that joint? 2. Also, they measured incorrectly and cut the first two horizontal expansion joints on angles so they’re not parallel to the garage. One side is 6 in. further than the other. Can they recut the expansion joints and seal the angled cuts? 3. They spread concrete right up to garage floor and even slopped it onto sides of garage door trim. Will this pose any problems in Michigan winters? 4. They poured directly on sand, is that okay? 5. They added something to prevent freezing as it was 45-50 degrees and mid 30’s at night. When can we safely drive on it? Sorry for all the questions but they’ve been uncooperative since we asked them to dig out a 6×6 ft. solid concrete dumping (4″ thick solid washout waste bonded to curb, soil and grass) on our front lawn (still there!). Sincere thanks!

  99. Lee Brown says:

    For a while now, Iโ€™ve had a small gap between my foundation and the driveway. I can put a rod about 1.5 feet down into the hole. Do I need to fill that hole before I fix the seal?

  100. Donna says:

    I have a garage floor that has a cross through it and I assume it is a contraction joint. (Difcerence between saw cut and V contraction joints?) The edge or perimeter of garage has expansion joint around it with fiber board I assume ( it looks like a black felt) The end of your paragraph says Just remember that expansion joints should always be sealed and filled with flexible joint sealer and never be epoxies or coated over. Contraction joints can be filled in same manner after coating or sealer applied is this last sentence saying filled contraction joint after the coating. Is on We are having a professional place polyurea with polyaspartica too coat. Am I supposed to fill the contraction joint after ? It fors not make sense to me Is there any way to chat with you?

  101. David Wilkinson says:

    This article looks great on how to repair or replace the expansion joint filler on a driveway. I have an aggregate driveway and am having trouble finding a clear sealant to place over my backerrod. Using a colored sealant looks terrible on an aggregate driveway. Even stone colored sealant draws attention to the expansion joints. Any suggestions?

  102. Yvonne says:

    Can I use backer rod if I am sealing the base of a room that has no raised foundation and water is leaking in the room when it rains?

  103. Kim says:

    Hi! Great article. I have an unusual situation. My kids bought a house and just found out the have water penetrating the house and also have termites. Iโ€™m trying to find the cause, the removed a ton of moldy vinyl Plank laid over tile, then removed the tile to get down to slab. The previous owners did a room addition and thereโ€™s an expansion joint between the slabs. You can actually see dirt. It rained yesterday and the dirt is wet. The sheetrock by the joint is wet and moldy. The base plate has damage and the cabinets on other side of wall have mold in the back. I know we have to fix the joint to keep water from coming up. Is this a viable solution or will it deteriorate over time? I donโ€™t know if we need to fill the gap or take out part of the slab and re-pour it and tie the slabs together with rebar? Any advice appreciated! Kim

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  105. dpw says:

    Can you use sand in place of backer rod?
    You mention having a coating of 1/4″ – 1/2″ thick over the backer rod. Is that determined by the width of the joint?
    Should thicker joints be applied in layers, allowing one layer to cure before the stacking on a second layer?

  106. Salvatore Cucchiara says:

    Is there a way I can send you guys a photo of my drive way? It goes along with my question.

  107. Winterstorm says:

    Hi thank you very much for the useful info. Do you have any guidance on Driveway which has sunken due to erosion of soil underneath, do you have any recommendation? Is it better to reinstall concrete or use poly foam ? please advise or post video.

  108. Kirk says:

    Great advice. Thank you. I like the Sika Flex, but it has a shiny kind of finish that stands out a bit. Is it possible to add a sand / grit on top of the Sika Flex to give a more blended finish? I can’t find a such a product? Thanks!

  109. Tom says:

    Jeff I have har line crakes in my Pattio do I need to use a grinder to apple sikaflex leveling sealant

  110. Andrea nolan says:

    Do you anyone that does this kind of work.
    I need some work done on my balcony concrete.
    I am in Georgetown on
    Hoping you can recommend someone

  111. Geaux360 says:

    Great tutorial. Just to be clear the wider deep holes are the expansion joints but my driveway has skinnier shallow (nit cut through the slab) channels. These would be control joints correct? They are cracked so I thought about sealing them just with Sikaflex; any thoughts on that? Thanks for any information.

  112. SCOTT HOLLAND says:

    Hi Jeff, Wondering if you could or should put play sand in the joint before the backer rod

    1. Hey Scott, I only use the backer rod to ensure the joint will remain open to expansion and contraction during the hot and cold seasons.

  113. Barbara W. says:

    Hi Jeff, I recently had a slate patio repaired (removed slate, re-dug base, added rebar, reused existing slate). It all looks great except for the expansion joints which mason left as is. He insists they do not need to be sealed, that cutting down the backer rod will compromise it and cause problems and the Sika sealant will need replacement in a year. “They are suppose to be this way” He suggests I paint the foam if I don’t like the look of the exposed black backer rod!
    Would painting the foam rod even work or because it is new foam rod, can I apply Sika self-leveling sealant directly on it if I clean it up first?

  114. Mr Pete says:

    Jeff, some important items missed. I speak from the experience of now having to redo my entire set of driveway gaps ๐Ÿ™
    1) MOST important: the primary purpose of backing rod is to ensure the sealant does NOT stick to the bottom of the hole! It should ONLY stick to the two sides. If there’s no room for backing rod, “bond breaker tape” must be used. I haven’t found a local source ๐Ÿ™ — skip this and you get sealant stuck to one side, and the bottom… and NOT the other side.
    2) Sika strongly recommends tooling the sealant after applying, to ensure it pushes into the walls of the gap. Makes sense to me.
    3) Yes use tape on both sides. Unless you are amazing at filling with just the right amount.
    4) Many driveways have a slope. Doesn’t take much for the self-leveling sealant to run to one end (and no, taping the end doesn’t solve this.) Use “Sikaflex Concrete Fix” instead.
    5) Use matching-color sand on top of the sealant (wait an hour, sprinkle on, wait ~10 minutes, blow off) to make it match the driveway, and avoid tire marks.
    6) I love-love-love using my new multitool for removal. Way easier than grinder.

  115. Mitch Klebig says:

    I just read your tutorial on repairing/sealing concrete expansion joints, which was very helpful. I was ready to tackle the job on my expansion joints, but found that the fibrous backer board is still in the joints and is in good shape – not deteriorated and is glued tightly to the edge of the garage slab. However, there is a 1โ€ gap between the driveway slab and the board. Will the Sikaflex adhere to the backer board or should I remove the backer board?
    If I leave the board in, should I just fill the joint so the sikaflex seals up against the backer board, or should I maybe grind the top edge of the board down to about 1/2โ€ below the top of the concrete and then cover it with sealant? Thank you!

  116. Oleg says:


    Thanks a lot for great tutorial!

    You wrote” Push the backer rod down into the joint with your hand. The depth of the joint should be a minimum of 1/4 inch and a maximum of 1/2 inch below the concrete pads. This means the backer rod should be this far below the concrete pad surface.”
    How should I proceed if I have very deep joint, like 3-4 in? Should I just push the backer rod down not deeper than 1/2in and leave space underneath?

    Thanks a lot!

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