Filling concrete expansion joints

yadax3November 7, 2007

Hi all,

I tried posting this on another forum but no response. I'm hoping someone here might know the answer.

Anyway, I absolutely HATE concrete expansion joints - especially the ones on my patio. They catch dog hair and dirt and make sweeping much more difficult than if the patio were smooth.

I'm looking for some way to eliminate the expansion joints without tiling or laying down a rug and I've noticed stained concrete floors in stores where the expansion joints have been filled. They almost looks like grout joints. Does anyone here have any idea what I could use for this purpose? I need something that will hold up in hot/cold weather and won't come loose, peel up, etc.

Thanks for any advice you can offer,


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Expansion joints are just that, they are put in to keep your slab from cracking if you grout or otherwize limit the joint they may as well not even be there. J.

    Bookmark   November 8, 2007 at 4:59PM
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Thanks, John. I think I understand their purpose but how do the stores get away with filling the joints in their concrete floors? And how do people with stained concrete floors in their houses deal with them? I guess I just assumed stained concrete floors wouldn't be as popular as they seem to be if people had to live with expansion joints. Am I the only one bothered them? (I feel so alone with my obsession)

    Bookmark   November 8, 2007 at 7:49PM
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Expansion joints are usually only necessary where your concrete adjoins a structure or another pavement section with different properties. A concrete floor will typically not have expansion joints in the middle, but they will have contraction joints. These joints are not meant to expand and contract, but rather are just a weakened plane for the concrete to crack. These contraction joints remain very tight due to reinforcement in the slab. Therefore, these can be sealed and will remain tight. You also have to consider that concrete floors inside a controlled environment (i.e.-a house) will experience significantly less movement than a concrete patio that is exposed to varying temperatures and elements.

On to your question of what can be done with your expansion joints on your patio. You can fill expansion joints with a joint filler that can expand and contract with the concrete. You will need to put some sort of material in the bottom of the joint, typically called backer rod, which is a premolded plastic piece that you shove in the bottom of the joint (or I have seem fiber board or wood used as well). This just gives the joint sealant somewhere to rest while it sets up. Then the joint sealant is poured into the joint. Keep in mind that you will not have a perfectly level joint at all times. At times the material will be stretched and you will have a depression and at times the material will be compressed and you may have a little bump. Usually, depending on when it is applied you try eliminate the likelihood of the bump. I'm not sure of the exact brands of joint sealant, but I would think that a self-leveling silicone joint sealant would be available at your local home improvement store.


    Bookmark   November 9, 2007 at 9:18AM
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Thanks, Riles. I'll check into it. I appreciate all of the information you provided.


    Bookmark   November 9, 2007 at 3:52PM
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Hi again, Riles. The guy at HD said the backer rods are only needed for true expansion joints (i.e. the kind with the felt-like material in them). If they come to a 'V' like ours, he said we don't need the rods. Also, HD didn't have any filler that pours - just the kind you use with a caulking gun. It's self-leveling and comes in grey or sand colors. He showed me where they'd used it on their concrete floors, although their filler has cracked a bit - probably because the store is less than 2 years old. Our patio was poured 12 years ago, so I'm hoping it won't settle any more. Does this sound in line with what you know?

    Bookmark   November 11, 2007 at 10:44AM
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It sounds like you are dealing with contraction joints, not expansion joints. These joints are just meant to control cracking. The self-leveling sealer should work fine, however, I have to be honest I have limited experience with concrete patios. I design large concrete pavements for runways and airports. The applications are a little different. We seal our contraction joints with self-leveling silicone. My only fear is that your expectations might be a little overreaching. Your concrete is always going expand and contract, it's the nature of the beast. The sealer is really meant to eliminate water infiltration, not to provide a completely smooth surface. The troweled joints that you have may be very shallow as well, which might lend to the potential for the sealant to be pulled out due to the lack of vertical surfaces to adhere to. You might want to check with someone who pours concrete patio's or driveways and get their feedback. I don't think it could hurt to try it on a small area though to see if it meets your expectations. Let me know if I can be of any more assistance.


    Bookmark   November 12, 2007 at 9:29AM
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Hello, perhaps you could enlighten me as well. I have an 18 year old house with a 30 foot poured concrete driveway which is on a gentle slope toward the street. Originally, at the top of the driveway, where it meets the garage floor, there was one of those fiber expansion joints.

Over the years, the driveway slab moved toward the street, and the gap between the driveway and the garage floor widened.

It has been stable for a number of years now, and is 1" wide by 4" deep. How can I fill this? I have not been able to find a 1" wide fiber expansion joint to press into the gap.

Thank you.

    Bookmark   November 12, 2007 at 10:02PM
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I bought a house with a problem I have never seen before: The expansion joint material used in concrete back patio, driveway, front walkway and front porch area expanded so much that it in many areas it is two to three times the height. It looks unsightly and ugly and I don't know how to solve the problem. Any advice, ideas?


    Bookmark   December 28, 2008 at 3:42PM
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Katvil, Is the material a fiberous fiber board material? If so, take a utility razor blade knife and on each side of the joint, cut the material at an angle down as deep as you can get it cutting towards the center. You will probably go through a couple of blades because you want to use a sharp blade(s) and you will be making several passes each side. Go slow and be careful! If you want to fill over that once you are done, inquire at your local hardware store about a flexible epxoy filler for concrete cracks/ joints.

    Bookmark   December 29, 2008 at 11:03AM
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I have used the silicone self leveling stuff on my concrete driveway cracks. It really did self level, and looked nice too. I lived in the house for 3 more years before I sold it, and it remained like new.
I would think this would work for the poster with the joint between the garage and the driveway. You do want to fill in some of the deepest parts though... as I remember, the stuff is pricey, and one tube does not go all that far.

    Bookmark   January 3, 2009 at 7:50AM
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Does concrete expansion and/or contractor joint filler come in colors? All I ever see is gray.

    Bookmark   May 25, 2009 at 6:26AM
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I know how you feel about expansion joints! Last summer I was searching around for pavement sealants that would hold up well in expansion joints for the sidewalk leading up to my house. My friend recommended Dow Corning. The sealant has worked wonders so far. Hope this helps!

Here is a link that might be useful: Expansion Joints

    Bookmark   July 15, 2010 at 1:08PM
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I just replaced my old wood exspansion joints with GapArmour! Easy install,looks very clean,blocks weed's... 5 year warranty ! Check it out @

    Bookmark   April 9, 2011 at 10:43PM
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