Your grout is cracking for one reason and one reason only: your tile is moving. That’s it. Okay, that’s not it – Unless your grout is non-sanded and was installed in the last 28 days – your tile is moving. That’s it. Yes, 28 days has significance, it is the amount of time it took my teenage son to clean his room. It is also the amount of time it takes for grout to fully cure.

So let’s figure out why your grout is cracking:

Your grout is newly installed – incorrectly

If you do have grout that was installed within the last 28 days then your grout is not actually cracking – it is shrinking. Either your grout lines are too large for non-sanded grout (smaller than 1/8″)  or it was incorrectly mixed. NO! You cannot simply mix up more and fill it in. Read this post about adding more grout to your grout lines.

If your grout is not fresh, well, you need to repair the reason your tile is moving. And stop using your pogo stick in the house. Diagnosing the reason your tile is moving is extremely varied. It could be anything from inadequate deflection in your flooring for the type of tile all the way up to and including the aforementioned pogo stick.

The most likely reasons your tile is moving:

Your tile does not have proper thinset coverage

The most common reason I run into is improper coverage. This simply means that there is not enough thinset beneath your tile to properly adhere it to your substrate and support it. If there are any unsupported areas beneath your tile along the edge or in the corner of the tile, walking on it will eventually work what little support it may have loose and the tile will move down and up every time you step on it. The tile moves, the grout does not. The grout loses the battle and starts to crack out. By ‘crack out’ I don’t mean like that ridiculous Intervention show on cable, I mean it will start to crack and come loose.

To fix this you need to remove and properly reinstall the tile. If it is only one tile it may be an isolated incident in your installation and you will be fine. If you have cracked grout all over your tile installation it was either improperly installed or . . .

Your subfloor is moving

If you have a wooden subfloor and your tile is directly installed to it – go pick out new tile. That is more than likely an improper installation. While tile can be installed directly to plywood it requires a VERY specific method. And I do mean very specific. More than likely it is simply installed improperly probably by someone that did not know any better. If it was properly installed over plywood, well, your grout wouldn’t be cracking. Start reading this paragraph all over. Or . . .

Your backerboard was improperly installed

If you have Hardiebacker, Durock, or any other type of cementious backerboard beneath your tile it should have been installed in the proper manner. It needs to have thinset beneath it, it needs to be screwed down (properly), it needs proper spacing, etc., etc. Read How to Install Backerboards for Floor Tile to see all the things that should have been done.

More than likely there is no thinset beneath your backerboard. Thinset is not used to adhere the backerboards in any way – it is used simply to fill voids beneath the backerboard. It is placed there specifically to prevent your tile from moving. Moving tile leads to cracking grout. But you knew that – or you should start reading this page all over. This would be another time to start shopping for new tile.

Other reasons your tile is moving

You do not have expansion space around the perimeter of your tiled room. No, the tile will not expand – but your walls do. If there is no space between your tile and walls it will force all the pressure into your tile. This will cause cracking grout and, eventually, ‘tenting’ of your tile.

You do not have expansion joints in your tile. For every application there are specific spans of tile which can be installed before a ‘soft joint’ is required. This is simply a grout joint filled with a matching caulk or silicone to allow for movement without cracking your grout or tenting your tile. Most of these measurements are over 25 feet. So in English: if your room is not 25 feet long or wide this is not the reason your grout is cracking.

If your tile is on concrete – directly on concrete – your slab may not have proper expansion joints or the tile installation did not honor those. If installing tile directly to concrete (and you should not) there needs to be a soft joint directly above, or two inches on either side, of the slabs expansion joints. If not your slab will move differently than your tile.

And there could be a host of other, less apparent or less common problems. However, if your grout is cracking it is probably for one of the reasons above. The method of repairing it depends entirely on why it is cracking. Most of it, as with most tile installation problems, is due to improper installation.

Or your pogo stick.

If you have any questions about the proper way to repair your tile or grout just leave a comment. I answer every one of them – really, look around the site. I’m just super cool like that.

{ 1026 comments… add one }

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  • Nancy

    Hi there-early March we noticed a damaged ceiling in a corner of our kitchen directly below an upstairs toilet. Sure enough the toilet had a slow leak which we fixed. Now the grout around the toilet is discolored and cracking, chipping and spreading to other areas. I know you’re not a plumber but a floor guy and tough to diagnose without seeing but do you think it’s a weakened subfloor or just a leaky wax ring? Thoughts?

    Reply
    • Roger

      Hi Nancy,

      There is likely some damage to the subfloor but to determine whether or not it’s significant enough to need replacement you’ll need to pull the toilet and look at it and poke around it. You will be able to tell by pushing on it. If it’s solid then you’re likely fine, if it has any ‘give’ or feels ‘squishy’ (technical term…) then you’ll need to cut it out at least six inches around the weak areas and replace it.

      Reply
  • Lauren Sampley

    Roger,

    We recently moved into a newly remodeled home. After living here for about 2 weeks we noticed the grout was cracking around the tile as well as cracking into the tile causing hairline cracks across the tile. It first started in one room and has now happened in 3 bedrooms and area leading into laundry room from kitchen. We have no idea what the tile was laid on top of or the method used. However, the seller did have the foundation repaired and thought it could be a foundation issue. Well, it has a lifetime warranty and on the paperwork is a blueprint of my house with included the numbers (not sure what they intell) of the foundation repair. The foundation guy came to my house with machine and we walked around the house the numbers appearing on the machine are identical to the numbers I had from eight after the repair indicating the foundation had not moved. SO, with all that being said I feel it is something the tile guy did wrong or failed to do properly. Any ideas or suggestions?

    Reply
    • Roger

      Hi Lauren,

      In your case it does seem to indicate improper installation of the tile. It could be due to a number of issues, the most common two being that the thinset was either improperly mixed to a consistency which was too dry, or once spread on the substrate it was allowed to skim over before a tile was placed over it. I would guess that if a tile is removed from the substrate there is little to no thinset on the back of the tile itself. Either way it is an issue with the installation.

      Reply
  • Barry

    Had similar problem with new tile floor in kitchen. Our home was built in the 50’s so has been around the block a time or two. There was one particular area that kept breaking out soon after installation and again when regrouped. Went into crawl pace and added bracing. This seems to have eliminated the problem (knocking on wood for luck)

    Reply
  • Darren Campeau

    Appreciate your article, I have cracked grout in the heavily trafficked area of a bathroom floor made of 1″ pebbles. It’s become a mess in the area near the door, and I suspect that the subfloor (two layers of ½” plywood over a steel truss frame with a radiant floor pex embedded in the upper plywood). Other areas are fine, but trying to think of how to not repeat the situation if I reapply a new thinset base and start over. House and floor is now 10 years old. Any comments welcome.

    Reply
    • Roger

      Hi Darren,

      It sounds to me like the pebbles are installed directly to the upper layer of plywood – is that correct?

      Reply
  • Allison

    Thanks for this site! What would you do if you were me : we’re renting. Grout in 1 of three tiled rooms is crumbling. Tiles see-saw. We can’t clean the floor properly. The correct solution is to replace the tile… But renting. Is there a flexible-ish grout we can stick in there to make it livable until we move in a year (don’t want to involve the landlord… He might ask us not to use the room until he can get someone in to replace the floor), or caulk? Don’t love the idea of caulk cuz dirt usually sticks to it. Thoughts, comments, suggestions?

    Reply
    • Roger

      Hi Allison,

      A rug. Seriously, sorry. There is no ‘flexible’ grout and there is nothing you can really do to fix the issue short of replacing the tile. If the tiles ‘see-saw’ then they obviously aren’t bonded correctly, which means they will ALWAYS crack the grout. I understand not wanting to involve the landlord, but it’s really the only solution. And yes, I know that isn’t what you wanted to hear. :)

      Reply
  • Scott Friedericks

    I tiled my basement a week ago with pre mixed thinset, a small area in front of a door and it is still not dry. It felt fine to me 72 hours out so I grouted. I stayed off of it but after letting grout dry for two days I let my dog out. When she stepped on tile it sink down shifting tile thus separating from grout. Why hasn’t the thinset dried and any suggestions to fix grout without having to redo it?

    Reply
    • Roger

      Hi Scott,

      Because it isn’t thinset – it’s mastic with sand in it. You did not say how big the tiles you installed are but placing a tile over that stuff is just like putting the lid back on the bucket – it’ll never cure. Mastic (and that crap they call premixed thinset) requires air to cure – it can’t get that trapped beneath a tile. Thinset (the real stuff) on the other hand cures through hydration, meaning it does not require air to cure. Unfortunately it needs to be removed and reinstalled with real thinset, the powdered stuff you mix with water.

      Reply
      • Scott Friedericks

        You are absolutely right I just pulled the tiles up the stuff was still wet like I just pulled it out of the bucket after being down for a week. I just picked Versabond fortified thinset to make myself. Hopefully I will have better luck. Thanks

        Reply
        • Roger

          That’s the stuff you need. Good luck!

          Reply
  • Janine

    I just had a bathroom installed and the tiles are moving and grout cracking. The contractor is telling me my floor joists are loose. I haven’t read anywhere this is a problem. I think they didn’t put enough thunder or make sure floor was even. What’s your thoughts

    Reply
    • Roger

      Hi Janine,

      It was obviously improperly installed. The particular reason is impossible to determine without actually tearing it out. If tiles are moving and grout is cracking either the floor was not properly prepared or there was a problem with the thinset (allowed to dry, not enough, etc.). Either way it unfortunately needs to be removed and replaced. No, ‘loose’ joists are not a common issue, I’ve never heard of it. Sounds like a bullshit excuse to me. Somewhere the installer failed – bottom line.

      Reply
      • Janine

        Thank you that’s what I thought. They are here today redoing floor 🤞🏻🙏🏼

        Reply
  • Michael

    I have a single tile in a hallway that is moving and cracking the grout around it. I’m not certain at this point why the tile is moving but when I step on it I hear crunching sounds so I assume the thinset has broken loose so I assume I’ll have to replace the tile. I’ve never set tile so don’t know exactly how to remove the tile, clean the area under the tile, how to prep the area for new thinset, how much to apply, etc. I’d appreciate advice and instructions. Thanks

    Reply
    • Roger

      Hi Michael,

      It’s a fairly easy process, just pry the tile out and scrape everything beneath it flat. Only use enough new mortar to cover the bottom of the tile and get it flush with the surrounding tile.

      However (!) as I stated in the article above, the underlying issue will not be fixed and the problem is almost guaranteed to reoccur. The only exception would be if the thinset used to install that particular tile did not bond to either the tile or the substrate. If one or the other does not need to be scraped once you pull up the tile then that may be the issue.

      Reply
      • Michael

        Thanks much. I’ll let you know what I find. Is there any particular brand of thinnest you recommend?
        Thanks again. Very helpful.
        m

        Reply
        • Roger

          I prefer laticrete, but it’s difficult to get in some places. The easiest and best would likely be either custom’s versabond (home depot) or mapei ultraflex 2 (lowes).

          Reply
  • Apolinar

    Hi – awesome and informative site.

    I have grout cracking in very specific spots in the kitchen. The original floors had two layers of tile on them. I removed them completely and had to add new plywood as the base (3/4”) then used 1/4” hardibacker with the appropriate screws. Luckily I did not line up the backer as you mentioned in the other link. However I did not use thinset between the plywood and the hardibacker, not did I use tape to join them… wish I new that beforehand and now I’m kicking myself. The cracking started about a month after the installation. You are absolutely right the tile is clearly moving, first started with cracked grout, then I hear the tile beneath my feet when I walk on it. So the tile is loose. I feel the floor move also when I walk over that spot. What do you recommend as a fix? I was considering cleaning the grout out completely and pulling the tile off in the isolated affected area and reapplying the mortar and grout. But after reading I’m worried that I’ll have to redo the entire floor. Please let me know what your best recommendation is. Thanks in advance!

    Reply
    • Roger

      Hi Apolinar,

      Unfortunately the fact that you don’t have thinset beneath the 1/4″ backer is the issue. the backer has zero structural strength, so it is just following the substrate and is dependent upon the flatness of that to prevent voids. That never works. You can fix that area, but it will reoccur and you will likely have more issues pop up in the future. Sorry, I know that isn’t what you wanted to read…

      Reply
      • Apolinar

        Hey thanks for the amazing page again – you’ve been a huge help! So I forgot to mention important factors.
        The tiles are 24”x6” and when laying them they were not back buttered or back troweled. When I pulled them off there was zero mortar stuck to the back of them, so I’m guessing it’s both the subfloor and the fact that the mortar didn’t adhere to them.

        The spot I was telling you about I was able to pull off all the tile and used an angle grinder with a diamond blade to cut through the backer board and removed it. I applied thinset on the plywood and replaced the backer board with a new one. I scraped around the other spots and added more screws around the edges. Now I paid the tile again and back troweled them this time. Waiting for that mortar to cure now and will share the outcome after the grouting.

        Wish me luck!

        Reply
        • Roger

          I hope it works out! The lack of backbuttering is likely the culprit – no adhesion to the back of the tile.

          Reply
  • Jesse Ford

    I like how you mentioned that grout cracks for only one reason and that’s because the tile is moving. My brother is considering looking for a specialist to repair the grout in his home because he doesn’t want water or moisture to fall between the spaces and cause mold to grow. I think it’s a good investment to consider hiring a reputable professional that can help repair the walking surfaces of his home to prevent damage.

    Reply
    • Roger

      Hi Jesse,

      You are correct. “Fixing the grout” isn’t even a real thing – the grout is never the issue. :D

      Reply
  • Barry

    Recently had ceramic tile installed in kitchen. There is area around 3 tile (13 x 13) where the grout keeps chipping loose in less the 2 weeks. The rest of the floor (12’ X 14’) have no problem.

    Any suggestion on what to do would be greatly appreciated.

    Reply
    • Roger

      Hi Barry,

      You did not mention what is beneath the tile. It is something incorrect under your tile causing the issue. My guess would be that area of ditra is not properly bonded to the substrate, but that’s only an issue if they installed ditra as your underlayment. :D If not you need to let me know what you have beneath it.

      Reply
  • Nikki Murray-Mason

    Hi Roger
    I am a mosaic artist in Bermuda and installed my first floor 2 yrs ago. Having never installed one before I hired a professional tiler to help me lay it. It is the threshold if a busy jewelry store on the corner of a busy crossroads and pedestrians cut the corner and walk over it and business people roll suitcases over it occasionally as the gap between traffic. Lights and pillar is too narrow. So a lot of traffic. I have to go down to the store and fix the cracked grout and a few missing tiles probably every 4-6 months. Why is this? The floor was prepared by the contractors for me ie existing tile taken up and resurfaced to make smooth and we tiled directly into the concrete. Why is the grout cracking and crumbling. Is it too much movement? As you can see the floor is intricate and so I cannot take inall up and I just repair as needed ie take out old grout, replace broken tiles and regrout. Here r done pics the tiles missing pic is the worst it’s been, but I believe Someine dropped something here so am off to repair it soon thanks for any feedback Nikki

    Reply
    • Roger

      Hi Nikki,

      I believe it is too much movement. Not necessarily the people walking over it (although that contributes), but concrete, especially in an exterior application, moves A LOT. I know you said you can’t, but the only solid repair is to remove and replace it using some sort of cleavage membrane or substrate (even painting redgard over the concrete would likely help give it enough flexibility to withstand that movement), or using a high quality flexible mortar. Very nice work, by the way!

      Reply
      • Nikki Murray-Mason

        Thank you Roger, I thought as much grrrr! Lol. Sorry I did try to upload a pic showing the cracks but it wouldn’t let me. thanks again
        Nikki :)

        Reply
  • JayPoux

    Help!
    I have been installing tile for 6 years and never had in issue… till now. The Floor was plywood… weinstalled schluter ditra underlay with thinset. Let it dry 24hrs. Then tiled floor. Let it set for 24 hours then grouted. Now only after 1 month, the customer sent me a picture of the floor and the grout is completely crumbled and she said the tiles were chipping also??? dont understand!

    Reply
    • Roger

      Hi Jay,

      Wow, that’s, uh, general. It is impossible for me to give you a specific reason, it could be many, many things, either one or a combination of a few. My first guess would be the deflection of the floor – how are the joists spaced? What is the unsupported span? Do you know the specific build makeup of the floor you installed over? Was it hot that day (premature thinset skinning)? Did you backbutter? Is the floor being used as a trampoline? Are they driving forklifts over it? Is the cracking only over plywood seams? Or joists? How many layers of plywood? How thick? What thinset did you use? What product is being used to clean the grout? Are the tiles chipping or cracking?

      Just going over ‘plywood’ is all the info you’ve given me, I need many specifics to even take an educated guess. Even then it’s just that – a guess, without being able to examine it in person, or at least detailed photos. Did you do anything different with this install?

      Reply
  • Neil

    Hi Roger,
    A wise person has written: “While tile can be installed directly to plywood it requires a VERY specific method. And I do mean very specific.”
    Can you please share with us what that very specific method is?
    Thanks,
    Neil

    Reply
  • Katherine

    Hi Roger,
    Three years ago the tile was installed in the kitchen. Tile and grout in one half of the kitchen is fine but through the second half the installer was really rushing to finish. Six months later the first break in the grout appeared followed by the first hole after I vacuumed the floor. During the past three years this ‘rushed’ grout developed more and more brakes and by now there is almost no grout in-between the tiles. What do you think went wrong?
    Thank you.

    Reply
    • Roger

      Hi Katherine,

      It could simply have been mixed incorrectly (waaaaay too much water, but it makes it a lot easier to grout), or the structural integrity under that portion may be less. Was he rushing to finish setting that part as well? Or he could have started tiling on the part that is fine, and finished on the part that is not without mixing new thinset, the thinset became progressively less ‘effective’ at holding (beyond it’s pot life). There could be a number of reasons, I would need way more detail to help you nail down the cause.

      Reply
  • Cheryl

    Hi Roger, we moved into a new build home 4 months ago. We have cracked and crumbling grout between the baseboard and the ceramic tile in a couple of places in our home. Not more than a few feet in length. Can I just remove and replace the crumbling grout? The tiles don’t seem to be moving and are not cracked or raised. The tiles seem fine.

    Reply
    • Roger

      Hi Cheryl,

      You need to replace the grout along the baseboard with silicone. That is a change of plane, which means the two planes will move in different directions. Silicone can compensate for that movement, grout just cracks.

      Reply
  • Carol

    Ok, I’ll bite: What is the proper way to repair cracked floor grout? Tile is on concrete slab.
    Thanks! Nice site!

    Reply
    • Roger

      Hi Carol,

      If the tile is bonded directly to the concrete then you’ll need to remove and replace the grout. In that case the cracked grout is due to concrete movement. It may or may not last, depending on how much the concrete will move in the future. If there is a membrane such as ditra beneath the tile then there is likely an issue with the bond of the membrane to the concrete, in which case the underlying issue will need to be fixed or any fix of the existing grout will not last at all.

      Reply
      • Keith A Carter

        Thank you, much appreciated

        Reply
  • Keith Carter

    some more we always leave a partial or full box behind but a lot of time the cleaning people will toss themdown until it reaches a dead end or stopping point so we might want to wait a little bit before we do the repair I will look up and see what tile it is and get I can tell by the pictures that that is a crack in the cement which is breaking the grout along that long grout joint I believe it will probably spread further There’s nothing you can do until the crack stops moving through the cement padSo I would just wait it out for a bit and then do the repair a little bit later

    The response of my contractor to cracking grout in a new construction home I purchased 45 days ago, is it reasonable?

    Reply
    • Roger

      Hi Keith,

      I need a LOT more info to answer your question. I will say that a properly installed tile project will not have problems with cracking grout, because movement is compensated for in the installation. If the slab is cracking that quickly then the biggest issue is with the slab being either improperly mixed and installed or not having adequate joints, which, again, are compensated for with a properly installed tile installation. Is the tile bonded directly to the concrete?

      Reply
      • Keith A Carter

        Roger, thank you for the response. I know little to nothing about these floors. Tile is bonded to the concrete and the crack is one seam the entire length of the floor. Let me know what else you need to know.

        Reply
        • Roger

          In that case there absolutely should have been a membrane of some sort installed beneath your tile. There are many to choose from. They are most commonly referred to as crack-suppression membranes. The reason we install those between concrete and tile is specifically for this reason. There are two types of concrete – cracked and not cracked YET. The installation company should have known this. There are also mortars made specifically with some built-in flexibility to allow a bit of compensation with substrate movement, but it sounds to me like there was no compensation at all built into your tile.

          Do NOT let him go in and install over those cracks when it’s ‘done cracking’. It may be finished cracking, but it is never finished moving. That’s why it cracked where it did. There should have been a saw-cut isolation joint cut into the concrete at the very least. And a membrane put over that. I don’t know if you have any intentional joints in your slab, but something was done incorrectly there. And the fact that tile was installed directly to it without movement compensation is on the tile company. So between your tile company and concrete company (or, more likely, your builder who subcontracted those) they need to deal with the issue. And the only PROPER way to do that is to remove what is there and install it properly.

          The concrete can’t be redone, but joints can be sawn into it where need be. And some type of membrane needs to be under the tile.

          Reply
          • Keith A Carter

            I sincerely appreciate your expertise and insights.
            Thank you

            Reply
  • Ellen Crowling Rice

    My contractor renovated two bathrooms on my upstairs level about 1 year ago. The tiles are cracking, grout is coming up and one tile “pops” when you walk on it.
    He came today and said “his guys” would pull up the tiles and re grout the area and put the tiles back down. They were placed on plywood and he is not going to pull up the floor and redo it. I fear this is an ongoing problem and I have wasted 70K with this guy, I can’t afford to hire someone else as I given this guy all the money I had. I am disappointed with this industry and feel like there are no good people. I feel like these contractors hire unskilled laborers and charge insane amounts of money and pay them nothing- more profit for the contractor. Now the work is failing and I am screwed. Help!

    Reply
    • Roger

      Hi Ellen,

      Not sure where you’re located but if you speak to the building code department in your local area they can give you your options.

      There are a LOT of good professionals in this trade, unfortunately, like EVERY trade, the few bad ones screw it up for everyone. Everyone is driven by profit, but when that becomes your only motivation you should not be in this trade. Thorough research is the way to avoid these people. Make sure the guy in charge is going to be around, if not the guy doing the installation.

      Reply