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.

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Leave a Comment

  • Josh

    Hello Roger,

    There is a crack in the grout that runs straight across my house. The crack runs along a wall, passes through the kitchen, and continues on the other side of a big column. The crack has been there for over a year without widening, so is there anything I need to worry about other than it being not aesthetically pleasing?

    I also noticed that the wall adjacent to the crack is kind of bowing out a bit. Could that be the cause/a more serious issue to worry about?

    Reply
    • Roger

      Hi Josh,

      I’m assuming here that your substrate is concrete? If so given the fact that the crack leads to a column and is straight it is likely that the crack is directly over an expansion joint. It may widen over time, or not. It just depends on what the slab does. As long as each side of the crack remain level (one not higher than the other) then no, not really anything to worry about until the slab begins moving again.

      Reply
  • Jenn

    We are having tile installed and contractor wants to install tile directly onto slab.There is a thin, old layer of half on/half off linoleum. He explained installing this way, will eliminate any plywood, cement board issues. I dont know what to do. Any advice

    Reply
    • Roger

      Hi Jenn,

      The first thing you should do is find another installer. Tile can be bonded directly to a CLEAN slab. The biggest issue I see is that he is saying issues with plywood or cement board – neither of which can be installed over a slab beneath a tile installation. Products like sheet membranes or liquid membranes, or even flexbone made by ardex can be installed over a slab, but neither plywood nor cement board can. He’s blowing smoke up your ass telling you nonsensical things in order to placate you.

      Reply
  • Shirley

    Will thinset on the installed tile pull up concrete subfloor?

    Tile installer said the concrete is bad. Then pulled up a tile and a portion of the concrete surface came up. He primed before installation

    Reply
    • Roger

      Hi Shirley,

      Yes, if the concrete pulls up when a tile is removed then the concrete is the issue. Your installer is OBVIOUSLY getting a good bond.

      Reply
  • Stephanie

    Hi Roger,
    We moved into our new house 4 1/2 months ago. We have had a few issues with our grout. We have porcelain tile in 2 bathrooms, laundry room & master closet. First, the grout cracked all around our soaking tub. The tile guy came back & replaced it with caulk. About 1/5 of the grout around our shower drain has came out. They have put caulk in it for the 3rd time. There are also 3 places (2 in the laundry room & 1 in the closet) where the grout is cracked away from the edge of the tile. 1/8″-1/2″ long. He filled 1 of them with caulk. These cracks are not in high traffic areas. Is this normal? Is it ok to fix these cracks with caulk & is it ok to have caulk around drain?

    Reply
    • Roger

      Hi Stephanie,

      No, it is not normal. No, it is not okay to place caulk in those places. Something was installed incorrectly, causing movement in the tile, which cracked the grout. Either an improper product or installation of the substrate or poor/inadequate thinset bonding (could be caused by a lot of different improper installation techniques). Regardless, something was done incorrectly.

      Reply
      • Stephanie

        Thank you for answering. Could it be the grout was not mixed correctly? Just wondering since the grout came out around the drain. It started as tiny holes in the grout & eventually got larger. the cracks in the grout on the floors does not go across the grout it’s just where the grout meets the edge of the tile.

        Reply
        • Roger

          It could be incorrectly mixed grout. However, if that were the case these issues would show up within 28 days of the initial grouting, before a final cure is achieved, while the grout is still curing and shrinking. The edge along the tile is the first sign that is indicative of movement. Sorry.

          Reply
  • Stacey

    Hi Roger,

    We recently (less than 28 days) had 12×24″ tiles installed in our bathroom shower. A crack in our grout has developed where the wall tile meets the inset area for the toiletry alcove. Our installer said that it is the house moving, but since it was put in less than a month ago I find that hard to believe. His fix was to add caulk over the crack lines. Do you have any advice? I’ll try to post a good picture. Thanks so much in advance.

    Reply
    • Roger

      Hi Stacey,

      Something is moving, don’t know that it is the entire house. :D If I understand correctly this is an outside corner around the niche? If so then nothing should be moving enough to crack grout placed there. If that’s what cracked then something is likely installed incorrectly. Caulk over grout will not fix it. It will make it look better for a while, but the grout is still cracking behind it and will eventually debond the caulk.

      Besides – that looks like shit. :D

      Reply
  • Jim

    Hi Roger,
    My home is just shy of 7 years old. Lots of matching tile diagonal installed on concrete post tension floor. We have some tile in kitchen area where grout started popping up about 3 months ago. Now on occasion I can feel and hear tile movement when I step on the tile. More grout is popping off. When tapping on the tile in that area I hear a hollow sound from some. Tile no longer available from supplier. Tile installer out business. The rest of the house is fine….so far. 20 inch porcelain tile actually a little over 19 inches. I hate to think of redoing this entire house. Grrrr.. What would you do? Thanks!

    Reply
  • Julie H

    Hello there!

    I liked reading your comments and info. I doo NOT have a pogo stick :}

    Just a poorly built home in Florida. 2.5 years old. 16 cracked tiles in a line, zig zag. more than 16 have a grout crack following zig zag along either side.

    Builder tried 4 X to fix them, by jack hammering them up and replacing them. Still cracked AGAIN … they tried membrane, too

    Reply
    • Roger

      Hi Julie,

      What is the substrate? What is the tile bonded to? What type of ‘membrane’? Help me help you. :D

      Reply
      • Julie

        Hello

        Concrete slab. Single story home. I don’t know what they used. :(

        Thanks

        Reply
        • Roger

          My guess would be inadequate coverage of thinset when they were installed and the slab movement is causing them to become unbonded. Or there are saw-cut expansion joints beneath those cracks which are moving in different directions causing it to crack. Either way it sounds as if the slab movement was not compensated for in the initial installation.

          Reply
          • Julie H

            YES they are saw cut joints! Just had a few tiles pulled up and an engineer confirmed it. He said they probably cut them way to late :evilb: . Has to be done in 8 hours no later than 24 hours Does that sound right to you?

            Reply
            • Roger

              That is correct – and that’s the cause.

              Reply
  • Denise

    this is how our contractor laid our 12×12 marble tiles which we are now having issues with.. cracked tile (corner is cracked). Is this following installation method acceptable given we have these issues? The job was completed 3 wks ago. Thanks!

    The underlayment used is the Schluter Ditra heat uncoupling membrane -underlayment.
    The tile were thin set on top of Ditra heat cable and membrane.

    Reply
    • Roger

      Hi Denise,

      If you are talking about the ditra-heat, thinset and tile over the cable then yes, it’s the appropriate installation technique. However, an incorrect product (non-modified mortar used over wood to install the mat, for instance) could be the issue, as could something as simple as poor installation methods.

      Reply
  • Judy

    Hi ROger,
    We just renovated our entire kitchen. It was finished it December. In February I noticed that a tile seemed loose. Then the grout started to lift. Now I feel like the loose tiles are spreading. There is an electric heat mat under the tile. I called the contractor and he came to look at it and thought it was the thin set issue. Not sure what to do. Should we just replace the few tiles ( but what if loose tiles spread) should we get all new tiles or can we install wood floors??? Quite upsetting as we waited years to renovated the kitchen. Thank you for your advice!!

    Reply
    • Roger

      Hi Judy,

      It could be several reasons, but I would need detailed specs about the construction of the floor to nail down the cause definitively. A couple things to check:
      1. Pull one of the tiles up and see if there is any thinset on the back of the tile.
      2. If there is an slc (self-leveling cement) product over your heating wires check to see whether it is stable and intact.

      Start with those two things and, if you can, let me know the specific construction of the installation as far as the substrate, method of heating and specific products used.

      Reply
  • Dan Nelson

    Roger,

    Hi Dan,
    I thought I knew my stuff because I did many of my bathroom floors in the past and they still look great. This laundry room projects got me confused. 12′ by 6 1/2 room, new sub floor screwed down, 12×24 thin (standard) ceramic tiles with 1/8 gap spaces, lots of thin set applied. I grouted next day with a none sanded hand mixed grout. Three days later we started walking on it and a few days after that I noticed grout cracking away from the tiles in the high traffic areas. It only got worse from there. So, during the process of fighting all the old grout out, I noticed that there are a few tiles that have incremental movement with full weight applied. Also, I must add that I used only a large bottle of grout strengthener to mix the grout (no water) and it started to dry up just before I could finish.

    I’m ready to fill the gaps again but don’t want to make another mistake. How should I proceed? :whistle:

    Dan

    Reply
    • Roger

      Hi Dan,

      What, specifically, is a ‘new subfloor’? Wood? Was the tile bonded directly to wood or is there a proper substrate beneath it? And what, specifically, thinset was used – brand and type? Customblend? :D And what is ‘grout strengthener’? Something like grout boost? (I hate that shit…).

      I need more info to help. Help me help you. :D

      Reply
  • Sandra

    1 or 2 tiles are moving was installed over 10 years ago whole kitchen hall and bathroom cement floor had it installed so not sure so is removing all of the tiles my only option?

    Reply
    • Roger

      Hi Sandra,

      It depends on what kind of shape your installation is in. If it were mine and I didn’t want to replace everything I would likely just pull up those loose tiles and reinstall them. It may be just fine.

      Reply
  • Kie

    Hi Roger,
    We have placed marble tile in our bathroom and allowed 5 days for the thinset to set. Today we went in to clean off some dried on thinset before grouting…only to find one tile didnt set properly and was loose. We were able to literally just pull it up without much force. So then we cleaned the dried thinset off and back buttered new thinset on and replaced that tile. The thinset says wait 48-72 hours before grouting…does this mean we actually have to wait another 2-3 days to finally grout the whole bathroom? Then wait another at least 3 days for the grout to dry before re installing the sink and toilet?? This project has taken us a total of 2 weeks so far…first time laying tile. Any advice would be appreciated! Thank you!

    Reply
    • Roger

      Hi Kie,

      No, go ahead and grout it all tomorrow. It’ll be fine. You can set the toilet too – get this damn project finished already! :D

      Reply