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.

{ 1072 comments… add one }

Leave a Comment

  • Muhammad sohail

    I am contractor, recently I prepared grouting sample on marble substrate thickness 1 inch size 1 X 1 foot , then I installed 3″x3″ marble pieces thickness 12mm bounded with clear epoxy, after 30 minutes I checked it was bounded very well with marble substrate mean to say not moving any piece of marble, on next day I made grout Ratio : White cement + SBR latex 70% + water 30% , I mixed it very well, grout was not to much thick, it was little bit loss but not as much, the joints thickness is 5 mm & joints depth is 12mm, after completion of joints filling with this material, I left it to dry, I saw after 3 hours there was longitudenal cracks in between grout lines & as well along with marble tiles edges, I need to know why these crakes appears in this short period of time & how to prevent.

    • Roger

      Hi Muhammad,

      You don’t have any sand in it. Sand prevents the grout from shrinking. You should have about two to three times the ratio of sand as you do the white cement.

      • Muhammad sohail

        Mr Rojer do you mean ( 1 part cement + 2/3 Parts sand + SBR latex + water ) if I go with this way can it provide me end result with smooth grout line texture & waterproofing grouting because sand ratio will 2 times / 3 times then cement ratio & also with more sand water can panetrate to substrate ?
        Out most of projects are on exposed area like RCC roof slab / tareses, we are doing maintenance works regrouting for waterproofing purpose, kindly provide me best tips econmical, long lasting with best results.

      • Muhammad sohail

        Mr Rojer do you mean ( 1 part cement + 2/3 Parts sand + SBR latex + water ) if I go with this way can it provide me end result with smooth grout line texture & waterproofing grouting because sand ratio will 2 times / 3 times then cement ratio, I am agree with you it will provide reinforcement to grout, but do you think with more use of sand can panetrate water to substrate ?
        Our most of projects are on exposed area like RCC roof slab / tareses, we are doing maintenance works regrouting for waterproofing purpose, kindly provide me best tips economical, long lasting with best results.

        • Roger

          Grout used for tile installation is not waterproof, all the waterproofing lies behind the tile. The grout is there ONLY to fill be space between the tile. So no, it won’t be waterproof. If you need a waterproof grout for a roofing installation of some sort you would need to ask a roofing expert – I’m not that. :)

      • Muhammad sohail

        Mr Roger what about thermoplastic 25 – 30% instead of sand ratio for grouting purpose ?

        • Roger

          I suppose that would work, but I don’t know that it would make it waterproof.

  • Bronwen

    My tile grout is cracking about 5 months after install. Plywood was put over subfloor, and then schluter ditra was installed on top of plywood, then tile installed on top of ditra. Any ideas why it’s cracking ?

    • Roger

      Hi Bronwen,

      There is incomplete or incorrect support somewhere under your tile. That’s the short answer. It could be hollow spots beneath the plywood, incomplete bonding of the ditra to the plywood, incomplete filling of the cavities in the ditra, or incomplete or incorrect coverage between the tile and ditra.
      The only way to determine the cause is to remove at least one of the tiles where the cracking is occurring and see what is going on beneath it.
      If you can remove one and see how it is bonded to the ditra, or how the ditra is bonded to the plywood, we can likely figure out what needs to be done to rectify the situation.

  • Carol

    We had a tile floor installed in March, and over the past months, more and more grout is cracking and coming out. The tiles were installed over a linoleum floor after the installer put screws throughout the floor so it would not come up from the wooden subfloor. The grout is cracked and/or coming out on approximately 75% of the floor. Is the subfloor the issue??

    • Roger

      Hi Carol,

      Yes, absolutely the subfloor is the issue.
      He installed the tile directly to the linoleum floor?

      • Carol Raymond

        Hi Roger. Yes, he installed the tile directly over the vinyl (not linoleum as I incorrectly stated). He put screws throughout the floor to secure it to the wood under it.

        • Judy Wartinbee

          My grout crack in chunks less then 28 days. He layed a type of cement sheets down over top of the linoleum floor. Screwed down the sheets before putting down tiles. Was grout breakup his problem. It doesn’t crack anymore. Can I fill up the chunks with fresh grout?

          • Roger

            Hi Judy,

            Did he put thinset beneath the cement sheets before he screwed them down? Because if not then yes, the grout issue is his problem because the substrate was not correctly installed. It needs thinset beneath the backerboard to fill any hollow areas and ensure there is no flex to it. If that’s not done it leads to exactly the issue you’re having.

      • Carol Raymond

        Hi Roger. Yes, he installed the tile directly over the vinyl (not linoleum as I incorrectly stated).

        • Roger

          Then it doesn’t have a proper substrate beneath it. The main issue with that is that most vinyl is installed over 1/4 luan, which is a very thin vinyl substrate which is not nearly dense nor sturdy enough for tile to be installed over. There is flex beneath your tile due to an improper substrate, which is causing your issue.

  • Steve

    We have a house that was built 6 years ago. We can’t use the master bedroom shower. It has small tiles on the floor and large tiles on the walls. The builder sent somone out pretty much monthly for the first year. After the first year was up we had no warranty. They kept adding new grout or pulling up the ones that kept moving then recementing them in place with new grout. On more than one occasion the guy used silicone in place of grout. This only happens around the drain. Is this something a homeowner can fix or do I need to hire someone?

    • Roger

      Hi Steve,

      It is something you can likely do yourself, but you need to determine the cause of the movement. Since it is only happening around the drain my guess would be that there is either a leak at the drain, causing the underlying subfloor to deteriorate, or the drain flange is not screwed down to the subfloor, causing it to move when stepped on.
      You’ll need to remove at least 6″ worth around the entire drain (12″ total) and dig down to see what you’re dealing with. If you do that and take photos I can help you determine how to proceed from there.

  • Jean Hartke

    I have a kitchen tile floor installed 5 years ago. The grout in major walkways has continuly cracked out. This has been dug out and replaced once and needs to be done again.The porevious flooring was also tile and lasted 15 years with no problems. I am wondering if this orange webbing has something to do with problem?

    • Roger

      Hi Jean,

      I have absolutely no idea what ‘orange webbing’ you may be speaking of. The problem with it is obviously improper installation, there is excess movement under your tile due to something. May be the substrate, may be the mortar mixed improperly, may be an improper substrate…it may be a LOT of things. To narrow it down I need to know what your tile is actually bonded to or over.

  • Paula

    Hi, had bathroom redone about 7 yrs ago. After first year tile start to move and grout cracked in high traffic area. Basically in front of the sinks. I had the contractor come back and he said it must be MY subfloor that was causing the problem even though he was the contractor that had it installed. I argued the fact that it should have been fixed before floor laid but I got nowhere and decided to live with it until now. I got my hammer and siding bar and started uprooting tiles. The ones that were already loose came up easy. Ones closer to walls and tub took a little more effort to remove. From reading other posts and comments I was thinking maybe the mortar was too dry before they placed tiles or maybe it really is the subfloor? I still need to remove the mortar or whatever that white stuff is to see what that is on top of.

    • Roger

      Hi Paula,

      The number one cause of movement like that is actually inadequate prep. It may very well be YOUR subfloor, but the thing about that is it was HIS job to prepare your subfloor for a successful tile installation. If YOUR subfloor cause cracking grout, tiles, or any other issues, it means HE didn’t do HIS job.

  • Elissa

    Hi, looking for some insight. We have a newly installed kitchen tile floor which has had issues with cracks in the grout since installation in July. We have tried different grout, reinstalled tiles but are still having issues. The current theory from our contractor is that the tiles are moving from The subfloor. We are desperately trying not too pull out the whole kitchen to replace the subfloor. Our contractor had recommended ceramic tile grout as this will allow for some flexibility. Is this a thing? Will this last? Thanks

    • Doug

      Elissa, in 2018 we had the same problem. New kitchen, new kitchen floor, grout cracking all over. Our problem, which might not be yours, was that none of the tiles actually adhered to the mortar. When they went to pop up a tile to see what was going on, it took 3 seconds to pry the entire 12×24 tile up. Eventually we decided to remove all the tiles and the mortar and redo (almost) everything. The cabinets were custom and the counters were stone and it was all too much trouble to take it all out, especially because no one has insurance against this sort of mistake. If they had left the water on and damaged everything, it might have been covered. So anyway, they removed the toe kicks from the cabinets and then pulled up all the tile, breaking some, but it was so loose that a lot actually slid out from underneath the cabinets. We had electric heat, and they had to chop that up and remove the mortar. The subfloor was fine, but they relaid concrete board down and then put all the tile back down. It is god-awful ugly under the cabinets and appliances, but you would never know from looking at it now. We still have no idea what they did wrong, though I suspect that the trainee mixing the stuff didn’t mix it correctly or, more likely, they should have back buttered all the tile to ensure that it adhered to the mortar.

      Ceramic grout came up, but it wasn’t the right solution, and it will mess up the tiles if you try to reuse them. It is more expensive too. They should try to pop up a tile – if it comes up easily, grout isn’t going to help at all!!

      • Roger

        Doug is correct, grout is not going to help at all.

        There are a few issues that could have cause the problem with the tile not bonding in this case.

        Improper mortar mixing, no backbutter, an excess of kiln-release on the back of the tile (the white streaks) or, most commonly, the mortar allowed to flash over before the tile was installed. This means that the mortar was spread, then allowed to sit too long before placing a tile over it causing the very top of the mortar to essentially ‘dry out’ before tile. This will hinder bond to the tile.
        If, when pulling a tile up, the mortar is bonded well to the substrate and not the tile – that is the issue 95% of the time.

    • Roger

      Hi Elissa,

      It sounds like it is an issue with the substrate. However(!) that is an issue that would have been dealt with during installation by using proper substrate materials and proper methods. If it’s an issue after the fact it indicates improper installation.
      Do you know how it was installed? Like what the tile substrate actually is – what he bonded the tile to?

  • Kat

    We have tile in our bathroom that was installed 2 years ago. It was a full bathroom reno and there is radiant heat under the tile on the floor. The grout is crumbling around the tiles and some tiles make a popping sounds when stepped on (clearly moving). Installer insists everything was done correctly but the image I have from before I left for work the day they did tile was that i believe plywood on the floor. Unless 1 man is able to do everything else with flooring im thinking they installed on top of plywood. It was 1 guy doing all the tile.
    They attempted to fix it by injecting something between the tile/under but it didn’t work. Now they are suggesting regrouping with silicone grout…..
    At a loss of what to do and what’s right to do

    • Roger

      Hi Kat,

      Do you have a heater vent or something in the floor that you can pull up and see if they did, indeed, install the tile directly to plywood? From what you’re describing that sounds like what happened, as that is exactly what will most likely happen by doing that. If they did, the only viable solution is tearing it out and starting over with a correct substrate. And yes – the installer is responsible for that, although the ability to recoup that cost will depend upon your local contractor laws.