Why is my Floor Grout Cracking?

by Roger

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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There are some tiles coming off in the kitchen of the house we just bought. Mostly around the “baseboard” they created but also a few right in the floor. The tile came up pretty cleanly off the thinset. Can I use tile adhesive to stick it back down or do I need to chisel out the thinset?


floyd phillips

Hi Roger,

I installed ceramic tile in my kitchen 3 yrs ago, and this the second time that I have had to replace the grout lines in the high traffic area! What can I do to remedy this problem??




Thanks for your reply. And as mentioned…..my tile was installed about 7.5 months ago. Initially it was 3 tiles rocking, with grout crumbling. Now, it’s more than 15 tiles! I realize the tiles rocking are causing the grout to crumble. The big question is…..did my tile installer do something wrong, and also does my “in floor” heat play any part in this. I am now thinking my ENTIRE new floor is going to need to be replaced. That is going to entail taking up the toilet, moving my new vanity — that has a granite top and backsplash, which is now grouted to the wall, and also removing the wood panels that I had put on the sides of my jet tub! I am just upset that I have to pretty much disrupt everything in this new bathroom I just did not even 8 months ago. Also, I’m hoping I can get the same tiles again for the floor, since I picked them to match the wall tiles. But again….my big question, WHY did this happen? Not enough glue on the tiles, not the “right” glue with in floor heat?? I have no idea.



We did a complete bathroom renovation about 8 months ago. We chose to go with electric in floor heat (the coil type), and ceramic tile. About 2 weeks ago I noticed little bits of grout coming loose around 1 tile, followed by a “rocking” of the tile. Now, there are several areas of grout crumbling, and several rocking tiles! Any thoughts on why this is happening?

Thanks in advance for your thoughts,

Lisa :)



Hi Roger,

I want to install stone tile on my concrete slab floor. The location is near an exterior door but not a chronically wet location like a bathroom. I’ve looked for instructions telling how to prepare the surface and set the tile but all I’ve found is your admonition not to stick tiles directly to the concrete. Could you please point me to instructions on prep and setting for concrete slabs? I want to do it right the first time. Thanks!!



We have a porch in a nice rental house, and suddenly half of the whole porch tile has cracked up off the porch…This tile has been there for a while…like when we bought the house about 10 yrs. ago. All talked bout our beautiful tiled porch. Now, the porch is one mess. Cracked tile up off the porch floor and no person knows what to do bout the thing ?one half of the porch is cracked up off the concrete floor it was put on, and the other part is firmly in place. The neighbor down the street has the same thing. We do not know what is going on and what to do bout the whole thing? Help!!


C Kelly

I had a contractor install tile on my floor about a month or so ago. The tile grout is now cracking all over. It is in my entry way , hall and in my kitchen, this is not a big area. Entry is small, hall is narrow, about 12′-15′ long and the kitchen tiny. It’s a condo.

The contractor installed the tile over a old parquet floor. Does the tile and the parquet need to be removed and then re-done?

Thank you.

C Kelly


Audrey Reed

I live in and apartment 3 floors I am on the second floor above me are two people and the lady is about 300 pound when she walk on the floor at any time it is cracking and sometime she sound like she is coming through the floor she walks very hard because she heavy, what should I do at this point about that. When she walk any where in the apartment it cracks and the noise from that keeps us up all the time.


Matt Orrell

Hi Roger,

I am about to repair a tile (granite 12×12) floor installation. It’s been in for several years. The grout is cracking out in certain areas.

I’ve also noticed that the grout joints are very thin because tiles are either butting or close to butting. Should I rip out the entire floor to address joint width, is there a way to widen, should I not care?

Thanks in advance ,




This ass clown is really helpful to you clowns. Good thing you goof balls weren’t hanging from a cliff and needed help. Got to love the Interweb. :bonk: :bonk: :lol1:



i have a small amount of water coming out of my kitchen floor tiles where the grout is ?????????????????? what is wrong .


Emma Taylor

Hi, I have had porcelain tiles fitted in my kitchen and conservatory last October but the last couple of weeks the grout is cracking around the tiles in the conservatory only. They were laid onto a concrete base ? Do I call the guy back who fitted them? Is it possible for the grout to crack due to the heat in the conservatory? Thankyou. Emma



I had my bathroom gutted and redone a year ago. I had a stall shower installed with 3 sheets of plywood then a rubber mat then concrete then the tile with sanded grout. A few months after the install I noticed the grout cracking in a small spot and water was sitting under the tile in that spot. The grout was scraped out in that spot and the shower dried for 2 weeks before we regrouted. About a month or so after that all the grout on the floor started cracking along with some tiles and water sitting under the tile again. Now I am assuming the water under the tiles and settling has caused the marble threshold when you step into the shower to crack in the middle and water puddles in the corner of the shower instead of pitching to the drain like it used to. Will this require me to replace only the floor or will the whole shower need to be redone? I am so stressed about this!!!



I posted but it disappeared the same day. I had a flood in my basement and my porcelain / vinyl tiles were underwater for a period of time. When dried the premixed sanded acrylic grout had cracked and in some areas chunks of grout were loose and coming out. Can standing water do that to grout?


Marcia Hyde

I am unsure if my question actually was sent! I didn’t hear the “swoosh” sound, the typing just disappeared!?!
I’m resending short version. New construction. 10 week old concrete mono-slab. Barrier-free shower. Durock walls. Green board ceiling. Concrete floor pan (slope integrated at time of pour). Do I/can I/should I Redguard all five surfaces?



We just installed a ceramic tile floor in our bathroom. All was well until 2 weeks after we grouted. We now have one tile that’s moving and cracking the grout. How do I remove that one tile and replace it?? Hopefully that can be done. Thanks in advance for your help!



Use grinder with diamond n blade cut out grout joint smack it with hammer chisel out thin set reset n grout



Hi there. Our house has marble tile in the upstairs bathroom. The tile in the corner that meets the stand up shower and an interior wall cracked and a piece fell down leaving a hole. I’m naively hoping this doesn’t mean a full repair of subfloor, shower, and part of an interior wall/bedroom floor. Is the best first step to remove the broken tile and check for rot that way?



I am hoping maybe you can help. I had tile flooring installed throughout my entire house in June 2015 – 18″ tiles installed with 1/4″ sanded grout lines onto concrete subflooring. Within a few weeks, the grout in the living room had started to chip in several areas from my dog’s nails and furniture movement. The chipping starts as flakes of grouting coming off at the surface and then eventually the entire grout line is gone. The installer removed and replaced the grout in the damaged areas. However, the problem has persisted and is getting worse, with new areas having problems now months after the tile has been installed. The problem is only in the living room. After the second grout repair, in some areas, the grout will practically dissolve if it gets wet, but it’s only in some areas that were replaced. At this point the grout has been removed and replaced three times in damaged areas through my living room (basically everywhere that is not covered by rugs or furniture). I have asked the installer if improper thinset is the issue and the tile is moving. Of course they deny it. The installer has pointed the finger at the grout manufacturer, while the grout manufacturer says it’s because my dogs were allowed on the tile before the two week curing period was up (which we weren’t informed of, but that’s a side issue). However, my dogs being on the tile does not seem like the problem since my dogs are active throughout the house and not all areas are affected. Also, some of the areas didn’t start having problems until months after the tile was installed. Other rooms that were installed at the same time are not affected either. Frankly I am at a loss for what could cause such widespread damage in one room, but not others. Can you offer any insight into what might be the problem?

Other information that might be helpful: The area affected was previously covered with carpet. The concrete in the living room did not appear to have any damage or discoloration different from any of the other rooms of the house. Large cracks in the concrete were repaired in all affected rooms, including the living room, with some kind of hot pink/red paint on product. However, damage in the living room extends beyond the area painted and other rooms where the product was used are not affected.

Thank you in advance for any help or insight you may have!



Hi Roger
I installed tile 30 days ago In a “random” pattern using 6″,12″,&18″ square role. It’s gorgeous, but I have ONE f*#*#*g 18″ inch piece which is naturally in the highest traffic area in the center of the passage to the bedroom which is crunching when I step on it, and the grout is cracking. How do I remove, clean out the thin set and reset it? I used Ditra underneath and I am sure it will be rock hard with all the little squares filled in with hardened thin set now. I am sad?



Hi Sally,

Scrape the grout from around the tile, get a utility knife and cut around the tile into the ditra and remove the tile and ditra together. Replace the ditra and tile after scraping all the excess off the subfloor.



Thank Roger.
You ARE super cool.


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