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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Please help, Mr. Tile God,
Our new porcelain tile kitchen floor grout began to crack a few months after installation. Ditra, following the manufacturer’s specific instructions, was used with the appropriate mortar, etc. The cracks were in random location and a few were definitely due to tile movement. Those tiles were replaced, all the grout throughout the whole floor removed and replaced. Both times a quality grout product and admix was used. The same product has been used elsewhere with success. The floor is not too tight to the wall, etc. Oddly, this is occurring again. This time, again in random locations, the grout is soft and can be scraped with a fingernail. I have yet to see this addressed in any forum or help website. Do you have any ideas? The floor has been treated with TLC (we tiptoe) and also was not sealed until cured. Thanks much.
Hi Rhonda,
What grout did you use?
Dear Sir,
My contractor did not install a solid subfloor and now I believe the movement in the subfloor is cause the grout lines to crack. What or is their anything I can do to fix this? I have a crawl space about 40 inches tall under my kitchen so I can access the subfloor from underneath but is their anything I can do to support the subfloor to keep it from moving?
Hi Darren,
You can shore up your framing by cutting your unsupported span of the joists in half. There should be vertical supports for your joists and they are normally 10-12 feet or more apart. If you cut that in half it will stiffen the floor. Whether or not that will be enough to stop the movement and cracking I have no idea. It may be enough, it may not.
We are finishing up a complete kitchen remodel, the tile was installed 1.5 months ago and getting lots of grout cracks. I know the durorock was glued down and not thinset, I questioned the contractor about not using thinset, he assured me using construction adhesive works better. I feel sick. The kitchen was extended off the rear of our house, we beafed up on every part of the construction to minimize deflection etc Would you try redoing the grout or tear everything up and reinstall with thinset.
Hey Victor,
The glue is likely the problem. Thinset is under it to fully support it, not to bond it to the subfloor or glue it down. Using glue actually creates voids where there were none. Adhesive does work better to bond it, but that isn’t what the thinset is for, that’s what the screws are for. It needs to be reinstalled with thinset.
Sorry for the delay, your comment was sent to the spam folder for some reason.
Hey Roger,
In the “fog of war” in laying tile, we’ve now noticed that we’ve forgotten to place thin set under the HardieBacker cement board. We’ve not laid any tile yet, but it’s all screwed down with 1 1/4 Hardie screws (hundreds).
The sheets are properly laid out. The tile is 12″, Porcelain with sanded fortified grout.
I hate doing anything incorrectly but I’m really not interested in pulling up 500 bucks worth of material and restarting.
I know you can’t predict the future; my house is well built. Question: would you pull it up and redo?
Thanks,
Eric
Hey Eric,
I know what you want to hear, and I’m sorry I can’t tell you that. Yes, I would pull it up. Thinset beneath the backer is one of the most important aspects of a durable tile installation. Sorry.
Hey Roger,
I purchased a hi gloss polished porcelain 18 inch tile because i was sold on the look of a 1/16 grout line in order to obtain a mirror effect. i did my research in hiring a tiler who works with a laser. once the tiler started laying the tile, not setting it yet, he noticed a problem. There was no way these tiles were going to be butted 1/16 because the grout line was not even. meaning these rectified tiles were off. whats your take on this? am i looking for something that doesnt exist? the manufacturers website clearly states they can be grouted 2mm which in American measurement would be 1.25/16. although it isnt 1/16 its closer to 1/16 than 1/8. these tiles cost double the price of a regular polished porcelain tile and i was promised i would get “the look” i wanted. the tiles have been calibrated and they are definately uneven. in order to get this look it is neccessary that they be mirror images of each other? also, after reading some of your blogs i got this sick feeling. if i were able to get tiles that can be butted 1/16 am i taking a chance that they will crack because the grout line is so tiny? im looking for something really nice but im in no way looking for a headache after installation. i have a brand new mud floor over a slab foundation and the home was built in 1964. help! im a homemaker trying to make the best educated decisions possible.THANKS!
Hi Suzanna,
Rectified tiles should be EXACTLY the same facial dimensions. If they are not take them back and tell them what you want. If that’s what you mean by ‘mirror image of each other’ then yes, they should be the same. Measure the tiles corner to corner each direction and see if they are the same size. That means they are square (if the measurements match). You either have a 1/16″ grout line or the tile is butted, you will not have both. If they are butted they may chip and crack, a 1/16″ grout line won’t cause that.
Hi, I had my tile installed by someone a friend recommended last January, in the cold Wisconsin winter. We had the 6 x 24 inch porcelin tiles installed. Our original floor was vinyl with a lauan underlayment. The tile guy said he could lay it over top of it but I did my research on that and said no and told him to pull it up. The subfloor is 3/4 inch plywood and I had him go around and throw some extra screws in some known “soft spots” where the floor creeked a bit. The tile guy then laid ditra (on top of thinset) and then another layer of thinset on top of the ditra and finally the tiles (I watched him do some of the installation). About a month or so after the tile was installed, we noticed a clicking or popping sound when we stepped on a few areas of the tile (of course, only in the high traffic areas). Earlier in May, when the hot humid weather arrived, the clicking and popping increased in sounds and number of times it would happen. Finally the other day, I had grout crack and pop out. The tile goes from one end of the kitchen to the other end of the dinning room (about 36 ft). Most of the section is broken up by an island counter. The area where the tile is cracking is in the long, thin section that stretches from wall to wall (36 ft). Since the cracking of the grout happened, the tile has no longer been making the clicking or popping sound. I’m guessing it has something to do with expansion w/ the heat and humidity? What would you recommend? Thanks in advance for your comment!
Hey TJ,
Clicking or popping is indicative of an improper bond of either the ditra to the substrate or the tile to the ditra. Normally what you are hearing is thinset that has started cracking out. If it is an expansion issue (which it very well could be) you may have been hearing the tiles becoming unbonded as the pressure was built up. Once the grout cracked it relieved some of that pressure, but you still have something unbonded under there. I would remove a couple of the tiles in those areas and see what is going on with the thinset both between the tile and ditra as well as the ditra and the subfloor.
Well it’s been quite a while since I posted this comment and you were right….. The backer was not properly installed. When the back was put down we used liquid nails with roofing nails initially, them after that setup we then used the green cement board screws. Now I am at a point where I need to ditch this floor and install a new one properly. We’ve decided to go with a floating wood floor. So my question now is on the best way to remove the tile and backer. The tile is already moving and I imagine that will come up fairly easily. I’m a bit worked about the backer because of all of the screws. Any recommendations for this demo?
Thanks.
Hi Jim,
I have absolutely no idea which comment you are speaking of. I have over 16,000 comments on this site and if you don’t use the reply button on the actual comment I have no way to know what was said. Unfortunately when there are screws through the backer you can pry the backer out around the screws in pieces, but you’ll need to unscrew the screws to remove them without completely destroying the subfloor.
I know it sucks. Last week I removed a bathroom floor which actually did have thinset beneath the backer and the proper screws, but the seams were not taped and the floor failed. I spent a day removing backer from a bathroom floor. And no, I’m not the one who put it in.
It just takes time and it’ll frustrate the hell out of you, but it’s the only way.
Hello Jeff
I had my house built in 2004, from the start (6 months in) my grout has been cracking. The builder has fixed grout and had all grout removed and redone twice, the last time with an acrylic grout. The have re enforced the floor joist by blocking with 2X4 as well as using 2×6 between joist on bottom of sub floor. Sub floor is 5/8 OSB with 3/8 plywood on top for 12×12 ceramic tile. The grout lines are not consistent, some are 1/8 of an inch, some 1/4 of inch, some less or more than these ( I had complained but told there is no code for grout lines). Some tiles are raised about 1/4 of inch and will stub toe (told this was because tiles where not flat but had an elevation profile to them). I have multiple areas with grout cracked or all together missing. The house builder is sending quality control manager on Thursday, any suggestions?
Thanks Derek
I meant Roger, had just finished reading Jeff’s question. Sorry Roger.
Hey Derek,
An elevation profile???
All tile has an elevation profile, otherwise it’d just be a picture of a tile, no? 
The tile may have been inconsistent and not up to specs in regards to flatness across the plane, but that is still on the contractor to NOT install inferior or flawed tile. He’s supposed to be the expert, right? There are also standard as to the allowable ‘lippage’, or height differences from tile to tile. That goes way beyond what’s allowable.
There is no ‘code’ for most tile installation. There are standards in place, but they aren’t a code unless enforceable by the building department or some other governing body – they aren’t. I really wish they were. That, however, does not excuse inconsistent grout lines, that’s just BS. Who the hell doesn’t know that grout lines need to be consistent???
Blocking or placing 2×6′s between joists will do absolutely nothing if the floor framing does not have an adequate span. This is the distance between vertical supports of your joists. That may not be your problem, though. With the description of the installation itself it would be my bet that, if there is backerboard beneath your tile, there is no thinset beneath it or the bond between the thinset and backer is not adequate or properly bonded. If there is not backerboard beneath it and the tile is bonded directly to the plywood – that’s your problem right there.
No matter what the source, regrouting 1000 times isn’t going to fix it. There is something inadequate or done incorrectly in the substrate beneath the tile. They’re putting band-aids on something that needs a transplant.
Hi I moved into my new townhouse a year ago. A few months in I noticed the grout lines in the kitchen, dining room + attached bathroom are cracking. I am currently going through mediation. The builder wants to regrout the areas with the larger cracked grout lines + inject the tiles. Originally the tile companies guy said he noticed at least 12 lifted tiles through out the area + the whole floor needed to be redone. Any suggestions on how to determine what is causing the issue…or do you think the builders suggestion will fix the problem?thanks!
Hi Aeisha,
The builder’s fix will likely not fix anything at all. Regrouting tile that is moving will solve nothing, it will only cover it up until it begins to crack again, which won’t take long. The phrase “inject the tiles” means absolutely nothing. It is not a term used in tile installations and not any type of procedure anyone uses. I have no idea what he intends to inject them with. My guess is more thinset? But that’s simply a guess.
The problem is due to the tile moving. That could be caused by a number of things, the two most common being improper bond between the tile and substrate and cement backerboard being used as the substrate without thinset being installed beneath it. Another huge cause of tiles debonding is lack of movement joints, no room for regular movement. Regardless, the tile company’s guy is likely correct. Whether or not it needs to be completely redone needs to be determined after further inspection, but the builder’s fix is simply a band-aid which will not solve anything long-term.
Hi Roger
Thank you for your response.
Injection when I research it seems to be more of a cheaper alternative if you cannot afford to have the whole floor redone. Here is a link to the type of product.
http://www.iafsystems.com/html/floor_repair_adhesive.html
I do not think cement backboards was used. There is the subfloor which I believe is made out of wood/plywood.
Cool, glue in a tube.
Before agreeing please be wary of the insinuated, but not necessarily intended, use of this product for wood substrates. Right on the page you linked to it says “There is a solution to loose and hollow ceramic tile floors, and other hard surface floors that delaminate from the concrete slab.” (Bold is mine) There is no mention at all about using it over a wood floor substrate.
Keep in mind, it will likely work for a while. However, if the substrate itself is part of the problem the same thing will happen again. I’m fairly certain that the tile, at one point after it was finished, was bonded to the substrate just fine. Movement debonded it – this product will not fix that.
I just finished laying tile in my bathroom. I used non sanded grout and it is cracking. I was told I could use sanded and non sanded grout. I think that my tile may be moving just a bit. If I use sanded grout will that help the cracking from starting?
Hey Jeff,
No, it won’t do anything at all for it. If your tile is moving it is something below the tile which is not done correctly. It will continue to crack until that is remedied.
Since it is unsanded it may simply be shrinking, unsanded grout will do that.
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