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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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.

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Patty

Hi: My daughter has a 15 y.o. large house that she bought 6 years ago. Now, the tile in the kitchen is all cracking and breaking and two contractors told her that it is from subflooring not put in correctly. Does this mean she has to take out all the kitchen cabinets, the island, and appliances to repair the tile??? Please let me know if my carpenter sons can do this, what they need to do to get the job done correctly as these contractors are asking for big money. Thank you very much and have a good day. We are really on a tight budget here. Should she try to get the contractor who built the house and give him hell for being a jackass and not dong the job correctly????

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Vivian

Hi Roger, we had a dining area, kitchen, hallway, laundry room and half bath tiled over a concrete floor with a Ditra membrane over the entire area, and 12×24 Porcelain tiles with 1/8″ grout line, and the installer used unsanded grout. At least half of our tiles in the area sound hollow underneath and the grout was cracking and coming up. The installer came back and regrouted the whole floor and now it’s happening again. I’m thinking there’s not enough thinset under the tiles, and sanded grout should have been used. Can you PLEASE give me any advice?

Thanks,

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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!

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Roger

Hi Jim,

Do you have ANY soft joints in the installation at all?

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Merrill Warschoff

Hi Roger,
We are 2 years into a new kitchen porcelain tile floor, and there is one area where the grout has cracked (really it’s popping out in little chunks) and been repaired twice. Now the cracks are spreading. The first repair – contractor scraped out the grout and re-grouted, 2nd repair they pulled up 5 tiles, screwed down the wood subfloor more and replaced tile. Since the first crack, I’ve been complaining that the floor was never even in the first place once the old floor was pulled up. The tiles in that area straddled floor that used to be hardwood and floor that used to be old kitchen tile. The hardwood area seemed to dip. Contractor (and family) didn’t believe me then and keeps telling me I have too much movement and he doesn’t know why. Now – 2 repairs later and several other visits to view the damage, I can’t really feel the dip anymore. But, could this be the reason the grout is still cracking? I don’t know about thinset that was used. I do know there was no backerboard.

I’m very hesitant to have the original contractor come back again (he’d likely do the repair and I’d just have to buy the tile and grout.) He’s already had 3 strikes. But, I’m also hesitant (and low on cash and on extra tile) to start over with someone new who will need to replace a lot of tiles. But, the latter is probably my only choice?
What do you think?

Should I try the grout caulk myself? — it’s a large area, now that the spider web of erosion has spread.

My 25 year old kitchen tile and 50 year old hardwood were ugly but didn’t have any cracks.

Thanks!
Merrill

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Mary

Help, house moves a lot due to soil conditions…. need to re-grout stretched corners….shower , 3″ tiles.

What is best product for this type of ongoing movement that has some “give”

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Karen Gilliland

This is concerning a mobile home (yes, I imagine the floor is ALWAYS moving), with tile flooring. The grout is mostly gone/cracked in both the kitchen and bathroom–it is worse in the bathroom. Would it be best to install flexible grout? What about the “Ceramic Tile Pro Grout Bond patch and repair additive”? Would that help? I have grout left over from when it was originally installed–but hate to go to the trouble of regrouting if it is just going to crack and break again.

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Amiyra

Hi, so got brand new tile installed and the grout is cracking and when you walk on the tile you can clearly hear that the tile is shifting. I called the installer and he put down more grout and fixed it a couple weeks ago and it’s happening again. He came back and removed one of the tiles…… i don’t think this should look like this and I don’t know what to do about this guy…. so frustrating!!

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Amiyra

Attached photo!!!! Any help would be appreciated!!! Thx

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Shelby

We laid 12×24 porcelain tiles in our bathroom recently with 1/8 grout lines. We used Fusion grout and it has set well everywhere except around 4-6 tiles. We scraped it all out and reapplied and waited several days without walking on it and when we checked, it is doing the same thing. Not sure what to do next.

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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

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Roger

Hi Julie,

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

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Julie

Hello

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

Thanks

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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.

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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?

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Roger

That is correct – and that’s the cause.

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marilyn

I had handyman use durock on floor. Did not check computer for proper installation procedure until after project was done. First of all he screw down durock over existing vinyl over plywood floor. did not use thinset under durock only under ceramic tiles. This was done 7 days ago, now when i walk on floor can hear a cracking sound. Will call him today. What do you think should be done.

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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.

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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.

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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!!

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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.

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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

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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

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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?

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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.

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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!

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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

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