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.

Previous post:

Next post:

Declan mccarron

I just had a complete new shower installed this week. I’ve been letting everything set for a few days as advised. Today I was going to deal the grout and noticed cracks in several different places. I contacted the person that did the work and he told me to go ahead and seal it and that he would “re-grout a couple of touch ups”. Does this sound like an ok way to go? Or is there possibly bigger underlying problems?

Reply

Roger

Hi Declan,

No, that isn’t the way to go. Depending on the grout (unsanded) he may be able to just go over it. If the cracks get bigger then there is likely an larger underlying problem. I can’t say without specifics about the installation.

Reply

Declan mccarron

Yes it was unsanded grout. It looks like it was used in parts, that are certainly bigger than the 1/8″ recommendation.

Reply

Roger

Then it likely just shrunk. It needs to be filled before it can be sealed, though.

Reply

Beth

Hi-
We had porcelain tile installed over a infloor heat system. The grout is dark brown, almost black. I had the tile guy come back to clean up the grout twice because I felt as though the grout was ‘hazy’. Finally, it came out looking acceptable – wasn’t sure what he cleaned the grout with, is it possible he dug too deep & thinned the grout? Now, we have grout cracking on a few tiles in a high traffic area – it occurred to me after reading a few posts, the floor would bounce in the area where we now have issues. Is it possible the infloor heat was installed incorrectly? Or, the tile was installed improperly on top of it?

Reply

Roger

Hi Beth,

A LOT of things are possible, including improperly installed heat or tile, improper coverage of thinset or, most likely, improperly built substrate to support your tile installation. Grout is most likely NOT the problem.

Reply

KP

Will using epoxy grout to repair cracking grout lines in several places on recently installed hallway, (regardless of the fact that no thin set was used between 1/4″plywood & the backerboard), be a permanent fix? Tiles are also moving, slightly. Thanks Roger

Reply

Roger

Hi KP,

No, if they are moving the problem lies in your substrate. It must be properly repaired.

Reply

Kathy

If my ceramic tile floor has cracks around some of them and some of the are completely broken and pieces because my kids step on it all the time I have a 1yr old who bearly started walkin and the broken pieces call his attention and I’m scared because it’s dangerous my kid can eat the pieces or get cut I’ve asked my manager to change my tile wood floor and she has stated she can only replace the broken ones and with a different color than the other ones I have what can I do I don’t want mix and match tile floor

Reply

Roger

Hi Kathy,

I have no idea. I would begin at your local building department, they can likely tell you what recourse you have. I am a tile contractor, not a lawyer. :D

Reply

audrey

Hi. I had 12×12 ceramic tiles installed in my bathroom 2 months ago. about 80 sqr. feet. I was told the underlayment was in very good shape so they could lay my new tile on the top. Dont know what kind of adhesive was used to install tiles. My grout line is 1/4 inch wide. Grout line have been cracking and falling out in chunks since three days after install. Tiles have crunching sound when walked on. they have been back 2 times to regrout it but keeps happening. Dont know what to do, but I want my bathroom to be finished. Do you have any sugestions? Thanks.

Reply

Roger

Hi Audrey,

If it’s cracking, as I’ve indicated above, it is due to movement. Likely an improper substrate, so I’m guessing that no, your underlayment wasn’t in good shape, or was improperly installed, or wasn’t correct for tile, or…

It’s your substrate, it has nothing to do with your grout.

Reply

Sonya

I am tiling stairs and a landing/back porch that is also a laundry room. But for now I just want to do the stairs. There are 3 steps from the kitchen to the back door landing, and then 9 steps down to the basement. The stairs are fully enclosed by walls, and for the first three I have gotten nearly all the old lino/vinyl flooring off (2 layers!!)
The stair surface is wood – probably plywood by the look of the bits I hacked when scraping the lino backing off- but all seems extremely solid. Stairs are a little under 36 inches wide.
Do I NEED to put something under the tile? can I just use a thin layer of levelling compound overall and to correct the bad gouges?
I plan to tile them the way someone did my front steps for us just before we moved in- with the tile to the edge and a plan rounded bullnose glued and screwed to the front of the step. I still have the tile adhesive…..

Reply

Roger

Hi Sonya,

Yes, you absolutely need a substrate between the wood and tile if you want your stairs to last.

Reply

colin McCulloch

I have had similar problems in my Kitchen – insulation board put down over wooden floorboards/underfloor heating and then ceramic tiles – over last 2 years cracks are appearing everywhere – I think its because the original wooden floors are springy – causing the movement above.
Is this an insurance claim?

Reply

Roger

Hi Colin,

Normally no, it isn’t. If you had an independent contractor install your floor tile the fault lies with them, you need to start there.

Reply

Reg

Hi Roger, Just reading and thinking I am going to need to pull up tile. We redid a bathroom and installed a shower: plywood sub floor, backerboard, premade tile-able shower base over good layer of mortar, redguard, then 2 inch mosaic porcelain laid with ’tile adhesive’ (wrong, correct?), then good layer of sanded grout. It then took a couple of months to completely finish/tile the rest of the bathroom before the shower was used. No problems with shower floor grout during that time. Once the shower started being used, the grout started cracking out in the area stood on the most. Was planning to regrout after it is all dry but when I wet vacuumed the shower floor to start the drying process, I see some water coming from between tiles where the grout does not even appear damaged. I believe there must be a little movement in the floor under the tile, causing tiny cracks letting water in and the grout is cracking from water being underneath it. Is that likely? The tiles are absolutely solidly adhered but the floor must have a little give. If I pull up tile and retile using a good layer of real mortar, can I resolve this issue? Then regrout.

Reply

Roger

Hi Reg,

Water will ALWAYS get beneath your tile, cracked grout or not. If you use a pre-mixed adhesive that’s your problem. Yes, removing them and installing them with thinset will likely solve the problem.

Reply

Ryan

Hi Roger,

You mentioned that water will always get beneath the tiles whether its cracked or not since i understand that the tile is porous. But is it normal that water will stay underneath the tiles? Like when you put your weight on a tile when you step on it, water will come out from the grout or tile edges? Also when i was tapping the tiles to see if its properly attached to the floor it sounds solid. So how can water stay underneath the tiles and not drain? Will it need to just evaporate?

Reply

Roger

Your weep holes could be plugged. Something, somewhere is not draining properly. Water will not cause thinset to lose it’s bond, so they may not be loose at all, but it’s still not draining. Yes, evaporation is the only means of dissipation in that case.

Reply

Margaret

Hello,

Writing this from Australia! Had my shower tiled by a reputable firm and a wonderful rain showere installed. The shower base, is an extension of the floor..in other words not the usual plastic shower base. The grout in the shower base tiles just keeps popping out and now, I can hear squelshy sounds underfoot. Just one tile seems affected. What can I do?

Reply

Roger

Hi Margaret,

Call your reputable firm and have them come out and repair it. :D For some reason, if it’s just that one tile, it has somehow become unbonded, or never was to begin with. Either way they should be able to take care of that for you.

Reply

Sam

Dear Cool Elf,
We just had a tile installer put 12×24 tiles with 1/8 gap for grout around tub and on floor. We also used the floor bullnose tile as our wall trim instead of typical wood. In less than 45 days, I noticed the grout (confirmed it is sanded) has cracked from the tub up to the ceiling in both corners and has pulled away from the tub. *(tile was grouted around tub)
We were told by the original installer and a subsequent tile installer that this can be “normal” and that because the walls shrink/move, this can happen and the fix is to remove the grout and re-grout. This doesn’t make sense to me. According to your site, this should NOT happen and that we should question the use of grout in areas the plane changes. Can you clarify? I asked the two tile installers if it was standard to put grout in the change of plane areas… they both said it was standard because it is difficult to get caulk to match the grout. What do you think caused the cracking and what should we do to fix the cracking/pulled away grout now and for longer term?

Reply

Roger

Hi Sam,

It is cracking because your change of plane is grouted. It needs to be caulk or silicone. EVERY grout manufacturer has a silicone or caulk that matches the grout – every one.

Reply

KH

We just installed 12 x12 tile in our hall. We used the backbutter method and I am sad to say the coverage was poor on many of the tiles and the are moving quite abit. We don’t know what to do… we have not grouted yet because we know it will just crack. Do we need to just rip it up and start over (obviously we would like to avoid this)? or can we pull up individual problem tiles and replaces them? will we be able to get the dried tile adhesive of the subfloor? Any info is greatly appreciated.

Reply

Roger

Hi KH,

Not sure what you mean by the ‘backbutter method’, do you mean you just installed thinset to the back of the tile and put it down on the substrate? What is your substrate? I need a little more info to let you know how best to fix it.

Reply

KH

Yes, we just applied the tile adhesive to the back of the tile. The substrate is just plywood.

Reply

Roger

Tile adhesive? Do you mean mastic or thinset? Regardless the entire installation should be taken up, a proper substrate put down and the tile installed with thinset. The thinset needs to be forced into the substrate with the flat side of the trowel, then combed over the substrate, the tiles should have thinset forced into the back side with the flat side of the trowel, then placed onto the substrate with the combed thinset on it.

You are bonding tiles to a substrate which will be walked on and a lot of force will be applied to those tiles every day. You need to ensure that there is a suitable bond between the tile and substrate, and that you have a proper substrate which will not break that bond. Plywood expands and contracts A LOT, it will break that bond.

Sorry, I know that isn’t what you wanted to hear.

Reply

Marie

I have a 18×18 porcelain tile floor installed over a wooden subfloor. The unit is an old 70’s condo and is over two garages so my floors are wonky. The installation was not done by a professional the grout lines are not consistent, grout is crumbling and completely missing in some areas. My 2 questions are: can this floor be repaired or should I call it a day, smash it up and start over with a professional installation? My second question: If the advise is to start over do you think my uneven floor could have a engineered hardwood application? (I will use a professional)

Reply

Roger

Hi Marie,

In a case such as yours it is always something below the tile causing the problem. It can not be fixed at the point you describe. I don’t understand what you mean when you ask if it could have an engineered hardwood application. Yes, you can install engineered hardwood over it, if that’s what you’re asking. If it isn’t you’ll need to let me know what you mean.

Reply

madelyn

Poor workmanship with ceramic foor that tile has cracked and moved. Wooden sub floor needs replaced. Question. How long can we continue to walking on the floor?

Reply

Roger

Hi Madelyn,

Until you replace it, I assume. As for how long the tile will last, it is literally impossible for me to say. If the tiles are already moving it won’t take long before they begin cracking. Obviously you should replace it as soon as you can, but as far as how long it will last I really can’t say.

Reply

Ian

Hello Roger,

I tiled my lounge (never done tiling before) with 44cm tiles and 1cm spacers, but the grout in some areas has ‘sunk’ leaving deep grooves between the tiles. Is the reason for this that the space between the tiles is too big, and where did the grout go? It looked ok when I first did the job. Needless to say, the wife is not happy and muttering about getting proper people to do these jobs as she is finding the valleys between the tiles difficult to clean. And can I just add more grout where required or do I have to replace it ?
Thanking you in advance,

Ian

Reply

Roger

Hi Ian,

It shrunk, it didn’t sink. :D I’m assuming you used sanded grout, correct? If it has been installed more than seven days or so you need to replace the grout, new stuff won’t last over it. Too much water in the grout when mixed will cause it to shrink excessively.

Reply

Tyler

Hi Roger,

I’ve got a 5′ x 16′ concrete slab at ground level inside my house I want to cover with 14″ square porcelain tile, as well as concrete steps going down to the basement. Like everything else tile related, there seems to be 100 approaches suggested, and I just want someone smarter than me to tell me an easy solution for an amateur. I know I’m not supposed to put tile directly onto the concrete slab, but is that even true for really small areas like the steps, or the 3’x3′ landings I have at the top and bottom of them? Would it be sufficient to use redgard and then (modified?) thinset on top of that, or do I need something like ditra? I’ve never used ditra before so I’m trying to avoid it if I can, but I don’t think the added height is an issue.

Also with the steps, I see schluter makes stair nosing profiles (the TREP series) but they’re almost $40 a tread. Is there a cheaper option? The tile I have is non-slip, can I get away with using an outside corner trim piece like schluter rondec?

Thanks for your help.

Reply

Roger

Hi Tyler,

Redgard is a perfect solution. Yes, you can use the rondecs on steps, they work well.

Reply

Stewart Beller

Porcelain tile installed in my bathroom everte we shower ther is white spots on the tile contracter thougt it was haze had it cleaned pressure washed made it worse. I no it’s the grout coming off tile is done nice and tight I think they used unsanded grout how do I fix that can we just take out the grout and use new grout

Reply

Roger

Hi Stewart,

Yes, you can remove and regrout your tile.

Reply

Eva

I have granite tiles on my living/dining room floor, in the Philippines, set on concrete base. They have lifted for the second time now. They are set very tight together, with no grout, which seems to be a local procedure. We thought they lifted because the concrete rose up, but this time it does not seem that is why.

Any idea why they are lifting?

Reply

Roger

Hi Eva,

No grout or compensation for movement will cause pressure to build up in an installation and that pressure must go somewhere. It often sheers the tile from the underlying substrate. You need compensation for movement, especially in extremely humid areas such as the Philippines.

Reply

Ginny

THIS EXPLAINS EVERYTHING. YES I’M TYPING IN ALL CAPS BECAUSE IN MY HEAD I’M YELLING. I JUST WANT TO CRY!!! My husband installed wood look tile in a bathroom. After a few months the grout in a small section has started cracking. Ever since it was installed I could feel and hear a little “creaking” over a few of the tiles. We are supposed to be listing our house on Friday. Now we have to fix this! Ok…pity party over. We can do this. :)

Reply

Maricel

Hi Roger.

I’m from the Philippines…Quote:” 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.”…Cracking grout, tenting tiles happened this morning after 18 years, is it possible? Thanks!

Reply

Roger

Hi Maricel,

Absolutely it is. 18 years of expansion and contraction finally put enough pressure on the installation that it needed to release somewhere. If you can remove those tiles and reinstall them with a soft joint they should be fine for as long as you want to keep them.

Reply

Amber

Do you have a link to the very specific way to lay tile on plywood subfloor!

Reply

Roger

Hi Amber,

I can not find a specific link, but it really isn’t difficult. Just make sure that your top plywood seams are offset from the bottom ones (which should be directly over a joist) by 1/3 the length and width of the plywood sheet, ensure your joints are staggered (so you don’t have four corners in any area) and only screw the top layer into the bottom layer, not into the joists.

Reply

Emilie

Thanks Roger- Yes, I back buttered the tiles. I’m not sure the exact distance of support for the joists, probably somewhere around 12 feet is my guess from remembering what it looks like in the crawl space. The part that is most perplexing to me is how things have changed now that the air is less humid. I guess tile removal is in my future…thanks again.

Reply

Emilie

Hi Roger- I’m hoping you can help me out with a rather frustrating and puzzling tile issue related to cracking grout. I installed 600 sq feet of 18 inch porcelain tile last February in my kitchen/ front hallway. About 3-4 months later I noticed the grout began to crack in high traffic areas. Over the next few months I noticed small cracks even in non traffic areas (closet) and in high traffic areas grout crumbling. You could feel the tiles move when stepping on those where the grout completely failed. Here is the info for installation. 2 layers of 5/8 tongue & groove plywood over 2×6 16 inch on center. Modified thinset with 1/4 notched trowel, ditra membrane, unmodified thinset with 1/2 notched trowel, tile, sanded grout with 1/4 inch spacing. This is my 3rd time using the ditra & I’ve never had this problem before. I’m torn about whether it not to pull up what I have access to (installed under my new caninets) and start over or just regroup & see if it cracks again. Of interesting note, now that it’s winter and the humidity is down ( we lice in virginia) the cracking has stopped and the tiles no longer move or creek when you step on them. Any ideas?

Reply

Roger

Hi Emilie,

Do you know the unsupported span between your joists? While they may be 16 o.c. they may have a large span, lessening the deflection ratio. That may be the issue, but it sounds more likely to me that the tile itself is not bonded correctly to the ditra. Were the tiles backbuttered? The first step to determining the problem would be to pull up one or two tiles and see what type of coverage you have on the tile.

Reply

Cleo

Hi Roger. I’m a snowbird and spend winter (Nov-Apr) in Phoenix, Arizona. I had my bathroom tiled about this time last year. Upon returning to Arizona I noticed one area where the grout has chipped out. The bathroom is only about 7 ft x 10 ft so I guess one tile isn’t bad overall. The problem is that the contractor came back the mid January and regrouted that area and now it has separated from the tile and is beginning to crack again. When the tile was installed, backerboard was put down, but I don’t remember if any thinset was put down first. As I said it’s just the one area. No other tiles have grout that is cracking or chipping out. What do you think the problem might be and what can be done to correct this? Thanks.

Reply

Roger

Hi Cleo,

I’m thinking that the area cracking is directly over a seam in either the backer or subfloor and the backerboard seams were not taped and mudded. It could also be that there is no thinset beneath it. Either or both could cause that. The tile will need to be removed, the source of the problem identified (likely one of those) and fixed. Regrouting it will just lead to the same issue.

Reply

Leave a Comment

;) :wtf: :wink: :whistle: :twisted: :suspect: :shades: :roll: :rockon: :oops: :lol: :lol2: :lol1: :idea: :guedo: :evilb: :evil: :eek: :dance: :cry: :corn: :cool: :censored: :bonk: :arrow: :D :?: :-| :-o :-P :-D :-? :) :( :!: 8)