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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Amy

Three months ago we had 18 x 18 porcelain tile installed in our upstairs kitchen and entryway. A few weeks ago I noticed hairline cracks in the grout in the entryway right in front of the stairs. The installer came out without notification and laid more grout on top of it to cover the cracks. Unfortunately he didn’t let me know he was coming so only my kids were home. The following week I noticed some cracks in the grout in the kitchen in front of the dishwasher, again I called and this time when he came out he filled the cracks with an acrylic caulk. He also found several other places in the kitchen where this was happening and said it was due to the house settling. He claimed the caulk would make for more flexibility in the floor…or some such nonsense. I have looked online and cannot find reference to either of these methods being the correct resolution for any reason for grout cracking. It appears the correct method of installation was used, 5/16″ Ditra and 2 different kinds of thinset (one for between the plywood and Ditra and the other for in between the Ditra and the tile, I assume) Is my next step to find some independent expert to come look at it? I am very worried if there is all this cracking after only 3 months and the “coverup” will only last as long as whatever warranty I have…

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Reed

Recently, a homeowner contacted me to re-grout a neo-angle stall shower floor because after about 10 years the grout started to come loose. I told her on the phone usually grout loosens due to loose tile, but that I would check for that prior to grouting. Well, they all feel solid to the touch, no movement or hollow sounds. So I cleaned all grout joints well, vacuumed, cleaned, and vacuumed again. Mixed some sanded grout as I’ve done in the past and applied as usual. I’ve actually done this process twice now with the same results. It dries hard as a rock and apparently loosens and falls out after a couple weeks of everyday use. One of the users is probably over 400lbs. Is it possible the floor is shifting or deflecting with his weight? She said they had the entire shower with new pan, tile, and glass doors replaced 10 years ago and its been fine till now. I used a silicone, sanded grout/ caulk around the perimeter.

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Roger

Hi Reed,

If the tiles are bonded properly and are solid then deflection is likely the issue.

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Megan

Hi,
So we just had our whole house remodeled and put porcelain tile in all rooms except the bedrooms. They did put hardibacker under the tiles in the bathrooms, laundry room, and livingroom. But laid the tiles on our existing floor ( which is peel and stick linoleum) in the kitchen and hallways. I questioned this many times as we had several tilers come and do estimates on our house and listened to what everyone had said which was the same thing about ripping up the existing flooring and fiberboard. This guy said the same thing but didn’t do it. His explanation was its only necessary in wet places and if the floor isnt up to code in thickness and now all of the grout is coming up and we tiled under all of our new kitchen cabinets too. We told him about it the week after we had the kitchen tile laid and he said no problem we will regrout it so he did and a week later the same thing. Now all of our grout is coming up everywhere. Some tiles are coming loose too. Does this mean he needs to come back and redo all of our tile or should we go talk to a lawyer and try getting our money back for labor, tiles, and all the grout? Then have someone else come fix it. I’m scared he will do a cheap and cappy job if he has to redo it all. So stressed….

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Phil

The tile in our kitchen is approximately 8 years old. We bought the house 4 years ago. Within the last year the grout in the center of the kitchen has started cracking and crumbling. Our washing machine vibrates terribly so I thought that was the culprit but no damage is present in the bathroom where the washer is located. If I go to the trouble of replacing the grout would it help to install some bracing between the floor joists beneath the problem area? Also I’m unsure if proper underlayment was used. Thanks.

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Roger

Hi Phil,

It definitely couldn’t hurt, and may solve the problem. But if it happens again it’s indicative of either an improper substrate or improper installation.

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Jessica

Hi,
We are having an old airstream refinished and wanted to install mosaic tile on the bathroom floor and over corian countertop in the kitchen. The contractor said it was fine but then abruptly changed his mind saying the bathroom floor will move going down the road and the tile would crack. Is it a bad idea to install tile in a trailer? It’s mosaic tile for the counter and moonstone flat rock tile for the bathroom floor. Thank you for your advice!

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Roger

Hi Jessica,

It can be done, but it’s a pain. Especially with a mosaic. Normally ditra would tackle it, but the limitation on tile size is 2″ square or larger. Hydroban over cement board may work, if the proper thickness is achieved, but I really couldn’t guarantee that. Call laticrete tech support, they may have a better idea.

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Erica

Hi,
A year ago we had new tile installed in our kitchen and bathrooms. The grout in the bathrooms upstairs is literally crumbling in little pebble piece sizes and when we walk on it you can hear it cracking underneath. A few tiles you can now even feel move. I called the contractor and surprisingly he said he will come out to look at it. I don’t remember them ever adding anything to our subfloor so I’m assuming the tile is sitting directly on that. Can our floor be fixed by removing the damaged areas only or do we need to have everything removed and start from scratch? Also, do you recommend something be put down on top of the subfloor before reinstalling the tile? Thank you.

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Roger

Hi Erica,

Every question you’ve asked depends on whether or not the tile is installed directly to wood. If it is, the entire thing should be removed and properly installed. You need a proper substrate of some type over wood, wood is not a proper tile bonding surface. If there is a proper substrate, the fix depends on why your tiles are coming loose. Until you can elaborate on those I really would be just guessing at a proper solution.

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Justin

We recently purchase a brand new home and about one monthin we noticed one thin crack in grout. Builder has repaired cracked grout two to three times now and now we have about 50% of the grout cracked in kitchen. My concern is improper structural support from beneath as we do have a large island. They seem to think its the thin set. One of our neighboirs had similar problem and they ended up needing to double up joists and adding support posts.

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Roger

Hi Justin,

It’s normally indicative of an improper substrate (excessive deflection). It COULD be the thinset (improper coverage), but it’s doubtful. If it IS the thinset, it’s due to the improper installation of it, not the thinset itself (normally).

I don’t think I’ve ever had that many parentheses in one answer. :D

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Jack

I had a small addition put on our home about 2.5 years ago. It’s a master bath on the second floor and just unfinished storage beneath. The floor tile grout is crumbling and coming up. We had one tile grouted again about a year ago since grout was crumbling in the seam. It was really dry. The contractor told me that because we don’t have a humidifier and the top floor of our split level gets pretty warm (it does get very warm up there during the winter) it’s too hard on the grout. We live in Chicago so it’s not like we are in crazy dry climate. Nowwe are starting to see grout coming out of the seams in a few places. Can I regrout and put some sort of silicon sealer so they don’t dry out? Does it seem too late to get back in touch with my contractor (still in business) and hold them responsible? We love the addition but my wife and I are pretty bummed we have to deal with this so shortly after spending so much money. Thanks roger!

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Roger

Hi Jack,

As I indicated above, it is indicative of either movement or inadequate substrates. Grout is a concrete based product, warm air isn’t going to affect it – EVER! I’ve never seen a driveway in the Florida sun crumble and fall apart due to heat. :D Yes, I would call him back. He’ll want to regrout the whole thing first, but agree to that only with the (written) stipulation that if it happens again (it will) they will replace the floor.

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Michael Domingue

i have a floor that is eight years old and have grout cracking and coming out in one small area at a section where 4 tiles meet and going along the top and right grout line of the bottom left tile. The corner of that tile seems to flex where the grout has come out, but there doesn’t seem to be much movement otherwise. Is it possible to put some sort of filler or even grout under the corner to add support then regrout or am I looking at replacing that tile? I would prefer to do it that if possible, even if it is only a 50/50 chance of succes.

Thanks in andvance for any help.

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Roger

Hi Michael,

Grout will not support that corner. You can mix up some thinset and shove it down in there – go ahead and make a mess of it to ensure you have it packed well, then wait until it firms up a bit and dig it out of the grout lines, then wipe it all off the face of the tile and the edges. Once the thinset fully cures you should have plenty of support and your tile won’t move. Then just grout it.

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Lora

We have grout coming out for the 5th time..We hired the floor in our kitchen done by a contractor, who is no longer in business, and the section by our sink keeps coming out. My husband has removed the tiles and screwed the cement board down every 2-3 inches and put glue all over the tiles.

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Roger

Hi Lora,

I’m assuming this is a countertop? The substrate is done incorrectly, leading to movement, leading to cracking grout. Whether a counter or floor that part is universal. Is there thinset beneath the backer? What type of ‘glue’ did he put all over the tiles? (Tiles are not glued down, they are mortared down).

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Jeff

I’m seeing cracks in the grout along the edges of various tiles. The adjacent tiles appear to be moving (loose). The tile is about a year old, installed over a crawlspace with a 3/4 inch plywood subfloor with 1/4 inch cement board over that. However, the installer didn’t use mortar under the cement boarda although he did tape and mortar all the seams and he screwed the cement board directly to the subfloor, about 56 screws per 3×5 sheet. We plan to remove and replace the grout and loose tiles next week. Do you believe I will continue to experience these issues because mortar wasn’t used under the cement board? Thank you for your time and assistance.

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Roger

Hi Jeff,

Yes, absolutely I do. I would guess that the lack of mortar beneath the cement board, especially 1/4″, is the reason you are having problems.

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Nick

I had porcelain plank tile installed for a upstairs bathroom floor. The plywood floor was screwed down, and ditra mat was adhered with thin set. It has been 4 months since install, and i looked at the grout closely and there are now small hairline cracks running the length of the grout along the tile edge. This is happening in about 50% of the grout lines. Any suggests on the cause of this, and what can be done to fix it. Thanks a lot in advance, great blog page! :)

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Roger

Hi Nick,

There is either movement in the floor or the incorrect grout was used. If unsanded grout was used it’s likely due to the shrinking of the grout as it cured. Going over it with more grout can fix it. If it was sanded grout then there is some type of movement in the floor. Incomplete coverage, inadequate framing, allowing the thinset to skim over during installation, etc. There are a lot of reasons your tile can move, you’d need to remove a tile or two to determine the underlying cause.

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KP

Joe,
It’s the contractor, I’m pretty sure roger will tell you it’s the install of the substrate, it’s the contractor’s fault.

I had the same thing happen. I had the contractor come out three times to repair, it didn’t work, ridiculous repairs.
I asked another contractor for a bid & asked him to pull out a tile & investigate, sure enough, no adhesive between floors, no adhesive on joists, sheet rock screws used every 2-3 ft., the list goes on & on.

I sent the contractor an email telling him I was prepared to do the following if he didn’t return all my money including the tile. I had already started a file with Angie’s list, so he had that when I sent him my email, even though he wasn’t listed. It was threatening & maybe he realized I would follow through on the following. It worked, I got all money returned.

Department of Labor & industry (formal investigation)
Licensing Board
Angie’s List
American Arbitration Assoc.
BBB
Consumer Protection Board
Filing complaints & issuing bad reviews
Small Claims Court or Hire an Attorney
Contractor Recovery fund

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Joe

Thanks KP,
We now have the tile store manager where we purchased tiles from coming out later this week to home to inspect cracking tile and grout. When I asked him for a copy of receipts of purchase, he also expressed concern and wanting to come see cracking. Explained to him that within 5 months my new floor should not be cracking and at this point since it is extensive, it is a demo & redo job, and not a patch up job. Thinking the Tile store usually does not want to throw a tile contractor under the bus, but in the meantime wants to cover their tail. Told him will hold someone accountable.

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Joe

Cracking everywhere!
Had a company install approx 490 sqft of porcelain tile (12×12 and 12×24), in two joining rooms (kitchen and morning room) less than 5 months ago. He highly suggested using Latacrete Strata Mat instead of Wonderboard, Durrock, or cement board. He said they use mostly this new method, and especially better for our rooms. They installed this on top of what I believe is 3/4 inch OSB.
Two weeks ago (early June), wife noticed one cracked tile. Couple days later we noticed a couple more. Now few days later, we actually get closer and notice approx 6 cracked tiles, 30% of grout having cracks, and one even moves when step on it.
This is unacceptable with amount of money spent. I hired tile contractor because this is not my line of work and therefore relied on his suggestion & skill. What type of warranty is usually associated with this? At this point, who do you suggest I contact first: tile installer, tile store, product manufacturer? I don’t want them to play the blame game. Thanks.

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Roger

Hi Joe,

That is unacceptable with any amount of money spent! I will say that strata-mat is an excellent product, and this is not a problem when properly installed. It will end up being a problem with the installation of it, I can nearly guarantee that. However, I would begin by calling laticrete and getting a rep to come out. He will be able to tell you exactly what is wrong with it, that way when you do contact the installer you know exactly what was done incorrectly.

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Crystal E

Hi there, we just had a couple of guys install new porcelain tiles on our kitchen floor. They said they knew how to install tiles. They did the job a week ago, starting Friday, and finishing Saturday evening. They told me we needed to keep off the floor till at least Wednesday to allow the floor to cure. So, we did that. Then my husband begun to prep our walls for painting in the kitchen, mudding, & sanding spots on the walls. So I used our vacuum, with the smooth floor attachment to pick up the dust over the tiles. (This doesn’t use a roller or moving bristles of course.) I had cracking grout lifting up out from between some of the tiles. I got down on my knees and starting closely inspecting the job, and realized there are several spots around the floor that have grout cracking. There is Wonderboard underneath the tiles. We have a wood subfloor, and to be honest I don’t know if they did apply thinset under that Wonderboard, before they screwed that into the wooden subfloor. I took some pics on my phone and sent one of the guys who installed my floor a text showing him huge missing pieces of grout lines and chipping, telling him all I did was run my average vacuum over it and the dude was like, “OH, you can’t vacuum the grout and tile.” One side of our kitchen connects to a dining room that was carpeted. The guys didn’t take back the padding, and tiled about a good three inches over the padding. They didn’t cut the Wonderboard either to ensure it laid underneath that whole row of tiles, which spans twelve feet, twelve tiles long. I know that the Wonderboard is completely missing at least 3-4 inches under the edges of those tiles, and that is where the major cracking began and grout coming out completely. The day they finished, I asked why they hadn’t taken up the carpet padding and tiled over it instead of taking it up… It concerned me. Now that concern is a reality. Won’t they have to remove tiles, that padding and cut more Wonderboard to go completely to the edge of our tile, in order to fix this? This one guy who was involved in the installation said he would just “fix” the grout… But after a close inspection all over my flooring, I see more grout cracking at corners and along edges even into the middle of the floor. Is it likely we just got a really sucky tile job that has to be ripped up and started over again?

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Roger

Hi Crystal,

Unfortunately yes, you apparently had hacks installing your tile. Tiling over carpet pad??? WTF? I wouldn’t trust a damn thing they did. And waiting four days for it to cure – the only thing you’d do that with is mastic, which shouldn’t be used on your floor. A total replacement is very likely the only solution.

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gt

We installed tile to our bathroom floor. There is one tile that is moving a little since it was installed in front of the commode. Will this piece need to be removed and retiled or is it just not cured yet? It’s been 24 hours since installation.
Thank you for your feedback in advance.

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Roger

Hi GT,

If it continues to move you’ll need to remove it and reinstall it.

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David

I have a two week old brand-new shower and the grout is cracking from corner to corner on the line to the bottom of the tile contractor who refused to come out to repair it says that it’s normal and happens from time to time

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Roger

Hi David,

Do you mean there is grout in the corners and it’s cracking? If so then it’s because it should be silicone in any change of plane, not grout. If it’s cracking on the floor or on the wall in the field tile that is indicative of underlying movement and/or improper installation.

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C

common sense tells me you cannot use grout caulk to fill in for missing shower floor grout. for one, caulk would stick to showerer’s feet. correct?

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Roger

Hi C,

You’re correct, but not because it will stick to someone’s feet. Because it will eventually lose elasticity and become unbonded from the sides of the tile, leaving a cracked ‘grout line’. It simply will not last.

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Deborah Woodhouse

We have a keyway that installed in our newly built two year old home and since we have experienced bulking in the tiles in the floor, when we approached the builder he explained that the keyway is to help expand and contract minimize cracking and does not affect structural strength.

What things should I be concern about years from now about the tiles or flooring? Can this damage cause us undo heartaches later and a lot of expenses on our part to have tiles or floor replaced?

What should I be looking for or asking the contract to cover in a letter for future problems with this keyway not being installed correctly in the beginning?

We just know what to do about this situation.

Thank you, in advance for all your help in helping us get this issue resolved with out builder.

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Roger

Hi Deborah,

If you’re referring to a soft joint as a keyway, then he is correct. They are required as an expansion joint both at set distances in installations as well as over any expansion joints in the concrete slab. This should explain it better for you: Soft joints

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