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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Quentin

We have a 7 almost 8 year old house and a year ago we had over 10 tiles pop up in our kitchen. On the back of those tiles we noticed very little thinset and that most of the thinset was on the slab. We did not see any cracks in the slab so we just removed the old thinset and replaced the tile. Well starting from the original incident(before tile was replaced) to now we will occasionally hear popping from what we assume is grout cracking and the thinset coming loose from the tile. What could be causing this problem?

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Alex

Hi,
My husband and I bought an old house and re-did the kitchen. He originally Replaced the subfloor with wood, primed it with floor primer and then applied laminate adhesive tiles. So far I can’t feel, hear or see any tiles moving.
I have done all of the grouting myself. Both times it was done was with pre-mixed grout, which other users rated pretty well on the homedepot website. It started cracking and becoming discolored almost immediately; within 4 months it had cracked so bad, that large chunks were falling out on their own. I have regrouted since and 2 months later have started seeing cracking again. I used a well rated sealant the second time we grouted. I am seeing most of the cracking happening in high traffic areas, but still seeing some in areas hidden under the cabinet(no foot traffic). Any advice would be helpful! Thank you!

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Brian

You dont grout that tile are you on drougs lol lol

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Brian

The tile buts together

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Gail Benda

had the bathroom floor and small hallway redone last year and the grout is cracked & kinda sinking from edges of new tiles (that were placed over prior polyurethane flooring) Now I am afraid one cannot do what was done here….hallway tiles are actually popping up -does it need to be torn up and do what? either more polyurethane flooring which is ok or tiles? I am afraid I have been ripped off big time…..an the one who did the grouting committed suicide so nothing to recover from….Any advice is most appreciated…..they said it was to much work to remove the old flooring on a tiny bathroom :) an I knew them so didn’t have reason to not believe as I built the home so knew of no problems

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mia

hi,
I’m hoping u can help me…i had a tile redi shower pan installed 5 years ago. the grout failed almost immediately. over the years i have regrouted, added adhesives, blah blah blah,, finally couldnt take it anymore and ripped the floor tile up. there was green mossy stuff growing under the tile. they came up easy (almost in the original sheets) which leads me to believe the epoxy redi wasn’t installed. there is a lot of flex in the pan. heres my dilemma…im not going to dig out the mortar bed and shower pan…im just not. if i can re-tile the floor and get a couple of years out of it I’m good with that. what can i do to make the best out of this situation? Pro-lastic, tile and then grout? the Tile Shop guys reccomend these steps. Any info will help.
thank you!

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Michelle Galarneau

I have Adura Luxury Vinyl tile and the grout has separated from the tile. Local company says my house is settling and says the grout is not u der warranty even though the tile is. One tile is moving slightly. Any advice as to how to deal with would be appreciated.

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Dave

We had a water leak in our kitchen that ruined our maple flooring. We decided to replace with porcelain tiles and this work was done by the restoration company through our home insurance. About 2.5 years later we have several places with cracked grout and one loose tile (no broken tiles though). The cracking is in the higher volume traffic areas. Kitchen is not that big – about 12′ x 15′.

The restoration company sent someone out to look at it. He said it was not faulty work but instead probably caused by too much humidity. Our furnace is below the kitchen and the major duct work runs right along the line where there is a lot of the cracking (but there are some spots directly above the duct that are not cracked – lower volume areas). We have a dehumidifier that is part of the furnace, but it is very old and I’m not sure how well it works.

Could this be the cause or are they giving me the runaround? If it could be the cause, I either need to get a new dehumidifier installed or insulate the HVAC before I have the flooring fixed. If it is unlikely this is the cause, I want to press them to come back out and figure out the real cause and, if their fault, fix the problem.

Thanks for your help!

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E

I have a line thin crack in my grout running the width of my kitchen and two cracked tiles. I’m praying it’s not my foundation. I don’t know what to do or who to call. Any ideas?

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t

I have the same problem with tile that was installed a few months ago- its laticrete grout. What is happening? My contractor is claiming its an industry standard. please help!

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Roger

Hi T,

Cracking grout it RARELY due to the grout itself – it is normally the installation or substrate. What is your tile installed over?

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Roger

Hi E,

To be able to even guess I need to know if you have any type of membrane beneath your tile or if the tile is directly bonded to your concrete. If the latter it’s likely exactly where the expansion joint in the concrete lies.

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E

Hi Roger! Thanks for the speedy reply! I don’t know what underneath. I’ve been in my house for 3yrs but the house is 13yrs old. I don’t know who to call to check it? A contractor, foundation company, idk?!

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Roger

A professional tile contractor would be your best bet. Google the NTCA and you can find one through them for your area.

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Alex

Hello. I have laminate flooring in the living room and recently got water damage, i.am replacing it all, but under the laminate I have old original tiles. I was told to remove the old tiles and apply Mortar Mix prior to installing the new tiles cause the concrete floors willbe uneven once the old tiles is removed. Is this true?

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Roger

Hi Alex,

Yes, but it’s always best to remove absolutely as much of the cure thinset from the slab as you can. Once you do that, if you need to use thinset to flatten it out at that point you can.

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Annita

About 4 years ago I bought porcelain tiles for my kitchen. The installers helped me pick up the tiles and the thin set. Upon getting to my home, they said they would go to the store and buy tile glue to lay it with instead of using the thin set. I don’t know if it was because I did not want the floor to be higher than the carpet it was going near, or to save time because they decided to do the floor all in one day in a rush, but they said using it would be just as good as the thin set. Since then, the grout has been coming out on the more trafficked area. I have been told that some of the tiles are loose and the entire floor has to come up. I have had some tiles reset and regrouted, but the problem still occurs. I had a professional grouter come by yesterday to look at it. He said that he can get a special grout ..I think mixed with something like glue that may flex more. He says he can fix it and the grout will not come out. It is expensive, but not as much as ripping up and getting a new floor.

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Roger

Hi Annita,

He is wrong. The product used to install your tile was the incorrect product, there is no magic grout that will fix failed bonding to a substrate, nor a substrate that is not adequately prepared to begin with. The floor must be replaced if you ever want it to stop coming apart like that. You’ll end up with the same problem with this magic grout, whatever it may be. It may just take longer to happen, then you’re out that amount of money as well. The underlying issue needs to be resolved, not have a band-aid applied to it. :)

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Mary

Our newly tiled walk in shower with rainhead and handheld showerhead is showing grout failure only on floor under the rainhead after only four days of use. The grout crumbles (cream colored tile, dark gray grout) and washes out. We have asked the contractor to fix this and it continues even after more sanded grout is applied and more sealant over it.

Do you have any thoughts as to why this keeps happening? This is a new installation and we have only used it a few times before the grout crumbles under our feet.

The contractor has speculated that our tile is so thin that there isn’t much grout between the tiles, and that the rainhead could be to blame.

This is not a widespread issue in our 10′ shower, only in the wet area

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Roger

Hi Mary,

What specific grout was used? How thin are your tiles? How soon after grouting was the sealer applied? What type of sealer?

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Mary Stillman

Tec Sanded Grout

American Olean Tiles
Uniform Squares Mosaic Ceramic Floor and Wall Tile
(Common: 12-in x 12-in; Actual: 11.87-in x 11.87-in)

Miracle Sealants Company Tile & Stone Sealer was applied at least 3 weeks after grouting was complete.

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Roger

If you push on the tiles in that area do they move up and down? Even a little bit?

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Mary Stillman

no movement at all, and now a white substance is bubbling up around where one tile’s grout has washed out.

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Roger

Was the floor tile set with mastic? Because that is exactly what you’re describing. The mastic will never fully cure, and is not made for ‘submersible’ applications, which a shower floor is. If that’s the case you may not see any movement yet – but you will. If you’re not sure and have no way of getting that answer, pull up one of those floor tiles and see if the setting material is fully cured. If it isn’t it’s mastic. If it is, or close, then it should feel rough like concrete, not solid and rubbery, like mastic. If it is indeed mastic it will need to be replaced properly using thinset.

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Mary

Thinset was TEC Latex Modified Mortar

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Roger

Hmmm, okay. Do you know how the shower floor substrate was constructed? Is it a preformed pan of some sort (schluter, laticrete, tile redi, etc.), or was it deck mud (cement based formed on site)? What you are describing, short of mastic leaching, is some sort of either latex leaching (from the thinset) or an emulsified substance leaching from the mud.

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Mary

it was deck mud. mixed, and poured onsite.
The product was 4to1 mix

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Roger

4 parts sand to one part portland cement? Do you know how thick it is? Do you know if metal lath was used? Do you know if there was a slip-sheet under the shower bed? (I’m assuming it’s over wood)

Thomas

I purchased a remodeled home 2 years ago and and now the 16″ tiles and grout are popping up. I removed a tile and whatever thinset or concrete base they used created 1/2″ to 1″ grooves and this stuff is at least 1/2″ deep. Can I use something to fill in the grooves then reset the tiles or is it a lost cause

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Roger

Hi Thomas,

Are they the grooves from the trowel when they put the thinset down? Is there any thinset on the back of the tile?

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Thomas

The gaps are too big to be made by a trowel and the back of the tile was clean. There’s over 2″ of of surface (thinset I think) between the grooves

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Roger

I have no idea what that may be. But yes, you can fill in between those to fill it. Make sure you burn thinset into the back of the tile when you reinstall it – that’s why the back of the tile is clean, that wasn’t done.

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Sarah

I installed 12 inch porcelain tiles over 3/4 inch plywood floors and hardibacker. I applied thinset under the hardibacker, and used cement screws, and also taped the seams with alkaline resistant tape and filled them before tiling. Now less than a year later my grout is coming up in the high traffic area of the floor. I can’t figure out what I did wrong. There is a heating/ac vent that runs directly below the floor. I also took the time to level the plywood beforehand with self leveling apoxy resin. I do have some matching sanded caulk, and I know that isn’t the proper way to fix it, but I’d hate to regrout and have the same thing happen again. What’s the best way to fix it?

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Roger

Hi Sarah,

A ‘self-leveling epoxy resin’??? What, specifically, is that? Because there are no epoxy resins in my industry made for leveling a floor to install tile – because thinset won’t bond to epoxy long-term. That may be your problem right there, the tile is unbonded from the epoxy product. The duct beneath shouldn’t have anything to do with it.

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Roger

I just noticed it sounds like you have the epoxy beneath the backer, correct? If so, that isn’t the issue. What type of thinset did you use? Did you back-butter the tile (skim-coat the back of the tile with the thinset)? What size trowel did you use? What are your floor joist specs?

You have movement in there somewhere, we need to figure out where it derives to be able to remedy the issue.

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Nicky D.

5 yrs ago I installed 12″ Porcelain tiles over over a decent condition 3/4″ sub-floor and Duroc/Cement board, screwed down at the pre-marked places. I did not thin-set the joints between the cement board.
2 years later i noticed a popping sound, just a “pop” when i walk on a particular spot. (i suspect the sub floor is moving, and there is a lot of humidity in our basement this year) Now, this year, the grout has cracked (chipped) in two places, and i suspect has pulled away from one of the tiles in a nice clean separation and (at the site where the popping has occurred, as if one tile isn’t moving and the other is when stepped upon. Can this be remedied without resorting to ripping up the entire floor (Id rather fix 2sq ft than replace 1600 sq ft. )

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Roger

Hi Nicky,

It depends on what the underlying issue is. Did you install thinset beneath your durock? If not then that is likely the leading cause, the subfloor is moving and has created a hollow area under a portion of the backer. If so, then you may be able to remove those tiles, tape and mud the seam, then reinstall them.

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janice

i have tile with ditra underneath and grout lines are cracking like crazy someone said the floor is moving,,,duh ditra makes the floor give i was told and move what do you think????

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Roger

Hi Janice,

Ditra does not make the floor ‘give’, or move, or anything else. It is simply a proper membrane to attach tile to your existing subfloor. If things are cracking either your subfloor was not properly prepared for a tile installation, or your ditra or tile was installed incorrectly. Ditra is not causing it. :)

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Lisa

I have a bathroom built over a garage that seems to have a problem with the grout cracking. When we bought the house 7 years ago, the builder grade tile on the floor was a mess- cracked grout and obviously replaced tiles. We thought it was just neglect, but we have since completed a thorough renovation and put in a heated floor, a few years ago. Anout a year after installation, we noticed some of the tiles popping up, so the installer came back and replaced them. He said he thinks we walked on it too soon after installation (he told us 24 hours and we followed his instructions). Now it is happening again. I am beginning to wonder if it is a problem associated with the movement of the garage door directly underneath the floor. Have you even heard of this before, and is there a solution? Maybe more installation in the ceiling of the garage? Any insight would be appreciated!

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Jennifer

My grout is cracking from loose tiles. Come to find out, the previous owners tiled over an existing tile floor. One by one they are starting to lift. How can I stop this domino effect without removing them all and starting from scratch?!

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Roger

Hi Jennifer,

Unfortunately you can’t. A tile installation is only as good as what’s beneath it. That includes the underlying tile as well as whatever they used to bond it. Apparently something isn’t correct, that means it will need to be removed to properly rectify the situation.

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Brian

It’s a waste of time and money,rip it all out down to main sub floor ,put half inch cement board in cut it all in then mix thin set up mud down cement board,set tile an grout do it right the first time, your floor is history start all over……..

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Jennifer

I figured :( It’s too bad… they’re beautiful tiles. Thanks.

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Lauren

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!

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Sally

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?

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Roger

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.

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Sally

Thank Roger.
You ARE super cool.

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