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.

{ 1088 comments… add one }

Leave a Comment

  • Bharat

    My Home entry to Kitchen from Hallway, approx 2*4 tiles in line jointly lift & Lost base Surface. coming popup. What could be primary reason.
    Thanks In advanced for your experience comment or neutral answer.

  • babinski

    only one straight line of cracked sanded grout across the 9′ length of bathroom. The width of the floor is 4′ and the crack is parallel to the long side 4″ from the wall.
    bought the house with 15 year old reno already done . bathroom floor is 2″ tiles in sheets, attached with unknown mortar or thinset. Under that is 5/8″ plywood over probably 3/4″ subfloor. I am remodelling the bathroom with new vanity and toilet and they were out when I discovered this crack. I cannot see any movement when I step on that area but I don’t know how the plywood was attached to the subfloor. I was not planning on replacing the tile floor. Since the floor is now clear, would it be unwise for me to just repair the grout or should i pull up some tiles to check the mortar or thinset? or worst case, how do I know if I should really be replacing the whole floor ? thank you in advance. It is fantastic that you share your knowledge with everyone.

  • Tom

    Hey there Elf,
    Had a bathroom remodel….licensed contractor…12 x12 Tile floor with radiant heat pad installed. I believe all installed properly but what do I know? We waited the proper curing time for the mortar before turning the heat on. Then one day I was just standing on the floor….not doing anything when I heard and felt a CRACK under my feet. I looked at all the tile joints as well as all the tiles themselves and found nothing wrong.
    This was weeks ago.
    There is still no obvious problem except that a few of the tiles make a little noise now when you step on them as if they are loose. The grout lines are good and I cannot move any of the tiles side to side.
    My wife wants the problem repaired …but how do I explain it to the contractor ? Could it be that the CRACK I heard and felt was the mortar cracking and is this a good reason to re-tile ?

    • scott

      Take a golf ball bounce it on every tile to fild hollow spots, have them re lay the tile in those areas.

  • Angela

    Hello Floor Elf,

    I need to have someone come out to properly assess what is going on with my kitchen flooring. Grout is cracking/crumbling in a certain area of the floor, but it appears to be spreading. I am concerned about foundation issues. I live in southern CA. Can earthquakes be the cause of part of my issue? My flooring was installed in 2011. Started noticing some localized grout issues a few years later. Please help. Thank you

  • Joel

    hello Floor Elf,

    our shower floor grout is separating slightly from the tiles in several areas. it’s not cracking (yet) but the small gaps are worrisome (where does the water go that seeps in between?).

    the grout is Bostik premixed urethane grout. the tile is travertine 4″x4″. the walls are fine, as is the bathroom floor (all same grout). only problem is the shower floor.

    i’ve been trying to get my tile contractor out to fix it, but no such luck. so….

    should I remove the grout and regrout with specralock epoxy? or can I just ignore it for now?

    thanks.
    Joel

    • Roger

      Hi Joel,

      Provided your shower is properly waterproofed the water will get below the tile and run into the drain. Grout has nothing at all to do with the water-tightness of your shower. I would call Bostik and tell them what’s happening – they would have the best solution for you.

  • South Austin TX

    Hi Floor Elf!

    So I’ve had a few tiles replaced because they were tenting… and now I have a few more that are doing so. It seems to be concentrated in one area of the floor (where it goes around a corner from living room to kitchen). My question is who can I contact to get a real answer about if the whole floor needs replacing or just replace a few more tiles? Thanks for your time and knowledge!
    South Austin TX

    • Roger

      Hi SA (I’ve never had a question from an actual city, it’s usually people in the city…),

      The problem isn’t replacing tiles, it’s expansion areas in the form of perimeter joints and soft joints.

  • Eld

    Hi, I got my kitchen utility re tiled April 2014. I had been living in the house with tiles that were eight years old and there was never any previous problems. The tiles are porcelain and they are 17 1/2 inches x 17 1/2 inches in size. The grout never seemed to settled and I noticed that while sweeping there was dust/dry sandy grout continually. Even in places that weren’t walked on or that were covered with mats. Eventually the grout company came to my house and said it was possibly a faulty batch and paid the tiler to re grout. However this didn’t resolve the problem and the loose grout continued. It became quiet low in places between the tiles. There didn’t seem to be any obvious cracks in the grout but there were holes in places where the grout was coming out over time. I kept in contact with the tiler and the tile shop and the tiler returned this summer to re grout again. The same problem persists. I have spent about €1000 on the tiles, labour and grout and there has been a continuous problem with it since it was initially done 18 months ago. The second time it was re grouted the tiler said he used a different brand but there is always sand when sweeping and now there are holes and deep groves between the tiles. The tiles aren’t like air holes. It looks more like someone used an instrument to scrape the grout on. The tiler has never seen it before and neither has the shop. The tiler has a good reputation.
    Do you know at all what could be going on? The floor doesn’t sound hollow at all and the tiling is done over concrete floor just like the last tiles. There are two cracks in both door ways that appeared after the first couple of weeks of the tiles being put down. Any advice you give me would be really appreciated. Thanks very much.

    • Roger

      Hi Eld,

      Is it over wood or concrete? It could be a few problems. When the tile was regrouted was the existing grout removed to 2/3 the depth of the tile first? If not, that is likely the issue. Grout bonds to the sides of the tile, not the substrate or grout beneath it. If it was not removed then the bad grout will still cause problems under the new grout.

  • Jim

    I’ve got 12×12 porcelain tiles with just a few failed grout lines. After scraping all the loose grout out (leaving tiles in place) and removing the thinset down to the subfloor, I’ve created cavities under the tile where the mortar crumbled or chipped. They appear to be less than 1/2″ under the edge. Any tips for a good way to force the thinset under the edge – without removing the tile?

    • Roger

      Hi Jim,

      You can fill the joints with a grout float like you would with grout, then scrape the excess out of the joint.

  • tom whiting

    Hey Roger, At my friends new Bakery she is having a problem with an old tiled floor. The tiles are cracking. On the edges it appears that they are “tenting” as well. They are layed on a concrete floor with no backing of any sort. The area is about twenty-five by twenty. There is no sign of mositure on either the tile or floor. There is no sign of cracking of the concrete. One crack runs the wideth of the room. Any info will be greatly appreciated.
    Tom twnitin1@san.rr.com

    • Roger

      Hi Tom,

      I’m guessing there are no soft joints and that the installation is grouted right up against the walls. It needs to have those expansion capabilities, especially if there is direct sunlight exposure.

  • Tom

    Hi Roger,

    A lot of good information here. My problem is cracked grout over that pink plastic substrate. Had the builder come back and take up tile and replaced pink stuff and reset the tile and re grout. They put down thinset then the pink plastic stuff then thinset and then the tile. No subfloor seam under it and 16″ oc floor joist go perpendicular to grout crack. I am thinking about filling crack with grout. Your thoughts?
    Thanks in advance

    • Roger

      Hi Tom,

      Filling it with grout will not solve the problem, and it will end up cracking out. You need to find out what the cause of the problem is, it sounds like they’ve only put a band-aid on the problem, they haven’t solved anything.

  • Bhattil

    6×18 porcelain tiles on cement board grout is coming out here and there but same installed in dining room no problem advise to fix the problem just a guess may be dishwasher causing it pl. advise via email could it be instead of grout mix water was used thanks. Bhatti

    • Roger

      Hi Bhattil,

      It could be a number of reasons, something under the failing floor is not the same as the other areas. The only way to effectively tell would be to remove some of the tiles in the damaged area and see what’s going on there.

  • Nell

    I had a bathroom renovated in May by a non-licensed but apparently (references) very experienced home renovator. He tended to work quickly (didn’t let wall paint dry before next coats applied), aggressively (every plumbing connection initially leaked because over tightened. (These points may be relevant to my problems.)

    The tub was set in a box which was tiled, the walls are tiled to typical wainscoting height with same tile to match tub box, the shower was tiled. Wall (and tub box) tiles are ceramic, floor tiles are slate, and shower is a glass mosaic. Grout was purchased for each of these tile types (wall grout, floor grout) and was all supposed to be the same colour, a medium gray.

    On the floor there is plywood, then kurdi with schluter heated floor wire running b/w the nipples, then thinset, then tile.

    There are two problems that developed. The first is colour. The floor grout turned out almost white and the wall tile is various shades of gray and white, inconsistent throughout the room.

    The second is grout cracking. Cracking is occurring along the vertical “seam” where walls meet at the corners (at a 90 deg >) in the shower stall, and along the edge of the outside of the shower where the floor tile meets the raised shower “box” edges (again, a 90 deg>).

    How can we fix the colour problem?

    How can we repair the grout cracks?

    Much obliged for your assistance.

    • Roger

      Hi Nell,

      First of all there is no such thing as wall grout and floor grout, there is sanded and unsanded. Granted, some places market them that way, but they aren’t. Not relevant, but that bugs me when people sell stuff like that. :D

      Your color inconsistencies are likely due to efflorescence, normally due to improper mixing of the grout or using too much water to wash it off. If you scrap the grout in an inconspicuous area on the floor is it the correct color? If so, that’s what you have (efflorescence is only on the surface). If it is then you can get an efflorescence cleaner at nearly any big box store.

      The cracking is due to grout being installed where it shouldn’t be installed. There should be silicone in any change of plane (all the areas you mentioned). The different planes will move in different directions, silicone can compensate for that, grout will just crack (but you already knew that :D )

  • Jonathan

    So the grout is cracked. What happens if you do nohting to fix it, and just let it be cracked?

    • Roger

      Hi Jonathon,

      Your dog bursts into flames!

      Nothing, really. It looks like shit and it leaves a great spot for stuff to get down in it and start growing in a humid environment.

  • joe

    First time tile guy and a little concerned. I completed my installation, but I made a huge mistake. I grouted around my perimeter. What can I do to rectify this issue? I am having a heart attack thinking that I have replaced a subfloor, put down my backboard, and applied my tiles perfectly and I am going to end up with tiles bursting at the seams. If I need to remove the grout what are your suggestions? My room is 12×10. Thank you.

    • Roger

      Hi Joe,

      Just get a grout saw and remove the grout from the perimeter. You can also get one that fits into a reciprocating saw or one for a fein type tool.

  • Dawn

    Oops sorry, my question portion didn’t save, just the rant. I am exhausted but love the porcelain wood look plank tile I picked . I just want the grout to hold up. Like I said pulled it 4 times now tried different combinations each time ( blamed sealer, grout, installer, everything) this last try was fusion premixed expoxy type and supposed to be indestructible! It washes out like sand . The field that are attempt 3 cont to fail. I am not sure what else to do. Are their pros( I know Home Depot would be considered one but NOT)that could say why. How long before I give up and have nervous breakdown. 14 months. Is there a type of home that can’t be tiles? They refused to do stairs due to slip fall risk so they tried to do tile with runner and that was horrible so I gave up cause it was obvious they did not know what they were doing. Now stuck with all carpet on stairs and hate it. Any hep or suggestion?

    • Roger

      Hi Dawn,

      Yes, there are pros that could tell you why. My guess, from here, is that the tile is improperly installed, or the substrate improperly prepared, and there is movement in your tile. Nearly anything can be tiled when done properly. To get a definitive answer you would need to call an independent pro and have them physically take a look at it.

      • Dawn

        Just to give you a update. Board of contractors involved. Home Depot has made a zillion visits. Last was with the rep from the Custom Building Fusion ( they decided to try that last- making it the 4 th attempt). He declared it was fine all grout leaches color and sand and that we should live with it. They also suggested some waterproof sealer trial. Fusion should not need a sealer, but what do I know. I have in the traffic areas where it is depleting out, not really cracking but ending up with holes either picking the grout up on our feet or mopping. This has been a 16 month process and I thought Board of contractors would help but Home Depot is not the least bit afraid. I have 4 different flavor of grout in my house none of which are gonna hold up is my guess.

  • Dawn

    I am in tile hell. We hired Home Depot and have had our grout pulled and replaced 4 times now and have been trying to get the floor right for 14 months!! Ridiculous. I have had every answer possible. Failed mix. Bad installer. Bad poly blend. Colored with pens . Efflorescence. Grout rolls scratched out easily especially in traffic areas. Finally called contractors board but they seem to be friends. The new baseboards are ruined! Front yard ruined from them spilling grout. Siding steel covered in it. Walls covered in grout dust ruined. Nightmare

  • Julie

    We have been dealing with a failing tile floor(s) since we purchased our home 6 years ago. It started with one tile, now is simply spreading to all of them. I found several problems, one was very thin product beneath the tiles, that I can easily scrape off with my finger nails. However, more concerning is that our Dura rock moves. When I pull up tiles, I can push on the Dura rock and it will flex. It appears the installer used a cement nail instead of screws, and now the heads are pulling through the Dura rock. Is this something we can fix, or will we have to remove the floor? If we remove the floor, I will go with Hardwood, which would require the Dura rock to be removed for natural Hardwood. Our home is 3300 square feet, and about 2000 square feet is tile. Thanks…

    • Roger

      Hi Julie,

      Unfortunately removing it and replacing it is the only solution. Nails are actually perfectly acceptable, but setting backer down without putting thinset beneath it for full support is not acceptable.

      • Mark

        When you say ” …setting backer down without putting thinset beneath it…”
        Do you mean thinset should go on the underside of the backer board?
        So going from bottom to top:
        Sub-floor > Thinset > Backer > Thinset > Tile
        ?

        • Roger

          Hi Mark,

          Yes, that is correct.

  • Megan

    Hello. I know less than nothing about tile, so i’ll try to explain this as best I can. We bought our house 2 years ago and I think the previous home owner did a lot of work on the house himself…so probably not properly. The hall bathroom has small square tile flooring…ceramic, I believe. It doesn’t appear that the grout was sealed. It feels rough like cement. One of the little blue tiles has come up completely, the grout around it completely broken. Now, less than a week later (i haven’t had time to try and find a way to fix it) it looks like the grout is starting to crack/break apart in more areas and I’m worried we are going to have to fix the whole floor at this point. So….i guess I’m just wondering if there is a quick fix…to just glue the tile back down? Or am I going to have to get someone to completely re-tile the bathroom floor? Oh…i saw lots of info about flooring…this is on the second floor. I have no idea if it’s on a concrete floor underneath?

    • jeffrey carr

      Rodger, You had me when in one of your replies you used the “BS” word. I like your straight forward approach. This is the poop. I have a home that’s 112 years old. I had the floor tiled in the kitchen recently by a guy that another guy knew (you see where this is going). the existing floor was linoleum. I wanted this removed and backer board applied but was told that there was no problem with tile over linoleum so I was overruled. So here we are two weeks later and about 1/4th of the tiles are loose and the grout will not not stop cracking. “dude” has re-grouted twice and I have done it once myself. I understand that in a home this old that the floor (a raised foundation) will flex/move some with each step I know that the grout can not withstand this flexing and does not “give”. I want to take up the whole job, remove the linoleum, apply backer board and retile. I hate to waste money but is the best answer to start all over and trash whats done? Any suggestions or thoughts are greatly appreciated.

      • Roger

        Hi Jeffrey,

        It’s due to movement somewhere, but my guess would be that he did not put thinset beneath the backer, correct? If so then that’s the problem. And yes, the only solution is to begin again. It can go over the lino if you want, but since you were writing the check I don’t understand why it wasn’t removed. ‘Dude’ needs to pull his head out. :D

    • Roger

      Hi Megan,

      Grout will always feel rough, sealer won’t change that. There is something done improperly with your tile installation, either an improper substrate or simply an incorrect installation, method, or product. You can bond the tile back down, but it’s only a temporary fix. Eventually you’ll need to have it removed and replaced with a proper installation.

  • Misti Graffis

    Floor elf,
    Our kitchen was recently damaged by water that poured through our roof from an ice dam into our kitchen. We had a company do all the repair work. Before the damage, we had hard wood floors. We decided to go with tile. Granted a very unusual tile but oh well. The tile is sold at Lowes, Tuscan colors shaped almost like a honey comb. The guys tore up our hardwood and the tile guy came in after that. There were chunks of hardwood still left attached to the floor along with thick black glue. Tile guy never took that off nor put anything down on it but some kind of white board. That white board is on top of all that. Then came grout or mud. Then the tile. It took him 30 days to lay the tile. Now for the past couple of months, the grout lines are sinking around the tile. There are gaps, some are cracking, well quite a few and in some places the tile is lowering or raising up. They keep coming back and adding grout but it disappears a week later. Then they sawed out all the grout along side the tile and replaced. Same thing occurred. I know they are doing it wrong. Can you tell me what’s wrong with all this? Thanks

    • Roger

      Hi Misti,

      There is white backerboard, so it may or may not be a proper substrate. But it’s happening because there was no thinset installed BENEATH the backer. You have voids beneath it, causing movement, causing the grout to crack, crumble and powder out.

  • Cindy

    I purchased a second floor condo 3 years ago. The tile floors were put in several years before I bought it. The grout recently had some slight hairline cracks. I had someone come and replace the grout in several of these areas. The grout is now after less then 2 weeks flaking and coming up, especially when vacuumed. The person who did it is saying its a foundation issue or the way they were put down years ago. Who should I call to find what the problem actually is?
    Thank you for your help.

    • Roger

      Hi Cindy,

      I just guessing here, but he didn’t remove the existing grout when he regrouted, did he? That’s why it’s coming out. Grout bonds to the sides of tile, not to the substrate (or grout) beneath it. Existing grout needs to be removed to 2/3 the depth of the tile, minimum, before installing new grout.

  • William P. King

    Floor Elf,
    A Google search yielded your site. From reading your concise discourse I believe I understand the cause, but I may be missing something, so here goes: After looking at a lot of wall tile for a powder room, my wife chose these 1 square foot “instant mosaic” sheets consisting of small glass tiles mounted on an adhesive backed sheet that contains an approximately 1/16″ foam layer. I installed them easily in a horizontal strip on two walls. My wife could not find a suitable grout color. I had a significant quantity of lemon yellow acrylic paint from the walls (about a year old). I experimented with mixing the white unsanded grout with this paint substituted for the water and grouted a scrap piece mounted on a thin piece of plywood. The grout set and it was the desired color (near that of the wall). There was some cracking in some of the joints which I took as due to flexing. I proceeded to grout the installed tile and got a similar result. (So much for additional experimentation to substantiate the hypothesis.) Anyway, I am curious to know to what you would attribute these results.
    Also, I was considered an admix of chalk with the same paint to fill the cracks.
    Thanks, in advance, for your response.

    • Roger

      Hi William,

      The acrylic likely did not allow the grout to consistently dissipate the unused water in the mix and once it evaporated the grout shrunk. I have no idea how I would fix that. You may want to just try to go over it with more of the same to fill the cracking.

  • Laurie

    Hi Roger,

    We’re tiling a 12′ x13′ bedroom with 6″ x 36″ and 8″ x 36″ plank tiles. About 18″ into the room, there is a crack in the concrete slab that runs wall to wall parallel to the doorway. It is at places about 1/8″ wide and looks like there is a piece of plastic in it. Is the a control joint in the slab? Our house is 20 years old so it’s not new concrete. One side of the crack is about 1/32″ to 1/16″ inch higher than the other side for about the middle 8′ of the crack. Should we grind this down to even it out? Also, do we need to put a membrane or Ditra down before tiling? The hallway that leads to this room is tiled. If we have to use Ditra, how do we handle the height difference? Thanks for your help.

    • Roger

      Hi Laurie,

      That is a control joint, you need a soft joint over it. Yes, you should grind it down, but that isn’t imperative with that small of a difference. It is always best to use a membrane. Schluter makes edge profiles that can compensate for the height difference.

  • Lisa

    Hello, Floor Elf –

    We just moved into a brand new house in central Ohio. It was a spec home and we’ve had a number of issues. Three of my bathrooms have ceramic tile floors installed within the last 8 months. In 2 bathrooms, we started seeing grout cracking over large areas of the floor. The 3rd just has a small crack so far. The builder had the flooring company repair the cracks 3 weeks ago. When I was preparing to seal the grout, I noticed several additional cracks. The flooring company is giving differing reasons for the cracking issue – house settling, humidity issues, etc. They were insulted when I told them I wanted a definitive diagnosis. Between this and all of our other issues, I am now also worried that the tile in the showers is installed wrong as well.
    What is your take on this? Are their responses valid (and all of this is normal in a new house) or should I be pursuing a real diagnosis? Any suggestions you can provide would be greatly appreciated. I am so worried that there are underlying issues that I will have to deal with when my 1 year warranty has expired. Thank you!

    • Roger

      Hi Lisa,

      It sounds to me like they are just excuses. A proper tile installation WILL NOT crack, whether it’s put in a new house or a 100 year old house. The ‘house settling’ excuse is one of my pet peeves, and complete bullshit. The house won’t ‘settle’ and move any more when new than it will in 50 years, it’s normal expansion and contraction, which a proper tile installation compensates for. Stick to demanding a definitive diagnoses, even if that requires a third party.

      A good way to non-intrusively examine the installation method is to pull up a heater vent if you have them and take a look at how it was installed.

      • Lisa

        Hi again, Roger – I took your advice and had a 3rd party contractor look at the tile. They took one look in the heating vent and confirmed that we have tile directly mortared onto a 3/8″ exterior grade plywood. No concrete backerboard in sight. He went through every single tile to listen for hollow sounds indicating that the tile was already not adhered to the mortar and found quite a lot of them.

        Also, we found that when the builder’s flooring company replaced a few tiles that were chipped, it appears they glued them to the existing mortar and now the grout (which was apparently just sitting as a thin layer on top of the white glue) is coming out at the lightest touch of a microfiber cloth.

        I had the original installation company out the next day looking at it (without revealing I’d gotten other opinions) and they told me it was an indoor/outdoor plywood on my subfloor and was perfectly fine and installed per the spec issued by the builder. I asked the builder for the spec and after (apparently) a lot of scrambling, they sent me a 3 line email with vague info in it, part of which included a marine grade plywood and did not address my questions on the type of waterproofing used in my tiled showers at all…. When I asked for more details, they didn’t have them and are scrambling more and told me they had to get the spec from the flooring company (you know…the spec the flooring company said was issued by the builder). I think they didn’t like it that I mentioned my past background working in the construction industry and that I knew what a proper spec should look like.

        Based on everything I’ve read on your site and the video’s I’ve watched and conversations I’ve had in tile stores and with the contractor I had out to the house, it sounds to me as though they need to (preferably pay a qualified company) demo all 3 of my tiled bathrooms and my tiled laundry room and reinstall with a proper method that includes (what I perceive as) the current industry standard of subfloor + mortar + proper backerboard + mortar + tile. Am I on the right track?

        Thanks so much for your help AND for your informative site. I now know more than I ever wanted to know about tile and grout.

        • Roger

          Hi Lisa,

          You are correct. You need a minimum of 1 1/8″ thick total subfloor over your joists, then a membrane or backer over that to bond the tile to. There are sheet membranes which allow installation over a single layer over your joists also, like ditra XL. But what they’ve done is definitely not up to par.

          And I know more about tile than I ever wanted to also. :D

  • sterling

    I just bought a house in louisiana the house was build 9 years ago, my ceramic tile in the livingroom and kitchen are lifting and cracking i found out by my home insurance that the floor might need an exspansion joint, but my livingroom is nowhere near 25 feet in lenght or width but i do have alot of loose tile and it was laid on top of the concrete slab

    • Roger

      Hi Sterling,

      Is there a perimeter joint, or is the tile butted directly to the wall? Because, no matter how small the installation, you always need perimeter joints. Also, over any concrete installation, the expansion joints in the concrete require a soft joint directly above them. That is where the concrete will crack, it will take the tile with it if there isn’t a joint there.

  • Robert

    Good afternoon Floor Elf,

    I noticed that the floor I put down several months ago in my master bath had some grout line cracks in it around 1 tile and upon further inspection discovered the tile was loose. I cut the grout out from around and was able to pull the tile out whole. Once I did, I was surprised to find that there was no thinset stuck to the tile, not a smear. The tile was dis colored where the thinset was touching it, the grooves from the trowel, but I can’t figure out why it didn’t stick.

    Is this a random incident, a common problem, or am I days away from replacing every tile I’ve laid? the tile is a 12×12 basic marble from your average hardware store. Thanks for the help.

    • Roger

      Hi Robert,

      It depends on how much contact you have with the marble in the rest of the installation. This is why backbuttering your stone is imperative, as is using a large enough trowel. It may be just that one tile, it may not. No way to tell other than waiting to see if more problems develop.