This is a question I get asked from time to time. The short answer is no, you should not. Although grout does not add to the stability of the tile installation (unless it is epoxy grout), you still need to grout it.

Why you need grout

A lot of natural stones, namely granites and marbles, are manufactured to be consistently sized. For the most part all the tiles are identical.  This makes a lot of people want to install them without grout lines. Although in some people’s opinion butting the tiles against one another looks better than having even the smallest grout lines, it is not a recommended installation procedure.

Even if all the tiles look like they are the same size I can nearly guarantee they are not. Unless they are “rectified” they will differ, even if only a tiny amount, from tile to tile. Attempting to butt the tiles will result in a “jog” of the lines between them. The larger the area, the more those lines will run off. By leaving even 1/32 of an inch grout line you will be able to compensate for the difference in tile widths.

You also need grout to ensure that nothing can get between your tiles. Look at it this way: would you rather have a very small grout line filled with grout or a very, very small grout line filled with spaghetti sauce? No matter how tightly you attempt to butt the tiles, there will still be the tiniest space between them. Not grouting them leaves open the possibility of all types of unruly things filling them. Then you have to clean them out risking the possibility of damaging one of the tiles.

The final reason I’ll throw out there is that no matter what substrate you are using there will always be movement. Always. Placing the tiles against each other will eventually damage them. If you continuously rub the edges of two tiles together one or both will eventually chip (and you need to get out of the house more, or at least find another hobby). The expansion and contraction of wood or concrete will do the same thing. Although you can minimize this using different underlayment materials, it will still move.

I hate grout, I really do. If it were up to me I would install most tile and all granite and marble with no grout lines at all. I can’t do it. Even though it will look better initially, eventually it will ruin the tile. The best thing to do is use the smallest grout line your particular tile will allow and get a grout that closely matches the tile. For most granite and marble tile I install I use either 1/32 or 1/16 inch grout lines. In most other tile I will use 1/16 or 1/8 inch lines. I try to use the smallest grout lines the tile will allow.

To figure out how small you can go, place nine tiles in a 3 X 3 foot square butted against each other. Measure corner to corner diagonally both ways and see how close they are. If they are within 1/16 inch that is the size grout line you can use safely.

Please resist the temptation to install your tile without grout. Grout sucks, believe me, I know. By choosing a matching grout, though, you’ll be happier in the end and your tile will last significantly longer.

Update: The photos below were sent in by a reader asking why his tiles were cracking. They are travertine tiles and the cracking is a direct result of having the tiles butted against each other with no grout lines. This is what can happen.

photo-1 photo-2 photo-3 photo-4

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  • Paula

    Hi, Great site
    I had a flood had to remove a large area of parquet (50 years old). Have to replace bathroom poolroom and large entryway. We have an senior citizen German shepherd. I want minimum grout. What’s best on floors: soapstone, cork? Or your best RX. Also have two transition locations where cement meets 3/4 inch marble. AppreciaTe your ideaS!!!!!!

    • Roger

      Hey Paula,

      As long as you get good tile and have a very flat floor you should be able to go down to 1/16″. Porcelain would be the most durable on a floor. If you want a solid, durable wood product bamboo is about the most solid you can get. has a lot of transitions that you can make that slope from the concrete to the marble. They have several different styles and colors.

  • Olivia

    I do art with marble tiles. I would like to do a painting on a 12 in. x 12 in. marble tile and adhere it to a 1/2 inch birch wood base (so that I can mount hanging hardware on the back of the wood base. It is simply a marble tile (that I will paint on) mounted on a birch base that is 1/2 inch.

    My question is what kind of adhesive I should use to be sure that the tile is secure on the wood and won’t fall off over time. Thanks!

    • Roger

      Hey Olivia,

      About the only thing that would guarantee it would remain attached long-term would be an epoxy setting material. While regular thinset would adhere it initially, it would eventually come loose from the wood expanding and contracting due to normal movement. Epoxy will keep it there permanently.

      And your other request has been taken care of. Have a great night.

  • Lili

    I recently had 12×12 granite tiles put down on my kitchen floor and the grout size is 1/4 inch. Is that to big? However, I did find a great matching grout color for the tiles. Thanks

    • Roger

      Hi Lili,

      1/4″ is a very large (actually the largest) grout line normally acceptable in a tile installation and usually reserved for tile such as terra cotta’s and other imperfect or varying sized tiles. It is much larger than I consider acceptable in a granite installation. I normally use no larger than 1/16″ for granite and sometimes even smaller than that. However, if you like it, you can use sanded grout for them and it will be just fine.

  • Sia


    I am having a granite slab shower built in the second floor. Is there a rule as to the thickness of the plywood to withstand the weight?

    Thank you so much

    • Roger

      Hi Sia,

      The thickness or amount of layers of plywood will do absolutely nothing to withstand the dead load of that much granite. The concern lies in the joists beneath the floor. Slab granite weighs between 14-21 lbs / square foot. Building an entire shower with granite slab would place a minimum dead load of 1200 lbs. That is a significant amount of weight over average joist spacing. You need to ensure your joists are built up enough to withstand that amount of weight.

      • Sia

        Hi Roger,

        Thanks for your response. What is the rule of thumb with respect to joist spacing (in inches) versus overburden weight? And how does one bulid up joist strength to handle larger weights. Isn’t the strength also a function of the weight distribution? If so if we extend the load to many joist spaces, wouldn’t that reduce the load on each joinst.

        Thanks again.


        • Roger

          Hey Sia,

          Yes, load distribution cuts down on each individual joists dead load. By doubling your joist count beneath that area you would effectively cut the dead load necessity of each in half. The dead load capabilities are determined by engineers and put in place by architects when designing a structure.

          The only aspect of that with which I deal is the deflection ratio of a particular joist system. The minimum deflection ratio for a normal natural stone installation is L720. Being that slab granite weighs at least twice as much as natural stone tiles you would need to double the deflection ratio of your joists simply to be able to have a proper stone installation at that particular thickness. This, however, doesn’t have much to do with dead-load capabilities – you would need to speak with an engineer for that.

          But the short answer is yes – by doubling your joists in that particular area and distributing the weight over twice as many joists you would double the load capability of your joist system.

  • Hajin Studio

    I know this is a old thread, but looking to use mount (2) 8×24 on the front of a fireplace butted up next to each other with no seam. Wondering if since this will be mounted on the fireplace with no movement if I can achieve that seamless look with no grout lines.

    • Roger

      Hi There, Hajin (? is that correct),

      It never matters how old a thread is – it still gets read every day and I still answer every one.

      The finish on the edge of the tile (the corners) will determine how it will look and how close you can butt them. If you’re asking whether it is feasible to butt them together on a fireplace – it won’t be a problem. A fireplace is one of the few areas you can butt tile together without problems.

  • Lynne

    I found this helpful website just in time. We are installing slate on our stairs with an oak riser and oak nosing. Is it fine to use sanded grout between the tile and wood nosing or is there a better choice? The rest of the grout lines in the hallway and between tiles on the stairs are 1/8″. I have seen it in many homes here in Whistler and it looks great.

    • Roger

      Hi Lynne,

      You want to use a caulk or silicone between the wood and slate. The wood will expand and contract at different rates and will end up cracking the grout eventually. The caulk gives it some flexibility to prevent that. Most grout manufacturers make a caulk that matches the colors. If yours does not you can probably find one that is very close from Laticrete.

  • Dawn

    Hi, love the information on your blog. I’m going to attemp my first tile job. It’s a very small (70’s style) master bathroom. I’m using the 6″ X 24″ wood looking tile and since reading, I was thinking i would use a very small grout line – like 1/32 or 1/16 with an epoxy grout. The question is the subfloor. I was hoping to lay right over the exsisting linoleum. Is this ok? I was going to sand it to get the gloss off. I tried a stripper – but it didn’t seem to take the shine away. Will this work? Or what should i do? The floor under the linoleum is cement – and this linoleum has been there for 35+ years. The existing floor is definately water tight.

    • Roger

      Hi Dawn,

      Unfortunately no, it won’t work. The biggest problem is getting a mortar which will adhere the tile to the linoleum over the long haul. The best thing to do would be to scrape up the linoleum as much as you possibly can. Ideally you want to get it all off down to bare concrete. While that may take some considerable effort it is really the only true way to know that your tile will last. If you don’t do that you are taking a chance on the integrity of the current flooring, the ability of the mortar to remain adhered to the linoleum, as well as a number of other factors stemming from those two alone.

      That’s some fairly expensive tile – you want it to last, yeah? :D


    On the thinnest grout lines subject…We recently just 18 x 18″ marble polished tile installed in our master bath. The tileman started out with 1/16″ grout lines at one end, but towards the middle to the far end only had 1/32″ to almost butting up the big tiles. He used unsanded linen colored grout, which really looked nice, but the next day the grout in the 1/32″ & butted up tiles, just flaked right out. He came back, regrouted, same thing. There are 8-10 tile lines that won’t hold the grout because the lines are so thin. What is the best fix at this point? Epoxy grout? Some sort of additive with the unsanded grout? Is there a diamond marble 4″ blade around 1/16″ available to open up the lines wider? Please help!

    • Roger

      Hi Patti,

      The grout is not sticking there because it can only stick to the v-shaped space from the bevel on the edge of the tile. But you knew that. The only thing that may work is epoxy grout. Once cured it will grab the tile and stay there. They do make tile and marble blades that fit on grinders but they are thicker than 1/16″ and would likely chip the hell out of the tile anyway. Epoxy would be your best bet.

  • Andrea Soloman

    I am about to embark on my first tile job but have a few questions – guy at home depot said I could use the 8 X 10 ceramic tiles on shower walls without using spacer – from what I’ve read so far – he’s wrong – so question is what size spacers should I use – and can I lay the tile either way 8X 10 vertically or horizontally? I already installed the backer hardebacker board (1/4inch) – help!

    • Roger

      Hi Andrea,

      That actually depends on the tile. Some, not all, but some, 8×10 tiles actually are what is called self-spacing. These tiles will have little ‘nubs’ or bumps along each edge – two per edge – which stack on the one beneath it to form a grout line just a little bit under 1/16″. Now, with that said, he works at home depot so he probably doesn’t know what the hell he’s talking about – just sayin’. :D Seriously, there aren’t that many 8×10 tiles that are made like that, but they do exist.

      Place two of those tiles against each other and see how much space is in between the back of the tiles. That is, if you lay them on your table how much of the table can you see between the tiles? If none, then they aren’t self-spacing and you need to use spacers. You can use 1/16″ spacers and they’ll work just fine.

      You can lay the 8×10’s vertically or horizontally – whichever way your little heart desires. (I like ’em vertical – they look cool like that)

  • Bob

    I am installiing a small 8 by 1 ft. kitchen backsplash using 3×6 in. glass tiles. Because the laminate countertop has a 4 in. backsplash already, and up until now (the past 20 years) there has only been painted drywall in this space, my wife would like the installation to be groutless. We’ve never really had any “splash” issue in this area, and so we think there is little risk of moisture getting between the tiles. And since the total cost of the glass tile is under $100, the worst case scenario would be to replace it and the drywall section behind it. Since the tiles are glass (which is quite uniform and desn’t expand or contract like other materials), they seem to butt together very snugly. I’d be interested in your comments.

    • Roger

      Hi Bob,

      The problem of movement and the stability of your installation are not the only things to consider, there is also the sanitation factor in a kitchen application. Whether or not your backsplash gets splashed a lot (and with the 4 inch existing backsplash that is probably the least of your worries) butting the tile together will still leave very tiny spaces here and there which become nearly impossible to clean and sanitize. Once something gets back in there it will remain there essentially forever.

      In a food environment there are a number of things that, while unseen, still manage to get in places they don’t belong. Even little things like cutting up a raw chicken causes juices from the chicken to essentially ‘spray’ out while cutting it – knowwhatimean? Chicken juice (sounds like a really bad energy drink, doesn’t it?) may spray into one of these very tiny spaces and has the potential to grow ridiculous amounts of bacteria and all sorts of unwanted things.

      You also pointed out another issue – glass expands and contracts at different rates than other materials. While the glass is very stable any substrate, as well as the wall studs and framing behind it, are not nearly as stable and will move much more. This may eventually lead to delamination of your tile assemble (that’s uppity tile-guy talk for your tile falling off the wall). Glass tile installations are different than any other tile installation. When you do install it, however you choose to do so, be sure to use the proper setting material specified by the tile manufacturer. Most glass tiles will have recommendations either on or in the box, if not try contacting the manufacturer. If all else fails use a very highly modified (read expensive) white thinset and be sure to rough up the paint on your drywall.

      With all that typed, install it however you choose. There are a number of sanitizing sprays available which will kill things like bacteria in chicken juice. Just be sure to stay adamant about cleaning it. As long as you stay after it there shouldn’t be any major problems with the first part of my ridiculously long answer. :D

      • Bob

        Roger – Sincere thanks for taking the time to reply with such thorough and understandable advice. What a great resource you are for all of us naive and inexperienced do-it-yourself wannabees!

        We did decide (and today finished) the groutless approach – it is a temporary fix we hope to last for 3 years, 4 at the most. Your advice on paying attention to the sanitary aspects are well noted – in our late 50’s, both my wife and I are certifiable OCD types about sanitation, so we think we can handle this for the next couple of years. And the results are stunning so far – as long as the tiles stay on the wall!

        Thanks, again – what a great site…


  • Darcey

    Great information – Thanks Roger!

    I’m wondering why I can’t use caulk (polyseamseal tub & tile) instead of grout in a shower? Other than longevity, and ignoring that grout often cracks…, I can’t seem to find a good reason not to use a high quality caulking for the entire job, not only along the bottom and corners. I’m guessing that using a caulking gun will take about 20% of the time of grouting, and NO MESS! Also, when it comes time to replace, wouldn’t the caulking be easier to remove than cutting out the grout?

    • Roger

      Hi Darcey,

      Well, let’s start with this: ‘Other than longevity, and ignoring that grout often cracks’ Grout ONLY cracks if there is movement in your substrate – it will never crack if properly mixed and cured – if it cracks after it has been installed 28 days then there are far more problems with an installation than grout.

      Here’s a good reason: caulk is not permanent. It is not meant to be. It is meant to be periodically replaced – do you want to do that every year or two? If you have ever seen a bead of silicone that is 2-3 years old then you have seen that the seal will eventually come loose. Once that seal is compromised it will allow moisture in behind the seal. Once moisture is back there, along with dirt, soap, all types of nasty things, it will begin to grow mold. I’m sure you’ve seen mold behind a clear bead of silicone, yes? The reason this happens is that because the silicone or caulk is permanently flexible it will continue to shrink – very slowly – but it will. This will eventually pull the seal loose.

      As far as faster I don’t believe that to be the case but maybe you caulk faster than me – I dunno. :D I can grout a normal 60 sq ft tub surround in about 45 minutes. It would probably take me 3-4 hours to hit every grout line evenly with caulk. If you think grout is messy try to wipe caulk off of tile cleanly without leaving streak marks from the sponge across every grout line. :eek: Removing it: the bulk of the caulk may be easier to remove but you will always have the little pieces that stick to the sides of the tile which will need to be removed with a razor knife – through every line – each way.

      You can use caulk if you choose to, but you shouldn’t. Correct tile installation, correct substrate, and correct grout choice and mixing will lead to a solid, long lasting installation which should NEVER need to be regrouted unless you get tired of the color. I understand how it may sound like a viable, even desired, alternative to grout – but it really isn’t for several reasons.

      Hope that helps.

      • Darcey

        Thanks for the reply Roger. I’m now on day three of grouting (shower, bathroom & kitchen backsplashes)…and will never ever purchase 3×3 tiles again….

  • Jeanine

    Hi. My husband just started a backsplash project for our kitchen. This is his first time laying tiles so I’m a little worried. We are using 1 x 2 mesh mounted split-face stone tiles. I read in one of your other posts about not being able to grout these tiles but sealing them. What type of sealer do you recommend? Also, should he caulk the top and bottom of the tiles. We are only going up about 4″ for the backsplash.

    Thanks for your help!

    • Roger

      Hi there Jeanine,

      Don’t worry – I’m sure your husband has it all under control. :D You want to use an impregnating or penetrating sealer. The price of the sealer is normally indicative of the quality – the more you pay the better it is. So spend as much as your budget allows for it – it is worth every penny, especially in a kitchen.

      Yes, you do want to caulk the top of the backsplash where the back of the tile meets the wall and the bottom where the tile meets the countertop. You can use clear silicone for that and it will probably give you the best result.

  • Richard Morford

    Roger, I read your grout article and it touches on an issue I am encountering in redoing our master bath. We have elected to put an accent tile around the bath. It is from the Roca Rock Art line and composed of small stones in a pattern. We are not using it in places where it will encounter water directly but when I took off a tile I put up a week ago (wife said it was upside down) I notice that in the current humidity (we’ve opened up the bath while working) there is a dark discoloring on the back side in one corner. It looks like a moisture problem to me. What can I do to ensure that moisture doesn’t get behind the stones? Is there a sealer that can be used in lieu of grout or is grout the only answer? The spaces look pretty small for grout which may harm the appearance and mute the design as well.

    Here is a picture of the accent tile we are using:

    Many thanks for your help. Dick

    • Roger

      Hey Dick,

      To be honest it is impossible to keep moisture from getting behind the stone – grouted or not. This is why the shower needs to be waterproof before any tile is installed. Using a sealer will slow down the absorption of moisture in the stone and that may be your best solution.

      As long as the stone does not have water directed at it then the moisture you’ve found is likely from vapor transmission through the stone. Natural stone will actually absorb vapor and condense it back into water which will migrate back into the stone. This is not a problem at all provided your shower is properly waterproofed. Sealer will prevent it from doing that so you don’t really *need* to grout the accent but can seal it instead and that should solve the problem.

  • Mike Dunn

    Hey Roger,

    Awesome site and some very informative info. Two quick questions. I’m redoing our bathroom and saw in an early reply that you could use 1/4″ backerboard on a floor, did I read that right? And I am attempting to make a buffet table into a vanity and wanted to put three pieces of marble on top. Since I wanted it to overhang a couple of inches in front I was thinking of butting them together (I can already hear you saying toothpaste will be getting in the small spaces). Should I go for the two playing cards grout line and try to come up with something that will allow me to grout all the way to the end of the tiles in the front or since their won’t be much movement could I butt them and seal everything real good. Thank you in advance for your help!


    • Roger

      Hi Mike,

      Thank you very much! Yes, you did read that correctly. 1/4″ backerboard may be used on the floor so long as it is only being used as the suitable substrate for tile installation. Meaning only that it is just there for a proper substrate to stick tile to. (WOW, my sentence structure sucks today) Your floor should be properly built to support the full tile installation and whether you use 1/4″ or 1/2″ the backerboard will not add any negligible support to your floor – you only need it to have a proper substrate for adhesion. If your floor is built properly it will be fine. If your floor is not built properly no amount of backerboard is going to make it work correctly.

      You know if you do that toothpaste will get in th……..oh, nevermind. I would use the two playing cards – but that isn’t the biggest issue you’re talking about here. :D The problem with what you are proposing is that normal 3/8″ thick marble tile will absolutely not withstand an unsupported overhang on your countertop. It is simply not strong enough. The first or second time you bump into it the marble will begin to weaken along the striations (the crystal channels in the marble) and will eventually break or chip off. If you want marble with a small overhang you can attach a piece of 1×2 to the front of the top and wrap the entire top (or at least the 1×2) with kerdi and have a 1 1/2″ strip of marble along the face of the vanity and you can run the pieces on top right up to the edge over those. This way it is all supported, you have a small overhang, and your marble won’t break off. Unsupported marble won’t work, though. Sorry.

      Now I’ve told you to use grout and support your marble – I’m just screwing your whole vision six ways to Sunday, aren’t I? Sorry, I just want you to have your hard work last a long time.

      • Mike

        Thanks for the quick reply and now my vision is ruined….. just kidding after reading your blogs my vision was changing. I just wanted to hear it from you, and now I have the proper vision. Like you said why do work if it’s not going to last. Thanks again.

  • Theresa

    HI Roger,
    I’m finally able to redo my bathroom and I hate the look of grout! I’ve picked an Emser slate for the shower itself with a pebble floor. My contractor, Antonio says I have to grout the slate as well as seal it. Do I have any real options as far as not grouting the slate. Hasn’t the industry been able to come up with some way to eliminate the grout? I won’t be able to redo this bathroom for a long, long time and the thought of using it every day and hating the look of the grout is stopping me from pulling the trigger. Any advice is greatly appreciated.

    • Roger

      Hi Theresa,

      Antonio is correct – slate absolutely must be grouted and sealed. Your absolute best option would be to purchase a gauged, rectified slate (it’s expensive) – perhaps even larger tiles like an 18″ or 20″ tile – and have Antonio use a 1/16″ grout line. Additionally you may want to use epoxy grout to assist with both cleaning and color consistency over time (won’t fade). If your tile is not grouted you will have all sorts of unsavory things between your tiles – wouldn’t you rather have grout? :D Please understand that using a minimum of grout lines as well as a larger tile will require an absolutely flat substrate which will require additional prep work. This method, however, will still give you a minimum of grout lines and if you choose a grout that matches the base color of your slate it will be a very nice looking installation.

      I just finished an entire slate bathroom which I will post on my professional blog shortly. Until then you can see a couple of photos of it on my facebook page HERE as well as my shower tile and bathroom gallery HERE.

      Hope that helps.

  • Sam


    We have had the tile that looks like hardwood installed in 850 sq. ft. of our house. The men who intalled it said the 1/16 spacers were just falling through the tile in many places, so they just butted them up against each other and decided against grouting it. Now, walking though the house, there are some spaces that are thicker than others. We have a three year old and really think it is most sanitary to grout it. The trouble is, we don’t know how to proceed with what we have… in the thinnest of spaces, will the grout just flake out?
    We originally purchased sanded grout that matched the tiles. Do we need to use unsanded grout instead since many spaces are so thin? I also bought some sealer and was advices to apply it with small applicator tubes to avoid creating a haze over the entire floor. We are in limbo right now, not living on the main floor of our home, trying to decide if we should grout or not, when my gut says we should. I just don’t know how to properly proceed without creating more of a mess for ourselves.
    Any adivce or helo you can give is enormously appreciated!

    • Roger

      Hi Sam – your installers were idiots! Sorry, just a personal opinion. :D

      You are absolutely correct – it needs to be grouted for sanitary reasons as well as simply aesthetic reasons. The problem with using sanded grout in smaller grout lines is the ability to properly pack it into the grout lines. If done correctly it will not flake out. However, since yours are butted you are working with lines going from nothing to probably about 1/16″ in spots. Your best bet would be an unsanded grout for your entire floor.

      As far as the sealer is concerned it is only necessary to prevent staining and assist in cleaning. Since it sounds like you have a darker grout and hardly any grout I wouldn’t bother sealing it.

  • pam fields

    one other question, what is the best grout to use for porcelain tile on flooring?

    • Roger

      Epoxy grout is always the best, most bulletproof grout for just about every application. For what you are installing if you do not use epoxy just use a regular sanded grout and you should seal it to prevent staining since it is a floor which will get relatively normal use.

  • pam fields

    we are laying tile in a room that gets alot of sunlight. the tiles are porcelain 13×13 and not rectified. can we use a 1/32 grout line or should we go with the 1/16? also, i read an earlier post about soft lines? do we have to put caulk in some of the lines? this is for a living/dining room.

    • Roger

      Hi Pam,

      You will not be able to use a 1/32″ grout line on non-rectified porcelain – the grout lines will eventually either run together or apart. Unless your floor is DEAD FLAT you need to use a 1/8″ grout line on it. It is the only way you will be able to keep the grout lines consistent.

      Normally on floors you need a soft joint every 20 – 25 feet in each direction. HOWEVER, on a floor exposed to direct sunlight you need a soft joint (movement joint, control joint) every 8 – 10 feet in each direction. The room itself, amount of traffic, etc. does not matter, it is the exposure to sunlight which will dictate where your joints are placed.

  • Janet

    Hi Roger!
    I know you are the tile guru and all you say is true! Do you also give advice on staircases or specifically overlaping stair nose?
    A fan from the past and fellow member of the secret society of fireplace installers.

    • Roger

      Hiya Janet – howareya?

      Onliest thing I know about stairs is how to put tile on them – when I absolutely have to. Beyond that it would simply be a guess on my part – sorry. Glad to see you’re still around and still working on the house, I see. :D


    A contractor said he would butt together the granite tile in the stall shower walls. And told me he would bond the tile together and not use grout. He said something about epoxy. What does this mean. Does it mean epoxy grout between the granite tile? I need your help – please reply to me at you can also let me know if you need my tel. no. to answer this. Need to pick a contractor. thanks for your help

    • Roger

      Hi Barbara,

      If by ‘epoxy’ he means epoxy setting material then yes, it is a viable installation procedure. However, the tile should still not be butted – for all the same reasons I’ve given in the post. The substrate beneath the tile will still move which means the tile will still move – epoxy or not. Epoxy setting material is also – literally – about seven times the cost of regular thinset for no viable advantage for your installation.

      ‘Bonding the tile together’ does not stop the substrate from moving. I’m unsure of what he plans for his installation procedure but I think you would be better off with regular thinset, a very small grout line, and epoxy grout. Regardless of the method grout needs to be used.

  • Jeff

    Hi Roger, good informative conduct going on here @ your blog, thanks!

    Just couple of questions; doing a 6×3 side entryway w/ 12″ marble tile over 5/8’s existing sanded plywood, (which I ripped off 2 layers of sheet vinyl and heat gunned what adhesive was left off)..the plywood is in near perfect shape as home is less then 25 yrs old..
    I will grout using the bare minimum 1/32 as per your info, as I also wanted to butt end but won’t now, however how much perimeter expansion should I allow?

    Also, what would be the best sealer for the marble to use before the grout is added, and should I worry about using a different sealer for the grout itself or seal the whole thing w/ the same when completed?

    I was unaware that marble tile should be sealed before grouting, maybe I’m has a premium polish already..


    • Roger

      Hi Jeff,

      The plywood may indeed be in good shape but you also need to be concerned with the proper layers and correct deflection. All that means is you need to be certain that your floor is stiff enough not only for installation of marble but for an installation with tiny, tiny grout lines. The smaller your grout line is the more support you need because you will have absolutely no give with grout lines that small.

      You need a minimum of 1 1/4″ total plywood layer beneath your tile. As long as you have an additional 5/8″ layer of plywood beneath that layer you’re fine. If not you will need to install an additional layer. You also should check your joists to ensure you have correct deflection. You can check the measurements and input everything HERE to make sure you have the minimum of L720 for your installation.

      With the size of your entry a 1/8″ expansion joint around the perimeter should be plenty. You’ve also worded your question as if you were going to install the marble directly to the plywood – I hope that’s not the case. You need a substrate suitable for installation such as Ditra or a cement backerboard. You can use a 1/4″ backerboard if you want, but you need something to adhere the marble to other than just plywood.

      I always prefer to use the same sealer consistently with any installation. I also prefer StoneTechs bulletproof sealer but any DuPont sealer is good. Sealer is one item you get what you pay for – the more expensive the better the sealer. Make sure you use an impregnating sealer rather than a topical sealer for marble. You really only need to seal it before you grout if there is a possibility of the grout staining the marble. If you have white marble and white grout just seal it after you’re done.

      • Jeff

        Thanks Roger, but is there an alternative to using backerboard? I’m asking as I don’t want to cut my metal door due to increased height from it..maybe some kind of floor leveler type of thing that’s non-porous?

        • Roger

          Hey Jeff,

          You can use Ditra directly over the plywood. With the ditra and thinset your total height below the tile should be right around 3/16″ or so. Noble company also makes a sheet membrane you can use as an underlayment but I’ve never used it and don’t know the total installed height. Just google flooring sheet membrane and there are several options available for you all with differing installed heights.

          You do not want to go directly to the plywood. The movement of the wood will eventually debond your tile installation. You need something appropriate to install the tile to.

  • Dave

    Also another question:

    What’s your recommendation for laying the rows? How many rows can I go up before waiting on the next or can it all be stacked at one time?

    Thanks again


    • Roger

      Hey Dave,

      You can go up as many rows as you wish. As long as you are using a spacer that does not compress when weighed down. If it compresses it will make your grout line smaller with every tile stacked over it – you don’t want that. If you have a solid spacer you can stack it 100 high and it won’t matter. (Be a pain in the ass to get the bottom spacers out the next day, though.)

  • Dave

    Hello Roger,

    First off , Id like to thank you for this very informative site. After scouring the web over and over ( Reading someones claims – then following up on other posts they’ve mad – in attempts to find out if they are feeding misinformation or not.) I ran across your site, It’s a breath of fresh air….

    In the past I’ve tiled my own floors, showers and even got the stones to do a granite tile counter top in my kitchen. Recently, I’ve replaced the paneling in my den with drywall and am now staring @ this atrocious 60’s style brick fireplace in the center of my wall.

    Thanks to your site, I’m following through with a fireplace face lift. I’m going to sheet rock from the mantle up and using 12×12 marble tile -hearth to mantle. I have a few stupid questions ( I’d rather ask a stupid question than make a stupid mistake!!!)…

    1 – I will be using cement board attached to the brick. Is 1/4 OK?

    2- My Marble is white. Is Spectralock white the color choice?

    3- The famous question… I’m using rectified tile, can I butt them or should I go 1/32?

    Thank you for your time and getting those of us DIYer’s with doubts ” on the path to a professional looking finished product”.


    P.S. Hope you don’t mind, I’ll be sending Before and After shots. If you choose to use them feel free…

    • Roger

      Hi Dave,

      1. Yes, 1/4″ is fine. What you are concerned with is ‘sheer’ strength. Gravity will be pulling down the entire length (face) of the board rather than pushing or pulling the width of the cross-section – entirely different animal.

      2. Maybe, I don’t know. Color choice is strictly aesthetic. You may think teal green looks good in white marble. If you do, find a teal green. :D Whatever you (your wife) thinks looks good would be the correct choice.

      3. With marble I would use a grout line of some type. Marble is a soft stone and chips easily. You can double up a playing card and use it. 1/32″ – taaadaaaaaa! :D

      Send the pictures. If I can get the elves off their asses I’ll get the page up for user’s photos. You know, eventually…

  • Leon

    There is a very nice porcelain tile we saw in Lowes, it’s very modern, looks like wood planks, it’s 4″x12″. On the board they have it without grout, basically right next to each other. There seems to be no space between, so it looks like hardwood or laminate installation. How would you recommend to install these kind of tiles so it still look modern, but wouldn’t allow a water to go between?

    • Roger

      Hi Leon,

      A wood-plank tile can be a very, very cool looking floor. However, there are a couple of things that are paramount to a good installation. First and foremost you need an absolutely flat floor. With the staggering and pattern of these types of tiles any substrate inconsistencies will be highly exaggerated. Also to get the ‘wood’ look you need to randomly stagger the tiles from row to row. My brain doesn’t do random – it’s hard. The best way to do it is probably three or four rows at a time, get to the wall and make your cuts, then use the remainder of the cut pieces to start the next rows. That’s as random as you will get.

      You also need to take into consideration how much bow the particular tiles have. If they are excessively bowed (more than 1/32 over 1 foot) you need to both mix them up and stagger your joints no more than 1/3 tile. With planks that small it shouldn’t be a problem but when you get into the bigger ones (over 2 feet in length) it becomes problematic.

      The best (only) method for a waterproof installation is to waterproof your substrate. But I don’t think that’s what you’re looking for. I think your best installation method would be to use the porcelain with a 1/16″ grout line (yes, standards now call for no less than 1/8″ – don’t tell anyone) with SpectraLOCK epoxy grout (which is waterproof). This would absolutely maximize waterproofing capabilities without actually waterproofing your substrate. On a normal floor such as a kitchen, bath, etc., this is more than enough. You can find a grout that is nearly identical to the base color of the tile and it will look very nice.

      As a side note: Thank you very much for doing some research and not simply assuming that because they have that tile on a board with no grout lines that it is an acceptable installation method! Lowe’s needs to pull their head out sometimes. I was in my local one last week and they had sample boards up with grout haze all over them – no kidding. Not really the best way to sell a tile in my opinion.

  • Bridge

    Hello Roger,

    Excellent information.

    Roger, I am thinking of having 16X16 granite tiles installed on the floor in a family room which measures 20X15. Do you recommend 1/8 or 1/16 grout line for this.

    Thanks in advance.


    • Roger

      Hi Bridge,

      With 16 x 16 granite tiles in a flooring application I would use 1/8″ grout joints. This will serve a couple of different purposes. Mainly it will allow you to adjust for any inconsistencies in the floor or the tile itself. Also new TCNA standards state that with this type of application a minimum 1/8″ grout joint be used. Specifically for the reason I mentioned. If you get a grout that closely matches your granite it will look good, time just needs to be taken with the install and the floor needs to be as absolutely flat as possible.

      Also, standards require a movement or ‘soft’ joint on interior applications every 20′ – 25′ in each direction so you’re fine there UNLESS the installation is exposed to direct sunlight. In that case a soft joint is required every 8′ – 12′. A soft joint is simply a grout joint that is filled with a flexible caulking or silicone rather than grout. Most grout manufacturers have a matching silicone or caulk for their grout colors.

      • Bridge

        Appreciate your reasoned and careful comments Roger. Based on reading your website, I went out and bought SpectraLOCK from Laticrete and asked the installer to try it. He has agreed to use it.

        There is a bit of the morning sun that will fall on a small portion of the tiles, mainly in the winter and it does not get too warm. Do you still think the soft grout is necessary, even with the SpectrLock? I asked the installer to aim for 1/8th, although the general standard here in Saskatchewan is 3/16 for floors.

        Thanks again Roger.

        • Roger

          Hey Bridge,

          I think you’ll be fine without the soft joints. That requirement is mainly for something such as a room with a south-facing window which will expose the floor to direct sunlight for most of the day.

          With granite your installer should be fine with the 1/8″ and I’m sure he’ll love the SpectraLOCK if he’s never used it. When he’s finished you can tell him I said ‘you’re welcome’. :D