There are numerous really cool mosaics and liners which can be installed as an accent into your main field tile to add a unique touch to an otherwise standard tile installation. These are products such as glass and natural stone mosaics, individual painted tiles, or custom accents.

The biggest problem with these, however, is they are oftentimes not the same thickness as your main tile – they are usually thinner. This is especially true of most glass mosaics. I usually solve this problem with Schluter Ditra. Although I use ditra as my example in this post, you can also use regular 1/4″ backerboard if your inserts are significantly thinner.

glass mosaic insert

Photo 1

See that glass (and metal) mosaic right there? (Photo 1 – You can click on it for a size larger than a small dog) It’s setting inside the main linear mosaics I’m installing on a backsplash. See how much thinner it is than the surrounding tile? That’s what we’re gonna fix. When you have your tile installed you want it all to be on the same flat plane without either tile sticking out (or sinking back). The best way to do this is to have an additional substrate behind your thinner tile to bump it out flush with the rest.

You want to cut your ditra about 1/16″ smaller than the overall size of your insert. You want to make sure you have enough support behind the insert, but you don’t want it larger. (Photo 2)

glass mosaic insert with ditra

Photo 2

glass mosaic insert with ditra

Photo 3








In Photo 3 you can see where I’ve flipped the ditra upside down so the fleece side is out. You want to install your insert onto the fleece side rather than the plastic, dovetailed side. this is much easier, especially with smaller tiles, and gives the insert more adhesion on the backside once installed. The thinset will ‘lock’ it to the wall doing it this way.

Photos 4 and 5 show how the ditra bumps it up to the same height as the field tile. If your insert is a LOT thinner, it may be better to use the 1/4″ backerboard, although you can double-up the ditra to make it thicker.

glass mosaic insert with ditra

Photo 4

glass mosaic insert with ditra

Photo 5








Once you get your ditra and inserts cut to size (cut all of them at once) get your thinset mixed up and cover the entire fleece side of the ditra inserts. Make sure the entire surface is covered, most mosaics are fairly small and any uncovered areas may lead to just one or two pieces not being adhered well. Spread it just like these here:

glass mosaic insert with ditra

Photo 6

glass mosaic insert with ditra

Photo 7









Then place your inserts onto the ditra and press down slightly – only slightly! Before you firmly press the inserts and the ditra together you want to flip them upside down. Doing this ensures that the face of your inserts, the shiny part that makes people go ‘ooooh, pretty’, is completely flat. Flipping them upside down, then pressing down firmly, will get the entire face totally flat and get a full bond onto the ditra. It is always best to use a flat surface on the back, squeezing them between the flat surface and the flat countertop or bench – whatever your wife lets you use. Like these:

glass mosaic insert with ditra

Photo 8

glass mosaic insert with ditra

Photo 9







Once you get them all installed to the ditra, flipped, and pressed down firmly to ensure a full bond – leave them alone! Give the thinset at least three hours to cure and get a grab, ideally let them set overnight. Really, leave them alone. Stop staring at them. Go have a beer Pepsi and have some dinner. We’ll get to them later.

glass mosaic insert with ditra


Once the thinset is cured you can fill the dovetails with the flat side of your trowel, then comb on the thinset with the notched side and install them into your design. You can cut your main field tile with spaces large enough for your insert (don’t forget the measurement for the grout line around the mosaics). And tile away. When you’re finished you should have two different tiles, with different thicknesses, installed flush on the same plane. Like this here:

glass mosaic insert with ditra


This method works for backsplashes, shower walls, even tile floors. As long as you have good contact with the insert to the ditra, and good contact behind the ditra to the substrate, you should have a nice, flush tile installation which makes people go ‘ooooh, pretty’. Like these here:

glass mosaic insert with ditra

Ooooh, Pretty...

Porcelain backsplash tile installation with glass mosaic inserts in Fort Collins, Colorado

Ooooh, Pretty < See?


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  • Chris

    Can this method of using Ditra be used if the backer is Kerdi Board?


    • Roger

      Hi Chris,



    Am getting ready to tile my whole house with 12X12 granite tiles and bought 10 24″X24″ medallions to lay out around my house. The problem that am having is that the medallions are thicker than the actual granite tiles. What should I do in this case? ThNls for your help. I will send a pick for reference. Tried to out a pic but I could not.

    • Roger

      Hi Daniel,

      Get a different medallion. Or double up your underlayment where the medallions are not. Or remove underlayment where they are (as long as you have a suitable substrate). Or use a thinner underlayment where they are (1/4″ backer rather than 1/2″). Or leave them sticking up and call it art. :D It’s hard to answer that question when you haven’t told me how much thicker they are, what your substrate it, etc. But with a thicker insert it is a huge pain in the ass.

  • Cindy

    The strips that I plan on using for borders in my bathroom are a bare 1/16″ thinner that the subway field tile. Will this even be an issue do you think?

    • Roger

      Hi Cindy,

      Maybe. If the individual tiles are tiny then you may have thinset squirting out between them. If they are just strips then you can just put more thinset behind those to flush them with the field tile. Normally that small of a difference isn’t an issue.

  • Jamie

    We have the opposite issue. Our glass liner is 3/8″ thick. Our field tile is 1/4″ thick. We typically use 1/2″ Kerdi board for our shower walls. How would you tackle this install? Use 5/8″ Kerdi board for everything except for the liner area where you could use 1/2″ And then just Kerdi fix the seams where the different thicknesses meet up?

    • Roger

      Hi Jamie,

      To be honest I would tackle that by choosing a different tile for one or the other. But your idea will work, it’s just a LOT of extra work for that particular combination.

      And yes, I realize this reply is likely too late, but the info will be here for others in the future. Sorry for the delay.

  • Mike

    Hey Roger,

    Late to the party here, this is a great solution but there are concerns of using the ditra for a solution on the floor, will it not be making a flex point under the mosaic when the remaining floor tiles are installed directly to hardy board ? The flooring will be 12×12 travertine with mosaic accents measuring 3-1/8×3-1/8 still installed on the factory mesh backing. Really not looking to have the 1/8 grout lines crack. Can you offer a more solid solution? For reference the travertine is 1/8” thicker then the mosaic. Hopefully this picture of the rough layout uploads, thanks.


    • Roger

      Hi Mike,

      It looks like the individual tiles may be smaller than 2×2″, so you shouldn’t use ditra with those – it will create a point load problem. You can use 1/8″ wedi, install the insert to kerdi (that way you can install it over as much thinset as needed without squeeze-through), or leave a 1/8″ bed of thinset in those spaces, let it cure, then install the mosaics.

      And yes, I realize this reply is likely too late, but the info will be here for others in the future. Sorry for the delay.

      • Mike

        It’s was too late but no problem, the actual mosaic measured 3-1/8” from edge of square to edge of square. I’m actually a union trades worked and in our training facility I spoke to the instructor for flooring, and while he doesn’t actually teach tile he told me about the ditra creating the point load issue like you said- sominstead on my own accord I did actually what you said and left a layer of thin set and let it cure- while I did fight with squeeze threw, the end result came out well, with a little patience and finesse I was able to control the challenges. Here is a picture to give you an idea. And again, thanks.

  • Fabian Barch II

    Thanks so much – I tile a lot but never had this problem before for a row running up a shower wall – plus tile was hard to hold in place. you solved my problem completely thanks again!

  • Gerald

    So how would you install a decorative 4″ band of mosaic tiles around a shower? would you install the ditra grid to the wall with thinset and let cure, then thinset on the mosaics? I have about 1/16″ depth when I hold the mosaics and ditra next to the wall tile where they will be placed.

    • Roger

      Hi Gerald,

      I normally install the mosaic to the fleece side of the ditra first, let that cure overnight, then install it to whatever thickness you need. By already having the mosaic you are guaranteed to have the ditra at the correct depth.

  • Francois

    Hi roger… i want to put four rows of 2×2 mosaic from floor to ceilling between 12×24 witch is trowelled with 3/8 square notch… do you have a trick to keep the mosaic flat and flush with the main tiles ??? (They have the same tickness ) mosaic is the same as shower floor on picure

    Thanks a lot

    • Roger

      Hi Francois,

      Install it on either a sheet of kerdi or kerdi-board (3/16″) and use a smaller trowel to do so. Let it cure overnight and put it on the wall with however much thinset you need behind it – it won’t be an issue if it’s mounted over a sheet or board – no squeeze-through.

      • Francois

        Modified or unmodified thinset ???

        • Roger

          Use whichever one you’re currently using. With an insert that size it really doesn’t make too much of a difference.

  • michael conforti

    Genius! Seriously that is a genius solution with the flipped over Ditra. You are a reno industry mensch. (Look it up if you don’t know what hat means).

    Thanks for all the invaluable free and some what funny advice 😉

  • Kerra

    Hi Roger,

    We installed a 4mm mosaic tile in our bathroom before installing the subway tile which is 8mm. The subway tile is not installed. Is there anything we can do to fix or make this look ok?

    Thank you!

    • Roger

      Hi Kerra,

      Unfortunately about the only thing you can do at this point is to remove the 4mm, install the subway, then reinstall the 4mm with a properly sized backing on it. You can’t make a tile thinner, but you can make it look thicker with more backing.

  • Caitlin


    Super happy to have found your site. It’s a fantastic resource. I’m tiling my shower and plan to use 4×16 subway tiles on the wall (going for a bit more modern look) with a shoulder height stripe of marble sheet mosaic. The marble is 10mm thick and the subway tile is a smidge thinner at 7.9mm (.313inch) :D I am assuming this difference in thickness is not *ideal*. However, in looking at how thick Ditra is, I would think using Ditra underneath the subway tiles would end up with the subway tiles being thicker than the marble. Perhaps I am overcomplicating this…but I want to do a great job and leave my bathroom looking professionally DIY’ed :D. Am I overcomplicating this? Is there a simple solution here?

    Thank you so much!

    • Roger

      Hi Caitlin,

      Yes, there is a simple solution. Use a larger notched trowel for your subway (which will leave more thinset behind it) and a smaller, or v-notch trowel for your insert. You do not want kerdi behind the entirety of your shower behind the subway.

  • pierce

    I’m setting 3″ square tiles that are 5/16″ thick, in cutouts in 1″ thick terra cotta tile, on a concrete substrate outdoors. Since the inset tiles are so small, I don’t think ditra is an option: agree? So then how do I build up the needed 1/2″ inch? Thinset doesn’t seem to be a good option, according to what I read; and when I use mortar, it does not bond to the concrete substrate well, and is crumbly. Should I use concrete for the buildup, and thinset the tiles onto it? Thanks.

    • Roger

      Hi Pierce,

      I assume you meant deck mud, not mortar, that doesn’t bond to the concrete? Either way, you can use concrete to build up about 1/2″ of base under the inserts, let it cure, then install the inserts.

  • Kendra

    Hi Rodger,
    I have these small 3d bronze metal accent tiles; shaped like a pyramid. They measure 3/4″ square and the peak at the center of the tile is 3/4″ tall. If you flip the tile over, you notice the backside of them are hollowed out like a bowl. My question is, is the purpose of this hallow back to hold extra thinset? And how should these tiles be installed? Thanks for your help!

    • Roger

      Hi Kendra,

      Those are for the mold. I fill them with thinset then just stick them up like a regular tile.

  • Ken Harge

    I’ve been doing tile for 30 years. Although I have used Ditra I never thought about turning it up side down and then letting it dry. Super awesome idea. Thanks!!!

  • Mike

    Can this Ditra technique be used for floor tiles of different thickness? We wanted to add 2 In wide non-glass mosaic strip length of hallway (25 Ft). Mosiac tile strips are thinner than 1 Ft x 2 Ft main floor porcelain tiles.

    • Roger

      Hi Mike,

      Yes it can.

  • Myles

    What if the thicker material is the medallion? I’m using a piece of marble as a medallion in porcelain tile. The marble is not quite an 1/8″ thicker but that will hurt if you stub your toe on it

    • Roger

      Hi Myles,

      Then you need to build up the surrounding tile. Either an additional 1/4″ substrate, or a bigger trowel (trowel is much easier and a better option).

      • Diana Lee Anderson

        By trowell, are you meaning that there would be a thicker layer of mastic or thinset behind the field tile?

        • Roger

          Hi Diana,

          Yes, I mean there will be a thicker layer of thinset behind the field tile. If there is a thicker layer of mastic then you have more problems than the tile not being flush. :D

      • Aaron

        Or u can take a grinder with a concrete polishing pad and take an 1/8 off the back side of the marvle insert. That seems more easy to do than floating the surrounding tile

  • Antonio Zepeda

    If using the 1/4″ cement board instead of the ditra for mosaic tile on a shower wall – is the 1/4″ screwed on the substrate first or cut into pieces like the ditra and layed up with the mosaics like any other tile?

  • Martine

    I need your advice. I have 4″ square stone tiles and a smaller glass tile which are not the same thickness. They are about 1/8 inch different. I bought some Ditra but now the glass tile is thicker than the stone. Either way one tile is going to be thicker. Would I be better off using the Ditra and having the glass tile thicker or not using it and having it recessed. Which will look better? Thanks so much for your advice.

  • Nancy

    Great instructions; I “plan” to install subway tile (2 rows) then a row of a glass/metal/stone mosaic then on up to the cabinet bottoms with subway. I don’t have the tiles with me but I suspect they are different thicknesses so this is wonderful knowledge. If I prepare the 3 inch strips of mosaic the day before, could I then set the subway and the mosaic at the same time (using modified mastic)?

    • Roger

      Hi Nancy,

      Yes, you can set them at the same time with modified thinset (not mastic, there is no such thing as modified mastic). If you are setting glass you do not want to do that with mastic, you want thinset.

  • Kevin

    An interesting solution, though Ditra can get expensive in large amounts. Also, since the Ditra creates a vapour barrier, you need to use a modified vs. Non modified thinset to secure it (I forget which) as it won’t cure properly when unable to dry.

    • Roger

      It will cure just fine Kevin. Really. :D

  • David

    Hi Roger,

    My question is: when installing one row of 12″ x 24″ heavy tile above 3 rows of smaller decorative tile (two rows of 2″ x 4″ separated by one row of 1″ x 2″
    ), how do you keep the upper heavier row of tile from squeezing the the lower three rows of decorative tile together.

    • Roger

      Hi David,

      You either use hard spacers in the smaller tile, use a non-sag thinset, or wait until the smaller rows have cured to install the larger above them.

  • Nathan

    Hi Roger,

    I’ve installed some slate tile “wainscot” to the height of my vanity and continued it all the way to my bathtub surround. Picture here:

    Next I’m planning on putting in a 8″ tall strip of glass/stone mosaic around the whole area. It wraps around the room for a total length of about 18 feet. That’ll be the top of the wainscot area, but then of course in the tub I’ll continue with the slate to the ceiling, with another smaller 4″ strip of mosaic somewhere in there.

    Some of the fine folks at the forums also recommended using Ditra to butt out the mosaic, and I found your article helpful, but it seems your method wouldn’t exactly work since I’m doing a full length of mosaic, not just little pieces. Any tips on how to go about it?


    • Roger

      Hi Nathan,

      It works exactly the same way, you would just have a full strip of ditra all the way around the room beneath the mosaics.

      • Nathan

        Thanks for the response! I was referring to the fact that you thinset the mosaic to the Ditra before putting the Ditra on the wall (I didn’t see how that could work with a really long section since the thinset would crack), and how you installed the Ditra flipped so that the fleece is against the mosaic instead of against the wall.

        I actually ended up putting the Ditra up yesterday (fleece side against the wall) and plan to fill in the waffles with thinset and add the mosaic tonight. Picture here:

        I may even add a layer of KERDI between the Ditra and mosaic because the Ditra still doesn’t quite push the mosaic out far enough.

  • Dave Bear

    What type of thinset do you use when putting the Ditra with tile on the wall, modified or unmodified?

    • Roger

      Hi Dave,

      You can use either. If you are installing glass tile you should use modified, anything else can be installed with either one.

  • Denise

    My tile guy just installed my tub surround with a 4″ row of glass tiles that are 1/8″ thinner than my field tile. The tile guy said he has had problems with the glass tiles falling off if he used something behind them to make the them the same thickness as my field tile. Have you experienced this problem if tiles falling off over time? When I asked him if he could put mud on the wall and let it dry and then put more mud on when he places the tiles so they would be flush with the field tile, he got defensive about his work and said it would take more time to do that. He assured me I would like the finished product. I’m not convinced after reading this. any suggestions on how to handle this.

    • Roger

      Hi Denise,

      No, I’ve never had any problems with tile falling off. If it does it means they weren’t properly installed to begin with.