Setting different thicknesses of tile for inserts

by Roger

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

STOP STARING! GO AWAY...

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

Finished

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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Robert K

Roger,

First…Thank you for doing what you do for us DIYers. I have a question regarding Ditra. Can I key in all of the Ditra, let it dry, and then come back and lay my tile? Will the thinset bond correctly to the keyed and dried Thinset?

Thank you,
Bob

Reply

Lynn Cleek

I’m a novice. You speak of Ditra. What is Ditra?

Thanks

Reply

Lou

Roger
We picked a large format rectified porcelain tile 12×24, you and the manufacture says no more then 33% off set. But i see running bond brick pattern in buildings and on all the tv home shows. I looked on line and saw boyertile.com and he agree with the TCNA no brick pattern because of lippage,warping and grout lines no less than 1/8″, 3/16 recommended. So whats the deal. P.S. I have all your books and yes its sill the same project from a year ago.

Reply

Roger

Hi Lou,

The deal is with large format tile the cooling process of the tile makes it ‘cup’, where the center of the tile will sit higher than the ends. The edges of the tile will cool faster than the center, causing the center to expand ‘up’ as it cools. Placing the corner of the tile (the lowest point) next to the center (the highest point) causes lippage issues. Offsetting it by 1/3 makes it much easier to get flat.

Reply

paul roman

Your tip worked great. One issue I did have is where I had to trim off about 1/4 inch from a three-tile row for a band of mosaic at the ceiling. Shower is about 99″ high and we used 6″x24″ porcelain set vertically with another mosaic band just above the niche. I could trim a few inches off the bottom row of tiles, but we did not want to increase the width of the band above the niche and I could not stretch the top row of tiles! (hence the 3″ gap). We were going to use PVC crown molding, which is in the main area of the bathroom, but liked the mosaic look better. Anyway, the flimsy backing on the mosaic did not like the wet saw (even after I used a bunch of blue tape) and about 20% of the row that I trimmed came off the backing. I will be patching them in. Because I had unmodified thinset (Kerdi membrane), I used it for the mosaics on the Ditra. Would I have been better off with modified thinset or would the result (losing tiles) most likely have been the same?

Reply

paul roman

Double repeat. I posted my reply to my follow-up. I think I have it now.

Figured out my problem with mosaics coming off. Enough blue tape, but not in the right places. I had covered near the cut, but not across it and not the rest of the sheet. I cut some tonight that I had put on some Kerdi. I placed them on top of a piece of plywood (second “Aha!” moment) and did not lose a single piece. Learning is fun!

Unrelated issue/comment. With a glass blade in, I found the glass and marble mosaics had a tendency to be pulled strongly into the blade. A couple of times the saw raced through two or three pieces before I could either get the feed under control or reach the off switch.

Reply

Roger

Hi Paul,

It likely would have been the same. For some ridiculous reason they use water soluble glue on most mosaics.

Reply

Michele

Roger,
I want to put a full 12 inch strip of mosaic set in field stone in our shower. Can I put the Ditra on the wall first and then apply the mosaic tile? The strip will be 11 feet long when it is wrapped around the shower.
Thank you!

Reply

Roger

Hi Michele,

Yes you can.

Reply

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