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Different thickness of tile on one floor.

GeorgeP's picture


I am tiling a floor where the center of the room will have a decorative rectangular mosaic piece.   That piece will be framed with border tiles.  The rest of the floor will be ceramic tile.  My problem is that the mosaic will be thinner than field tiles, perhaps by 1/8" and it is possible that, depending on tile choice, the  border tiles may be slightly thinner than the field tiles but thicker than the mosaic.  I am wondering what the best way to handle this is.

I will be putting down cement board and I was thinking that, before laying the board I would put down a spacer where the mosaic is, and if needed, for the border tiles.  That way, when I installed the cement board, the surface would beh uneven but when the tiles were installed they would all be at the same level.  A possible problem I see is that the cement board joints would align with the joints between the different tile types.  Is this an issue?  How are installation problems like this usually handled?

The photo shows the mosaic and some of the other tiles we are considering.



If it's a limited number of (post #214861, reply #1 of 5)

If it's a limited number of places where the tile is thinner, with most of the tile being the greater thickness, the most obvious thing is to just put the thinset on a bit thicker in the areas where thinner tile will go.  Or, depending on how much thickness you need to make up, you could perhaps use a layer of a thin tile underlayment of the Ditra genre.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Backbutter (post #214861, reply #2 of 5)

I would sprea my thinset as you are doing for teh field tiles.  Then I would thcken the thinset under teh decorative tile by adding (backbuttering) moer thinset to teh decorative tile.  Then set it.  If it is still too low, pull it up and add more.  if it is to high, pull it up and remove some.  It may take a bit of playing around.

The only problem I see is if this decorative tile is not a tile at all but a true mosaic.  If it is a true mosaic, it could be a hugh mess to try to pull it make up to adjust.  In that case you might need to pull a dozen or so piece of mosaic off and set them until you figure out hte proper thickness of thinset.


Yes it is a true mosaic so I (post #214861, reply #3 of 5)

Yes it is a true mosaic so I don't think extra thinset is an option.  I considered using thinset to make up the difference but I am afraid of all that thinset coming through the mosaic gaps and screwing up my grouting.  Something I am concerned about anyway.  Also,as you say,  I don't want to have to pull up and reset the mosaic.  I guess what I will do is use a spacer under the mosaic and, if needed, use extra thinset to set the border tiles correctly.

When laying the tile would you start from the center, putting the mosaic down first or start from a corner and end up leaving a blank space for the mosaic?  I'm leaning toward putting the mosaic down first.  Of course, everything will be measured and test laid out before setting any tile.

Finally, this is a 3-season porch that gets a lot of sun and the area is large enough to need an expansion joint.  I have never done that before.  Any recommendations on the best way/product to use to make the joint?  Should the joint follow the long or short dimension of the rectangular porch?


I am not an expert tiler, but... (post #214861, reply #4 of 5)

I always lay my tile out so as to plan where full tiles will land.   I like full tiles at doorways and centered on the door if possible.  I like full tiles up against the front of bath tubs.  I like cut tiles around the edge of the whole room (unless you are lucky to have full tiles everywhere)  If cut tiles are on the perimeter, I like more than half tiles and not skinny tiles.  Obviously it is not possible to acheive all of these goals so you need to let some go.

However, once you have the plan, there really is no need to test lay the tile out on the floor.   I set tile in the middle and work out.  I like to set a straight row down the middle of the room and then add rows next to it working out.  This make is it easy to set all full tiles and then do all the cutting last.

I don't know what you are planning to use for a spaer under your mosaic. A thin ... anyting ... makes me nervous.  It seems hard to find something which yu can bond to teh underlayment and then bond the tile too. i think I would figure out where the mosaic goes and just mix a small amount of thinset and towel it on thin. I think you could figure out what an 1/8 looks like. You would need to do this to the exact size of the mosaic.  Let it dry and then set the mosiac in the same manner as other tiles. The border tiles could be done with back buttering and trial and error. Could be tricky.

Good luck.

You could set your field tiles in an L around the area of your decoration.  then set teh border tiles in the same L.  This would help you get the border tiles to the same height as the filed tiles.  Then do the scratch coat where the mosiac will go.  Then set hte mosic, rest of the border and then finish the floor.

Let us know what you decide to do and how it worked out.


Hi there,  Others have good (post #214861, reply #5 of 5)

Hi there,  Others have good suggestions.  What you want to avoid is setting very thin tile in lots of mortar.  That is always a mess and almost impossible to get flat.  Leaving the mosaic for last is best and building the underlay up in that section with a layer of 1/4" Hardie Backer works well sometimes height-wise.  If you only need to make up an 1/8" or so then a skim of thinset is your best option.  For small peice mosaics we like that skim to be super flat so we make a screed to ride across the top of the already set field tile.  I attached a quick sketch showing the basic setup.  Good luck. 

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