Expert Answers
Backer Board Ceramic and Porcelain Tile Expert Answers Grout installation Moisture Problems Mold sealers Showers Wet Areas
Can I install Onyx mosaics in my Shower that don't have grout joints?
4 thoughts on “Can I install Onyx mosaics in my Shower that don’t have grout joints?”
Comments are closed.
Yes, I’m using the Ditra on the wall so the mosaic tile will be even with the porcelain on each side.
The mosaics tiles I’m using have fingers on each end that interlock so there will be no room for grout unless I separate them a little but not sure if much point in doing that because of the many other smaller pieces within each tile that cannot be grouted. However, I’ve considered flexing each row open and running a bead of matching colored silicone between each row/pressing together and wiping off excess.
I am considering two options for installing the Ditra:
1) Drill small holes in each square of the Ditra before applying to the wall, so if water gets in, there will be way for water to drain out at bottom (there will be 1/8 gap between last tile and ledge at bottom), and install orange side facing out. This should work if there are any voids in the thinset between the mosiac and the Ditra.
2) Install the Ditra backwards since the white fiber backing is porous and if water gets behind the tiles it may be possible for any water can drain to bottom it there are any voids in the thinset.
Which of two options is best?
I was at tile store today and there is a new underlayment by Mapei called Mapeguard that’s same thickness as the Ditra. Have you heard of it and do you think it would be better to use than the Ditra behind the mosaic tiles?
The way you are suggesting in not using the products as they were designed and intended to be used, then that makes what you are doing an experiment. With experiments they may or may not work well, and there are no guarantees.
Our recommendations are always follow industry standards and the product manufacturers’ directions.
I’ve seen recommendations to use 5/8 backerboard/cement board when using onyx on floors. Does that mean even well designed, aged and mature concrete basement floors which should be stable after decades of aging (assuming not in earth quake zones).
There is no practical reasons to install a backer board over a concrete substrate. Backer boards are meant for surfaces that don’t have the more substantial concrete or mortar substrate.
If the concrete substrate is not flat or level or sloped the way you want it, by installing a backer board, then nothing has changed. Normally a concrete substrate not designed for a tile installation will be irregular. So to adjust it, all you need to do is scarify the concrete to remove any contaminates and open up the pores. Then apply a mortar bed or a patching mortar to adjust the surface to the intended flat finish.