Tile Installation: >> Irregular Stone and Ceramic Tiles (Special/Decorative)
For the setting of these products, the installer must insure that the proper bond coat is chosen. This can be accomplished using Manufacturers instructions and recommendations. The general principle of back buttering will normally take care of the coverage requirements.
This applies to stone and ceramic tile that has a back that is not in plane, like some Saltillo pavers. The danger lies in the application of too much Portland cement thin set mortars. In the case of Saltillo pavers, a skim coat to level the back of the tile is generally not too much. However, if the tile is out of plane and not equal in thickness, a medium bed thin set mortar might be a better choice. Again, check with the Manufacturers advice for the intended tile.
Some stone and ceramic tile is so irregular that it requires a special technique called "box setting." This is a useful technique for applying mortar to the back of the stone or tile. It is commonly used for applying the buttering mix to the back of glass mosaic tile. The process is simple.
The thickest tile is measured and the necessary depth of mortar is added. A wood box is constructed that is large enough to hold the largest stone or ceramic tile laid flat top down. The depth of the box includes the intended mortar depth and the tile thickness. Then the tile is laid in the box and the mortar is applied to the back. A straight edge is drawn over the tile cutting off the excess mortar.
Using this method, all of the tile that is prepared is the same thickness including the mortar bed. The substrate is then prepared to receive the tile in the appropriate manner. Meaning that a pure coat of Portland cement paste is applied to a mortar bed that is non-cured or Portland cement thin set mortar to a cured bed.
Please browse the CTIOA documents relating to special or decorative tile installations for more information on: