Ten or fifteen years ago, when nearly all commercial glass tiles were 1/8″ thick, installers had a recurring problem of having to fit thin glass tiles into a thicker ceramic tile installation. Today, many glass tiles are produced in thicknesses matching ceramic tile, but there will always be cases when the problem of various tile thickness needs to be addressed.
Thinset, as the name implies, has been designed to be applied in a thin layer. If applied in a thick layer it will dry on the outside only, leaving the inside soft and wet for a long time. If glass or glass tile is stuck to the outside of this slowly shrinking blob, the tile can crack during the long drying process.
Dry pack mixture is designed to be more stable and will not shrink and crack (or at least, it will shrink much less than a thick layer of thinset adhesive). To do this properly you would have to partially fill the space for the glass tile with dry pack, let that dry and finally install the glass tile with a good flexible, rapid setting, white thinset that has been tested with glass tiles (such as Mapei’s Granirapid).
A better method is to install a flexible matting to the substrate, then thinset the thinner glass tiles to it. There are at least two methods of achieving this.
One is take waterproof membrane like Ditra , cut it into strips, and use that to support rows of your relatively thin tiles. Another method is to use a plastic strip, that either by accident or design provides thickness as well as grip for the thinset to adhere to. Our sponsor includes a specialized plastic strip with each order; it may be the simplest, low-cost solution out there.
– John Dumbrille
Information on these pages is offered as a background and guideline. No warranty is implied. Always check with your manufacturer for an installation method that they will stand behind.