Glass tiles are a popular alternative to ceramic or stone tiles, and use the same basic installation methods. There are several different types of glass tile available. Glass mosaic tiles, the most familiar, are 1” or 2” tiles face-mounted on sheets, uncoated glass tiles larger than 2” x 2” and coated glass tiles larger than 2” x 2”. Glass tiles share some similarities with ceramic tiles: The thin decorative surface of glazed wall tiles is glass, and the entire body of porcelain ceramic tiles is vitrified like glass. Nevertheless, glass tiles require careful detailing for a successful, long-lasting installation.
Of the three major types of glass tiles, those larger than 2” x 2” and those with coated backs may be difficult to bond properly to either dry or wet-area substrates – even though glass, by itself, is an ideal material for use in wet areas. Back-coatings may be nothing more than regular paint, but coatings may also be made from durable, water-resistant materials. Some are made of colored glass fused to the backs of the tiles, and the backs of some glass tiles may be coated with reflective films. Regardless of the composition of the coating, following the glass tile manufacturer’s adhesive recommendations is essential to eliminate any compatibility issues.
The same recommendations apply to non-coated and mosaic glass tiles. Plain glass tiles may not have any compatibility issues, but coated or not, glass tiles may be difficult to bond properly. Additionally, since uncoated glass tiles are transparent, how an adhesive is applied is an important consideration for two reasons: Notch trowel marks can be seen through the tiles, and if water or moisture seeps into the resulting adhesive voids, mold can grow and give the glass tiles an unsightly appearance that is impossible to remove.
As with any tile – ceramic, stone, or glass – using the right size notch is one of the most important parts of a tile installation for either a dry or wet area. Eliminating any voids behind a tile helps prevent cracking and the appearance of mold, and on exterior installations minimizes freeze/thaw problems. The best way to do this is to maintain the industry-recommended minimum 95% adhesive coverage (the industry minimum for tiles installed in dry areas is less, but installers will do well to stick with the 95% minimum). While 95% is good, when you can see right through the body of glass tiles, even the slightest voids will be visible.
The type and color of the adhesive are also important. Use whatever the glass tile manufacturer requires, but if nothing is specified, a high-strength latex or epoxy thinset should be used. As for color, to help produce a bright appearance, use white thinset because grey tends to dull down the color.
Next, the mosaic sheets are installed (Photo 2) and positioned so that the joints between sheets are uniform and match the grout joint width (Photo 3). Once positioned, the sheets are flattened with a beating block and hammer (Photo 4). This step not only smoothes the surface of the sheets, but ensures that each tile is fully bedded in the adhesive. At this point, the adhesive is allowed to harden and cure.
If you follow all of these steps, you will create a beautiful, durable installation. It can only elevate your career to learn how to install glass tile correctly.