Installer Briefing: Don’t Be Afraid of Installing Glass Tile
May 1st, 2005


By Arthur Mintie
May-June 2005

Glass tile has been with us for many years, but nowhere near the level at which it is today. The number of colors, the different sizes, the unique shapes and the opportunities it offers for creative design are all growing at breakneck speed. Robert E. Daniels, Former Executive Director of The Tile Council of America, corroborates this, saying, “From anecdotal evidence, we know that ‘specialty’ tiles are growing in volume at a rapid pace. This category would include glass tiles. Glass tiles can go virtually anywhere and are definitely popular in high-end residential as well as most commercial applications involving the retail public.”

Whereas the popularity of glass tiles is increasing, there is a discomfort factor with some contractors. Familiar with installing traditional ceramic tile via traditional methods, they view today’s glass tile as a foreign element, which requires special procedures relative to installation. This small group really has nothing to be concerned about. Glass tile should be installed professionally and problem-free with every project, providing the contractors are knowledgeable relative to certain techniques. Here are some answers to frequently asked questions relative to glass tile installation.

Why are contractors afraid to work with glass tiles and glass mosaics?

Since glass is impervious, it requires good mortar mixing and mortar spreading techniques as well as consistent and accurate tile placement. Additionally, most installers have had bad experiences with glass tiles losing bond, generally because they did not use quality liquid latex fortified Portland cement mortar. Impervious tiles like glass require a thin-set mortar with tenacious bond strength. Simple dry-set mortars and most low-end, multi-

purpose thin-set mortars do not have the bond strength to ensure a good “grip” to the glass surface. Also, most of the glass mosaic tile made in the past was paper-face mounted. Working with paper-faced tiles requires more skill and accuracy than other type of mosaic tile applications where the tile is generally back dot-mounted or rear mesh-mounted. Most installers have had bad experiences with these types of applications and, therefore, they shy away from installations similar to these.

When installing glass tiles in “wet areas,” what are some of the considerations?

For areas where damage can occur to adjacent or spaces below the tile application (e.g. bathrooms, showers, countertops, etc.), installers should use a waterproofing membrane below the tile installation. Consult with the manufacturer of the tile installation materials to specify a compatible waterproofing membrane system relative to the buildings substrate, which could consist of a number of different materials.

What are the special techniques for installing glass tiles?

There are two methods for installing glass mosaics:

A. One Step Method—Thin-Set and Grout in one step

If the glass mosaics are paper-face mounted, installers may use the one-step method of installation. In this method, the thin-set mortar should be spread on the substrate with a 3/16″ square notch trowel and then additional thin-set mortar is combed onto the backs of the tile sheets, (in effect, filling the grout joints with the thin-set mortar).

Using a liquid latex thin-set mortar designed for this purpose, contractors should then mix in a Sanded Grout and use this combination of material as a “colored” thin-set mortar. The tile sheets should then be placed into the freshly spread thin-set mortar spread onto the surface and tapped into place with a beating block or rubber grout float. Via this technique, the contractor will have installed and grouted the tiles in one application. Once the tiles have reached an initial set, then the paper facing should be peeled off. After the tiles are set firm, the same “colored” mortar should be used to touch up the grout joints where the sheets meet and for any other pinholes, imperfections, etc.

B. Conventional Two-Step Method

For rear mesh-mounted or paper-face mounted tile, spread the thin-set mortar (generally white in color) using a 3/16″ square notch trowel, onto the substrate. Then, carefully set the sheets into place and tap with a beating block or rubber grout float. (For paper face-mounted tiles, once the tiles reach an initial set, peel off the paper.) Once the tiles are set firmly in place, contractors then can grout all tiles in the normal fashion.

In either method used, installers should be as accurate as possible in placing the tiles. Rear mesh-mounted tiles are more forgiving in that the tiles can be more easily adjusted (if necessary.)

Installing glass tiles (not mosaics)

Use high-quality liquid latex fortified thin-set mortar (generally a white thin-set is used). If installing for walls, start from the bottom up—use a supporting ledger board fastened to the wall, in order to support the weight of the installation. Spread the thin-set mortar, using a notch trowel to ensure maximum coverage. The tiles should also be back-troweled with additional thin-set mortar to ensure that the mortar’s trowel lines do not show through the glass tiles.

The tiles then should be tapped into place, with either a rubber grout float or a rubber mallet. For larger format glass tiles, layout can make the difference in the final appearance. Spread out the work to visualize the finished job. This is done so that cuts ultimately are minimized. The more full tiles one sees, the better the installation appears.

Special Tools Required:

For Glass Mosaics

Glass Mosaic Tile Nippers—a special type of nipper that has cutting wheels on both nipper arms give this tool the ability to cut through the glass and make very accurate, very straight cuts.

3/16″ Square notch trowel—a great trowel for installing glass mosaics—however, it is hard to find. You may have to special-order this tool.

For Glass Tiles (Not Mosaics)

Conventional tools are required as needed.

Cutting Glass Mosaic Tiles:

Use the Glass Mosaic Tile Nipper to make accurate cuts for glass mosaics.

For larger format Glass Tiles, Villiglas® recommends the following cutting and fitting guidelines:

Straight cuts: Score and snap with hand cutter, newer 8 mm carbide wheel housed in a ball bearing casing. The lighter one scores (applying the least amount of pressure to score the tile) the better it snaps—the glass tile does not break because of the force; it breaks because of the heat generated from the carbide wheel.

Corners: Nip with nippers.

L-shaped cuts:

(a) Marble diamond bit (5″ wheel) on an electric hand grinder. Using masking tape over cutting line may minimize chipping.

(b) Water jet.

(c) Wet saw (may result in chipping top and bottom of tile causing an irregular edge and some color loss) is only recommended when cut area will be covered by more than ¼” of switch plate or molding. Using masking tape over the cutting line may minimize chipping. Wet saws, generally, are not recommended for cutting high quality glass. High-quality glass tile has a manufacturing process resulting in tile with breaking strength that exceeds 970 lbs. per sq. inch. Most wet saws cannot cut the tile without excessive vibrations, which cause chipping.

Drilling: Holes may be drilled in high-quality glass tile using a wet drill process.

Edge finishing: It is recommended to use a rubbing stone or Dremel® (rotating electric sanding/smoothing device).

What type of grout should be used when installing glass tiles?

For best performance in all types of installations, and to get a grout joint as dense and easy to clean as the glass itself, I recommend using an epoxy grout. (NOTE: Epoxy grout can only be used in the conventional two-step method of tile installation). Generally, epoxy grout is best for wet area applications.

Installers can also use a non-sanded or sanded grout depending on the grout joint texture desired. The non-sanded grouts will have a smoother texture, while the sanded grouts can look a little more rustic. Also, note that most sanded grouts will achieve higher strengths than non-sanded grouts.

There is more that could be written here, but the main point overall is that installation of glass tiles, whether they are mosaics or larger format units, is nothing to be afraid of. Glass tile is so beautiful, that if every project is installed correctly, the subsequent outcome should ultimately be a brilliant, work of art!

Arthur Mintie is Technical Services Supervisor at LATICRETE International, Inc. Prior to working for the firm, he was a ceramic tile installation professional for over a decade. He may be contacted via phone at 800-243-4788 ext. 326 or via email at

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