Glass tile has been with us for many years, however, nowhere near the level at which it is today. The amount of colors, the different sizes, the unique shapes and the opportunities it offers for creative design, all are growing at breakneck speed.

Whereas the popularity of glass tiles is increasing, there is a fear 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. When glass tile is installed professionally, problem-free results can be achieved. Glass tile installation professionals have a great understanding of the nuances of glass tile applications. Special and unique installation techniques may be required to install some of the newer glass tile products. Here are some answers to frequently asked questions relative to glass tile installation.

What are the concerns relative to installing 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 mortars. 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. In addition, 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. Installers have to remember that working with glass is not like working with typical ceramic and porcelain tile. Glass tile applications are works of art. More time and concentration is required when working with glass. Precision is the key to a beautiful installation. I am continually impressed with the high quality work that glass tile professionals can put together.

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. In addition, some glass tile manufacturers may have specific installation requirements for the type and placement of waterproofing membranes in glass tile applications. Consult with the specific glass tile manufacturer for more information on this.

Are there special techniques for installing glass tiles?

There are two methods for installing glass mosaics:

One Step Method - thin-set and grout in one-step

Using a liquid latex thin-set mortar designed for this purpose, colored sanded grout is mixed with the latex in lieu of a standard thin-set mortar. This combination of material now becomes a "colored" thin-set mortar. 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 the trowel ridges are flattened. Next, additional thin-set mortar is combed onto the backs of the tile sheets, (in effect, filling the grout joints with the 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.

Conventional Two-step method

For rear mesh-mounted or paper-face mounted tile, spread the latex fortified thin-set mortar (generally white in color) using a 3/16" square notch trowel, onto the substrate, and then flatten the trowel ridges. Next, additional thin-set mortar is combed onto the backs of the tiles. Then, carefully set the tiles 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).

Techniques for installing large format glass tiles;

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 and 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 and then flatten the trowel ridges. The tiles should also be back-troweled with additional thin-set mortar to ensure that the 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.

Some glass tiles have unique backings and mountings. Many of these special backings/mountings require the use of an epoxy based thin-set mortar. In some rare cases, they may even require the use of a silicone adhesive. It is always best to consult with the glass tile manufacturer and/or distributor for their special installation recommendations.

Movement joint placement is also a critical component of a successful glass tile installation. To ensure success, correct movement joint design, placement and construct is critical. A silicone sealant or another suitable flexible sealant should be used to treat these joints.

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 and straight cuts.

3/16" (4.5mm) Square notch trowel - is a great trowel for installing glass mosaics - however, it is hard to find. You may have to special-order this tool.

For large format glass tiles -

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, some manufacturers recommend 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" {125mm} 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 ?" (6mm) 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. Some tempered glass tiles cannot be cut at all. The manufacturer may have to provide non-tempered glass for cuts. 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 may 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. However, consult with the glass tile manufacturer for their thoughts on this process. They may have specific grouting recommendations for the unique application that is being done.

Installers can also use latex fortified 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 field tiles, is nothing to be afraid of. Glass tile is so beautiful, that if every project is installed correctly, the outcome should ultimately be a brilliant work of art!