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Despite
wind, weather, and extreme heights, the Des Moines Marble and Mantel Co. was
able to install 1.8 million pieces of 5/8” x 5/8” mosaic glass tiles on the
118-foot Paragon Prairie Tower. |
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The amount of colors, the different sizes, the unique shapes
and the opportunities glass tile offers for creative design, all are growing
significantly. Clearly, glass tile should be installed professionally and
problem-free with every project, providing that contractors are knowledgeable
relative to certain techniques.
Since glass is impervious, it
requires good mortar mixing and mortar spreading techniques as well as
consistent and accurate tile placement. Additionally, some 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, shied away from installations similar to these.
For areas where water damage can
occur to adjacent or spaces below tile application, use a waterproofing
membrane below the tile installation. Consult with the installation materials’
manufacturer to specify a compatible waterproofing membrane system relative to
the buildings substrate.
There are several basic methods for
installing glass mosaics:
One Step Method: thin-set and
grout in one step. If glass mosaics are face-mounted, installers may use this
technique. 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. Tile sheets should 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. The contractor will then have
installed and grouted the tiles in one application. Once tiles have reached an
initial set, paper facing should be peeled off. After tiles are set firm, the
same “colored” mortar should be used to touch up 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 thin-set mortar
(generally white in color) using a 3/16” square notch trowel, onto the
substrate. Then, carefully set sheets into place and tap with a beating block
or rubber grout float. Once the tiles are set firmly in place and paper is
peeled off, contractors then can grout all tiles in the normal fashion.
Techniques for installing glass
tiles (not mosaics):
Use high-quality liquid latex
fortified thin-set mortar. 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. Next, knock down the trowel ridges to ensure a
continuous coating of thin-set mortar. Tiles should also be back-toweled with
additional thin-set mortar to ensuring 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.
For best overall performance, 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. These are some general guidelines that can be used to
install glass tile. However, since there are so many types of glass tiles
available in the market, follow the installation instructions of the specific
glass tile manufacturer concerning technique, surface preparation, membrane use
and placement, adhesive mortar type, grout type and movement joint design and
placement.