Installation Guide

THREE TYPES OF GLASS TILE; ONE THIN-SET MORTAR SOLUTION
The ANSI A137.2 standard identifies three different types of glass
tile: cast glass tile, fused glass tile, and low-temperature-coated
glass tile. It also defines large format glass tile as any tile with
dimensions greater than 3" x 3". TCNA recommends the use of
a high-performing thin-set mortar meeting the requirements of
ANSI A118.4 and with bond strength greater than 400 psi per
section 5.2.4. Because of the smooth surface of the glass tile, it
is important to use a premium, high-performance thin-set mortar
with higher polymer content. The polymer enhances the
bonding to the smooth glass. CUSTOM’s Glass Tile Premium
Thin-Set Mortar meets this requirement with high polymer
content and a polymer compound that was selected for its
higher bond strength to glass surfaces.
Be aware that there are also a large number of glass tile products
available through small boutique glass tile manufacturers that
do not meet the requirements of the ANSI A137.2 standard.
It is important that each of these be assessed for suitability.
Backings, either metallic or painted, are not compatible with
cement-based thin-set mortars. The alkali in the cement can
react with the backing in wet environments and loosen the
mortar’s bond to the glass tile. Any glass tile that does not
conform to ANSI A137.2 should be tested with the thin-set mortar
prior to installation. Also, some mosaic glass tiles are mounted
on a mesh to simplify their installation. It is important that the
adhesive used to hold the mesh on the back of the tiles resists
water and will be compatible with the cement mortar used.
Many times the mesh is not bonded well, which can result in
loose tiles in the installation. If there is doubt about a glass tile,
the Custom Building Products Technical Service department is
available by phone to answer any questions (800-282-8786).
While installation failures with glass tile installations are
uncommon, when they do happen they are usually related to
exposure to sunlight or other forms of heat. The coefficient of
thermo expansion and durability of glass tile is quite different
than that of the cement based thin-set mortar and ceramic tile.
The polymer in the flexible thin-set mortar will absorb some of this
movement, but it is more critical with glass than with ceramic tile
to incorporate soft movement joints in the glass tile assembly.
This will allow the tile to expand as it is heated and prevent
cracking of the glass from compression. The TCNA movement
CUSTOM's Glass Tile Premium
Thin-Set Mortar meets the TCNA
(A137.2) requirement for a
high-performing thin-set mortar.
Technical White Paper
GLASS TILE