Installation of Glass Tile over a Sealed Shower System
The Schluter-Shower System is a waterproofing system for showers, steam showers and tub surrounds. It is used to create a waterproof and vaportight enclosure prior to setting the tile. If the KERDI is installed properly (i.e., Schluter ALL-Set/Schluter SET or non-Schluter branded unmodified thinset thin-set mortar with 2" overlaps, etc.) in conjunction with the KERDI-DRAIN, KERDI-LINE and VARIO, then Schluter Systems will guarantee a waterproof and vaportight enclosure.
However, Schluter-Systems cannot guarantee the performance of the glass tile over KERDI.
The KERDI membrane features a fleece webbing that will accept a bond to Schluter modified and non-modified mortars, and any commercially available premium grade non-modified thin-set mortars used to install tile. Furthermore, we recommend relatively stable backings for KERDI in our Handbook to promote successful tile installations. We know that ceramic, porcelain, and stone tiles can be bonded with ANSI A118.1 unmodified thin-set mortar (excluding moisture-sensitive stones and resin-backed tiles as noted in the limitations in the Shower System Handbook), and that the mortar will cure properly between the tiles and the membrane. As such, when it comes to use of competitive branded mortars, we can be confident making the recommendation to use unmodified thin-set mortar to bond the tile as seen in the Handbook.
However, glass tile varies significantly from manufacturer to manufacturer and the glass tile manufacturer should be consulted prior to installation to determine the appropriate setting material.
Thus, we recommend the following:
- Use Schluter mortars (ALL-Set modified or SET unmodified), or non-Schluter branded unmodified thin-set mortar to install and seam Schluter-KERDI.
- Confirm with the glass tile manufacturer (1) that the glass tile is suitable for use in wet areas and (2) can be installed directly over a bonded waterproof membrane such as Schluter-KERDI.
- Check with glass tile manufacturer and setting materials manufacturer for setting materials recommendations.
Be sure to provide relevant information to the setting materials manufacturer, including tile manufacturer, description of backing, etc. If a modified thin-set mortar is required to set the glass tile, extended curing times may be required. Ask the setting materials manufacturer for required curing times when the modified thin-set mortar is used between a waterproofing membrane and the glass tile, based on the size of the tiles (e.g., 2" x 2", 3" x 3", etc.). The setting material manufacturer must confirm that the thin-set mortar will gain strength and remain stable in this type of application (e.g., shower, steam shower or tub surround).
