Problem with mesh backed glass mosaic tiles installation

Glass tile is increasingly favoured by designers and homeowners seeking a clean, vibrant aesthetic. This trend has led to a rise in glass tile installations in areas traditionally dominated by ceramic tiles. To address this shift, the Tile Council of North America (TCNA), in collaboration with glass tile manufacturers, has established a new standard for glass tile, known as ANSI A137.2.

Now a days not only glass, you can find you will find mosaics made out of glass, marble, travertine, pebbles, metals, ceramic, porcelain, and blended glass & stone too in the market.

The ANSI A137.2 standard classifies glass tile into three types: cast glass tile, fused glass tile, and low-temperature-coated glass tile. It designates large format glass tile as any tile larger than 3" x 3". The Tile Council of North America (TCNA) advises using a high-performance thin-set mortar that meets ANSI A118.4 standards and has a bond strength greater than 400 psi, as per section 5.2.4. Due to the smooth surface of glass tile, it is crucial to use a premium, high-performance thin-set mortar with a higher polymer content to enhance bonding. CUSTOM's Glass Tile Premium Thin-Set Mortar meets this criterion, featuring a high polymer content and a specially selected polymer compound for superior bond strength to glass surfaces.

While installation failures with glass tile installations are uncommon, below are some of the points with some guidelines, I wish to provide:

1. When exposed to sunlight or other heat sources, glass mosaic tile systems experience different rates of thermal expansion and durability compared to cement-based thin-set mortar. Although the polymer in flexible thin-set mortar can absorb some of this movement, the disparity is more significant with glass mosaic tiles, which can result in bond failure.

  

2. Mosaic tiles are typically attached to fibreglass mesh sheets, which keep the tiles aligned and make installation easier than placing each tile individually. Despite this, careful handling of mosaic tile sheets is necessary, as they can be tricky to work with at times. 

  

Adhesives commonly used to bond reinforcing mesh to tiles or stone include  PVA (Poly Vinyl Acetate), polyester resin, epoxy, or urethane-based coatings. Although PVA is usually resistant to water solubility, the absence of standardized guidelines can result in some adhesives loosening or dissolving when exposed to mortars or water. These materials soften and weaken when exposed to constant moisture, posing a significant problem for ponds and swimming pools. In these settings, while the tile adhesive stays bonded to the mesh, the mesh can detach from the tile, causing itface-mounted to fall off. 

Polyester resin-backed tiles can sometimes be effectively bonded using high-performance, polymer-modified cement mortars. However, due to variations in resin composition, not all types of resin backings will consistently perform well.

3. The recommendation is that mesh glue should not cover more than 10-15% maximum of the tile face-mounted back face, if not, failure will happen.

4. Since glass tiles are typically sold and installed as pre-mounted assemblies, whether it is face-mounted or back-mounted is a crucial consideration. According to ANSI A137.2 recommendations, glass tiles intended for submerged applications should be face-mounted. This helps prevent issues arising from inadequate coverage or failures in backing materials. 

5. Use paper faced glass mosaic tiles 

 

6. Use thin plastic face-mounted mosaic tile sheets

7. You can also go with Dot-mounted glass mosaics tile sheet:

8. Use tiles fixed with epoxy or PU or any glue that is non-water soluble in water/chlorinated water with less than 10% coverage at the back of the tile sheet.

9. You need to remember the below points of coverage at different are of application. AS39581.1-2007 Ceramic Tiles, Part 1: Guide to the Installation of Ceramic Tiles, was introduced and became effective. This standard specifies minimum adhesive bed coverage requirements for tile faces and substrates in various applications under Clause 5.6.4.2:

Internal residential walls: 65%

Residential floors: 80%

Commercial and industrial walls: 80%

Commercial and industrial floors: 90%

Wet areas: 90%

Swimming pools: 90%

External walls: 90%

Exterior floors, decks, and roofs: 90%

10. Conduct a test for 48-hour water immersion, with the selected glass mosaic tiles at site level, if the tiles are getting de-bonded, or mesh glue is not dissolving in water, you can use the tile sheet or else, rejection has to be made.

11. Grouting glass tiles requires meticulous attention to detail because their thinness can cause the adhesive to fill the joint gaps. The installation process is slow and labour-intensive, especially for intricate designs that demand additional time and skill. Any imperfections will be visible due to the transparency of the tiles. For best results, use cement polymer-based grout mixed with latex or opt for epoxy grout.

12. Use suitable hydrostatic-resistant waterproofing membranes for the structure. 

13. For sub/underground structures, always go with negative waterproofing treatment. As all waterproofing treatments, are not able to resist negative hydrostatic pressure.

14. every day is a new day, technology will keep on changing, always, consult the Technical support Manager for suitable adhesives to be used in your project.

All details are based on my personal experience and information gathered from various sources including Google and other websites.

You are welcome to add your knowledge in the below comment.