lizing natural stone, it is advisable to discuss with the supplier the possibility of the stone arriving with fiberglass mesh or resin back- ing so proper arrangements can be made. The application should be discussed, and suitability should be determined for areas such as showers, steam showers, sub- merged and exterior applications. Fiberglass mesh or resin-backed stones should not be used in exte- rior freeze-thaw applications. Setting material options should then be reviewed. Epoxy mortar is the fall-back option, but there is also the possibility of successfully using a primer developed for this application in conjunction with a cementitious mortar. In all cases, it is strongly advised to involve the setting material manufacturer in the discussion early on in the process, and potentially send them stone samples for testing per ASTM C482 and product recommendations. Mesh-backed mosaics Fiberglass mesh is also common- ly used as a netting for mosaics. Fiberglass is preferable to paper mesh, which should not be used in wet areas. Ideally, the correct amount of adhesive is used to adhere the mesh to the mosaic, facilitating transport and installa- tion, while still allowing setting material contact to the stone or ceramic. If too much adhesive is used, bond to the actual mosaic may be compromised. The smaller the mosaic pieces, the greater the likelihood there is too much adhesive and not enough clean stone or ceramic surface area for bonding mortar. For glass mosaics, request ANSI A137.2 testing, which should val- idate that proper bond can be achieved to the specific finish. It is incumbent upon the installer to verify the proper bond to a mosa- ic sheet, perhaps by producing a small mock up. Fiberglass-backed thin porcelain tile Thin porcelain tiles (6mm or less) have grown in prominence in the marketplace, and in some cases also utilize fiberglass mesh backing. However, manufacturing standards and general characteristics for this man-made product are more con- sistent and predictable than with natural stone. As with natural stone with fiberglass mesh and/or resin backing, it is advised to consult with the specific product manufac- turer for recommendations on usage and installation method, bearing in mind that instructions can vary from product to product. To increase the likelihood of a successful application, as well as reduce the risk to the installing contractor, it is suggested that this list of best practices is followed when installing fiberglass mesh or resin backed stone or porcelain: • Discuss the possibility of fiber- glass mesh and/or resin backing STONE ––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 86 TileLetter | December 2017