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Mesh-Backed Stone and Tile White Paper (cont.)

acteristics for this man-made product are more consistent 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 manufacturer for recommendations on usage and installation method, bearing in mind that instruc tions 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 fiberglass mesh and/or resin back ing early in the design and construction process. • Verify suitability of the stone or porcelain for the particular ap plication. • Make appropriate setting material choice based on the actual backing and site conditions by involving the setting material manufacturer of choice. • Ask for written installation instructions from the supplier on any stone or porcelain with epoxy, resin or mesh backing. • If others supply stone, contractor should add a note to all quotes for cement based mortar installations that pricing is not valid for fiberglass mesh and/or resin backed stones. • During installation, verify the integrity of the bond between fiberglass mesh and/or resin to the stone by checking a min imum of one piece per box. If adequate bond does not exist, do not proceed with installation until appropriate remedial measures have been prescribed. • Throughout installation, ensure proper trowel size and tech niques are utilized to ensure adequate coverage. Although the application of fiberglass mesh and/or resin rein forcing has been practiced for quite some time, as its use con tinues to escalate, the discussion is likely to expand as well. As demand for these types of products increases and the sup porting technology continues to grow, further development of industry standards is in the best interest of all concerned. Keep informed of the latest developments via your stone and tile sup pliers, setting material manufacturers, industry publications and trade show education. By combining the best practices discussed earlier in this paper and ongoing developments, you have a better chance of avoiding costly installation errors.

Communication concerning fiberglass mesh or resin backed stones presents a challenge to the industry. The timing of when the contractor is informed of the reinforcement on the stone product is critical. If a contractor learns of the requirements to either use epoxy-based setting material or remove the rein forcement after contracts have been written, the opportunity to adjust the bid price to reflect the increased costs has passed. When working on a project utilizing natural stone, it is advisable to discuss with the supplier the possibility of the stone arriving with fiberglass mesh or resin backing so proper arrangements can be made. The application should be discussed, and suit ability should be determined for areas such as showers, steam showers, submerged and exterior applications. Fiberglass mesh or resin backed stones should not be used in exterior freeze-thaw applications. Setting material options should then be reviewed. Epoxy mortar is the fall back option, but there is also the possibility of suc cessfully using a primer developed for this application in con junction with a cementitious mortar. In all cases, it is strong ly 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 recom mendations. Fiberglass mesh is also commonly used as a netting for mosa ics. 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 installation, 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 validate that proper bond can be achieved to the specif ic finish. It is incumbent upon the installer to verify the proper bond to a mosaic sheet, perhaps by producing a small mock up. 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 char

NTCA Reference Manual | 2024 / 2025

Chapter 6 | Natural Stone Installations

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