Gauged porcelain tile panels/slabs (GPTP) have gained popularity as an interior finish and as an exterior cladding. ANSI A137.3, American National Standard Specifications for Gauged Porcelain Tiles and Gauged Porcelain Panels/Slabs, defines GPTP as a ceramic tile of size, greater than or equal to 1 m2 (10 sf); however, GPTP can range upwards in size to more than 5 m2 (53 sf) and is currently manufactured in lengths above 3 m (9 ft). Commonly offered in nominal thicknesses of 6 mm (0.2 in.), 12 mm (0.4 in.), and 20 mm (0.7 in.), interior applications of GPTP are typically specified to be fully adhered to an approved backer board via a thin mortar setting bed.
Considering GPTP is a relatively thin material compared to its overall dimension, its units are subject to bending fracture during movement and setting and, as such, require a suction-cupped frame for proper handling. The recommended bonding mortar also needs to be applied in a specific manner using specialized trowels that support ridge collapse and ensure proper contact of the bonding mortar to the substrate and tile panel/slab; bonding mortar needs to be applied to both contact surfaces in the same manner. Once set in position, GPTP need to be vibrated in the short direction using high speed sanders with non-abrasive pads or other padded equipment. Vibration is performed from the center of the panel toward both edges, to force air out from between mortar ridges and maximize edge-to-edge mortar coverage. Lippage control systems are required for GPTP with any side greater than 990 mm (39 in.).
Considering GPTP cannot be shifted into position during placement, or periodically removed to confirm if the percentage of mortar contact meets the minimum requirement of 80 percent for walls and 85 percent for floors, industry associations have developed standards to ensure proper installation.
The American National Standards Institute (ANSI) and the Tile Council of North America (TCNA) have issued a joint publication titled, “American National Standard Specifications for Gauged Porcelain Tiles and Gauged Porcelain Tile Panels/Slabs (Materials and Installation Standards),” which is intended to be included or referenced in project specifications and/or contracts. This publication includes the following three GPTP standards:
- ANSI A137.3, which provides minimum physical properties and grading procedures.
- ANSI A108.19, which provides interior installation procedures and requirements using thin bed methods.
- ANSI A108.20, which provides exterior vertical and overhead installation procedures and requirements using thin bed methods.
Codes and other industry standards, such as the International Building Code (IBC), chapters 14 and 21; ANSI 108.5; The Masonry Society standard, TMS 402, sections 12.1 and 12.3; and the “TCNA Handbook for Ceramic, Glass, and Stone Tile Installation” also address adhered veneer systems regardless of panel size.
While these codes and standards have yet to reference the most current ANSI standards specific to GPTP, they are based on a minimum adhesive mortar contact between the tile and substrate of 80 percent (note that more stringent requirements exist for exterior and shower applications) and a minimum gross shear bond strength of 344 kPa (50 psi).
Although the list of requirements for installing GPTP is long, ensuring the maximum coverage of the bedding mortar is critical for a successful installation. Understanding and following these standards will help avoid undesirable conditions.
Jeffrey Sutterlin, PE, is an architectural engineer and associate principal with Wiss, Janney, Elstner Associates (WJE) in Princeton, New Jersey, office. He specializes in investigation and repair of the building enclosure.
He can be reached at email@example.com.
David S. Patterson, AIA, is an architect and senior principal with Wiss, Janney, Elstner Associates (WJE) in Princeton, New Jersey. He specializes in investigation and repair of the building envelope. He can be reached at firstname.lastname@example.org.
The opinions expressed in Failures are based on the authors’ experiences and do not necessarily reflect that of The Construction Specifier or CSI.