LARGE-FORMAT TILE –––––––––––––––––––––––––––––––––––––––––––––––– only. I suggest checking with the gypsum board installation contractor for this project. They will be familiar with the requirements of GA-216 and GA-214 and able to tell you whether those requirements have been met on this particular installation. “In addition, the substrate flatness must meet the standard of 1/8˝ in 10´ for installation of large-format tile to ensure proper bond coat cover- age and a finished surface within tolerance for lippage standards,” he added. “FYI – GA-216 and GA-214 include nominal tolerance require- ments for in-plane alignment of stud faces before gypsum board is installed. This is critical to ensure a flat substrate meeting the 1/8” in 10’ for a large format tile installation is achieved.” Heinlein explained, “Since you are tiling in a commercial appli- cation, the Environmental Exposure Classification needs to be considered. Method W243 provides a COM 1 (Commercial Dry) exposure rating. That means this method is accept- able for tile surfaces that will not be exposed to moisture or liquid, except for cleaning purposes. Examples of COM 1 exposure include: dry area ceilings; soffits; decorative/accent walls; corridor walls. Commercial cleaning and maintenance practices typically generate greater water expo- sure than residential practices. “I suggest that a greater exposure rating for this area may be needed,” Heinlein continued. “You mentioned fiber cement backer board. Method W244F provides a COM 1, 2 or 5 MAPEI Ultralite™ S2 is a pre- mium-grade, lightweight, sin- gle-component, thin-set mortar that is ideal for thin-tile applications. This high- performance, h i g h l y - deformable, p o l y m e r - m o d i f i e d mortar is formulated with Easy Glide Technology™ for ease of applica- tion. MAPEI Ultralite S2 features a long open time, extended cov- erage and superior transfer prop- erties to enhance back-butter- ing, which is ideal for thin por- celain tiles as well as ceramic tiles and stone material. MAPEI Ultralite S2’s unique Ultralite Technology™ provides twice the coverage of a standard thin- set mortar per pound/kg and is TCNA Green Squared Certified® for use on sustainable projects. mapei.com 58 TileLetter | September 2017