Coverage calculation: A stan- dardized evaluation to calculate coverage was developed. ANSI A108.19 states, “In any single square foot under the embed- ded tile, coverage... is calcu- lated by measuring the voids and the marked off square foot, and dividing by 144 square inches (929 square cm) where the dry set mortar is not in full contact from the back of the tile to the substrate.” Substrates: Standardized suit- able substrates for the installation of gauged porcelain tiles and tile panels/slabs are mostly consistent with those of traditional tile, with the exception of direct bonding to plywood floors, which requires the use of a mortar bed or speci- fied backer board and referenc- ing floor rigidity requirements established by building codes and other widespread industry specifications. Applicable to all substrates, ANSI A108.19 details required flatness as maximum deviation of 1/8” over 10’ (3mm in 3m) from the required plane when measured from the high points in the surface. Material handling: Qualified labor and other provisions also taken into account through dis- cussion and A108.19 standardiza- tion were adequate jobsite storage, space to maneuver panels, preven- tion of damage while handling and time for mortar curing. Another critical aspect of ANSI A108.19 involves usage of properly qualified installers who are equipped with proper tools and have acquired sufficient product knowledge and installation experience. There are several other key pro- visions contained within ANSI A108.19, including grouting, workmanship, movement accom- modation, and maintenance, completing a very comprehensive specification for how to install products defined by ANSI A137.3. For the full paper, including foot- notes, go to https://bit.ly/2GyzZlk. TECH TALK –––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Visual examination of mortar voids under clear Plexiglas with marked square-foot partitions. 66 TileLetter | April 2018