proper slope, mortar coverage and troweling techniques must be used to prevent any water accumulating underneath the tile surface.” Steve Young of Steve Young & Associates, White Plain, Ga., concurred. Heinlein provided the contrac- tor with documentation they could present to the client to address a similar problem on other showers on a current project. “Page 252 of the 2018 NTCA Reference Manual is a sample letter (with photos) to prospective clients regarding this matter,” Heinlein said. “I have also spoken with James Woelfel, Chairman of the NTCA’s Technical Committee. James concurs with Martin’s assessment in that it is likely the troweled mortar ridges under the tile on the pan are not fully collapsed. This allows water to run under the tile through the bond coat and on top of the waterproofing membrane until it hits the drain assembly, where it then begins to pool in the uncollapsed ridges and is further absorbed by the tile. Additionally, there are some concerns that the stone could be sourced from quar- ries around the world and may be a similar species as Calacatta Marble, but may not have the same proper- ties as Calacatta Marble.” The contractor was elated at the information and solution to the mystery. “Thanks so much all!” she said. “We are so grateful to have such accessible expert resources!” STONE –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Formore information, contact us at: 1-800-726-7845 I www.bostik.com/us • Outstanding application & clean-up properties • Excellent working time • Very color consistent • Efflorescence resistant • Fiber reinforced for added durability • 1/16" to 1/2" grout joints Learn how Bostik has raised the bar once again with the highest performing cement-based grout now available! Watch the Hydroment® Vivid™ video: http:/ /bit.ly/VividVideo Foran easierinstall, use Hydroment ® Vivid ™ high performance grout • Outstanding application & clean-up properties • Excellent working time • Very color consistent • Efflorescence resistant • Fiber reinforced for added durability • 1/16" to 1/2" grout joints 92 TileLetter | November 2018