industry experts to provide an answer, as well as giving his expert opinion. “There is indeed concern in the tile industry regarding the situ- ation you described,” Heinlein said. “The NTCA’s Technical Committee has been giving this issue serious consideration and has appointed a subcommittee to gather data in an attempt to quan- tify and hopefully identify the nature of the problem. To help me respond to your question, I have addressed Mr. Martin Brookes and Mr. Steve Young, who have been the persons actively pursu- ing the causes of this issue.” Martin Brookes, of NTCA Five- Star Contractor Heritage Tile and Marble in Mill Valley, Calif., offered these thoughts: “The problem with this type of shower pan assembly is that there is no accommoda- tion for a weep system and all water is evacuated topically. This in turn could create a problem around the drain with light colored stones or transparent tile,” he said. “The moisture can’t evacuate like a tra- ditional water-in/water-out shower pan liner with a weep system. In addition, since the stone material is directly bonded to the mem- brane, allowing no room for error in the installation process, water can pool under the tile especially if the ridges are not fully collapsed. It is my opinion that if this type of system is used with the light colored stones or transparent tile, UltraCare™ Penetrating Plus SB Stone & Porcelain Tile Sealer is a premium, natural-look, solvent-based p e n e t r a t i n g sealer that uses VOC-exempt materials and will provide maximum protection against most common stains for all interior and exterior natural stone (marble, limestone, sandstone, slate, granite, travertine, etc.), unglazed porcelain and ceramic tiles, masonry, quarry tiles and cementitious grout. The product can also be used as a pre-grouting sealer. UltraCare Penetrating Plus SB Stone & Porcelain Tile Sealer was specially designed for dense stones such as granite and unglazed por- celain tiles. It can be used on interior and exterior applications, and it meets all EPA and SCAQMD standards for VOCs. For more information about UltraCare Penetrating Plus SB Stone & Porcelain Tile Sealer and other fine products in the UltraCare family, visit www.mapei.com. STONE –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 90 TileLetter | November 2018