ASK THE EXPERTS QUESTION Have you guys ever seen this before? It seems to be where the mesh is holding the tile together. This is a 2” x 4” glass mosaic (approximately a 12” sheet). I know this is asking a lot without actu- ally seeing the install and product in person. Note the “voids” around the periphery of each piece of tile. Does this look like a troweling error or product defect to you? Please let me know. I’d love to know your insight on this. ANSWER You are correct – this is diffi- cult to fully and accurately assess without being on site and person- ally inspecting an uninstalled tile, inspecting the completed installa- tion and interviewing the installer. However, based on the photo you sent I would hazard a guess that the anomalies we are seeing are uncol- lapsed ridges made with an approxi- mately 3/16” V-notch trowel. – Mark Heinlein NTCA Training Director QUESTION I know the TCNA Handbook for Ceramic, Glass and Stone Tile Installation says that paint is not a recommended surface for tile instal- lation but here is the situation. I am doing a commercial job and did a wall of large subways. The owner was taken with the installa- tion and has tripled the areas she now wants tiled. Of course she already paid for the drywall guys and the painter to finish these areas. What I should I recommend as best and acceptable course of action? Of course money is an issue. ANSWER Congratulations on having your scope of work triple in size. Installing tile on gypsum board and painted gypsum board is always an intriguing question to consider. It is always best that the design and construction of the substructure and selection and installation of the sub- strate be done to meet the require- ments necessary to support a tile installation. Sponsored by Ask the Experts Q&As are culled from member inqui- ries to NTCA’s Technical Support staff. To become a member and make use of personal, targeted answers from Technical Support staff to your installation ques- tions, contact Jim Olson at jim@tile-assn.com. 24 TileLetter | January 2019