ASK THE EXPERTS QUESTION I’ve got a new question for you all. What about homes with sub- floors consisting of T&G boards, not plywood? They run diagonally. In this one specific case, there is actually 3/4” solid wood installed over the top of it. My thought is that it would require double 3/4” plywood, and I can’t find a single method in the book that identifies such a subfloor. ANSWER Attached are pictures of different installed tile work examples incor- porating movement accommodation joints. The first is a residential instal- lation with porcelain plank tile where a change of pattern is in a doorway to allow for a nearly unnoticeable movement accommodation joint. The other two are from commercial jobs where large areas of tile happen quite frequently. In the TCNA Handbook from page 430 to 437 is section EJ171. It states under location and fre- quency of joints: • Interior – maximum of 25’ each direction; Exterior – 8’ to 12’ in each direction. • Interior tile work exposed to direct sunlight (heat) or mois- ture – maximum of 12’ each 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. e-Learning Program Industry and product information in short, easy segments Train from the comfort of your home or office anytime Fast and easy to access, listen, and complete A-8493-0618 ©2018 LATICRETE International, Inc. All trademarks shown are the intellectual properties of their respective owners. Register today at laticrete.com/university Globally Proven Construction Solutions 22 TileLetter | June 2018