the framing. I have seen problems in other areas due to adhesive shrink- ing as it dries. We have found when wall board is installed with adhesive and screws that the screws and plas- ter above them can show up as little humps on the surface of the board as the adhesive dries and pulls the wall board closer to the framing. It is only a fraction of an inch but I have seen this happen many times before – as the board moves closer to stud and the screw stays fixed, you get a hump. This is only a theory but if the plywood got pulled tighter to the framing as the glue dried, could that small shift in the floor sub floor cause the crack in the tile? Total guess. Also the non-fully-engaged tongue could have had something to do with it on the long side. Though short side of the ply was firmly seated on a joist, and we had stress crack here, too. Marble is much softer than other stones or porcelain tile. Like I said before, I have never seen this hap- pen before and we have used this type of assembly successfully for many years. Anyway, we decided to add rows of blocking between the joists along the 8´ length to make sure that side of the plywood was more secure. We re-installed the ply- wood and were planning on using uncoupling membrane under the tile to avoid further stress cracks in the marble. The LATICRETE® HYDRO BAN® pre-formed shower sys- tem products include an expan- sive line of pre-sloped shower pans, linear shower pans, nich- es, seats, benches and acces- sories – all made with a high- density polystyrene core. Complemented with a variety of adhesives, grouts and seal- ant caulk options, including HYDRO BAN, HYDRO BAN Sheet Membrane, HYDRO BAN Board and HYDRO BAN Adhesive & Sealant, LATICRETE shower systems provide every- thing needed for a flawless shower installation, backed by the industry’s best warranty. www.laticrete.com. ASK THE EXPERTS –––––––––––––––––––––––––––––––––––––––––––––––––––– 22 TileLetter | February 2018