Since the long grain is adjacent to the tile field, I wouldn't expect that there would be any wood movement problems. I made a tray for my sister in law with a tile field.brentray.jpg and I used a caulk material for the grout and it did shrink a bit over time. If I were to do this again, I would use the Musselbound adhesive mat material to hold the tile in place and then use the Laticrete epoxy grout. I used the mat for our kitchen back splash and so far all the tiles are securely in place. The Laticrete grout is stain proof so nothing that gets spilled will stain it.