Thanks Mick, I knew someone was gonna ask! I did not only because I was afraid of the weight of a bunch of them being together at one time and all falling! I used Laticrete 255 Multimax thanks to Henry and my rep and its holding power is amazing, just didn't see the need with it being up 10 feet. But no, to answer your question, didn't really need it there, or in the mosaic stone floor, or niche, but everywhere else