Hi guys. I will redo my bathroom in a few months time ( floor tiles down) and in my previous thread i was made aware of the problem when two different floor substrates join up ( in my case the substrate is concrete with a 25mm step and to make up that 25mm difference in height, a 25mm thick plywood sheet 800mm by 1800mm has been screwed down onto the concrete to bring the floor level allover) regarding the expansion and retraction of the plywood and the concrete and therefore the chances that the tile or the grout could crack. In this forum i was made aware of the existence of an uncoupling membrane ( Schluter) which sounds like it could be a good option, however i passed a shop yesterday and a couple of tilers were working in it and asked them if there was another alternative to that suggested above. They said that, where they find the above issue, they skim a thin layer of Latex slc allover the plywood, up and slightly over the gap where the two different substrates meet. Has any professional tiler in this forum ever used the above mentioned technique successfully? I am trying to gather as much infos as possible in order to come up with a final and sensible decision in the end. Thanks again for your time.