Seen plenty of people on here saying to use ply for bedding a shower tray, but what type? Will a regular sheet of hardwood ply from b&q do or do I need to source some marine/wbp? I have some mapei waterproofing left over so is it an idea to use that over the normal ply? And also plenty of people say about using tile adhesive for the trays, and most people suggest rapid set, is this needed or just easier for people with experience to get it done quicker.
Depends on the type of tray. Some can be fitted on adjustable legs ( riser kit ). Saves all the fratting about with plywood and adhedive etc. Of course this type is no good if you want to have the tray near floor level ,and the trap and waste pipework not accessible below floor level.
I did buy a riser kit for it. It was a plastic stick on one. Seemed pretty good and solid, but up on trying to fit last night, I found when putting weight on the tray it would move, no matter how much I adjusted the legs. With some assistance I managed to find out the movement was in the legs them selves. I did want the tray on the floor, although the drain lays right on a joist, so I have opted to build a wooden riser from some cls timber I have, I just don't have the ply so was checking which sort I needed.
18 mm thick plywood will make a sound base. Doesnt need to be marine ply . the frame just needs to be made to adequately support it. And flexi rapid set tile adhesive is ideal.