Hi all,I am seeking advice on fitting a cast shower base.I am doing a refurbish for my daughter,she bought this base from b and q ,the instructions show it being fitted with adjustable feet,however looking at forums and YouTube the way to go is to lay tray on a bed of mortar on min 18mm ply (fitting to a wooden floor)I have decided to use the mortar fixing method,this is where the fun starts! The existing floorboards are 30mm thick,the tray is 30mm thick once I cut out the floor for the plywood and lay tray on mortar bed then lay floortiles with adhesive and backing boards the tray will be virtually flush with floor,what to do?is it better to fit fresh floorboards once hole for tray is cut out and screw ply on top of this instead of directly on to joists,this way at least tray won't be left looking too low,any suggestions gratefully accepted,cheers