Hi everyone, sorry to keep coming back but my builder is back tomorrow and I've watched a few youtube videos and just want to be sure. Can you tile straight on to this or does it need to have a membrane on top? Also my bathroom floor is level and the tiler is supposed to be creating the slope on top of tile rite matting and creating the slope with I don't know what. All the videos I have seen on YouTube show the tile backer board being prepped with a waterproof membrane and sometimes plastic sheet behind it to stop the wall behind it getting wet (there is a stud wall behind to hide the soil pipe from upstairs). The videos also show the shower area usually has a tray in the shower area that you tile on? Also being really picky but there are chunks out of the tile backer board right behind the bath and the screws aren't flush (probably being really picky at this point but it's not hard to do it properly). Any advice appreciated.