So we have our trays in - made the plumber follow your shower tray instructions to the letter and looks good. He was impressed at the method and use of Sikaflex vs standard silicone and the masking tape trick- says he'll do it this way from now on  Impey wet-room former also in for the smaller shower, we removed the existing 22mm deck and laid a 12mm ply section  - this will ensure the former is flush with the floor once the backer board and UFH matt is laid. The Impey installation inst