Weyroc was ply'd with 12mm and then Amtico'd.  As I didn't know at the time that the ply was so thick I set that tray straight on the pozi's.    Yup. Iirc the Impey tray is 22mm but when you bed it down with a super-generous lashing of Sikaflex EBT it gains a couple of mm, which is usually fine if your either over boarding 18mm deck with 9mm ply or 22mm deck with 4 or 6mm ply ( thinner ones glued and screwed ). As this was quite an adverse install I decided to let the  Amtico gu