Hi. Hoping someone can help with floor lining thicknesses. Im just about to line and ply my floor. I have got 7mm dodo deadn duo pro twin which from what i have read is best to lay over the top of floor batons rather than i between. I have a vanstyle deep step which says is suitable for 12mm or 14mm ply and the flooring i am laying on the ply is 4.5mm thick. My question is should i use 6mm or 9mm battons on the floor then line over these and would i be better with 9mm or 12mm ply for the step to fit. Cheers