I've got myself in a right mess here. I have a victorian terrace and in the downstairs toilet the floor had cracked and was unlevel so I removed two layers of screed(about 40mm) to reveil a solid brick floor. There is obviously no dpm in the floor. Ideally I was going to rescreed the floor(40mm) and them put a block floor down adhering it to the floor with a bitumen glue to act as dpm. I cannot make the screed any deeper as the doorway into the room is darn low as it is and you would smack your head if I highered the floor any more. Is what I propose possible or can anyone give any suggestions please because I always seem to get it wrong thankyou dan290571