Makes sense, thanks.
Its not as if its pouring in or even visibly dripping, its just preparing for the inevitable as I live in NE England and it rains A LOT
I'm converting a brick outbuilding to a utility room and was planning on using a basement Tanking damp proof membrane to line the walls before Battens and insulated plaster boards go on.
The roof is flat concrete with rebar running across tieing in to next doors so as expected the ceiling can...