A cavity wall has a "tide mark" about 200mm above the floor. The wall
was originally an external wall but, as a result of building an
extension, is now an internal wall. The wall has a 1930s DPC and the
floors have modern DPMs.
I assume that the old DPC has failed so am wondering what the best
options are. At the moment I'm thinking of knocking-off the plaster to
about 300mm, coating the wall with something and then
rendering/plastering with an additive.
The question is what to put on the wall: liquid DPM? bitumen? cement
board (hardiebacker)? foil-backed plasterboard?
What does the team think?