I have a damp issue on an external wall. The wall is part of an extension built in 1979. I can see that slate appears to have been used as a dpc. I am not sure whether it is rising up, coming through the wall or coming down (maybe somthing wrong with the roof?? It's not a flat roof) The wall forms part of a downstairs loo 2ft wide maybe 6/8ft long. I'd like to get it fixed but not sure what trade to call in.
