Yes sand/cement & waterproofing was used prior to the plastering.
My husband has been in the loft and can't see anything at all. All the roof seems to be well sealed and the wall all dry.
We live in a mid-terrace built in the early 1900s. It has had a damp proof course treatment and this appears to be working effectively. Our problem is in the upstairs bedroom and the front room.
• Upstairs there is a brown stain that that runs vertically down the wall.
• Downstairs in one...