One Damp Room

You’ve just bought a 1900s terrace with solid brick walls. The ground-floor back room is a bedroom, with the bathroom directly above it. By your first winter, the room shows three marks:

• Black mould in the top corner where the back wall meets the ceiling. It comes every winter, worse in weeks when the washing dries on an airer in there.
• A damp band along the bottom of the side wall, about a hand’s width high, with white crystals on the plaster. It is there all year. Outside, a slate damp-proof course shows as a thin line a few courses up the front wall; round the side, the previous owner built a raised flowerbed against the wall that buries that line.
• A brown ring on the ceiling near the light fitting, below the bathroom. It grows a little after showers.

A damp company sends a surveyor. He runs a pin meter round the room, finds red readings along the side wall and in the top corner, and quotes: “Rising damp throughout. Inject and replaster.” The price is held until Friday.