Hall ceiling stain that grew on quiet days
The property
A Victorian house in Hertford with its bathroom above the hall. The toilet's cold feed runs under the boards, over a lath and plaster ceiling.
The problem
A brown mark on the hall ceiling widened even when the house stood empty. Two coats of paint had not kept it away.
How we found it
Readings narrowed the stain to one corner. Flushing and running taps changed nothing, which pointed to a pressurised pipe. The toilet's feed then failed a pressure test, and a thermal image agreed.
The outcome
Only the boards beside the toilet came up, at our mark. The repair was costed separately, and the ceiling could dry before redecorating.