Stain on a hall ceiling below the landing
The property
A detached house on one of the later estates, with plastic hot and cold pipes under the chipboard landing floor feeding the bathroom and en suite.
The problem
A pale ring appeared on the hall ceiling and slowly widened. It sat under neither bathroom, and resealing the shower had made no difference.
How we found it
Readings centred the damp below the airing cupboard. The hot side lost pressure when isolated, the cold held, and a running hot tap showed a warm patch on camera at one joint.
The outcome
The landing floor was opened over the mark and the joint remade on the visit. The owners kept our report for their insurer while the ceiling dried.