The dilemma

The house is four flats. Gerry owns yours and the one he lives in at the top, and the other two belong to somebody else and are let through an agent. You are the named tenant. You cannot open a wall or hire a plumber, and everything you can do here is words: what you write down, and who you say it to. You have wiped the patch back to plaster twice since March without saying anything to Gerry. Both times it came back the same shape, on the same wall, the one you share with number 4.

Your options

1. Buy a humidity meter and log the room for two weeks.
2. Ring the council's environmental health team today.
3. Put it to Gerry in writing, with dated photos.