We have an extension with a concrete flat roof. It has 3 sections- a pantry, toilet and utility. The pantry is the only part without a plasterboard ceiling. Earlier this year we had a terrible problem with wetness on the ceiling of the ceiling. A local tradesman said we needed a new cover on our flat roof - so £500 pounds later we have one. Now the problem is back. It does not affect the other areas of the extension. I assume the new roof is not the problem, the tradesman says it may be condensation. Thoughts please?

Julie FAwcett, December 2009

It's condensation

Warm wet air rises and meets the cold cold ceiling - water is squeezed from the air. Insulate - a plasterboard ceiling may solve it for you.

Peccavi, December 2009

Sadly, with many years experience as a householder in various properties, I fear it was, and still is, plain old condensation.
If you have no wall or ceiling vent in that room, or an opening window, it would be highly likely, so you can only mop it away, dry out the room, and keep the door shut to stop more moist air entering. Polystyrene liner could help, and then you'll find it will land on the walls, and so on...

Fran, December 2009