Mouldy ceilings worry people.
However, not all mouldy ceilings are caused by leaking roofs. Most mouldy ceilings have nothing to do with roof leaks.
If you have an ugly mould area in an isolated area of your ceiling – along with brown staining, then you probably have a roof leak.
The brown staining is the fine dust on your ceiling that has been dissolved by the rain water and is leaching through the plaster. The mould is because the ceiling is damp (usually due to the ceiling insulation getting soaked by the roof leak).
If this is the case with your ceiling, then you should contact me to check out your roof.
However, I am asked to inspect a lot of mouldy ceilings that has nothing to do with a leak.
If the whole ceiling is covered by a fine layer of mould, then it is probably not a roof leak. If there are patches of fine mould around the cornices with no brown staining – then it is just a damp room. Not a roof leak.
Dampness on a ceiling is a good attraction for mould growth. In the winter time, ceilings are prone to dampness because room heating and the presence of our warm bodies send warm moist air upwards. This moist air hits the cold ceiling (more pronounced on ceilings that are not insulated) and forms condensation. When mould spores are around, they migrate to the moist environment and thrive. Very quickly, they multiply and soon you have a fine coating of mould all over your ceiling.
Some rooms are more prone to dampness. Bathrooms and bedrooms are the worst because they are more private and are often closed and unventilated.
The solution to damp rooms causing mould growth on ceilings is to make sure that you have good ceiling insulation. The insulation keeps the ceiling warmer in the wintertime and there will be less condensation. The room needs to be ventilated. And it is very important to kill off the mould effectively, remove it and apply a good quality ceiling paint. I do not do any of these things – so find a good ceiling insulator and a good painter…