My comment is going to go against pretty well all previous. Our house has somewhat high ceilings and ten years ago I was looking at false ceiling material for use in the kitchen and bathroom. The supplier was most insistent that the material (Armstrong) is quite unsuitable for either location, particularly because of humidity. I ignored that and installed it in both, bringing the ceiling down to about 2.5m in each room. Today both ceilings look to us exactly as they did when installed and we have absolutely no mould. Bath/shower room mould is not a problem in other countries I know (Europe and elsewhere) and from what I can see it need not be in Britain either. We do not open the window when showering, but as the rest of the house the place is permanently heated to daytime 20 degrees, 18 at night, and we do not close the door behind us when finished. Condensation on the window is only detectable on the very coldest days and is then only very slight and very briefly there. It seems to me the British attitude to heating is the main problem together with the habit of keeping all doors within the dwelling closed at all times.