Mildew in the Bathroom and PVA treatment

In my experience only ventilation and heat will stop black mould.

I guess your problem is condensation so sealing the ceiling will have no affect, in fact it could make it worse.

If the shower is upstairs check that there is a good layer of loft insulation, with no gaps, over the bathroom.

Best black mould killer I've found is 50% diluted bleach, but it'll come back like the Terminator if a surface is damp most of the time.

Chris

It will get rid of your current crop of mould, but you'll soon have a new crop. The only way to fix it is to sufficiently ventilate the room. Does it have an extractor fan? Is it working properly?

Most importantly, check that there is an effective vapour barrier under the insulation. This will consist of aluminium foil or plastic sheeting. This prevents the copious amount of water vapour going into the insulation, cooling and condensing and dripping back down onto the plasterboard. Instead, it will hopefully remain warm and vaporised in the bathroom until it is removed by the extractor.

Christian.

Infact I had the same problem with a patch of mould reappearing in the corner of my shower room and upon inspecting in the loft I found that the previous owner had kindly rolled back the loft insulation to exactly where the mould patch kept on re-appearing. Simply rolling the insulation back into place has resulted in no more patches.

Andrew.