damp interior walls

[gazmond]

Hi, I realise that this might be a duplicated question but....
I live in a converted victorian building and have just noticed dampness in my bedroom and lounge on the exterior walls. It is a kind of greeny/black, very fine "fur" for want of a better word. I am presuming this is a type of damp however it does not appear to me to be penetrating from the outside wall. Is it possible that it is a result of my bathroom and shower? I must admit I rarely close my door when having a shower.

Thanks

[stuart C]

This is probably caused by condensation. Mould prefers the purer water which is produced by condensation. Its not good for the health of the inhabitants, especially the very young or with chest problems.
You need to get the correct balance of heating and ventilation. Insulating the exterior walls is another option.