I live in a 4 store old (from about 1930's) building. Occasionally (in autumn, winter or spring) all gable walls have mold/mould/fungus in the wall and ceiling connection. Under my flat there's only roof (no other floors or attic).
Wall is facing east, it's standard brick wall with no special insulation. Plaster is partially already shattered and off.
How to fight with that mold?
EDIT: I bought hygrometer and it shows 70% @ 22°C, and i peak even 82% (at night in bedroom)