Hello,   This is in a kitchen with bathroom wall behind. Both are dry to the touch. There was a leak through roof 1.5 years ago- very sudden due to a central heating install overflow. It started from 40cm up from the floor. Today I went to scrape a bit and paint over it to see what happened… all the paint is easily falling off in layers, leaving plaster underneath. There is a dampish, musty smell but no obvious mould. Thank you