I'm in a flat roof mid-terrace 1940's house. Have always had to be careful with damp upstairs but in particular inside my sliderobes on the ceiling and side walls are covered in black mould which is creating a 'damp' smell in the house. Despite periodically wiping with bleach I can't get rid of this mould. I also get black spots of mould appearing on all the upstairs ceilings (artex). I use a dehumidifier regularly but really need advice on how to get rid of the mould and how to treat the walls after that to prevent it coming back - do I need to replaster? Thanks