I used to have a lodger, during the meeting I asked why she was moving from her current 1 bed flat and she said it is full of mould and my landlord isn’t doing much to fix it, she showed me pictures and it was awful.
Within a month of her living here I went into her bedroom for some reason and noted all around the window was full of mould like I had never seen. Before her my previous lodger never had a problem with mould. I told her I would get some remover and look into what could be causing it. For unrelated reasons I told her to move out a couple of weeks later. Since then I’ve had 2 more lodgers, one never left the bedroom, never seemed to open the window and no issues at all. The second was in and out all day, liked the room to be cold so window always open and again no mould. It is now my child’s bedroom and again not a spec of mould.
What could she have been doing to create it, it was so bad I thought there was something structurally wrong with my house, the entire area around the window was completely black, it wasn’t just a small amount.