Has anybody done this, had an extra storey lowered on to their building? I live in a little 50s house in London with a flat roof, and as planning applications are being relaxed & I can't afford the bigger houses in my area, which are all Victorian & megabucks, it seems like a great idea. I can't find anything about people's experiences online & would love to hear from anyone who's done it or tried and failed, or companies that sell the prefabs, good resources. I'm really not sure where to start.