I had a leak on my own flat roof a couple of years ago, went to investigate and ended up going through it with my knee. There was no sign of wear and tear at all and it made me realise what a complete gamble it was every time I went on a customers. I also found out my insurance didn't cover it despite being asked when filling out details on comparison websites about whether I had one and how big it was etc, spoke to my insurance people and they claimed it was a commen misconception and that by far the majority of people with flat roofs aren't covered!! This begs the question of what happens if the worse occurs? Will our own liability insurance cover it, I'd like to think it would but wouldn't want to put it to test, my experience of insurance companies is that if they can find a loophole they will. Never been on anyone else's flat roof since, and never will. Explained to existing customers the situation and they were fine, now use steps and longer pole for some and leave one or two altogether.