The flat roof on my extension, although not leaking as far as I'm aware, is in a poor state. There was a few splits at the edges and one about a meter from the edge which I have patched up for now. I think the boards beneath the felt are rotten as when I walk on the roof its very springy and the roof dips downin several areas. So to my question, I have never been a fan of flat roofs but I know it would be cheaper to have it reboarded and re-felted than to have a proper pitch roof installed but how much of a difference are we talking, the roof area is 5m x 3m can anyone give me an idea as to the cost of a new flat roof and proper pitched tiled roof.