Ive had a dormer extension done to our house. It has a flat roof on top of the dormer and then a small pitched area below the windows of about 4 courses of concrete tiles. There was no gutter on the flat roof so the water was dripping all across the window cills and the pitched roof. I have know put a gutter along the fascia of the flat roof, and i need to run a downpipe down, but can only run it onto the picthed element to discharge it (no where else it can go because of the roof and conservatory at the back etc etc. Is it worth putting any sort of lead flashing under the point where it discharges?