I have a metal roof. I only have to remove about 3 feet from the edge. The sun hits it and keeps it clean

If I don't then ice will form. When I moved into my home I didn't realize this. I had 4 inches of thick ice hanging off the roof. It was about 6 feet long and curled under. I could not knock out off or even put a dent in it. When it came down it crushed my metal bulkhead. Ice went into the basement. Three grown men could jump up and down on the bulkhead and not even put a dent in it. The ice destroyed it. If a person was under that ice when it let go he would be dead