Why Not Painted Metal?
Unfortunately, the sun is murder on the very best finishes available for metal roofing. Promises are high, but look around. If you can find any metal roof that is more than fifteen years old which does not look old and faded, we would like to know about it. We haven't found any yet. Not even annodized aluminum is immune from the dammaging effects of ultra-violet light. It is no fun having a forty or fifty-year roof lose its lustre after ten years and start looking downright ugly after fifteen years.
If you want to avoid that, there are three realistic possibilities: slate, tile and stone-coated steel