After 15 years--and a few leaks--a local roofer with a good reputation inspected our roof and said that the 30 year shingle we thought we had might be good for a few more but that's it. Lot's of cracked shingles and we seem to be loosing more with every storm so he recommended re-roofing in the next few years: removing rather than shingling over what's down and putting in a waterproof membrane to prevent leaks. According to him the quality of asphalt shingles has declined over the years to the point of roughly a 20 year life span at best. Our existing shingle is from OC. His estimate took me by surprise-$15K--but this is a cape with a wrap porch,attached screened in porch, requiring a lot of shingles and care putting it down. Since--according to him, asphalt shingles are only good for 15-20year and we aren't going anywhere, I wondered if it was time to consider a metal roof or something else. When I mentioned metal roof his estimate went up 3X--wheich means it isn't going t happen. Any other roofing material alternatives out there with good lifespans, that are reasonably comparable to the AS ? thanks for any help.