The materials used to make metal roofs usually contains more than 25 percent of recyclable material. In addition to that, the metal roof as whole is 100 percent recyclable and it has a low weight so shipping it is easy.
Most of metal roofs are made of any of the following metals, aluminum, copper, zinc, stainless steel, galvanized steel or galvalume coated steel. As for asphalt roofs they are made of crude oil, fiberglass, mineral filler something like silica or limestone, and gravel. Some asphalt roofs do tear during manufacturing and during re-roofing.
This roofs are not 100 percent recyclable like metal roofs but the asphalt roof wastes can be re-used in road construction projects.