Metal roofing is composed of eco-friendly and sustainable materials. Some of the most common materials used are zinc, copper, titanium, steel and aluminum with steel and aluminum being by far the most popular. The majority of metal roofs are made from 30-60% recycled materials. With materials such as aluminum, steel and copper, your metal roofing will be able to resist deterioration, such as cracking and shrinking. It is also usually coated with a layer of metallic coating that allows for a rust-free finish.