Roofing contractors often specialize in various types of roofs, such as asphalt shingles, metal roofs

http://rafaelggwn355.tearosediner.net/residential-vs-commercial-roofing-which-is-right-for-you

Roofing contractors often specialize in various types of roofs, such as asphalt shingles, metal roofs, or flat roofing systems, depending on your needs.