how long are roofs good for
Flat roofs usually come with a 10- to 20-year warranty but the roofs can last 25 years if properly installed and maintained. Built-Up Roof (BUR) The traditional hot-tar-and-gravel roof is built from three or more plies of waterproof material alternated with hot tar and ballasted by a layer of smooth river stone.
Average Life Expectancies. Slate roofs can last 100 years or more, and clay roof tiles, on average, endure 100 years. Cooper and other metal roofs have life expectancies of at least 50 years. While concrete tile roofs are marketed as having 50-year life expectancies, Roofkey.com points out that their underlayment and batten systems need replacement after 30 or 40 years.