There are many reasons that metal roofs are becoming more popular. One of the biggest draws is the fact that metal roofs require little maintenance. They can also be installed over existing roofs, can last for 40 to over 100 years, are very durable, are more energy efficient, will not be affected by termites, rot, or mildew, and are recyclable. For these reasons, metal roof installations are increasing by about 3% each year.