The longevity of slate roofs is legendary. Well-built slate roofs have been known to last 150 years or longer. With regular maintenance they will last 100 years. If you already have one, you will need a great slate roofing company. If you are considering a slate roof (it will come with a cost) know it will last three or four times longer than other common asphalt roofing types. You will also need a great local slate roofing company for the install.