Metal is very light weight (50-150 pounds). Although it is light weight it is resistant to fire, mildew, and insects. It seals out water and is able to survive high winds. Often times it can be applied over an existing roof for additional structured support. When it is applied over an existing roof it clears out any noise due to a hail/rain storm. Metal roof is also not known to be dangerous during lighting storms. Depending on the manufactures warranty metal roof should last as long as the house.