The two most common materials used for flat roofs are asphalt and PVC. The asphalt based system that we use at DUBO is called Torch Grade Modified. It normally lasts 12-13 years, but can be incredibly hot because it is black and asphalt based. PVC, or Polyvinyl chloride, is a plastic polymer that is known for its durability and low maintenance. The PVC system used by DUBO is called Duro-Last. It is designed to last about 22-25 years, and is also much cooler than the Modified roofing because it is white and plastic.