Two factors will determine the lifespan of a commercial roof: the type of material and whether it is regularly maintained. A commercial roof can generally last anything between 20 and 45 years, with the longest lifespan achieved from metal, then asphalt. Single-ply membrane materials tend to yield shorter lifespans, say up to 30 years. Remember, regular maintenance and additional roof coating can add some good couple years onto the life of your commercial roof.