Commercial Roofs put on correctly can last upwards of 25-30 years if properly maintained and preventive maintenance completed. It is important to you to have your roof inspected twice a year and have any deficiencies addressed. Many things can cause roofs to leak such as inclement weather, foot traffic, other mechanical contractors (HVAC/Window Washers), debris, leaf buildup. Over time your roof will wear and UV rays and heat from the sun can cause material deterioration, failed sealants and dry rot of pitch pockets. Having your roof inspected twice a year and preventive maintenance completed will go a long way in staving off a roof-replacement.