In my research on roofing systems I came across a company Duro-Last. There system sounds great, but I want to know how it rates in the industry. Also what is the difference between that type of system and a PVC roof with a gravel top. I have to replace a flat roof on a commercial building in New York City. The built up roofing system seems to require far more maintenance than the above mentioned options. Please share your thoughts on these matters, as time is short before the weather prevents replacement until next spring

Why would a built up roof require more maintenance than a single ply system? We have been removing single ply systems and installing cold applied 3 ply built ups to eliminate maintenance problems. We have a building with a PVC membrane and it has not been a particularly good roof. The key to any reroof project is in paying attention to the details. 90% of roof leaks occur in 10% of the roof and that is generally around penetrations such as vent pipes and along wall flashings. As a rule you will likely pay 30% more for a good quality built up over a single ply, but the expected lifespan will be double. Another consideration is the amount of foot traffic on your roof. Single plys hate foot traffic and if you have any equipment located on the roof that requires maintenance, you can expect to have issues when you have only .045-.060 inch between you and mother nature. My experience has been that HVAC mechanics love to leave screws on the roof which soon end up stepped into a single ply. A typical problem with PVC roofs in the past has been poor resistance to UV degradation. Some early versions were so bad that they would literally shatter with sudden temperature changes. Good Luck with whatever you choose.