The roof material is rubber membrane. It was replaced 7 years ago with a 10 year warranty, but the shop that did the repair is no longer in business and the manufacturer declines any warranty. We have been very proactive with visual inspection and cleaning at least once a year. Last time we looked was several months ago and the crew that was up there to clean did not note any problems or weakness in the roof. We are in a heavily wooded area and know that several limbs have fallen on the roof in the past six months during storms. The insurance claim rep could not identify the damage as being related to falling tree stuff. We have had some very severe storms recently.