Single ply roof guarantees, often 15-20 years, cover materials and workmanship...

https://www.romeo-bookmarks.win/single-ply-roofs-often-come-with-15-20-year-guarantees-but-they-can-last-25-40

Single ply roof guarantees, often 15-20 years, cover materials and workmanship but don’t always reflect the full lifespan, which can stretch 25-40 years with proper care