Single ply roof guarantees usually cover 15-20 years, but the actual roof can...

https://www.inter-bookmarks.win/single-ply-roofing-guarantees-usually-15-20-years-cover-manufacturing-faults

Single ply roof guarantees usually cover 15-20 years, but the actual roof can often last 25-40 years. That’s because guarantees focus on materials and installation issues, not wear and tear over time