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

https://www.cast-bookmarks.win/single-ply-roof-guarantees-typically-last-15-20-years-but-the-roof-itself-can

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years with proper care. These guarantees often focus on material faults, not wear or external damage