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

https://www.cast-bookmarks.win/single-ply-roof-guarantees-often-cover-15-20-years-reflecting-manufacturer

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years with proper care. Guarantees focus on materials and workmanship, not wear and tear or maintenance issues