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

https://wiki-net.win/index.php/If_My_Guarantee_Expired,_Does_That_Mean_My_Roof_Is_Done%3F

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