Single ply roof guarantees usually cover 15-20 years, focusing on material...

https://golf-wiki.win/index.php/Why_Is_My_Single_Ply_Roof_Guarantee_Only_15_Years_If_People_Say_40%3F

Single ply roof guarantees usually cover 15-20 years, focusing on material defects and workmanship, but the actual roof can last 25-40 years with proper care