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

https://zoom-wiki.win/index.php/What_Does_a_Bad_Vapour_Control_Layer_Do_to_a_Flat_Roof%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