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

https://www.booknose.win/single-ply-roof-guarantees-usually-15-20-years-cover-defects-but-don-t-always

Single ply roof guarantees usually cover 15-20 years, focusing on workmanship and materials, but the real service life often stretches to 25-40 years with proper care