Single ply roof guarantees, typically 15-20 years, cover manufacturer...

https://www.third-bookmarks.win/single-ply-roof-guarantees-usually-cover-15-20-years-but-the-actual-service

Single ply roof guarantees, typically 15-20 years, cover manufacturer defects—but real service life often stretches to 25-40 years with proper care. The key difference is how well the roof’s maintained