Single ply roof guarantees often last 15-20 years, but the real service life...

https://www.pawn-bookmarks.win/single-ply-roof-guarantees-typically-cover-15-20-years-but-the-actual-roof-can

Single ply roof guarantees often last 15-20 years, but the real service life can stretch to 25-40 years with proper care. Guarantees cover material faults, not wear and tear or poor maintenance