Single ply roof guarantees typically cover 15-20 years, but the actual roof can...

https://www.a1bookmarks.win/single-ply-roof-guarantees-typically-cover-15-20-years-but-a-roof-s-real

Single ply roof guarantees typically cover 15-20 years, but the actual roof can last 25-40 years if looked after properly. Guarantees cover material defects, not wear and tear or poor maintenance