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

https://www.acid-bookmarks.win/single-ply-roof-guarantees-usually-cover-15-20-years-but-the-actual-roof-can-2

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