Single ply roof guarantees usually cover 15-20 years, but the roof itself can...

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

Single ply roof guarantees usually cover 15-20 years, but the roof itself can last 25-40 years if looked after properly. Guarantees often only cover faults from installation or materials, not wear and tear or poor maintenance