Single ply roof guarantees usually run 15-20 years, but the actual service life...

https://www.wall-bookmarkings.win/single-ply-roof-guarantees-often-15-20-years-cover-materials-and

Single ply roof guarantees usually run 15-20 years, but the actual service life can stretch to 25-40 years if the roof’s looked after properly. The guarantee covers manufacturing flaws, not wear and tear or poor upkeep