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

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

Single ply roof guarantees usually last 15-20 years, but the real service life can often stretch to 25-40 years. The guarantee covers specific issues, not everyday wear and tear or poor maintenance