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

https://www.phone-bookmarks.win/single-ply-roof-guarantees-usually-15-20-years-cover-product-defects-but

Single ply roof guarantees usually cover 15-20 years, but the actual service life can stretch to 25-40 years if looked after properly. That’s because guarantees focus on material faults, not wear and tear or maintenance issues