Single ply roof guarantees, usually 15-20 years, cover workmanship and material...

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

Single ply roof guarantees, usually 15-20 years, cover workmanship and material faults but don’t always reflect the roof’s full life, which can stretch 25-40 years with good care