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

https://www.acid-bookmarks.win/single-ply-roof-guarantees-typically-cover-15-20-years-but-the-roof-can

Single ply roof guarantees often cover 15-20 years, but the actual service life can stretch 25-40 years if well maintained. Think of the guarantee as a promise on material and workmanship, not the full lifespan