Single ply roof guarantees typically cover 15-20 years, but the actual roof can...

https://www.list-bookmarks.win/single-ply-roof-guarantees-typically-cover-15-20-years-focusing-on-material

Single ply roof guarantees typically cover 15-20 years, but the actual roof can last 25-40 years with proper care. The guarantee mainly protects against manufacturer faults, not wear and tear or poor maintenance