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

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

Single ply roof guarantees typically cover 15-20 years, but the actual roof can last 25-40 years with proper care. The guarantee mainly covers material faults, not issues from wear or poor maintenance