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

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

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years if well cared for. The guarantee mainly covers manufacturing faults, not wear and tear or damage from poor maintenance