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

https://brooksfznx367.theburnward.com/how-can-i-tell-if-a-leak-is-workmanship-or-material-failure

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