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

https://shed-wiki.win/index.php/EPDM_Roof_Lifespan_-_Can_It_Really_Go_Past_35_Years%3F

Single ply roof guarantees usually last 15-20 years, but the actual roof can often go on for 25-40 years with the right care. Guarantees cover faults, not wear and tear or damage from poor maintenance