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

https://super-wiki.win/index.php/What_Parts_of_a_Membrane_Roof_Usually_Fail_First%3F

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years with proper care. These warranties focus on materials, not wear and tear or damage from weather