Single ply roof guarantees often cover 15-20 years, but in reality, these roofs...

https://wiki-stock.win/index.php/Is_It_Normal_for_a_Roof_to_Blister_if_the_Design_Is_Wrong%3F

Single ply roof guarantees often cover 15-20 years, but in reality, these roofs can last 25-40 years with the right care. Guarantees focus on materials, not wear and tear or poor maintenance, which shortens life