Single ply roofing guarantees typically span 15-20 years, covering material...

https://wiki-cafe.win/index.php/How_Do_I_Stop_People_Walking_All_Over_the_Membrane_Roof%3F

Single ply roofing guarantees typically span 15-20 years, covering material defects but not the entire roof’s life. In reality, with good care, these roofs can last 25-40 years