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

https://smart-wiki.win/index.php/What_Maintenance_Records_Should_I_Keep_for_a_Commercial_Roof%3F

Single ply roof guarantees usually cover 15-20 years, but the actual service life often stretches to 25-40 years. That’s because guarantees focus on materials, not wear and tear or maintenance