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

https://magic-wiki.win/index.php/Are_Manufacturers_Honest_When_They_Say_Membranes_Outlast_Guarantees%3F

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years with the right care. Guarantees focus on materials and installation, not wear and tear or neglect