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

https://wiki-planet.win/index.php/Single_Ply_vs_EPDM_%E2%80%93_Which_One_Lasts_Longer_on_a_Warehouse%3F

Single ply roof guarantees usually cover 15-20 years, but the real service life can stretch well beyond that, often 25-40 years. Guarantees focus on material faults, while actual lifespan depends on maintenance, weather, and installation