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

https://wiki-nest.win/index.php/Is_It_Normal_for_a_Roof_to_Blister_if_the_Design_Is_Wrong%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