Single ply roof guarantees, typically 15-20 years, cover manufacturer...

https://claytoncllo171.tearosediner.net/why-do-roof-problems-show-up-after-two-winters

Single ply roof guarantees, typically 15-20 years, cover manufacturer defects—but real service life often stretches to 25-40 years with proper care. The key difference is how well the roof’s maintained