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

https://andreocln282.lucialpiazzale.com/what-questions-should-i-ask-before-signing-a-single-ply-roof-contract

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