A single ply roof guarantee usually covers 15-20 years, but the roof itself can...

https://melissafreshmaid.com/tpo-vs-pvc-lifespan-what-matters-more-than-the-material/

A single ply roof guarantee usually covers 15-20 years, but the roof itself can last 25-40 years if looked after properly. Guarantees often only cover manufacturing defects, not wear and tear or poor maintenance