Single ply roof guarantees usually cover 15-20 years, focusing on material...

https://www.slideserve.com/gwyneyxcez/why-do-roof-problems-show-up-after-two-winters

Single ply roof guarantees usually cover 15-20 years, focusing on material defects rather than actual wear and tear. In reality, these roofs often last 25-40 years with proper care