Single ply roof guarantees usually cover 15-20 years, reflecting the...

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

Single ply roof guarantees usually cover 15-20 years, reflecting the manufacturer's confidence in the material under ideal conditions. But in reality, with proper care, these roofs often last 25-40 years