Single ply roof guarantees usually cover 15-20 years, but the actual roof can...

https://www.tumblr.com/bravelyetherealodyssey/823645056255819776/do-i-really-need-wind-uplift-calculations-for-a

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years with proper care. Guarantees focus on materials and installation, not wear and tear over time