Single ply roof guarantees usually last 15-20 years, focusing on the product...

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

Single ply roof guarantees usually last 15-20 years, focusing on the product and installation quality at that time. However, the actual service life can stretch to 25-40 years with proper care