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

https://brooksfznx367.theburnward.com/how-can-i-tell-if-a-leak-is-workmanship-or-material-failure

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