Single ply roof guarantees, typically 15-20 years, cover manufacturing defects...

https://jasperotbu571.iamarrows.com/single-ply-roof-on-an-industrial-estate-with-metal-roofs-too-who-coordinates-it

Single ply roof guarantees, typically 15-20 years, cover manufacturing defects but don’t always reflect how long the roof will actually last—often 25-40 years with proper care