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

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

Single ply roof guarantees typically cover 15-20 years, but the actual roof can last 25-40 years with proper care. Guarantees focus on the material’s performance, not the whole system or wear and tear