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

https://www.bookmarkpage.win/single-ply-roof-guarantees-usually-cover-15-20-years-but-the-real-service-life

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years if cared for properly. Guarantees mainly cover material faults, not age or wear