A single ply roof guarantee usually covers 15-20 years, but the roof itself can...

https://www.bookmarkidea.win/a-single-ply-roof-guarantee-usually-covers-15-20-years-but-the-actual-roof-can

A single ply roof guarantee usually covers 15-20 years, but the roof itself can last 25-40 years if looked after properly. Guarantees often only cover manufacturing defects, not wear and tear or poor maintenance