Single ply roof guarantees typically cover 15-20 years, focusing on material...

https://mighty-wiki.win/index.php/What_Should_Be_on_an_Annual_Flat_Roof_Inspection_Checklist%3F

Single ply roof guarantees typically cover 15-20 years, focusing on material defects and workmanship. However, the actual service life can stretch well beyond 25-40 years with proper care