Single ply roof guarantees usually last 15-20 years, but the roof’s real...

https://mega-wiki.win/index.php/Why_Do_Roof_Problems_Show_Up_After_Two_Winters%3F

Single ply roof guarantees usually last 15-20 years, but the roof’s real service life can stretch to 25-40 years. Guarantees cover materials and workmanship, but don’t always factor in weathering or maintenance