Single ply roof guarantees typically cover 15-20 years, but the real service...

https://blast-wiki.win/index.php/Managed_Decline:_Can_You_Plan_Replacement_Without_an_Emergency%3F

Single ply roof guarantees typically cover 15-20 years, but the real service life can stretch to 25-40 years if properly maintained. Guarantees mostly protect against material failures, not wear and tear or damage from poor upkeep