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

https://blogfreely.net/rothesqlmw/why-does-the-cheapest-flat-roof-quote-often-fail-early

Single ply roof guarantees typically cover 15-20 years, but the actual service life can stretch up to 25-40 years if the roof is properly maintained. Guarantees focus on materials and installation, not wear from weather or blocked drains