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

https://landenuzqb895.theglensecret.com/what-parts-of-a-membrane-roof-usually-fail-first

Single ply roof guarantees usually cover 15-20 years, but the actual service life can stretch to 25-40 years with the right care. The difference comes down to day-to-day wear, weather, and maintenance