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

https://www.4shared.com/office/Q9ZZDzKPge/pdf-27402-44163.html

Single ply roof guarantees usually cover 15-20 years, but the actual service life often stretches to 25-40 years. Guarantees focus on materials and workmanship, not wear and tear or maintenance