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

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

Single ply roof guarantees often cover 15-20 years, but the real service life can stretch to 25-40 years if looked after properly. Guarantees focus on materials and workmanship, not wear and tear or maintenance issues