Why choose a metal roof? They are very durable, reflective—which adds energy efficiency—durable, even against hail, and last 50 to 75 years.However, metal roofs aren't completely waterproof, so don't forget to take the extra steps to waterproof your roof. In this video, you'll see how Delta Trela underlayer by Cosella Dorken provides an air gap that allows condensation to dry out of your metal roofs and siding.You will see that a 3-D mesh is bonded to polypropylene material, which provide a ¾" air gap between the metal roof and underlayment. The air gap will ensure that any trapped moisture can escape without soaking into the underlayment.Join Matt Risinger on the sky-lift to for a bird's eye view of the underlayment. As an added and unexpected bonus, the Delta Trela reduces sound by 15 decibels.