The roof deck (wood) lays between the structural components of a roof (the joists, rafters etc), the insulation, and the waterproofing layers (ice and water shield, synthetic felt, shingles etc). The roof deck is the section of the roof where everything else is placed. If your deck is compromised, your entire roofing system is compromised!

Ice and water shield is a self-adhering waterproofing underlayment that is used in roofing to help prevent damage caused by ice dams and wind driven rain.

Roofing Synthetic felt is composed of a base, made from fiberglass or polyester, and then coated or saturated with a protective coating such as bitumen (asphalt), which repels water but still allows the product to breathe. It is 600% greater tear strength than a standard 30 pound felt.

A standing seam system consists of wide, relatively flat metal
panels that have vertical legs (or ribs) on each end. The metal
panels are designed to lock together, and are mounted to the
roof by being fastened to the sheathing underneath through a
series of hidden clips. Metal is extremely durable and can
handle the elements much better than most roofing systems.

Ventilation is essential to ensure the roof performs correctly. Installing roof vents moderates the temperature in an attic or roof space. By preventing a roof space from getting too hot or too cold you reduce the build-up of moisture levels. This will prevent mold building up in the house and ensure the roofing components perform properly.