How should I insure an adequate amount of air flow and ventilation under the roof sheathing?
To insure proper air flow under a roof of this kind (and above the insulation on the floor below it), air chutes should be installed up against the roof. Chutes will provide an unobstructed clear path for air coming up through the eaves and flowing out vent openings at or near the top of the roof. Vent openings are usually in the form of grilles or ventilators installed at or near the peak of the roof — or by cutting through the roof itself. The air chutes are installed by either nailing or stapling them up against the underside of the roof sheathing.
