Do you have any guidelines for venting cathedral ceilings also called vaulted ceilings?

To vent a vaulted or cathedral ceiling attic there must be an air space between the roof deck and the insulation.

Air Vent recommends a 1.5-inch to 2-inch air space in all cathedral/vaulted or otherwise compact roof systems. The maximum length of rafter that one should use the 1.5-inch air space is 30-35 feet. For longer rafter runs a 2-inch or even 3-inch air space is recommended. Air Vent recommends insulation baffles be used for the entire length even with fiberglass batt insulation. For more information on cathedral ceilings visit Air Vent University on our website.