Above sheathing ventilation system

A roof structure, comprising:

• a roof deck;
• a layer of roof cover elements spaced above the roof deck to define an air layer between the roof deck and the layer of roof cover elements;
• and
• a plurality of vent members each replacing and mimicking an appearance of one or more roof cover elements in the layer of roof cover elements, each vent member comprising an opening permitting air flow between the air layer and a region above the vent member;
• wherein at least one of the vent members comprises an ember impedance structure that substantially prevents ingress of floating embers through the opening of the vent member while permitting air flow through the opening;
• wherein the roof deck does not include any openings that permit air flow between the air layer and a region below the roof deck;
• wherein the ember impedance structure comprises a baffle structure, wherein the baffle structure comprises:
• an elongated first baffle member comprising a first plate portion and at least one edge portion connected to a lateral edge of the first plate portion and extending generally away from the first plate portion in a first direction, the first plate portion and the at least one edge portion of the first baffle member being substantially parallel to a longitudinal axis of the first baffle member;
• and
• an elongated second baffle member comprising a second plate portion and at least one edge portion connected to a lateral edge of the second plate portion and extending generally away from the second plate portion in a second direction substantially opposing the first direction, the second plate portion and the at least one edge portion of the second baffle member being substantially parallel to a longitudinal axis of the second baffle member;
• wherein the longitudinal axes of the first and second baffle members are substantially parallel to one another, and the edge portions of the first and second baffle members overlap to form a narrow passage therebetween, such that at least some of the air that flows through the baffle structure traverses a circuitous path partially formed by the narrow passage.