A vent baffle assembly provides air ventilation in a cathedral ceiling having rafter beams and roof sheathing. The vent baffle assembly includes a first vent sheet and a second vent sheet. The first vent sheet has first and second ends, first and second longitudinal ribs and a first lateral stiffener extending generally perpendicularly to the ribs. The second vent sheet includes third and fourth ends, third and fourth longitudinal ribs, and a second lateral stiffener extending perpendicularly to the ribs. The first vent sheet is positioned between adjacent rafters with the ribs oriented parallel to the rafters. The second vent sheet overlaps the first vent sheet with respective ribs interengaged to limit lateral movement of the first vent sheet relative to the second vent sheet. The first lateral stiffener engages the second lateral stiffener to limit longitudinal movement of the first vent sheet relative to the second vent sheet.