A vented ridge closure for covering a ventilation gap formed in the metal roof of a building includes U-shaped deck caps extending over the uppermost ends of the roof deck panels. The deck caps close-off the valleys of the roof deck panels, while providing air flow openings for directing hot air to the exterior. The air flow openings may be louvered. A ridge cap extending along the ridge of the roof above the ventilation gap. Side flanges of the ridge cap engage top panels of the deck caps, and are secured by fasteners to ribs of the underlying roof deck panels, or by inwardly-turned lips to the peripheral edges of the deck caps. Sealing material is preferably provided between a central panel of each deck cap and the abutting uppermost ends of the roof deck panels engaged therewith.