Abstract: An overfire draft system for a waste burner is disclosed. Such system comprises air vents arranged circumferentially around the base of the burner for communicating the interior of the burner to the atmosphere and a draft modulated damper plate located in each air vent for automatically regulating the volume of overfire air delivered to the interior of the burner. Each draft modulated damper plate is provided with a lower lip which is deflected by a predetermined angle with respect to the plate to create an aerodynamic lift effect with large opening moment to assist the damper plate in its response under low air velocity conditions, and an oppositely deflected upper lip with proportionately less bent surface to avoid flutter or hunting of the damper as it approaches the maximum open position and to provide added dynamic opening force.