The present invention generally relates to a backdraft damper having a flap valve, a dust collector having a backdraft damper and a method for preventing a pressure wave from propagating upstream of a dust collector. In one embodiment, a backdraft damper is provided that includes a body having a flap valve disposed therein. The flap valve includes a valve seat disposed in an interior volume of the body. The flap valve includes a blade moveable between an open position and a closed position which prevents fluid flow between an inlet and an outlet of the body. The blade of the flap valve includes a core material sandwiched between a first plate and a second plate.