Self-venting closure

A closure assembly comprising:

• a closure body having
• a deck with a peripheral mounting skirt,
• a flattened annular sealing rib on an underside of the deck adjacent to the peripheral mounting skirt, said flattened annular sealing rib having a downward facing engagement surface generally parallel to the deck,
• a valve seat within the deck, and
• a vent opening disposed within the valve seat;
• an annular gasket received adjacent to the underside of the deck and having an upward facing top surface in engagement with said downward facing engagement surface of said flattened annular sealing rib, said flattened annular sealing rib having an inward angle on an outer peripheral surface thereof;
• and
• an elastomeric umbrella valve mounted to the deck and having a valve flap arranged on an underside of the valve seat, said valve flap cooperating with said vent opening to normally seal said vent opening but permitting air to flow into an interior of the closure body.