A screen panel for a roll-up door is configured to be slidably coupled to the door adjacent a bottom portion of the door. The panel is generally parallel to the bottom portion when installed and movable between a retracted position, wherein a bottom edge of the panel is generally aligned with a bottom edge of the door, and an extended position, wherein the bottom edge of the panel is located below the bottom portion. A biasing device biases the panel toward the retracted position with a biasing force that is sufficient to move the panel to the retracted position only when the panel is positioned in an orientation other than a vertical orientation.