Abstract: A damage minimizing closure door that is moved vertically between open and closed positions in which the door is a flexible curtain and a guide assembly is mounted on the side edges of the doorway for receiving and guiding the side edges of the flexible door during vertical movement. A counterbalancing power spring is associated with the door to assist in raising and lowering the curtain. The flexible door or curtain and the guide assembly include unique features which enable the side edges of the curtain to separate from the guide assembly upon being impacted by an externally applied force, such as by a vehicle, with little if any damage occurring to the curtain or guide assembly.