Fastening assembly

A roll-up door assembly for closing an opening having parallel sides, the door assembly comprising:

• parallel track means positioned at the sides of the opening;
• a plurality of slats hingeably coupled to one another to form a door and including means for slidably engaging the door in the track means for movement between a closed position and an open position;
• an idler positioned at an end of the track means for receiving and guiding the door as it is moved between said positions;
• a balancer parallel to the idler and mounted for rotation, the balancer including biasing means;
• an elongate flexible element coupling one of the slats to the balancer, the element being attached to said one of the slats at two points adjacent respective ends of the slat;
• and
• attachment means coupled to the balancer and slidably receiving the flexible element to permit the element to be positioned relative to the balancer and said one of the slats, so that on assembly the element will wrap around the balancer and provide substantially equal loadings on the slat at said two points whereby the door will ride smoothly in the tracks as the door is moved between said positions.