Abstract: On October 14, 2005, Employee #1 was working on the flat roof of a school under construction. He was installing a layer of styrofoam insulation on the roof. An uncovered 4-ft by 5-ft floor opening was less than 1.5 ft away from the location, where Employee #1 was working. The uncovered opening was present when the roofing crew started working that morning. Despite that fact, the foreman of the roofing crew allowed his crew to work on the roof without taking any action to correct the hazardous conditions. However, two days prior to the accident, a warning line was marked around the floor opening, but the opening was left uncovered. Neither a barricade was put around the opening. At the time of the accident even the warning line was not in place. Employee #1 was working with his back turned to the opening. He finished laying in place the section of foam insulation that he was working on, stood up and stepped backwards into the floor opening. He fell from a height of 14.5 ft and landed on his head on the concrete floor. Employee #1 died two days after the fall.