Abstract: At approximately 10:00 a.m. on September 12, 1990, Employee #1 and a coworker were installing curbs for an air conditioning system on the roof of a one-story, concrete, tilt-up warehouse office building under construction. They had moved eight curbs onto the roof using a 25 ft extension ladder that was set up through one of the 4 ft by 9 ft skylight openings. Employee #1 picked up the top of the ladder and started walking backward, pulling the ladder up from the floor. He had backed up approximately 16 ft when he fell 14 ft 9 in. through another skylight opening. He landed on the concrete floor and sustained a broken left wrist and a gash on the side of his head. He was hospitalized for treatment and observation. There were 15 skylight roof openings spaced 16 ft apart on two buildings.