Abstract: At approximately 1:15 p.m., on September 14, 2005, Employee #1 and a coworker were installing a roof vent in a metal building housing an air-make-up heater. The heater was on the roof of an existing plant building, about 20 ft above the ground. The building was surrounded by warehouses. An apprentice employee returned to the company truck to get a drill bit. The journeyman, Employee #1, decided to step onto the south warehouse roof and then onto the west warehouse roof, which was at the same height as the new smaller building housing the make-up heater. While he was on the warehouse roof, Employee #1 did not recognize that the roof had rows of built-in fiberglass skylights. He stepped on a skylight panel, the panel broke, and the employee fell about 25 ft to a concrete floor. He died of injuries sustained in the fall.