Abstract: At approximately 2:10 p.m. on March 29, 2004, Employee #1, a carpenter, was working on a roof under construction. The height of the roof was approximately 36-ft. As Employee #1 occupied a 6-ft by 10-ft segment of the roof, it collapsed underneath him. He fell along with a gasoline portable generator, tools, and lumber. The collapsed roof segment was connected to the steel joists of the wood nailers via four TF-46 hangers and two TF-34 hangers. Two TF-46 (A & B) and one TF-34 (C) were attached to each side of the wooden panel that was assembled on the ground. The remaining hangers were to be nailed on the roof: one TF-46 (D), one TF-46 (E), and one TF- 34 (F). A 4-ft by 8-ft skylight opening was bordered by four 4-in. by 6-ft subpurlins. TF hangers D, E, and F came down with the collapsed roof segment, while TF hanger A and B remained nailed to the roof. TF hanger C also came down, however nailed to a ripped piece of its wood nailer. Initially, employer secures the hangers on the roof using 16D 2.125-in. by 0.148-in. screw shank nails, one nail per sheet for every 4 ft. Accordingly, if the TF-34 is nailed, the two TF-46 will not be nailed, and if the two TF-46 are nailed, the TF-34 will not be nailed. There was no evidence that hangers D, E, and F were nailed. The hangers are nailed off completely by the nailing crew when the entire deck nailing takes place, normally after 30,000 square feet of the roof has been completed. According to the hangers' manufacturer, 2-10D nails are required to secure the hangers to obtain the listed maximum allowable load of 825-lb. The manufacturer does not have any maximum allowable load data when one nail or no nails used with these hangers. The live load exerted on this roof segment was approximately 560-lb, and the dead load was approximately 240-lb, which was a total of weight 800-lb near the maximum load. Employee #1 was transported via helicopter to a medical center for treatment and hospitalized for postoperative care lasting three weeks.