Abstract: Employee #1, age 17, and four coworkers, all carpenters, were using nail guns to install decking and wall sheathing in different areas on the second floor of a building under construction. At times, the carpenters had to lean out between 2 by 4 wall struts and bend down to nail the outside sheathing in place. Employee #1 was apparently kneeling on the west side of the second floor and was leaning out over the edge and against two struts when the strut closest to the window broke free at the bottom and moved away from the building. He lost his balance and fell22 ft 6 in. through the opening left by the failed strut, landing on the ground. Employee #1 suffered injuries to his back, neck, and shoulders. He was transported to the shock trauma unit, where he was treated and released the following day with instructions to take 7 to 10 days off from work. He later stated that he had somehow managed to land on his feet before collapsing to the ground. The failed strut had been secured with three 12-penny nails.