The first occurred five years ago and involved a roofer who fell 12 feet off a wooden-framed structure. Recently another man fell five feet off a scaffold and suffered a broken arm. The pre-engineered metal building was being constructed on a concrete slab, and was to be used for production and assembly work. The crew had completed attaching the entire ceiling from the inside of the building. The screws were attached with an electric screwdriver equipped with a variable ratchet clutch, with the torque set by the degree of pressure applied to the screwdriver.
Workers state that it is possible to apply too much pressure and strip the heads off the screws.
The crew were in the process of insulating the roof and applying the top layer of sheet metal to the building. Normally at this stage workers walk on the metal purlins and not on the top surface of the ceiling panels. The victim was working alone on the top of the building at the time of the fall. He apparently was walking on the purlin and slipped, with his foot landing on an overlapped seam in the ceiling panels. He weighed over 200 pounds, which was sufficient to break screws directly under his foot, allowing the seam to split open.