Abstract: On November 14, 2005, Employee #1, a foreman working for a subcontractor, was installing insulation with a coworker in a building with an approximately 10,000 square ft area. The roof height was about 14 ft and the ventilation ducts were 9 ft from the floor level. The employees were stapling FSK coil insulation to the 2-in. by 10-in. wooden joists below the roof. To access the roof joist, they used a metal rolling scaffold (manufactured by ABSS Manufacturing Co. Inc. with model number AP7510 and a load capacity of 50 psf), with a platform height of 7.5 ft and a 5 ft by 10 ft surface area. The employees did not install the scaffold guardrails because they would interfere with the ducts below the roof level. In addition, the wheels of the scaffold were not locked to prevent it from moving when the employees were working. In fact, they wanted to move the scaffold while on the platform as they did not want to reposition the scaffold from ground level. At the time of the incident, the employees were placed on opposite sides of the platform, each being on either side of a duct. After the coworker installed insulation on his side, he passed the coil to Employee #1 who began by unwinding the coil on the joist surface and then stapled the insulation. As he was unwinding the coil onto the joist, he was moving forward while looking up. When he reached the end of the scaffold platform, he inadvertently stepped off the scaffold and fell. He sustained a compression fracture of the L2 vertebrae and a fractured pelvic bone. Employee #1 was transported to the Long Beach Memorial Medical Center in Long Beach, CA, where he remained for twenty five days.