Abstract: Employees #1 through #5 were working on a 2-story frame office building. Employee #1 was working on a second floor wall; Employee #2 was standing on a sawhorse furring out a wall; Employees #3 and #4 were standing on the trusses over a beam; and Employee #5 was supervising the framing. A loud crack and then shouted warnings were heard. The beam broke and the partially completed roof collapsed. Employees #1, #2, #4, and #5 were bruised and Employee #3 sustained fractures; all five employees were treated at a local hospital. The roof trusses had not been adequately braced during construction, causing the 4 by 6 treated timber roof support beam that was being used as the center interior bearing to fail under truss "A." In addition to the inadequate design of the beam, several bundles of 4 by 8 ft plywood sheets weighing 3,000 lb had been lying on the wood roof for four to seven days. Bracing/blocks were being installed on the trusses. Spreading bundles on the roof was a common construction practice.