Abstract: A four man crew was setting prefab roof trusses on three adjacent townhouse units, 11 per unit on 2 ft centers. These units were adjacent to three other units on which trusses had been set by another employer's crew. The first truss was scabbed to the existing trusses by a 2 by 4. The succeeding trusses were braced only by one run of metal spacer straps except that the trusses between the three units were scabbed by two 2 by 4s. There was no lateral or diagonal bracing. While setting the next to last truss at the cable end, the other crew, which was now sheathing, removed the single slab holding the first truss in place. The entire three units of trusses fell over like dominoes and partially sagged or fell into the top story of the townhouse units. Employees #1 and #2 were struck by the trusses and bruised. They were sent to the hospital across the road for x-rays and released within two hours. The method used to set up the trusses did not resemble the method recommended by the Truss Plate Institute.