Abstract: On August 18, 1987, Employees #1 through #6 were involved in the erection of 67 ft 7 1/2 in. long wood trusses at the west end of a building. The trusses were supported by a wood frame wall on the south side and a concrete block wall on the north side, both 20 ft high. To secure the trusses both for permanent structural strength and for temporary bracing to prevent collapse, the contractor used six rows of stay laths (2 by 4 by 12 ft long) on the top chord plane, sheeting on the sides as the trusses were put in place, and placement of plywood as the roof work progressed. Thirty-two trusses, which started falling from the west end, tipped east with a domino effect, and buckled, forcing out both walls and falling to the ground. Employees #1 through #6 were injured, falling with the trusses. Contributing factors to the collapse may have been (a) that not less than 4 bundles of plywood (approximately 2, 800 lb each) were on the roof and trusses at one time and as much as 4,496 lb was on the roof at the time of the collapse, (b) possible damage to the trusses while they were being hoisted by a 25 ft long spreader, and (c) inadequate bracing of the trusses (no web plane or bottom chord plane bracing) of the wood and masonry walls.