Oregon OSHA Health and Safety

RESOURCE

April 2016

Safety Notes

Accident Report

  • Incident | Truss collapse
  • Business | Construction
  • Employee | Carpenters

Four carpenters setting up trusses on a garage were injured when the temporary framework supporting the trusses collapsed.

The construction crew leader began his workday in the morning by getting ready to set up trusses on a new garage with three of his co-workers. He put on his fall-protection gear and climbed up a ladder to inspect the temporary framework that he built the day before to support the trusses on their sides and keep them from bowing. He built many of these structures without a problem and expected this one to be just like the others. (Temporary frameworks are necessary to support the trusses because garages do not have interior walls.)

The three workers in his crew arrived an hour later. Two of them climbed up on the garage top plate with the crew leader to set up the trusses, but they were not wearing fall-protection gear. The third worker stayed on the ground to hand up tools and supplies.

With the crew leader standing at the center of the first truss and the other two standing on each side, they began raising it. Then, the entire framework collapsed, trapping all four of the workers under the trusses.

When emergency responders arrived, they lifted the trusses off the workers and then rushed the workers to local hospitals. Three of the workers were released later that day following treatment for their injuries. The crew leader was hospitalized for two days so he could recover from injuries to his right leg.

Findings

The temporary framework was not constructed to hold the weight of the trusses and the workers. The nine trusses on the garage top plate weighed 1,700 pounds and required support across 902 square feet of open horizontal space above the garage. The top of the temporary framework was 12 feet, 10.5 inches above the unfinished garage floor. Truss sets are typically banded and set on the top plate by a crane. However, one of the three sets on the garage top plate was not banded, which concentrated the set's 955 pounds in one area, rather than over the entire temporary framework.

The workers had no formal training on the construction of temporary frameworks. When asked about the workers' training for building temporary frameworks, the company's president said it was not necessary because they had prior experience.

Two of the three workers were working on the temporary framework without fall protection. Measurements taken during the investigation showed the distance between the garage top plate and the unfinished gravel floor was 12 feet, 10.5 inches.

Applicable standards

437-003-0915: "During erection, alteration, or repair, structures were not braced or guyed as necessary to prevent overturning or collapse."

437-003-1501: "The employer did not ensure that fall protection systems were provided, installed, and implemented according to the criteria in 1926.502. 1

926.21(b)(2): "The employer did not instruct each employee in the recognition and avoidance of unsafe conditions… to control or eliminate any hazards…"

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