Date of incident: October 2021
Notice of incident number: 2021189770010
Employers: Demolition subcontractor; demolition firm; construction company; property development company (prime contractor)

Incident summary
Three workers were doing manual labour to prepare a commercial building for machine-assisted demolition. Components of the roof system, including the roof membrane and roof sheathing, had already been removed. One worker was standing on a fixed awning and two workers were standing on a temporary plywood work platform that had been placed over the exposed roof joists (small timbers spanning the roof from wall to wall). The awning collapsed, and the worker on the awning fell to the ground. Three joists were pulled down by the weight of the awning when it fell, and the two workers who were standing on the plywood platform were thrown off the building. All three workers sustained injuries, some serious.

Investigation conclusions

Cause

• Awning structurally compromised by removal of roof components. Before the incident, the removal of structural roof components compromised the awning the roof system had been supporting. The awning was attached to the building by four tie-backs — rods that pass through the concrete block parapet at the front of the building and attach to the joists to provide support for the awning. When bolts that secured one of the tie-backs to a joist were removed, the three remaining tie-backs could not support the awning.

Contributing factors

• Lack of hazard identification and safe work procedures. The demolition firm, which hired the demolition subcontractor to do manual labour before excavators completed the demolition, had a written demolition plan. However, the plan did not address the hands-on work being done by the demolition subcontractor’s workers to remove the building’s valuable structural timbers for salvage. The demolition firm and the demolition subcontractor did not identify the hazards of the manual work or determine how to remove the structural components in a manner that did not destabilize the structure. The employers did not provide any instructions to the workers on how to ensure that the removal of the structural components did not compromise the structural integrity of the building or the awning.
• Inadequate training and supervision. One of the workers was a new worker and another was a young and new worker. The employer did not give them any relevant training or an orientation before starting work that day and did not inform them of the hazards at the site. Neither the demolition firm nor the demolition subcontractor ensured that the work was being adequately supervised.
• Inadequate prime contractor coordination. A construction company had been hired as the construction manager but, according to the contract with the developer, was not to start fulfilling its contractual obligations until the demolition was complete. Therefore, the construction company was not obligated to supervise or coordinate safety during the demolition phase. Because the construction manager contract did not specify a prime contractor, the developer was deemed to be the prime contractor. The lack of clarity in the contract as to which firm held prime contractor responsibilities contributed to the developer not having an adequate system in place to coordinate health and safety for this work.
• Method of roof access. To access the roof, the demolition subcontractor relied on an extension ladder at the front of the awning. A mechanical (scissor) lift, scaffolding, or temporary stairs had been requested from the employer to provide safe access to the roof and roof joists. However, only the ladder was provided, which exposed the workers to a higher risk of falling — especially because they had to carry tools and materials up and down the ladder. If a scissor lift, scaffolding, or stairs had been used, there would have been no need for workers to stand on the awning.

Other health and safety issues

• Lack of fall protection. A fall protection system is required when a worker is exposed to a fall hazard of 3 metres or greater. In this case, the roof was 6 metres from the ground and the awning was 4.3 metres from the ground, so a fall protection system should have been in place for certain aspects of the work. There was no fall protection system in use when the incident occurred, and the employer did not provide any training on how or when to use fall protection.

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