CNESST: Rooftop fall that killed Installation MB worker was preventable with proper safety measures
An 8.7-metre fall onto concrete was caused by unmarked openings covered with insulation that gave a false appearance of solid roof, investigators found.
Sources · Quebec Nouvelles
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A worker for Installation MB fell 8.7 metres through unmarked roof openings on November 13, 2025, landing on a concrete floor inside a boiler room in what Quebec's workplace safety regulator has concluded was a preventable accident.
The CNESST released its investigation report Thursday. The worker was moving a plywood panel on the roof when he stepped on rigid polyurethane insulation covering an opening approximately 48 centimetres square. The insulation failed under his weight. Snow accumulated on the roof at the time, further disguising the hazard.
The worksite, managed by Pomerleau, had two unsecured openings of the same size. Architectural and engineering plans prepared by the client's professionals contained no documentation of these openings. Their visual appearance — concrete edges and insulation panels integrated into the structure — gave the false impression of solid roof bases. An inspection from inside the building would have revealed the hazard, but this was not conducted.
The CNESST found that danger identification and communication were deficient and corrective measures inadequate. The regulator states that guardrails are required where workers are exposed to fall danger exceeding 3 metres, or alternative fall protection measures if guardrails are impossible.
No statement from Installation MB, Pomerleau, or the worksite client is included in the report release.
What regulatory action, citations, or penalties has the CNESST issued against Installation MB or Pomerleau?
Has the worksite principal or client implemented additional safety protocols?
We'll update this story as answers emerge.
The facts
What caused the fatal fall at the Installation MB worksite?
A worker stepped on rigid polyurethane insulation covering an unmarked roof opening approximately 48 centimetres square. The insulation failed under his weight, and snow on the roof further disguised the hazard.
How far did the worker fall?
The worker fell 8.7 metres onto a concrete floor inside a boiler room.
When did this accident occur?
The fall occurred on November 13, 2025.
What did CNESST say was missing from the worksite?
The worksite lacked guardrails or alternative fall protection measures at the two unsecured roof openings, and an inspection from inside the building that would have revealed the hazard was not conducted.
