Roof Collapse — Twice — Why Composite Floors Need Engineering Approval

Composite Floor Collapse — What Happens When You Skip the Engineer

Let's talk about what happened at two London, Ontario construction sites in 2022 and 2023. EllisDon Forming Ltd. was installing CANAM Hambro D500 composite floor systems — a legitimate, widely-used technology. But on both projects, workers loaded those systems before a professional engineer had reviewed and approved the plans. The result was predictable: collapse. The first time, on July 22, 2022, at 3080 Bostwick Road, supervisor Corey Jones oversaw a penthouse rooftop installation where required cross-bracing had not been installed. The design drawings were unclear — and the company treated that ambiguity as permission to proceed. While workers poured concrete, the composite floor system shifted and failed. No workers were injured that day. The company had a chance to learn the lesson. They didn't. On January 5, 2023, at 131 King Street, supervisor Matthew Thompson oversaw a concrete pour on the 26th floor. Again, bracing was incomplete. Again, the company allowed the pour to proceed without engineering confirmation. The floor system collapsed mid-pour, and four workers fell to the level below. All sustained injuries. The Ministry investigation found the pattern. EllisDon Forming did not have a mandatory engineering review process. Supervisors were making structural safety decisions instead of following engineer-approved specifications. The company's failure to implement what Section 89(2) of Ontario Regulation 213/91 plainly requires was not a one-time lapse — it was how they operated.

What the Law Requires

Section 89(2) of Ontario Regulation 213/91 is unambiguous: 'No employer shall cause or permit a worker to apply a load to a form or shoring system unless a professional engineer has reviewed the plans and determined that the system is capable of supporting the load.' Basically, what this means is simple: before anyone pours concrete on a composite floor system, a licensed professional engineer must have looked at the plans and said, in writing, that the system can handle the load. This is not a suggestion. It is not a best practice that applies only to complex layouts. It is a legal requirement that applies every time — without exception. Section 31(1)(b) adds: 'Every part of a project, including temporary structures and excavations, shall be adequately braced to prevent movement, failure or collapse.' This means the bracing specified in the engineer-approved plans must be fully installed before any load is applied. The court found that EllisDon Forming failed on both counts. The company loaded composite systems without engineer approval. It allowed supervisors to make structural decisions. It had incomplete bracing on both projects. And when faced with unclear design drawings — rather than pausing to get engineering clarification — supervisors proceeded. In the court's view, this was not a paperwork oversight or a design interpretation issue — it was systematic neglect of worker safety. The company had already experienced one collapse and failed to change its practices. The $130,000 fine and the convictions of both the company and its supervisors reflect how seriously the court takes the failure to obtain mandatory engineering approval.

What Supervisors Must Do

• Before any pour begins, obtain the engineer-approved floor plan and bracing specifications for your section — do not rely on general drawings
• Walk the floor system with the crew before loading and verify every bracing member, connection, and support specified on the approved plan is physically installed
• Do not proceed with concrete pouring or material loading if any bracing element is missing or you are unsure whether it matches the engineer's specifications
• Document the bracing inspection with photos and a signed checklist; your sign-off confirms that the installed work matches the engineer-approved plan
• If design drawings are unclear, stop work and contact the structural engineer for written clarification — never substitute your judgment for engineering review
• Keep asking: 'Has a professional engineer reviewed and approved these plans, and have I verified that every bracing element specified is in place before we load the system?'

What Employers Must Do

• Establish a mandatory engineering review process for every composite floor installation — no exceptions for simpler layouts or repeat project types
• Require written approval from a professional engineer before any load is applied to any floor system; keep the approval on-site and available to supervisors
• Create a bracing checklist tied directly to engineer-approved plans; supervisors must complete and sign off before loading begins
• Conduct pre-pour inspections that explicitly verify each bracing element against the engineer's specifications — a general walk-through is not sufficient
• Implement a stop-work authority: if any bracing element is missing or questionable, all work stops until engineering confirms the system is safe to load
• Train all supervisors on composite floor systems, bracing requirements, and the legal requirement for engineering approval under Section 89(2), O. Reg. 213/91
• After any incident or near-miss involving a structural system, conduct a formal lessons-learned review and update procedures before resuming comparable work on any site

How to Use This Case in Your Workplace

This case is a valuable safety conversation starter. Use it during pre-project meetings for all composite floor and high-rise concrete pours, monthly safety meetings with supervisors and project managers, structural trade training on engineered systems, and new-hire orientation for all workers on formwork and structural projects. Walk your team through the site and ask: 'Is there a professional engineer's approval letter for every floor system we're planning to load — and where is it posted?' 'Have supervisors walked the floor and confirmed every bracing element matches the engineer's approved plan?' 'If a supervisor had a question about the design drawings, who did they contact — and did they wait for written engineering clarification before proceeding?' This case reinforces a simple message: composite floors and engineered structural systems are not places for judgment calls. Professional engineers provide the approval. Supervisors verify the installed work matches that approval. Workers load the system only when both are confirmed.