Ministry of Labour, Training and Skills Development (MLTSD) personnel have encountered prefabricated aluminum guardrail post assemblies being used incorrectly as fall protection on construction sites. The assembly consists of a post with brackets for horizontal rails (top, intermediate and toe board) inserted into a base assembly which is itself attached to an existing structural member or work surface. A worker was fatally injured by a fall when this type of guardrail failed to protect the worker due to poor installation of the bracket to the work surface.

Photo of prefabricated aluminum guardrail brackets incorrectly mounted on roof

Figure 1: Improperly installed aluminum guard rails

Diagram of an aluminum guardrail showing the top rail, aluminum post, mid rail, bottom rail and aluminum bracket.

Figure 2: Aluminum guardrail post assembly


The type of vertical hollow structural section (HSS) aluminum guardrail post and base assembly depicted may not be adequate to support the loads specified in subsection 26.3(5) of Ontario Regulation 213/91 (the Construction Projects Regulation). MLTSD personnel have encountered these guardrail systems being used on projects without any engineering drawings to indicate the limitations of the system and the maximum loads and load configuration for which the system was designed. Furthermore, there are sometimes no manufacturer’s instructions/documentation for installation requirements, installation procedures and method of securement and strength requirements of the member and structure to which it is ultimately attached. The employer should be able to provide documentation that the guardrail complies with the load requirements outlined in section 26.3(5) of the Construction Regulation.

Method of installation

MLTSD personnel have observed installation of this guardrail system that is not in compliance with the construction regulation including the following:

  • The toe board for this system has been spaced approximately 170 mm from the outside edge of the work surface, which is not in compliance with subsection 26.3(4), paragraphs 4.1 and 5, see figure 1. The legislation stipulates that the distance of the toe board shall not be greater than 300 mm from the inner edge of the work surface (not the outer edge where the post would be positioned beyond the edge of the work surface) and that it shall extend from the surface to which the guardrail system is attached to a height of at least 89 mm.
  • The vertical guard rail posts are inserted into the base brackets, so that the rail brackets face away from the work area.
  • The fasteners may pull through worn holes in the mounting bracket if the fastener heads are too small for the bracket’s worn holes. This allows the bracket to detach from the work surface while the fasteners remain embedded in the supporting structure. As per section 25 (1)(b) of the Occupational Health and Safety Act, the employer shall ensure that the equipment, materials and protective devices provided by the employer are maintained in good condition.

For the purposes of checking if the vertical aluminum post was strong enough to withstand the specified forces outlined in subsection 26.3(5), the capacity of an aluminum post assembly was calculated, and it was determined that the posts assembly may not be adequate to support the loads specified in subsection 26.3(5) of Ontario Regulation 213/91.

Required action

Recommended when procuring a new/used guardrail system

  • Make sure the guardrail system is supported by manufacturer’s instructions/documentation on how to install the system, including the anchoring requirements i.e., what base material and fasteners should be used.
  • Ensure that the manufacturer’s instructions/documentation provide details of the system’s limitations, and loads for which the system was designed or reference that the system complies with the prescribed requirements in subsection 26.3(5) of Ontario Regulation 213/91. Other details, such as size and type of fasteners to be used, supporting member dimensional requirements, welds, member sizes and material description, should be included in the manufacturer’s documentation.

Recommended steps during installation of the guardrail post

  • Check that the system has the dimensions required in subsection 26.3(4) of the Construction Regulation.
  • Check whether the aluminum components appear worn or damaged (bent posts, elongated or enlarged fastener holes, bent rail brackets, cracked welds, etc.).
  • Check that the posts are properly installed in accordance with the manufacturer’s instructions. Check that there are no gaps between the edge of the working surface and the guardrail.
  • If there are no manufacturer’s instructions/documentation to review, or if there are serious concerns regarding the ability of the system to safeguard workers, either do not purchase the system, or obtain the advice of a professional engineer that the system meets the prescribed requirements in subsection 26.3(5) of Ontario Regulation 213/91.
  • Ensure that the system is installed strictly according to the manufacturer’s instructions or the engineer’s instructions.

For more information

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This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply and enforce these laws based on the facts they find in the workplace.