Concrete companies use extra concrete to produce blocks of various dimensions. Some blocks are simply square or rectangular in shape, while others have additional physical attributes, such as connecting links, peaked tops and recessed bottoms, which are used to prevent relative horizontal movement between layers of blocks or adjacent blocks during the storage of material within the concrete walls. As these blocks are sometimes used to construct walls, the walls can vary in height depending on the number of blocks used. These blocks walls are used for bunkers and for material storage.

The locations and sectors that use outdoor bulk storage of materials where these concrete blocks may be used include landscaping and landscaping suppliers, recycling centers, construction yards, cement plants and yards, concrete block plants and farms.

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.


In many sectors and cases, blocks are stacked on top of each other to add height to the storage areas. When materials are stored, loaded or unloaded in these storage areas, forces may be placed on the blocks which can cause them to move or collapse. A worker may be endangered if the concrete blocks were to move or collapse while he or she was in close proximity to them.

Workers may also be endangered when stacking the blocks to build the walls, as the blocks may tip and fall while the wall is being built. The blocks may also be too heavy for the lifting device being used causing overturning or failure of the device.

Most resulting injuries are crushing injuries or amputation of fingers, hands, arms and feet. Some injuries are fatal.

Some relevant legislative requirements and suggested precautions

  • Blocks used for walls should be installed and used in accordance with the manufacturer’s instructions and specifications. In the absence of such information, the employer should rely upon the advice of a professional engineer for each specific wall application to ensure adequate stability is maintained at all times.
  • The lateral forces exerted on the blocks will vary greatly depending on the density/weight of the material stored and the methods used to add and remove materials to/from the storage area. The safe height of the block stack will depend largely on density/weight and should monitored for any movement.
  • Periodic reassessment of the alignment and stability of the concrete blocks should take place to determine if any excessive movement has occurred. Section 25(1)(e) of the Occupational Health and Safety Act (OHSA) requires the employer to ensure that any wall/pillar/support or part of a workplace is capable of supporting all loads to which it may be subjected without causing material to be stressed beyond the allowable unit stresses established under the Building Code Act.
  • Employers should assess the effect of the weather on the area under consideration such as excessive rain, water accumulation from surrounding areas and freezing and thawing conditions as these may affect the stability of the blocks and cause movement or settlement.
  • The employer shall, as required under Section 25(1)(c) of the OHSA, ensure that prescribed procedures and measure are carried out in the workplace. Also, in workplaces which are subject to the Industrial Regulation, as required under Section 45, specified materials, articles or things shall be carried, moved, and lifted in the prescribed manner and shall be transported, placed or stored so that they do not tip and fall and so that they may be removed or withdrawn without endangering any worker. Any machinery, equipment or material that may tip or fall shall be secured against tipping or falling.
  • In workplaces to which the Industrial Regulation applies, any lifting device shall be marked such that the operator of the device can determine the maximum rated load that the device is capable of lifting under any operating condition. The lifting device shall be operated by a competent person or worker as required by subsection 51(2) of the Industrial Regulation.
  • The employer should provide barrier guarding of workers in hazard zones to maintain safe distances for workers when working with heavy equipment in areas near retaining walls.
  • Workers who are working around the area, should maintain a safe distance from the walls and the operating equipment that could cause movement or collapse of the walls.
  • All workers working with or in proximity to these concrete block walls should be informed, instructed and trained in their work and acquainted with any hazards by the employer as required respectively under Section 25(2)(a) and Section 25(2)(d) of the OHSA.

Legislative requirements

The Ontario Occupational Health and Safety Act applies to all provincially regulated workplaces and specific regulations apply to workplaces in specific sectors as well as workers and employers in those workplaces.