Timber Shoring Safety
The Problem
Excavation work remains one of the most hazardous activities on any construction site, with trench cave-ins being a leading cause of serious injuries and fatalities. While less common today due to the use of modern protective systems, timber shoring still plays a critical role—especially in complex trenches containing multiple utilities or services.
Identify the Hazards
- Improper Installation:
Timber shoring that is not installed under the supervision of a Competent Person increases the risk of structural failure.
- Component Damage:
Broken or split timbers, bent screw-jack pipes, or loose cross braces can weaken the system and compromise its integrity.
- Unstable Soil:
Shifting or saturated ground conditions around timber shoring can lead to a sudden collapse.
- Unsafe Entry/Exit:
Climbing on cross braces or using makeshift access points raises the risk of falls and serious injury.
Safety Practices and Preventative Measures
Competent Person Approval
- Timber shoring must be installed and signed off by a Competent Person, as defined under applicable provincial regulations.
- Use only shoring systems approved by regulatory authorities or follow an engineered design when required.
Safe Entry and Exit
- Use secured ladders or designated access points only.
- Ladders must extend at least one metre above the trench edge for safe access and egress.
- Never climb on cross braces or screw jacks—they are not designed to support body weight and pose a fall risk.
Hazard Awareness
- Avoid Unprotected Areas: Only enter and work within the shored portion of the trench. Unshored areas can collapse without warning.
- Inspect for Damage: Watch for cracked timbers, shifting braces, or signs of ground movement. Report any issues immediately.
Inspection and Maintenance
- Ensure all components—such as pipe screw jacks and braces—are properly in place and secure.
- Excavation below the bottom of timber shoring must be inspected and authorized by a Competent Person before proceeding.
Stability During Excavation
- Make sure uprights are snug against the trench wall to eliminate gaps and prevent shifting.
- Any movement, such as dislodged braces or sliding uprights, must be reported and corrected before continuing work.
Real-Life Case or Scenario
Last year, a worker entered a trench where timber braces had come loose due to soft, shifting soil conditions. The trench had not been inspected prior to re-entry. A partial collapse occurred, burying the worker up to his waist. Fortunately, co-workers responded quickly and were able to prevent more serious injury. This incident could have been prevented with a proper inspection and approval by a Competent Person. It highlights the critical importance of following inspection protocols before re-entering any trench.
Employee Responsibilities
Employer Responsibilities
- Ensure timber shoring is designed, installed, and maintained according to provincial occupational health and safety regulations or an engineered plan.
- Appoint a Competent Person to supervise and inspect all trenching and excavation work.
- Immediately replace or repair any damaged or compromised shoring components.
- Provide thorough training and instruction to workers on the safe use and hazards of timber shoring.
Discussion & Questions
- “What do you look for when inspecting timber shoring before entering a trench?”
- “Have you observed any trench stability issues or problems with timber shoring on site?”
- “What’s the best way to stay in contact with the Competent Person during trench work?”
Encourage team members to share their ideas, experiences, and any questions about the process. Open discussion helps improve safety awareness and teamwork.
Commitment/Action Plan
Let’s commit to inspecting all timber shoring before entering any trench and ensuring safe entry and exit procedures are strictly followed. Starting today, no one enters a trench without approval from a Competent Person. If you notice unstable soil, broken timber, or shifting supports, report it immediately.
Wrap-Up
Timber shoring, when used correctly, provides vital protection against trench collapse. However, it must be properly installed, regularly inspected, and used safely. By working closely with the Competent Person and following established best practices, we can protect ourselves and our co-workers. Thank you for your ongoing commitment to safety.
Standards Overview
Under Canadian occupational health and safety legislation—including provincial regulations and guidance from the Canadian Centre for Occupational Health and Safety (CCOHS)—employers and supervisors must:
- Use protective systems (such as timber shoring) in trenches deeper than 1.5 metres, unless the trench walls are sloped or benched to a safe angle as prescribed by local regulations.
- Ensure all trench work is supervised and inspected by a Competent Person, as defined by applicable provincial standards.
- Follow timber shoring load charts or an engineered design when using timber support systems.
- Excavation up to 600 mm below the bottom of timber shores may be allowed, but only under direct supervision and with careful inspection.
- Refer to your provincial excavation safety regulations (e.g., OHSA in Ontario or WorkSafeBC guidelines) and CCOHS trenching safety resources for detailed requirements.
Disclaimer
“The information provided in this toolbox talk is intended for informational and educational purposes only. It is not a substitute for professional legal, safety, or regulatory advice. The content reflects general best practices and industry standards but may not be applicable to all workplace environments or jurisdictions.
It is the responsibility of employers, supervisors, and workers to ensure compliance with applicable federal, provincial, and territorial laws, regulations, and standards, including but not limited to those set by the Canadian Centre for Occupational Health and Safety (CCOHS) and relevant provincial occupational health and safety authorities. Site App Pro, its affiliates, agents, or representatives—as well as the authors, presenters, and distributors of this toolbox talk—assume no liability for the use or application of the information provided.
Participants are strongly encouraged to consult appropriate legal, safety, or regulatory professionals regarding specific workplace concerns or questions. Always adhere to your organisation’s policies and procedures for health and safety and hazard management.
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