How to Use Shoring: A Complete Guide to Trench Safety

When working on excavation and trenching projects, soil stability is one of the greatest safety challenges. Without proper protective systems, trench walls can collapse in seconds, posing a deadly risk to workers.

That’s why OSHA requires protective systems like shoring for trenches deeper than 5 feet (or less, if conditions are unstable). But what exactly is shoring, and how do you use it properly?This guide breaks down how to shore safely, different shoring methods, and best practices for compliance.

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What Is Shoring?

Shoring is the process of installing supports along trench or excavation walls to prevent cave-ins. Unlike sloping(cutting back the trench wall at an angle) or shielding (using trench boxes), shoring directly reinforces the trench wall to keep soil from collapsing.

For a comparison of non-destructive digging techniques, see our guide on Why Contractors Choose Hydrovacing Over Traditional Methods.

When Is Shoring Required?

According to OSHA excavation standards:

  • Shoring is required for trenches 5 feet or deeper unless the soil is stable rock.
  • Shoring may also be required for shallower trenches if the soil is loose or conditions are hazardous.
  • A competent person must evaluate soil type and decide which protective system is required.

Types of Shoring Systems

Different job sites require different shoring solutions. Common methods include:

  1. Hydraulic Shoring
    • Prefabricated aluminum hydraulic cylinders are placed against trench walls.
    • Pressure is applied with a pump to push plates against the soil.
    • Quick to install and adjustable to trench dimensions.
  2. Timber Shoring
  1. Uses heavy wood planks (sheathing) supported by uprights and cross braces.
  2. Traditional method still used in certain projects.
  3. Aluminum Hydraulic Shoring with Plywood
  1. Aluminum cylinders combined with plywood sheeting for added soil support.
  2. Lightweight, portable, and effective in various soil types.
  3. Screw Jack Shoring
  1. Mechanical version of hydraulic shoring using adjustable screw jacks.
  2. Requires manual adjustment but no hydraulic pump.

Want to see how soil conditions affect trenching methods? Check out our article on Utility Corridor Congestion: Why Hydrovacing Is the Solution

Step-by-Step: How to Shore a Trench

  1. Soil Analysis
    • A competent person must classify soil as Type A, B, or C (with C being the least stable).
    • Soil type determines spacing and size of shoring.
  2. Select the Right Shoring System
    • Hydraulic systems are common for fast-moving projects.
    • Timber shoring is often used for specialized or deep trenches.
  3. Prepare the Trench
    • Remove loose soil from trench edges.
    • Ensure safe access/egress (ladders within 25 feet of workers).
  4. Install Shoring Components
    • Place vertical uprights or hydraulic cylinders against trench walls.
    • Add cross braces to hold uprights in place.
    • Ensure even spacing according to OSHA tables.
  5. Pressurize/Brace the System
    • For hydraulic systems, pump cylinders until they apply firm pressure.
    • For timber systems, secure cross braces tightly.
  6. Inspect Before Entry
    • Check that all components are secure and soil pressure is stabilized.
    • Inspect regularly throughout the shift, especially after rain or vibration.
  7. Remove Shoring Safely
    • Workers should exit before dismantling.
    • Release hydraulic pressure gradually.
    • Backfill the trench as soon as possible.

OSHA Shoring Requirements

OSHA’s excavation standard (29 CFR 1926 Subpart P) provides tables and charts that dictate:

  • Maximum trench depth and spacing for shoring members.
  • Soil-type-specific requirements.
  • Installation and removal procedures.

Key Rule: Only a competent person may design, install, or inspect shoring systems.

Shoring Best Practices

  • Always pair shoring with access controls, traffic safety, and site protection.
  • Inspect shoring after heavy rain, vibrations, or soil changes.
  • Never allow workers in an unprotected trench.
  • Train all employees on shoring installation and hazards.

For operators, we also recommend reading our Hydro Excavation Safety Best Practices to reinforce job site safety beyond trenching.

Final Thoughts

Shoring is one of the most effective ways to prevent trench collapses and protect workers in deep excavation projects. By using hydraulic or timber systems properly — and following OSHA’s strict requirements — companies can dramatically reduce excavation risks.

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Frequently Asked Questions (FAQ)

Q1: What is shoring in excavation?
Shoring is the process of supporting trench walls to prevent soil collapse.

Q2: When is shoring required by OSHA?
Shoring is required for trenches 5 feet or deeper, or shallower if soil is unstable.

Q3: What are the types of shoring systems?
Hydraulic shoring, timber shoring, aluminum shoring, and screw jack systems.

Q4: Who can install shoring?
A trained competent person must oversee installation and inspection.

Q5: How is hydraulic shoring different from shielding?
Hydraulic shoring supports the trench walls, while shielding (trench boxes) protects workers inside without supporting soil.