What Are Outriggers on Scaffolding?

Outriggers are structural components of scaffold frames that are added to the bottom of scaffolding units to provide increased stability. Outriggers can commonly be a beam or frame that extends from the legs of the scaffold, and would also either have casters or leveling jacks on them. Outriggers create a bigger base, or lateral support because they would decrease the center of gravity and make the scaffold less likely to tip on footprint., especially in taller scaffolds or scaffolds exposed to lateral force.

Often outriggers are confused with side-arms. Outriggers are added to scaffolds to provide more stability at the base, and side-arms are added at whatever working level to allow the worker to get as close to the work surface as possible like a wall. The terms are often confused, because they both communicate to provide assistance, but they perform distinctly different functions.

Why Are Outriggers so Important?

Outriggers play an important role in keeping scaffolds stable, particularly in higher risk situations. The Occupational Safety and Health Administration (OSHA) require that supported scaffolds that are more than 4 to 1 height-to-base widths be prevented from tipping with either guying, tying, bracing, or outriggers. For mobile scaffolds, a height to base width ratio of 2 to 1 or less must be used to avoid tipping.

Outriggers are helpful in these situations:

Tall and narrow scaffolds: When the scaffold’s height is high in relation to the scaffold’s base width.

• Cantilevered platforms: When platforms extend beyond the scaffold's frame, uneven loads are created.
• Untied scaffolds: When the scaffold does not tie into an adjacent structure.
• Uneven surfaces: When the ground provides unstable and uneven surfaces and tipping chances increases.
• By expanding the scaffold’s footprint: outriggers distribute weight more evenly, enhancing resistance to tipping and ensuring a safer working environment.

When Are Outriggers Required?

The need for outriggers depends on the scaffold’s configuration, type, and regulatory requirements. Key scenarios include:

• Height-to-Base Ratio Exceeds 4:1: Stabilization is required by OSHA for scaffolds exceeding four times the base width. For example, a scaffold that is 5 feet wide and 20 feet high (4:1 ratio) would require outriggers or other forms of stabilization if they wanted to increase the height to 25 feet (5:1 ratio).
• Specific Scaffolds: There are some narrow scaffolds, like baker scaffolds (typically 29 inches wide), that may require outriggers at lesser heights. They would be required to provide outriggers if double or triple stacked: They are often required when the platform height exceeds 6 feet or when stacking more than 3 sections (approximately 18 feet).
• The scaffold is facing the wall: In large open spaces where there isn’t a wall adjacent to the scaffolding, 4 outriggers will often be required to prevent tipping in 360 degrees. If the scaffold is adjacent to the wall, the wall is a natural outrigger that occurs on one side and, therefore, the requirements will be reduced to two outriggers on the opposite side.
• Even when not mandatory: using outriggers can be a proactive safety measure, particularly in windy conditions or when handling heavy loads.

Table: Outrigger Requirements for Scaffolds

Types of Scaffolding Outriggers

Outriggers come in various types, each tailored to specific scaffolding needs. Understanding these options helps in selecting the right outrigger for a project:

• Adjustable Outriggers: With advanced features such as emergency systems and overload sensors, these outriggers meet OSHA 1910.66 and ASME A-120 for high safety applications.
• Baker Scaffolding Outriggers: Baker scaffolding outriggers are designed for baker scaffolds which typically include caster wheels to help solve the stability concerns of narrower scaffolds.
• Fixed Outrigger Systems: Fixed outrigger systems are affixed permanently and are used for buildings that require long-term maintenance of stationary scaffolds.
• Transportable Outrigger Systems: These lightweight outriggers are supplied with casters to make them easy to move without counterweights. They are suitable for temporary or moving outrigger setups.
• Push-Thru Systems: Push-thru systems quickly connect to a fixed stand and can typically be assembled quickly along with a building to give quick access to the facade of the building.

Table: Types of Scaffolding Outriggers

How to Use and Install Outriggers Properly

Proper installation and use of outriggers are crucial for scaffold safety. Follow these guidelines:

• Select the Right Type: Choose outriggers compatible with the scaffold and project needs.
• Secure Attachment: Attach outriggers firmly to scaffold legs or frames per manufacturer instructions.
• Leveling: Use jacks or leveling devices to ensure a stable base.
• Bracing: For rolling scaffolds, brace outriggers with bay braces for added stability.
• Load Capacity: Verify that outriggers are rated for the intended load, including workers and materials.
• Regular Inspection: Check outriggers for damage or wear and replace as needed.
• Training: Ensure all personnel are trained in outrigger use and scaffold safety.

Safety Considerations and Best Practices

Outriggers enhance stability but are not a substitute for comprehensive safety measures. Best practices include:

• Tie-Off When Possible: Secure the scaffold to an adjacent structure for added stability.
• Use Guardrails: Install guardrails and toeboards to prevent falls.
• Lock Casters: For mobile scaffolds, lock casters during use to prevent movement.
• Avoid Overloading: Respect the scaffold’s load capacity, even with outriggers.
• Monitor Environmental Conditions: Account for wind or weather that could affect stability, using additional securing measures if needed.
• Regular Maintenance: Inspect and maintain scaffolds and outriggers to ensure reliability.

Common Mistakes and Tips

Avoid these common mistakes when using outriggers:

Incorrect Installation: Failing to secure outriggers properly can lead to instability.

Overloading: Exceeding load capacity risks tipping or collapse.

Neglecting Inspections: Regular checks are essential to identify wear or damage.

Using Inappropriate Types: Mismatched outriggers reduce effectiveness.

Tips for Effective Use:

Consult Experts: Seek advice from scaffolding professionals if unsure about requirements.

Follow Standards: Ensure outriggers meet OSHA, ASME, or local regulations.

Train Personnel: Comprehensive training enhances safety and compliance.

Plan Ahead: Incorporate outriggers into project planning for seamless integration.

Conclusion

Outriggers are indispensable for ensuring scaffold stability and worker safety. By widening the scaffold’s base, they prevent tipping, particularly for tall or narrow setups. Understanding when outriggers are required, selecting the appropriate type, and following best practices for installation and use are essential for safe scaffolding operations. By adhering to OSHA regulations, training personnel, and prioritizing safety, construction professionals can minimize risks and complete projects successfully.

FAQ

Can outriggers be used on uneven surfaces?

• Yes, outriggers with leveling jacks can stabilize scaffolds on uneven surfaces. Proper adjustment and secure attachment are critical to ensure the scaffold remains level and safe.

Do outriggers eliminate the need for tying a scaffold to a structure?

• No, outriggers enhance stability but don’t fully replace tying. Tying the scaffold to a structure provides additional security, especially for tall scaffolds or in windy conditions.

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