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Scaffolding Basics

Introduction

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When scaffolds are not erected or used properly, fall hazards can occur. About 2.3 million construction workers frequently work on scaffolds. Protecting these workers from scaffold-related accidents would prevent an estimated 4,500 injuries and over 50 fatalities each year.

When OSHA revised its scaffolds standard back in 1996, the Bureau of Labor and Statistics (BLS) showed that 25% of workers injured in scaffold accidents had not received any scaffold training. Also, 77% of scaffolds were not equipped with guardrails to keep workers safe.

In a recent BLS study, 72% of workers injured in scaffold accidents say the accident was caused by either planking or support giving way, employees slipping on surfaces, or employees being struck by falling objects.

Click the button to see a real-life summary of a scaffold accident.

Real-Life Scenario

A mason was fatally injured when he fell approximately twelve feet from the second level of an unguarded tubular welded scaffold system. It is not known what the victim was doing at the time of the incident; however, a witness saw him walk to the edge of the scaffold and place his foot on a piece of iron scaffold bracing. He either tripped or lost his balance, and fell to the sand covered asphalt below. The victim was transported to the local hospital where he died approximately two hours later.

Investigators concluded that in order to prevent similar future occurrences, employers should:

  1. Install guardrails on all open sides of scaffolds which are more than ten feet above ground.
  2. Ensure that scaffolding is properly erected, maintained, moved, dismantled and/or altered only under the supervision of a competent person.
  3. Develop and implement a comprehensive safety program that includes, but is not limited to, training in fall hazard recognition and the use of fall protection devices.

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1. Each of the following events contribute to most scaffold accidents EXCEPT _____.

a. Planking or supports giving way
b. Employee slipping on surfaces
c. Falling through defective guardrails
d. Being struck by a falling object

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What is a Scaffold?

A scaffold is defined as an elevated, temporary work platform. There are three basic types of scaffolds:

  1. Supported scaffolds, which consist of one or more platforms supported by rigid, load- bearing members, such as poles, legs, frames, outriggers, etc.
  2. Suspended scaffolds, which are one or more platforms suspended by ropes or other non-rigid, overhead support.
  3. Other scaffolds, principally man lifts, personnel hoists, etc., which are sometimes thought of as vehicles or machinery, but can be regarded as another type of supported scaffold.

We will cover the common supported and suspended scaffold types. Click on the button to see a more complete list of scaffold types.

  • Single-pole wood pole scaffolds
  • Independent wood pole scaffolds
  • Tube and coupler scaffolds
  • Fabricated frame scaffolds
  • Plasterers', decorators' and large area scaffolds
  • Bricklayers' square scaffolds
  • Horse scaffolds
  • Form scaffolds and carpenters' bracket scaffolds
  • Roof bracket scaffolds
  • Outrigger scaffolds (one level)
  • Pump jack scaffolds
  • Ladder jack scaffolds
  • Window jack scaffolds
  • Crawling boards (chicken ladders)
  • Step, platform and trestle ladder scaffolds
  • Single-point adjustable suspension scaffolds
  • Two-point adjustable suspension scaffolds
  • Stonesetters' multi-point adjustable suspension scaffolds
  • Masons' multi-point adjustable suspension scaffolds
  • Catenary scaffolds
  • Float (ship) scaffolds
  • Interior hung scaffolds
  • Needle beam scaffolds
  • Multi-level suspension scaffolds
  • Mobile scaffolds
  • Repair bracket scaffolds
  • Stilts
  • Tank builders' scaffolds

suspended scaffold
suspended scaffold
suspended scaffold

2. Which of the following is NOT one of the three basic types of scaffolds?

a. Supported scaffolds
b. Articulating scaffolds
c. Suspended scaffolds
d. Other scaffolds

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Who Uses Scaffolds

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Workers on scaffolds can be divided into two groups, erectors/dismantlers and users:

Erectors/Dismantlers

Erectors and dismantlers are those workers whose are mainly responsible for assembling and disassembling scaffolding. This is done before other work can continue, and/or after work has been completed.

Users

Scaffold users are those whose work requires them, at least some of the time, to be supported by scaffolding. Employers are required to have a qualified person provide training to each employee who uses the scaffold.

Real-Life Scenario

In August, 1992, two workers were erecting an aluminum pump jack scaffold. As they were raising the second aluminum pole, the pole apparently contacted an overhead power line. The pole being raised was 29 feet 10 inches long and the line was 28 feet 10 inches high. The line was approximately 11 feet from the house. One employee died and the other suffered severe burns and was hospitalized. The surviving employee noted that he thought they had enough room to work around the power lines, which were not de-energized or shielded.

3. Each of the following is a category of scaffold worker EXCEPT _____.

a. dismantler
b. installer
c. user
d. inspector

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Scaffolding Terms

It’s important to know some of the common terms when dealing with scaffolding. For example, when an employee goes from one job site to another, knowing the proper scaffolding terms will improve communications and safety.

For a more complete list of terms with definitions, see OSHA's 1926.450, Scaffolds.

Click on the button to see some definitions for the more common scaffold terms.

Scaffold Terms

  • Adjustable suspension scaffold means a suspension scaffold equipped with a hoist(s) that can be operated by an employee(s) on the scaffold.
  • Bearer (putlog) means a horizontal transverse scaffold member (which may be supported by ledgers or runners) upon which the scaffold platform rests and which joins scaffold uprights, posts, poles, and similar members.
  • Brace means a device that holds one scaffold member in a fixed position with respect to another member.
  • Cleat means a structural block used at the end of a platform to prevent the platform from slipping off its supports. Cleats are also used to provide footing on sloped surfaces such as crawling boards.
  • Tube and Coupler Scaffold
    Tube and Coupler Scaffold Components
  • Coupler means a device for locking together the tubes of a tube and coupler scaffold.
  • Crawling board (chicken ladder) means a supported scaffold consisting of a plank with cleats spaced and secured to provide footing, for use on sloped surfaces such as roofs.
  • Fabricated decking and planking means manufactured platforms made of wood (including laminated wood, and solid sawn wood planks), metal or other materials.
  • Guardrail system means a vertical barrier, consisting of, but not limited to, toprails, midrails, and posts, erected to prevent employees from falling off a scaffold platform or walkway to lower levels.
  • Hoist means a manual or power-operated mechanical device to raise or lower a suspended scaffold.
  • Landing means a platform at the end of a flight of stairs.
  • Open sides and ends means the edges of a platform that are more than 14 inches (36 cm) away horizontally from a sturdy, continuous, vertical surface (such as a building wall) or a sturdy, continuous horizontal surface (such as a floor), or a point of access. Exception: For plastering and lathing operations the horizontal threshold distance is 18 inches (46 cm).
  • Outrigger means the structural member of a supported scaffold used to increase the base width of a scaffold in order to provide support for and increased stability of the scaffold.
  • Outrigger beam (Thrustout) means the structural member of a suspension scaffold or outrigger scaffold which provides support for the scaffold by extending the scaffold point of attachment to a point out and away from the structure or building.
  • Platform means a work surface elevated above lower levels. Platforms can be constructed using individual wood planks, fabricated planks, fabricated decks, and fabricated platforms.
  • Power operated hoist means a hoist which is powered by other than human energy.
  • Runner (ledger or ribbon) means the lengthwise horizontal spacing or bracing member which may support the bearers.
  • Safety Screen means a wire or plastic screening that protects the workers and passers-by below from dropped items.
  • Sill means a footing (usually wood) which distributes the vertical loads to the ground or slab below.
  • Stilts means a pair of poles or similar supports with raised footrests, used to permit walking above the ground or working surface.
  • Tie means a device used between scaffold component and the building or structure to enhance lateral stability.
  • Toeboard means a barrier secured along the sides and the ends of a platform unit to guard against the falling of material, tools and other loose objects.
  • Toprail means a the uppermost horizontal rail of a guardrail system.
  • Unstable objects means items whose strength, configuration, or lack of stability may allow them to become dislocated and shift and therefore may not properly support the loads imposed on them. Unstable objects do not constitute a safe base support for scaffolds, platforms, or employees. Examples include, but are not limited to, barrels, boxes, loose brick, and concrete blocks.
  • Vertical pickup means a rope used to support the horizontal rope in catenary scaffolds.
  • Walkway means a portion of a scaffold platform used only for access and not as a work level.

4. Which of the following scaffold terms means a work surface elevated above lower levels?

a. Platform
b. Landing
c. Running board
d. Walkway

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General Requirements in 1926.451

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OSHA's scaffolding standard has number of key provisions:

  • Fall protection or fall arrest systems -- Each employee more than 10 feet above a lower level shall be protected from falls by guardrails or a fall arrest system, except those on single-point and two-point adjustable suspension scaffolds. Each employee on a single-point and two-point adjustable suspended scaffold shall be protected by both a personal fall arrest system and a guardrail. 1926.451(g)(1)
  • Guardrail height -- The height of the toprail for scaffolds manufactured and placed in service after January 1, 2000 must be between 38 inches (0.9 meters) and 45 inches (1.2 meters). The height of the toprail for scaffolds manufactured and placed in service before January 1, 2000 can be between 36 inches (0.9 meters) and 45 inches (1.2 meters). 1926.451(g)(4)(ii)
  • Crossbracing -- When the crosspoint of crossbracing is used as a toprail, it must be between 38 inches (0.97 m) and 48 inches (1.3 meters) above the work platform. 1926.451(g)(4)(xv)
  • Midrails -- Midrails must be installed approximately halfway between the toprail and the platform surface. When a crosspoint of crossbracing is used as a midrail, it must be between 20 inches (0.5 meters) and 30 inches (0.8 m) above the work platform. 1926.451(g)(4)
  • Footings -- Support scaffold footings shall be level and capable of supporting the loaded scaffold. The legs, poles, frames, and uprights shall bear on base plates and mud sills. 1926.451(c)(2)
  • Platforms -- Supported scaffold platforms shall be fully planked or decked. 1926.451(b)
  • Guying ties, and braces -- Supported scaffolds with a height-to-base of more than 4:1 shall be restrained from tipping by guying, tying, bracing, or the equivalent. 1926.451(c)(1)
  • Capacity -- Scaffolds and scaffold components must support at least 4 times the maximum intended load. Suspension scaffold rigging must at least 6 times the intended load. 1926.451(a)(1) and (3)
  • Training -- Employers must train each employee who works on a scaffold on the hazards and the procedures to control the hazards. 1926.454
  • Inspections -- Before each work shift and after any occurrence that could affect the structural integrity, a competent person must inspect the scaffold and scaffold components for visible defects. 1926.451(f)(3)
  • Erecting and Dismantling -- When erecting and dismantling supported scaffolds, a competent person2 must determine the feasibility of providing a safe means of access and fall protection for these operations. 1926.451(e)(9) & (g)(2)

5. Scaffolds and scaffold components must support _____.

a. up to twice the actual load
b. 3 times the potential load
c. at least 4 times the intended load
d. 10 times the expected load

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Competent Persons

OSHA's scaffolding standard defines a competent person as "one who is capable of identifying existing and predictable hazards in the surroundings or working conditions, which are unsanitary, hazardous to employees, and who has authorization to take prompt corrective measures to eliminate them."

The standard requires a competent person to perform the following duties under these circumstances:

Click on the button to see competent person duties and responsibilities.

Competent persons are responsible to:

  • Select and direct employees who erect, dismantle, move, or alter scaffolds.
  • Determine if it is safe for employees to work on or from a scaffold during storms or high winds and to ensure that a personal fall arrest system or wind screens protect these employees.
  • Train employees involved in erecting, disassembling, moving, operating, repairing, maintaining, or inspecting scaffolds to recognize associated work hazards.
  • Inspect scaffolds and scaffold components for visible defects before each work shift and after any occurrence which could affect the structural integrity and to authorize prompt corrective actions.
  • Inspect ropes on suspended scaffolds prior to each workshift and after every occurrence which could affect the structural integrity and to authorize prompt corrective actions.
  • Inspect manila or plastic (or other synthetic) rope being used for toprails or midrails.
  • For Suspension Scaffolds: evaluate direct connections to support the load, and evaluate the need to secure two-point and multi-point scaffolds to prevent swaying.
  • For Erectors and Dismantlers: determine the feasibility and safety of providing fall protection and access, and train erectors and dismantlers to recognize associated work hazards.
  • For Scaffold Components: determine if a scaffold will be structurally sound when intermixing components from different manufacturers, and determine if galvanic action has affected the capacity when using components of dissimilar metals.

6. Who must conduct scaffold training in erecting, disassembling, operating, repairing, and maintaining scaffolds?

a. A designated person
b. A qualified person
c. An authorized person
d. A competent person

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Qualified Persons

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The scaffold standard defines a qualified person as "one who -- by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience -- has successfully demonstrated his/her ability to solve or resolve problems related to the subject matter, the work, or the project."

The qualified person must perform the following duties in these circumstances:

Click on the button to see qualified person duties and responsibilities.

Qualified persons are responsible to:

  • Design and load scaffolds in accordance with that design.
  • Train employees working on the scaffolds to recognize the associated hazards and understand procedures to control or minimize those hazards.
  • Design the rigging for single-point adjustable suspension scaffolds.
  • Design platforms on two-point adjustable suspension types that are less than 36 inches (0.9 m) wide to prevent instability.
  • Make swaged attachments or spliced eyes on wire suspension ropes.
  • Design scaffold components construction in accordance with the design.

Registered Engineers

A "Registered Professional Engineer" is a person who is registered as a professional engineer in the state where the work is to be performed. However, a professional engineer, registered in any state is deemed to be a "registered professional engineer" within the meaning of OSHA standards.

The scaffold standard requires a registered professional engineer to perform the following duties in these circumstances:

Click on the button to see registered engineer responsibilities.

Registered engineers are responsible to:

  • Design the direct connections of masons' multi-point adjustable suspension scaffolds.
  • Design scaffolds that are to be moved when employees are on them.
  • Design pole scaffolds over 60 feet (18.3 meters) in height.
  • Design tube and coupler scaffolds over 125 feet (38 meters) in height.
  • Design fabricated frame scaffolds over 125 feet (38 meters) in height above their base plates. 1926.452(c)(6)
  • Design brackets on fabricated frame scaffolds used to support cantilevered loads in addition to workers.
  • Design outrigger scaffolds and scaffold components.

Qualified Trainer

Scaffold training should be conducted by a qualified person certified by the employer to conduct training. Certified trainers must train all employees who erect, disassemble, move, operate, repair, maintain, or inspect scaffolds.

Click on the button to see criteria for a qualified scaffold trainer.

Qualified Trainer Criteria:

  • adequate practical experience and fully knowledgeable of the topics being taught;
  • necessary skills to demonstrate safe procedures and practices;
  • adequate skills to train, test, and evaluate student knowledge, skills, and abilities (KSAs);
  • successful evaluation by the employer of the person's training KSAs; and
  • certification by the employer as qualified and authorized to conduct training.

7. Who is primarily responsible for developing and approving scaffold design?

a. A registered engineer
b. A qualified person
c. An authorized person
d. A competent person

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Training Requirements

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Scope of training

The employer must have each employee who performs work while on a scaffold trained by a person qualified in the subject matter to recognize the hazards associated with the type of scaffold being used and to understand the procedures to control or minimize those hazards. The training must include the following areas, as applicable:

Click on the button to see general mandatory scaffold training topics.

General mandatory training topics include:

  • fall hazards and falling object hazards in the work area;
  • procedures for dealing with electrical hazards;
  • erecting, maintaining, and disassembling the fall protection systems and falling object protection systems being used;
  • proper use of the scaffold, and the proper handling of materials on the scaffold;
  • the maximum intended load-carrying capacities of the scaffold, and
  • any other pertinent requirements of the standard.

Erector and Dismantler Training Topics

In additional to the mandatory general training, scaffold erectors and dismantlers should also receive specific training for the type of supported scaffold being erected or dismantled.

Click on the button to see specific scaffold training topics for erectors and dismantlers.

Additional Erector and Dismantler Training Topics

Training for the specific types of scaffolds being erected or dismantled includes:

  • erection/dismantling planning
  • PPE and proper procedures
  • specific fall protection
  • materials handling
  • components
  • parts inspection
  • specific safety requirements
  • access and platforms
  • working platforms
  • foundations
  • buttresses, cantilevers, & bridges
  • guys, ties and braces
  • rolling scaffold assembly
  • putlogs

Retraining

When the employer has reason to believe that an employee lacks the skill or understanding needed for safe work involving the erection, use or dismantling of scaffolds, the employer must retrain each such employee so that the requisite proficiency is regained.

Click on the button to see when retraining is required.

Retraining should be accomplished when the following conditions exist:

  • where changes at the worksite present a hazard about which an employee has not been previously trained; or
  • where changes in the types of scaffolds, fall protection, falling object protection, or other equipment present a hazard about which an employee has not been previously trained; or
  • where inadequacies in an affected employee's work involving scaffolds indicate that the employee has not retained the requisite proficiency.

8. Which of the following is an additional specific training topic for scaffold erectors and dismantlers?

a. Electrical hazards
b. Guys, ties and braces
c. Maximum intended load requirements
d. Fall hazards and falling object hazards

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.

Video

Video

Watch this NAHBTV video on scaffold safety. Scaffolds, or temporary work platforms, can provide a safe and more efficient way to work in construction, but the use of scaffolds is also one of the leading causes of injuries on construction sites.

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