Safety guides and audits to make your job as a safety professional easier

Supported Scaffolds

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Supported scaffolds consist of one or more platforms supported by legs, outrigger beams, brackets, poles, uprights, posts, frames, or similar rigid support. 1926.451(b)

Frame or Fabricated

Fabricated frame scaffolds are the most common type of scaffold because they are versatile, economical, and easy to use. They are frequently used in one or two tiers by residential contractors, painters, etc., but their modular frames can also be stacked several stories high for use on large-scale construction jobs. More information on this scaffold.

Tube and Coupler

Tube and coupler scaffolds are so-named because they are built from tubing connected by coupling devices. Due to their strength, they are frequently used where heavy loads need to be carried, or where multiple platforms must reach several stories high. Their versatility, which enables them to be assembled in multiple directions in a variety of settings, also makes them hard to build correctly.More information on this scaffold.

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1. What is the most common supported scaffold?

a. Pole or wood pole
b. Mast climber
c. Tube and coupler
d. Fabricated

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Supported Scaffolds (Continued)

Pole or Wood Pole

Pole scaffolds are a type of supported scaffold in which every structural component, from uprights to braces to platforms, is made of wood. OSHA has standards for two kinds: single-pole, which are supported on their interior side by a structure or wall, and double-pole, which are supported by double uprights independent of any structure.

Because they have to be built from scratch and cannot easily be reused, pole scaffolds are considered old-fashioned and are rarely used today.More information on this scaffold.

Mast Climbers

Mast climbing supported scaffolds (mast climbers) carry much heavier loads than traditional scaffolding and are used to position personnel and the necessary tools, equipment, and materials needed to perform work at great heights.

Mast climbers can be free-standing or tied to a structure at intervals for stability at increased heights. The mast may be supported on a stationary base, or for some projects that are lower, on a mobile base. Because mast climbers may be easily adjusted to optimize of working heights, they can reduce the potential for shoulder and lower back injuries to workers. Proper platform positioning reduces material handling hazards and fatigue and improves productivity. More information on this scaffold.

Click on the image below to see the mast climber scaffold that was involved in a multiple-fatality accident.

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2. Which type of supported scaffold can carry much heavier loads than traditional scaffolding?

a. Wood pole
b. Mast climber
c. Fabricated
d. Tube and coupler

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Supported Scaffolds (Continued)

Ladder Jack

A ladder jack scaffold is a system designed to perform activities, such as: installing building exteriors, trim, and finishes. Contractors widely use ladder jack scaffolds because of their cost effectiveness, portability, and quick erection and dismantling procedures, as well as their adaptability for use in narrow spaces at construction worksites. More information on this scaffold.

Pump Jack

Pump jacks are a uniquely designed scaffold consisting of a platform supported by moveable brackets on vertical poles. The brackets are designed to be raised and lowered in a manner similar to an automobile jack. Pump jacks are appealing for certain applications because they are easily adjusted to variable heights, and are relatively inexpensive. More information on this 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.

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3. Which of the following supported scaffolds consists of a platform supported by moveable brackets on vertical poles?

a. Mast climbing scaffolds
b. Outrigger scaffolds
c. Pump jack scaffolds
d. Ladder jack scaffolds

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Supported Scaffolds (Continued)

Mobile (Manually or Propelled)

Mobile scaffolds are a type of supported scaffold set on wheels or casters. They are designed to be easily moved and are commonly used for things like painting and plastering, where workers must frequently change position. More information on this scaffold.

Specialty and Other

Many scaffold types regulated by OSHA standards are rarely used, and designed for a very narrow and specific range of applications. Specialty scaffolds include:

Click on the button to see the various types of specialty scaffolds.

Types of specialty scaffolds

  • Plasterers', Decorators', and Large-Area Scaffolds
  • Bricklayers' Square Scaffolds
  • Horse Scaffolds
  • Form Scaffolds and Carpenters' Bracket Scaffolds
  • Roof Bracket Scaffolds
  • Outrigger Scaffolds
  • Window Jack Scaffolds
  • Crawling Boards (Chicken Ladders)
  • Step, Platform, and Trestle Ladder Scaffolds
  • Stilts

More information on specialty scaffolds.

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4. Which of the following types of scaffolds are commonly used for painting and plastering?

a. Mobile scaffolds
b. Ladder jack scaffolds
c. Roof bracket scaffolds
d. Trestle ladder scaffolds

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Criteria for Supported Scaffolds

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This unstable foundation caused the scaffold to lean.

Foundations

Supported scaffolds' poles, legs, posts, frames, and uprights must bear on base plates and mud sills, or other adequate firm foundation. 1926.451(c)(2)(i) and (ii)

Restraining

Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guying, tying, bracing, or an equivalent means. 1926.451(c)(1)

Either the manufacturers' recommendation or the following placements must be used for guys, ties, and braces:

  • Install guys, ties, or braces at the closest horizontal member to the 4:1 height and repeat vertically with the top restraint no further than the 4:1 height from the top.
  • Vertically -- every 20 feet (6.1 meters) or less for scaffolds less than three feet (0.91 meters) wide; every 26 feet (7.9 meters) or less for scaffolds more than three feet (0.91 meters) wide.
  • Horizontally -- at each end; at intervals not to exceed 30 feet (9.1 meters) from one end. 1926.451(c)(1)
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To stabilize the scaffold, struts push it away from building, and tie wires pull it toward the building.
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Never place a scaffold on an unstable foundation.

5. Supported scaffolds must be restrained by guying, tying, bracing, or an equivalent means when _____.

a. unfavorable weather conditions are expected
b. more than three employees work on the scaffold
c. the scaffold is located next to a public walkway
d. the height to base width ratio is more than 4:1

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Criteria for Supported Scaffolds (Continued)

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Never do this to raise the height of a scaffold.

Forklifts, Front-end Loaders, or Similar Equipment Support Platforms

Forklifts can support platforms only when the entire platform is attached to the fork and the forklift does not move horizontally when workers are on the platform. 1926.451(c)(2)(v)

Front-end loaders and similar equipment can support scaffold platforms only when they have been specifically designed by the manufacturer for such use. 1926.451(c)(2)(iv)

Increasing Working Heights

OSHA prohibits using "makeshift" objects (e.g., saw horses, buckets, milk crates, concrete blocks, etc.) to increase the working height of a scaffold, because an unstable platform increases the likelihood of collapse or a fall.

Stilts means a pair of poles or similar supports with raised footrests, used to walk above the ground or above the working surface. Stilts are often used for sheetrock installation as well as for painting and decorating and other tasks requiring walking mobility with increased height/reach. They may also be used on a large-area scaffold. When a guardrail system is used, the guardrail height must be increased in height equal to the height of the stilts. The manufacturer must approve any alterations to the stilts. 1926.452(v)

Note: A large area scaffold consists of a pole, tube and coupler systems, or a fabricated frame scaffold erected over substantially the entire work area. 1926.451(b)

6. Which of the following objects may be used to increase the working height on supported large-area scaffolds?

a. Pallets
b. Stilts
c. Saw horses
d. Concrete blocks

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Access Requirements

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Access using a scaffold ladder section.

Employers must provide access when the scaffold platforms are more than 2 feet (0.6 meters) above or below a point of access. 1926.451(e)(1)

Direct access is acceptable when the scaffold is not more than 14 inches (36 centimeters) horizontally and not more than 24 inches (61 centimeters) vertically from the other surfaces. 1926.451(e)(8)

The standard prohibits the use of crossbraces as a means of access. 1926.451(e)(1)

What types of access can be used?

Several types of access are permitted:

  • Ladders, such as portable, hook-on, attachable, and stairway 1926.451 (e)(2),
  • Stair towers 1926.451(e)(4),
  • Ramps and walkways 1926.451(e)(5), and
  • Integral prefabricated frames (1926.451(e)(6).

Access While Erecting and Dismantling Supported Scaffolds?

Employees erecting and dismantling supported scaffolding must have a safe means of access provided when a competent person has determined the feasibility and analyzed the site conditions. 1926.451(e)

7. All of the following are permitted methods of access to scaffolds EXCEPT _____.

a. Crossbraces
b. Ramps and walkways
c. Stair towers
d. Ladders

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Use Requirements

Prohibited Scaffolds

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Shore or Lean-to Scaffold. (Don't do this at home!)

Shore and lean-to scaffolds are strictly prohibited. 1926.451(f)(2)

Also, employees are prohibited from working on scaffolds covered with snow, ice, or other slippery materials, except to remove these substances. 1926.451(f)(8)

The shore scaffold in the image to the right is not permitted to be used per OSHA or ANSI. In this picture, the workers have a shore scaffold on top of another shore scaffold. Access is unsafe both from above and below. The only thing holding this scaffold up is the DUMPSTER!

Clearance Distances

Scaffolds must not be erected, used, dismantled, altered, or moved such that they or any conductive material handled on them might come closer to exposed and energized power lines than as follows: 1926.451(f)(6)

Click on the button to see the table of insulated and non-insulated clearance distances.

Insulated Lines

Voltage

Minimum Distance

Alternatives

Less than 300 volts

3 feet

-

300 volts to 50 kilovolts (kV)

10 feet

-

More than 50 kV

10 feet plus 0.4 inches
for each 1 kV more than 50 kV

2 times the length of the line insulator,
but never less than 10 feet

Uninsulated Lines

Voltage

Minimum Distance

Alternatives

Less than 50 kV

10 feet

-

More than 50 kV

10 feet plus 0.4 inches
for each 1 kV more than 50 kV

2 times the length of the line insulator,
but never less than 10 feet

8. Which of the following types of scaffolds is strictly prohibited by OSHA?

a. Ladder jack scaffolds
b. Shore and lean-to scaffolds
c. Large-area scaffolds
d. Chicken ladder scaffolds

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Fall Protection

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Workers must be protected from falling and from being injured from falling objects.

Guardrails must be installed on all scaffold platforms in accordance with OSHA 1910.451 and at least consist of top rails, midrails and toeboards.

Fall Protection Systems

Workers on suspended scaffolds must use a fall protection system to protect them against scaffold failure. This system will usually consist of a full body harness, lanyard, rope grab, independent vertical lifeline and an independent lifeline anchorage. Remember, fall protection is only as good as its anchorage. The anchorage points are independent points on structures where lifelines are securely attached. These points must be able to support at least 5,000 pounds per employee.

Protection from Falling Objects

Workers and others located at lower levels need to be protected from objects falling off scaffolds using the following methods:

  • Toeboards. Toeboards must be installed on platforms higher than 10 feet above lower levels, at least 3½ inches high, and strong enough to withstand a force of at least 50 pounds applied downward or outward.
  • Panels and screens. if you need to pile material higher than the top edge of a toeboard, install panels or screens to keep the material from dropping over the edge.
  • Canopies. Make sure canopies won't collapse or tear from an object's impact.

9. Employers must provide fall protection for each employee on a scaffold _____.

a. more than 4 feet above ground level
b. 6 feet or more above the ground
c. more than 10 feet above a lower level
d. if the working surface is 12 feet above a lower level

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

This SW MGT video gives examples of fall hazards while working on scaffolds.

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