• Scaffolds and scaffold components must be capable of supporting, without failure, their own weight and at least 4 times their maximum intended load (Figure 1). [1926.451(a)]
  


• Scaffolds shall be altered only under the supervision and direction of a competent person. [1926.451(f)(7)]

TIP: A scaffold can be overloaded by removing the braces, which causes the weight on the scaffold to be distributed to fewer structural members. Even if they are "in the way," braces should not be removed while work is being performed on a scaffold!

Figure 1. When scaffold frames are interconnected, failure of one frame can cause the whole system to collapse.

Worker Falls from Collapsing Scaffold

Case Report from OSHA files

• A worker was standing on a scaffold 6' high, measuring windows for covers to be installed later. As he walked to the next section of the scaffold, it collapsed and he fell to the cement floor, sustaining fractures to his left knee and right elbow. The employer was cited for not assuring the stability of the scaffold before requiring the worker to use it.

• Frames and panels must be connected by cross, horizontal, or diagonal braces, alone or in combination, which secure vertical members together laterally. [1926.452(c)(2)]
  


• As frames are stacked, cross braces must be of such length as will automatically keep the scaffold plumb, level, and square. [1926.452(c)(2)]
  


• All brace connections must be secured to prevent dislodging (Figure 2). [1926.452(c)(2)]

TIP: A level may be used frequently during assembly to guarantee that new structural components remain in line.

Figure 2. Poor attempt at securing cross bracing with wire.

• Frames and panels must be joined together vertically by coupling or stacking pins or equivalent means. [1926.452(c)(3)]
  


• Frames and panels must be locked together to prevent uplift, where uplift can occur. Uplift is the separation of a frame from the frame below it. [1926.452(c)(4)]

TIP: Separation of frames can occur in high winds (uplift), or when workers climb endframes, overload the platform, or strike the scaffold with tools, materials, etc.

Improper Coupling Results in Two Deaths

Case Report from OSHA files

• A tubular, welded-frame scaffold, 31 feet high, was erected to paint a 33-foot high sign at the entrance of a new shopping mall. After the sign had been partially painted, the scaffold was moved to allow concrete to be placed around the sign. Several days later, a crew of seven workers was instructed to replace the scaffold and finish painting the sign. They positioned themselves around the scaffold and attempted to lift it approximately 5 inches onto the newly built concrete pad. As they were lifting the scaffold, the top section partially separated from the adjoining section, toppled over, and contacted a power line. A 28-year old carpenter and a 31-year old laborer were electrocuted. The other five workers were hospitalized with electrical burns.

• Scaffold components manufactured by different manufacturers must not be intermixed, unless they fit together without being forced and the scaffold's structural integrity is maintained. [1926.451(b)(10)]
  


• Scaffold components manufactured by different manufacturers are not allowed to be modified to make them fit together, unless a competent person determines that the resulting scaffold is structurally sound. [1926.451(b)(10)]
  


• Scaffold components made of dissimilar metals must not be used together unless a competent person has determined that galvanic action will not reduce the strength of any component below OSHA standards. [1926.451(b)(11)]