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  Keeping Upright
Keeping Upright
Once a scaffold is built, even if it is compliant with every other standard relating to footings, structure, capacity, etc., it still will not provide a safe work platform if it does not remain upright. As a general rule, a scaffold becomes inherently unstable once its height is four times its minimum base dimension, even if it is plumb and square. Extreme weather or damage to structural components can also affect a scaffold's stability. Note: Except where indicated, these requirements also apply to manually propelled, pump jack, ladder jack, tube and coupler, and pole scaffolds, as well as the specialty scaffolds described in the Supported Scaffolds module.
Guys, Ties, and Braces
  • When a supported scaffold reaches a height that is more than four times its minimum base dimension (4:1), it must be restrained by guys, ties, or braces to prevent it from tipping. [1926.451(c)(1)]

    • Guys, ties, and braces must be installed at locations where horizontal scaffold components support both inner and outer legs. [1926.451(c)(1)(i)]

    • Guys, ties, and braces must be installed according to the scaffold manufacturer's recommendations or at the closest horizontal member to the 4:1 height ratio and be repeated every 20 vertical feet for narrow scaffolds (3 feet or less in width), and every 26 vertical feet for scaffolds greater than 3 feet in width. [1926.451(c)(1)(ii)]

    • Ties, guys, braces, or outriggers shall be used to prevent tipping of supported scaffolds bearing eccentric loads, such as cantilevered work platforms. [1926.451(c)(1)(iii)]
Figure 1. Good example of a scaffold braced into a building.

Figure 1.
Good example of a scaffold braced into a building.

  • Scaffolds and scaffold components must be inspected for visible defects before each shift by a competent person, and after each occurrence that could affect a scaffold's integrity (such as being struck by a crane). [1926.451(f)(3)]

  • Any part of a scaffold that has been damaged or weakened so that it no longer meets OSHA strength requirements must either be repaired, replaced, braced, or removed from service. [1926.451(f)(4)]

Moving Scaffolds
  • Scaffolds may not be moved horizontally while employees are on them, unless they have been designed for that purpose by a registered professional engineer, or in the case of mobile scaffolds, where the provisions of 1926.452(w) are followed 1926.451(f)(5).

  • Employees are not permitted to work on or from a scaffold during storms or high wind, unless a competent person has determined that it is safe, and those employees are protected by:

    • Personal fall arrest systems, or

    • Wind screens (when wind screens are used the scaffold must be secured against the anticipated wind forces). [1926.451(f)(12)]
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