The following is a clarification of OSHA Standard 29 CFR 1926.451(c)(2)(i) which requires that: “Footings shall be level, sound, rigid, and capable of supporting the loaded scaffold without settling or displacement.”
This standard addresses the hazard of a foundation that is insufficient to support the scaffold. The intent of the standard is to require that scaffold foundations are adequate; that is, they have sufficient strength, are stable, and the footing compensates for non-level surfaces that can introduce horizontal forces which have not been restrained.
The claim has been made that swivel screwjacks cannot be used with scaffolds since they bear on non-level surfaces. This claim is incorrect since the screwjacks are being used to create the level surface that the standard requires. While it might be argued that the screwjack is part of the scaffold and consequently must bear on a level surface, this argument is without merit for the simple fact that the swivel screwjack is specifically used for the purpose of bearing on sloped surfaces.
Standards have never precluded the use of swivel jacks with scaffolds. The truth is quite the opposite: swivel screwjacks are used to create the level surface that is required so that scaffold legs are stable. Interestingly enough wedges and shims are also used to create a level surface. By disallowing swivel jacks, it can be argued that wedges and shims cannot be used since they are not part of the foundation but rather are a part of the scaffold. In other words, if it were not that the scaffold is at a specific location, the wedges and shims would also not be there.
In summary, swivel jacks are a permissible component to be used in the construction of a scaffold. As with all scaffolds, the scaffold shall be designed by a Qualified Person who will address the issue of horizontal forces when designing the foundation.