The majority of construction workers---a little more than two-thirds---work on scaffolding. According to the Bureau of Labor Statistics, there were about 4,500 injuries and 60 deaths over the course of a two-year period---2003 to 2004---that the BLS conducted the study. Nearly three-quarters of scaffold-related injuries are caused by one of three factors: planking giving way, workers slipping off the scaffolding,or workers being hit by falling objects. As a consequence, OSHA has issued and refined standards to try to address these risks which can be found in the Code of Federal Regulations, part 1926.451. The standards are very extensive and cover seven major areas: capacity, platform construction, criteria for supported scaffolds and suspended scaffolds, access to scaffolds, use of scaffolds, fall protection and falling-object protection. Because the regulations for scaffolding are both extremely detailed and broad, there isn't enough room to cover them all here. We will cover the major points of each section. For more details on any of the major points, see References.
Scaffolding must be able to support, without failure, its own weight and at least four times the maximum intended load applied to it. Direct connections to roofs and counterweights used to balance suspension scaffolds must also be capable of resisting 4 times the tipping moment imposed by the scaffold operating at the rated load of the hoist. That is 1.5 times (minimum) the tipping moment imposed by the scaffold operating at the stall load of the hoist, whichever is greater. Each suspension rope, including connecting hardware, used on non-adjustable suspension scaffolds should be capable of supporting, without failure, at least 6 times the maximum intended load applied or transmitted to that rope. Scaffolds should be designed by a qualified person and should be constructed and loaded in accordance with that design.
Scaffold platform construction
OSHA standards require that each platform be installed so that the space between adjacent units and the space between the platform and the uprights is no more than 1 inch wide, except where the employer can demonstrate that a wider space is necessary. Scaffolds must be at least 18 inches wide. In a situation where it is impossible to make the platform 18 inches wide, there must be guardrails. The front edge of the platform must never be more than 14 inches from the face of the work being performed, unless guardrails are installed along the front edge of the platform. Wood platforms should not be covered with opaque finishes, and must be coated periodically with wood preservatives, fire-retardant finishes, and slip-resistant finishes.
Criteria for supported scaffolds
Supported scaffolds with a height-to-base width ratio (including outrigger supports, if used) of more than four to one (4:1) should be restrained from tipping by guying, tying, bracing or equivalent means.
Criteria for suspension scaffolds
All suspension scaffold supports should rest on surfaces capable of supporting at least 4 times the load imposed on them by the scaffold operating at the rated load of the hoist (or at least 1.5 times the load imposed on them by the scaffold at the stall capacity of the hoist, whichever is greater). Suspension scaffold outrigger beams should be made of structural metal or equivalent strength material, and should be restrained. The inboard ends of suspension scaffold outrigger beams should be stabilised by direct connections to the floor or roof deck, or they should have their inboard ends stabilised by counterweights. Before the scaffold is used, direct connections should be evaluated by a competent person who should confirm that the supporting surfaces are capable of supporting loads to be imposed. Only those items specifically designed as counterweights should be used to counterweight scaffold systems. Counterweights should be secured by mechanical means to the outrigger beams to prevent accidental displacement and not be removed from an outrigger beam until the scaffold is disassembled. Outrigger beams which are not stabilised by direct connections should be secured by tiebacks equivalent in strength to the suspension ropes. Outrigger beams should be placed perpendicular to their bearing support (usually the face of the building or structure). However, where the employer can demonstrate that it is not possible to place an outrigger beam perpendicular to the face of the building, the outrigger beam may be placed at some other angle, provided opposing angle tiebacks are used. Tiebacks should be secured to a structurally sound anchorage on the building or structure. Tiebacks should be installed perpendicular to the face of the building or structure, or opposing angle tiebacks should be installed. Single tiebacks installed at an angle are prohibited.
When scaffold platforms are more than 2 feet above or below a point of access, portable ladders, hook-on ladders, attachable ladders, stair towers (scaffold stairways/towers), stairway-type ladders (such as ladder stands), ramps, walkways, or similar structures must be used. Each scaffold stairway must be at least 18 inches (45.7cm) wide between stair rails. Treads and landings shall have slip-resistant surfaces. Stairways shall be installed between 40 degrees and 60 degrees from the horizontal.
Scaffolds and scaffold components shall not be loaded in excess of their maximum intended loads or rated capacities, whichever is less. Scaffolds and scaffold components shall be inspected for visible defects by a competent person before each work shift, and after any occurrence which could affect a scaffold's structural integrity.
Each employee on a scaffold more than 10 feet above a lower level must be protected from falling to that lower level. Depending on the situation, regulations require either a personal fall arrest system or a guardrail.
Falling object protection
In addition to wearing hardhats each employee on a scaffold shall be provided with additional protection from falling hand tools, debris, and other small objects through the installation of toeboards, screens, or guardrail systems, or through the erection of debris nets, catch platforms, or canopy structures that contain or deflect the falling objects. When the falling objects are too large, heavy or massive to be contained or deflected by any of the above-listed measures, the employer must place such potential falling objects away from the edge of the surface from which they could fall and shall secure those materials as necessary to prevent their falling