13.3: Scaffold Components

Capacity requirements for all scaffolds

Each scaffold and scaffold component must support without failure its own weight and at least four times the maximum intended load applied or transmitted to it. A qualified person must design the scaffolds, which are loaded in accordance with that design. Scaffolds and scaffold components must not be loaded in excess of their maximum intended loads or rated capacities, whichever is less. Load carrying timber members should be a minimum of 1,500 lb-f/in² construction grade lumber.

Scaffold platform construction

Each scaffold platform must be planked and decked as fully as possible with the space between the platform and uprights not more than 1 inch (2.5 centimeters) wide. The space must not exceed 9 inches (24.1 centimeters) when side brackets or odd-shaped structures result in a wider opening between the platform and the uprights. Scaffold planking must be able to support, without failure, its own weight and at least four times the intended load. Solid sawn wood, fabricated planks, and fabri­cated platforms may be used as scaffold planks following the recommendations by the manufac­turer or a lumber grading association or inspection agency. The platform must not deflect more than 1/60 of the span when loaded. Each scaffold platform and walkway must be at least 18 inches (46 centimeters) wide. When the work area is less than 18 inches (46 centimeters) wide, guardrails and/or personal fall arrest systems must be used.

The standard requires employers to protect each employee on a scaffold more than 10 feet (3.1 m) above a lower level from falling to that lower level. To ensure adequate protection, install guardrails along all open sides and ends before releasing the scaffold for use by employees, other than the erection and dismantling crews. Guardrails are not required, however, when the front end of all platforms are less than 14 inches (36 centimeters) from the face of the work; when outrigger scaffolds are 3 inches (8 centimeters) or less from the front edge. Place platforms so that the spaces between them do not exceed one inch unless more space is necessary (for fitting around uprights with side brackets to extend platform width, for example).

Supported Scaffolds

Supported scaffolds are platforms supported by legs, outrigger beams, brackets, poles, uprights, posts, frames, or similar rigid support. The structural members, poles, legs, posts, frames, and uprights, must be plumb and braced to prevent swaying and displacement. When employees are plastering and lathing 18 inches (46 centimeters) or less from the front edge. All employees must be trained by a qualified person to recognize the hazards associated with the type of scaffold being used and how to control or minimize those hazards. The training must include fall hazards, falling object hazards, electrical hazards, proper use of the scaffold, and handling of materials.

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. 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. Supported scaffolds’ poles, legs, posts, frames, and uprights must bear on base plates and mud sills, or other adequate firm foundation. 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. Front-end loaders and similar equipment can support scaffold platforms only when they have been specifically designed by the manufacturer for such use. Stilts may 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. 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.

Suspended Scaffolds

A suspension scaffold contains one or more platforms suspended by ropes or other non-rigid means from an overhead structure, such as the following scaffolds: single-point, multi-point, multi-level, two-point, adjustable, boatswains’ chair, catenary, chimney hoist, continuous run, elevator false car, go-devils, interior hung, masons’, and stone setters’.

Some of the requirements for all types of suspension scaffolds include: Employers must ensure that all employees are trained to recognize the hazards associated with the type of scaffold being used. All support devices must rest on surfaces capable of supporting at least four times the load imposed on them by the scaffold when operating at the rated load of the hoist, or at least one-and-a-half times the load imposed on them by the scaffold at the stall capacity of the hoist, whichever is greater. A competent person must evaluate all direct connections prior to use to confirm that the sup­porting surfaces are able to support the imposed load. All suspension scaffolds must be tied or otherwise secured to prevent them from swaying, as deter­mined by a competent person. Guardrails, a personal fall arrest system, or both must protect each employee more than 10 feet (3.1 meters) above a lower level from falling. A competent person must inspect ropes for defects prior to each workshift and after every occurrence that could affect a rope’s integrity. When scaffold platforms are more than 24 inches (61 centimeters) above or below a point of access, ladders, ramps, walkways, or similar surfaces must be used. When using direct access, the surface must not be more than 24 inches (61 centimeters) above or 14 inches (36 cm) horizontally from the surface. When lanyards are connected to horizontal lifelines or structural members on single-point or two-point adjustable scaffolds, the scaffold must have additional independent support lines equal in number and strength to the suspension lines and have automatic locking devices. Emergency escape and rescue devices must not be used as working platforms, unless designed to function as suspension scaffolds and emergency systems.

Counterweights used to balance adjustable suspension scaffolds must be able to resist at least four times the tipping moment imposed by the scaffold operating at either the rated load of the hoist, or one-and-a-half (minimum) times the tipping moment imposed by the scaffold operating at the stall load of the hoist, whichever is greater. Only those items specifically designed as coun­terweights must be used. Counterweights used for suspended scaffolds must be made of materials that can not be easily dislocated. Flowable material, such as sand or water, cannot be used. Counterweights must be secured by mechanical means to the outrigger beams. Vertical lifelines must not be fastened to counterweights. No materials or devices may be used to increase the working height on a suspension scaffold. This includes ladders, boxes, and barrels.

Narrow Frame Scaffolds

Narrow frame scaffolds, also known as Baker/Perry style scaffolds, are among the most popular pieces of construction equipment. Due to their versatility many contractors use them instead of ladders because they allow workers to maintain their balance and work more easily from the platform. A narrow frame scaffold has wheels and is often used as a mobile scaffold with the end frame measuring 3 feet or less in width. Designed to be easily moved, they are used for operations such as painting, drywall installation, plastering, and other jobs where workers must frequently change position. Scaffolds can be adapted to stairs, ramps, and other uneven surfaces.

Some of the hazards associated with narrow frame scaffolds, can lead to personal injury or death; they include: Falls from an elevated level, Tip-overs, Electric shocks, and Structural failures (collapse).

Improper Scaffold Construction

Working with heavy equipment and building materials on the limited space of a scaffold is difficult. Without fall protection or safe access, it becomes hazardous. Falls from such improperly constructed scaffolds can result in injuries ranging from sprains to death.

How Do I Avoid Hazards?

• Construct all scaffolds according to the manufacturer's instructions.
• Install guardrail systems along all open sides and ends of platforms.
• Use at least one of the following for scaffolds more than 10 feet above a lower level:

• • Guardrail Systems

• • Personal Fall Arrest Systems

• Provide safe access to scaffold platforms.
• Do not climb cross-bracing as a means of access.

The majority of the workers injured in scaffold accidents attribute the accident to factors like the planking or support giving way, or to lack of guardrails or other fall protection. OSHA’s most frequently cited serious scaffold violations include lack of fall protection; scaffold access; use of aerial lifts without body belts and lanyards, platform construction and no worker training.

Scaffold work requires guardrails or a personal fall arrest system on any platform 10 feet or higher. Also, do not climb cross-bracing as a means of access; safe access must be provided by your employer. Ensure that your fall protection equipment is right for the work you are doing, in good condition, and that you use it properly. Remember that your employer needs to provide you with protection to prevent falls at your worksite.