Jobsite conditions are in a state of constant change. Weather conditions, activities by workers from other trades, and the wear from daily use can affect the integrity of equipment. Scaffolds are no exception. OSHA requires the inspection of scaffolds before each shift and after an event that could affect the scaffold’s structural integrity. Inspections must be performed by a competent person, but anyone who uses a scaffold should check for potential problems before use.
When inspecting a scaffold you should check for physical defects in the scaffold and environmental conditions, which affect safety as well as OSHA compliance. Check all scaffold components. Make sure ropes on suspended scaffolds are not worn or damaged by chemicals or heat. Kinks, that impair wrapping, six randomly broken wires in a rope lay or abrasion greater than 1/3 the width mandate replacement of the rope. Also check the tubes of supported scaffolds and welds for splitting, cracks or excessive rust. All mechanical components such as the gears and brakes of a hoist must be in proper working order. Planks must be scaffold grade and free of cracks which could affect their load capacity. Make sure the scaffold rests on a firm foundation. Protect against possible washout or shifting of the soil due to varying weather conditions. Ensure the scaffold has not been compromised by snow or ice conditions.
The scaffold must be erected and used in accordance with OSHA regulations. Make sure a proper access is provided. Review the foundation. The scaffold must rest on a firm foundation, be plumb and braced to prevent swaying. This may include the use of base plates, mudsills or other materials to ensure an adequate foundation. Check the construction of working platforms. The surface must be fully planked with a maximum of 1 inch between planks unless it has been demonstrated a wider space is needed. The planks must extend at least 6 inches beyond the support, but no more than 12 inches (For platforms greater than 10 feet the extension may be 18 inches.) Platforms, which are cleated or stabilized by hooks need not extend beyond the support.
Fall protection and falling object protection must be in place. If a guardrail system is used, it must protect all open sides. The opening facing the work area need not be protected if the scaffold is less than 14 inches away. A toe board, mesh, screens or panels, safety nets, or canopies must also be properly erected. Barricading may be used. Make sure one of these protective measures is in place, in addition to the use of hard hats.
The height to base ratio for a supported scaffold must be 4:1 (state plans may vary). If the ratio is not maintained, ties or guys must be used. They must be placed every 20 feet vertically and every 30 feet horizontally for scaffolds 3 feet wide or less. The placement of ties for scaffolds wider than 3 feet may not exceed 26 feet vertically. Make sure all guys and ties are secure. Make sure all couplers, braces and locks are in place.
Evaluate the weight of workers, their tools and materials to be placed on the scaffold. Make sure load capacity is not exceeded. Scaffold components including platforms, outrigger beams and supports must be able to withstand at least four times the intended load. The ropes used on suspension scaffolds must be capable of supporting six times the intended load.
Observe the use of a scaffold. Make sure the platform and work activity is away from electrical lines. Debris must be cleared from the scaffold surface. Makeshift devices and ladders cannot be used to extend the height of the scaffold. Correct these actions as needed.
A scaffold can be dangerous if it is not erected properly, used correctly, or components have been compromised. Your inspection must review and evaluate the components, its use, and structure. Whether a problem is a violation of a specific requirement in the standard or simply a defect in the materials, correcting the problem will help you avoid an accident.
Scaffolding must be erected on firm footing capable of carrying the maximum intended load. Boxes, barrels, loose concrete blocks or brick must not be used to support the structure.
Consideration must be given to the weight the scaffold is to carry. It must be capable of supporting, without failure, four times the maximum intended load. The load includes not only the weight of the people on the scaffold but also any supplies and equipment being used. Scaffolding is naturally unstable because it is usually a tall structure with a narrow base. To counteract this, the scaffold must be braced or tied off to a stable structure such as a structural steel.
The planking used must be “scaffold grade.” The wood must be clear, free of loose knots, splits, or other defects. To create a proper work surface, generally two planks need to be laid side by side to create a 20″ wide work platform. At the ends, the planking must overlap at least 6″ but no more than 12″ unless the planks are fastened to the supporting members. Toe boards at least 4″ high (3 1/2″ for construction) should be installed along the outer scaffold edge, to prevent tools or materials from falling onto workers below.
Guardrail requirements for supported scaffolds vary for different industries. The federal OSHA standard for construction and general industry requires guardrails when a platform is 10 feet or higher. In shipyards, they must be installed if the work platform is 5 feet or more above a solid surface, or at any distance above water. Some state codes may set the height at 6 feet. You must know the rule for your state or jurisdiction.
Guardrails are usually made of 2×4 lumber or steel pipe. The top rail should be about 42″ above the scaffold-walking surface, with a “mid-rail” at about 21 inches. Fiber or wire rope can be used if it is attached to rigid supports and kept taut. However, a variance may be needed to do so in some jurisdictions. It should be noted that the railings must be of adequate strength to restrain someone who has started to fall. Railings can be omitted if a structure, such as a ship’s hull prevents their use. However, in these circumstances, you must wear a safety harness and life line if you working more than 5 feet above a solid surface.
If over water, you must wear an approved buoyant work vest.
Finally, never make any changes to scaffolding yourself. Only designated “Competent Persons” should make modifications.
SCAFFOLD LOAD CAPACITY AND MATERIAL HANDLING
Scaffolds must be designed to allow work to be performed at various heights. This means that a worker, their tools and the materials for the job must be safely supported. Before you access a scaffold you should know whether or not it will support your weight and the materials you intend to use.
The manufacturer rates scaffolds based on the load it will carry. This rating must provide for a safety factor. OSHA requires that a scaffold be able to support its own weight and four times the maximum intended load. Ropes for suspended scaffolds must support six times the maximum intended load. If you are using a manufactured scaffold, the load you may place on it will be identified. Supported scaffolds will have a duty rating. On a suspended scaffold the actual weight or load capacity should be listed in a chart attached to the scaffold. The chart will compare the length of the platform to the allowable load. If it is not provided, ask your supervisor or contact the manufacturer. When selecting an anchor or support, the counterweights, outrigger beams, etc., for a suspended scaffold make sure you include the weight of the scaffold and four times the intended load.
OSHA provides general guidelines on duty rates for scaffolds and scaffold components. When using the ratings identified by OSHA, manufacturers’ must ensure the components address the safety factor. In determining the appropriate scaffold design and components for your use, both the frame and plank rating can be evaluated. The plank offers the easiest guide. The capacity of the planks and the distance between their supporting frames, governs the weight that will bear on each frame. Using the plank as a guide will provide an estimate of the load that can be placed on a scaffold. Scaffold planks placed on a 7-8-foot span will support 50 pounds per square foot. On a 6-foot span 75 pounds per square foot is allowed. The total allowable load can be calculated by multiplying the total square footage of the platform times the pounds per square foot.
Another load indicator is the deflection of the plank. If you are using Laminated Veneer Lumber (LVL), a 6-foot span should deflect no more than 1 1/4 inch. A 7-foot span should deflect no more than 13/8 inch. Check with the manufacturer if you are using any other type of scaffold grade lumber. Discard any lumber that has been overloaded.
Loading material onto a scaffold presents several problems. First you must make sure you do not overload the scaffold. Know the weight of the material and use the information provided on load capacity. A typical pallet of block weighs approximately 4,000 lbs. and will add to the weight of other materials and the workers. This weight should be distributed evenly on the platform. The safest method for this is to hand load the block. If a pallet is forklifted to the platform, it should be loaded over the frame. Special care should be taken if a hoist is used. Hoists cause excessive force to the frame of a scaffold. Make sure the hoist is designed to lift your material and properly secured.
Material limits the work area and mobility. It also provides additional objects, which present a hazard to workers below. Make sure falling object protection is in place. Remove debris as soon as possible from the working surface.