The Bureau of Labor Statistics reports that 72 per cent of injuries on scaffolds are caused by planking giving way, slips and falling objects. Many of these accidents can be avoided by following official standards on the construction and maintenance of scaffolding. OSHA, the Occupational Safety and Health Administration, provides specific guidelines contractors must follow. You need to calculate the maximum live load of a scaffolding before you erect it, so you can choose the right type of tubing, bracing and planks for the job. A scaffold live load is the weight of the workers, equipment and materials which will be used on at any one time on the scaffold. As it is impossible to know exactly how much weight a scaffold will have to withstand there are formulas and guidelines you can use to estimate a structure's live load.
Estimate conservatively the weight of the workers, materials, supplies and equipment your scaffold will have to withstand at any one moment. Use a project's work schedule, list of materials and the equipment that will be needed to complete the job to help you calculate the total weight estimate. For instance, if you are going to have a maximum of 10 men working at the same time and the weight of the materials and equipment is 2,000kg, you would multiply 10 by the average weight of your workers and add the total weight of the scaffolding standards, planking and other accessories. If you use an average weight of 100kg, the live load would amount to 3,000kg.
Divide by three. Each standard, or vertical post, of a scaffold bay is designed to bear a third of a scaffold's live load. Following the example, 3,000kg divided by three is 1,000kg.
Multiply by the number of platforms on your scaffolding unit. That is your scaffold's live load. Following the example, if you have a two-level scaffold, multiply 1,000kg by two, which is 2,000kg.
There are several ways of calculating a scaffold's live load. Check to make sure your local building and planning authority approves the method you use.
Never erect a scaffold if you do not have the experience and know how. Mistakes in the design and construction of a scaffold can cause serious accidents.