A scaffold is defined as any temporary elevated work platform (supported or suspended) and its supporting structure (including points of anchorage) used for supporting employees or materials or both. Note that there are three main points to the definition: it is elevated, it is temporary, and it supports either personnel or materials or both.
Scaffolds are divided into two main categories, those supported from underneath, or those suspended from above. OSHA has specific rules for 25 different types of scaffolds in 29CFR 1926.452. This paper is a short overview of some of the general requirements for supported scaffolds.
When planning a scaffold job, one of the first considerations is training of personnel. All personnel who will use a scaffold must have User training, covering such topics as fall protection, loading, electrical safety, material handling, falling object protection and safe work practices (1926.454(a)). All personnel involved in inspecting, erecting, or modifying scaffolds must be trained in scaffold hazards, assembly procedures, design criteria, loading, OSHA regulations, and manufacturer's recommended assembly instructions as applicable to the type of scaffold being used. (1926.454(b)). A Competent Person must supervise erection and perform inspections every work shift (1926.451(f)(7) and 1926.451(f)(3).
A Qualified Person should design the scaffold job (1926.451(a)(6)). Since each jobsite presents unique conditions, the following items must be considered:
Proximity of electric lines 1926.45 (f)(6), process piping or overhead obstructions.
Adequate access to the job site.
Weather conditions and wind/weather protection.
Openings, pits and ground conditions.
Adequate foundations of sufficient strength to support scaffolds from a sound, stable surface that assures support of the intended loads.
Interference with other jobs or workers.
Environmental hazards.
Proper bracing that is rigid in all directions.
Safe and easy means of access and egress to the platform.
Fall protection for workers using the scaffold.
Adequate decking materials and overhead protection, where required.
Falling object protection of people passing, working near or underneath the scaffold.
Planning for the loading (weight) on the scaffold.
Loading on the scaffold is a major item to consider when planning a scaffold job. Historically, the scaffold structure loading calculations have been based on one of three anticipated load ratings. Light duty is the term for up to 25 pounds per square foot. Medium duty is the term for up to 50 pounds per square foot. Heavy duty is the term for up to 75 pounds per square foot. The user should know how much weight they will place on the platform with workers, tools, materials, and plan for the corresponding rating. The anticipated loading should be communicated to the erector. Consult the manufacturer of the specific equipment for allowable load limits.
