Scaffolding is a temporarily-constructed surface that supports elevated equipment, or that allows workers to gain access to buildings or equipment. Scaffolds are used mainly in the construction, repair, and maintenance of buildings and other large structure. Typically, scaffolding is made of metal. Aluminum scaffolding and steel scaffolding are the two most common types. Guard rails, side rails, folding trestles, and casters are common features. In the United States, the Occupational Safety and Health Administration (OSHA) define requirements for scaffolding safety. Private organizations such as the Scaffold Industry Association (SIA) also issue scaffolding guidelines.

Parts of a Scaffold

The main parts of a scaffold are the standards, ledgers, and transoms. The standards or uprights are vertical tubes that transfer the weight of the scaffolding to the ground. There, a base plate distributes the load. Ledgers are horizontal tubes that connect the standards. Transoms rest upon the ledgers at right angles. There are two types of transoms: main and intermediate. Main transoms hold the standards in place. Intermediate transoms provide extra support for the wooden boards upon which workers stand. Scaffolding components also include the inside board. Bay length, base lift, scaffolding width, and lift height are important specifications to consider.

Types of Scaffolding

There are many types of scaffolding. Choices include birdcage, tower, mobile, and hung scaffolds. Birdcage scaffolds have more than two rows of standards in both directions, and are connected by ledgers and transoms. These independent scaffolds are designed for work at a single level (such as a ceiling). Tower scaffolds consist of four vertical members that are connected longitudinally and transversely. Mobile scaffolds are portable and mount on casters. Hung scaffolding can be hung from another structure (such as a building), but cannot be raised or lowered when in use.


Unlike hung scaffolding, suspended scaffolds or swingstage scaffolds have a platform that can be raised or lowered as necessary. Typically, these scaffolds are used by window washers. Scaffold types also include cantilever and single-pole products. Cantilever scaffolds are attached or supported at only one end. Single-pole scaffolds consist of a single row of standards that are connected by ledgers. Putlogs are fixed to the ledgers and built into the wall of the building or structure. Because a single-pole scaffold depends upon the structure against which it is placed for support, however, scaffolding components should not be removed until the entire scaffold is dismantled.