The structural member of a supported scaffold is used to extend the breadth of a scaffold's base in order to provide support and boost the scaffold's stability. Scaffold outriggers vary in size and design, but they all serve one purpose: to provide additional load-bearing capacity to the structure.
Outriggers are used most commonly on flat work surfaces, such as horizontal roof surfaces or floor joists. But because outriggers can be designed with any shape or angle of attachment, they're useful for providing support where it's needed most. For example, an outrigger can be used to strengthen a scaffold's base under a heavy window frame without interfering with the job being done on top of the scaffold.
Scaffold outriggers have several names depending on which part of the world you're in: booms, extensions, piers, posts, stilts - they're all terms used to describe this same piece of equipment. The word "outrigger" comes from the fact that they extend beyond the perimeter of the scaffold base - usually well beyond. There are two types of outriggers: internal and external.
Supported scaffolds are made up of one or more platforms that are held together by outrigger beams, brackets, poles, legs, uprights, posts, frames, or other rigid supports. The requirements for the other scaffold kinds are only detailed in their respective modules. Supported scaffolds must be designed and constructed to meet or exceed all standards required by their respective categories.
The American National Standards Institute/American Society of Mechanical Engineers A101.1:2007 Scaffolding Design and Construction provides the following definition: "A supported scaffold is a platform built using one or more supporting members (beams, columns, piers, etc.) upon which scaffolding boards or panels are mounted for performing work at a height above the ground or floor surface."
This means that a scaffold can be considered as a type of platform structure. It is used to provide a flat working surface at a height above the ground or floor. Scaffolds come in many shapes and sizes but they all have two things in common: they are both supported and constructed so they will not collapse under their own weight.
Scaffolds are used in construction and industrial jobs where it is necessary to get a worker into a high-up position to do work that is difficult or impossible to perform from the ground or floor.
Scaffolds are classified into two types:
Suspension scaffold outrigger beams, cornice hooks, parapet clamps, and similar devices must be supported by surfaces that can withstand at least four times the weight imposed by the scaffold while working at the rated load of the hoist. The outrigger beam and hook must be straight and uniform in size. Corbels, batterboards, and other support structures used to hold the scaffold in place must be firmly fixed to the building or structure being worked on.
The components of a suspended scaffold include: outrigger beams, which support the scaffolding above the headway; hooks, which support the ends of the outriggers over opposite sides of the construction zone; pins, which connect the outriggers together into one continuous surface for loading from the hoist; and counterweights, which provide stability when lifting heavy loads.
Outrigger beams are usually made of steel or aluminum, but wood has also been used successfully as long as it is bolted or welded into a rigid frame. The length of an outrigger beam should be at least three times its maximum width to provide sufficient strength and rigidity for withstanding the stress of carrying heavy loads. The thickness of the beam should be no less than 1-1/4 inches nor more than 2-1/2 inches.
Scaffolding for swing stages must be able to support the weight of workers and equipment, so it needs to be strong enough to be secured to a structure with hooks or bolts. This type of scaffold is used when you want to work on an assembly line situation where multiple jobs need to be done simultaneously.
Suspended scaffolds are usually made of aluminum tubing with polypropylene or other plastic connectors that connect each section together. These can be assembled in different configurations to fit your working conditions. The height can be adjusted easily by changing the length of the suspension cables.
The most common type of suspended scaffold is the horizontal truss system. It consists of three main elements: a headboard, two sideboards, and one or more end panels. The headboard and sideboards are connected by two trusses. The trusses have holes through which you can attach tools or material. They provide extra strength while allowing you to adjust the height of the scaffold.
End panels are needed if you want to keep some space clear below the scaffold. Otherwise, all the material attached to the scaffold will block its use. End panels also protect people from falling objects.