Types of Scaffolding

What Is A Scaffold?

Three basic types:

ØSupported scaffolds -- platforms supported by rigid, load bearing members, such as poles, legs, frames, & outriggers

ØSuspended scaffolds -- platforms suspended by ropes or other non-rigid, overhead support

ØAerial Lifts -- such as “cherry pickers” or “boom trucks”

Some Supported Scaffolds

Aerial Lifts

Hazards

Types of Scaffolds - Load

light duty scaffold: A scaffold designed and constructed to carry a working load not to exceed 25 pounds per square foot.

Medium duty scaffold: A scaffold designed and constructed to carry a working load not to exceed 50 pounds per square foot.

Heavy duty scaffold: A scaffold designed and constructed to carry a working load not to exceed 75 pounds per square foot.

Rated Load Capacity

Maximum Capacity

To determine the maximum weight that can be applied to the scaffold, determine the square footage and multiply it by the manufacturer’s rated load capacity.

Example:  scaffold size is 7’ x 5’ = 35sq. ft.

35 x 25 psf (light-duty) = 875 pounds

Types of Scaffolding

A- Frame Scaffolding

The primary steel scaffolding system.

It is primarily for rectangular jobs.

It is relatively simple and fast to erect, provided the surface is level, and the access is not restricted.

Frame Scaffold

OSHA refers to frame scaffolds as sectional steel scaffold.

There are two basic parts to a frame scaffolds – The frame and the cross brace.

Frame Selection

Scaffold frames are available in two basic configurations – the end frame and the walk-through frame. 

Access Onto Scaffold

OSHA requires that adequate means of access is given to the scaffold platform.

Stairways or demountable ladders.

In addition Waco has a walk-through and an end frame with built-in ladders.

Scaffold Access

No access by crossbraces

When using ladders, bottom rung no more than 24 inches high

Can use some end frames

Can access from another scaffold, structure or hoist

B- Tube and Clamp

To accommodate jobs too difficult for frame scaffolding, because of the obstruction, limited access.

Tube and clamp requires much greater expertise to erect.

Oil Refineries

C- Modular System Scaffolds

The advantage that modular systems have over tube and clamp is that they do not require the high degree of expertise .

Once the base is set, the erector does not have to worry about the location of connections

D- Rolling Scaffolds

When height to minimum base width ratio of the scaffold exceeds 4:1, stabilizers are required.

Casters (brakes)

Adjustable screws with base plates.

 E- Suspended Scaffolds