Supported Scaffolding
A construction worker is shown accessing and inspecting a scaffold system.
Date Posted: 05/30/2024
According to the United States Bureau of Labor Statistics (BLS), scaffold-related accidents result in roughly 60 deaths and 4,500 injuries yearly throughout the country. Falls from scaffolds account for approximately 25% of fatal falls from all working surfaces. In the BLS study, 72% of workers injured in scaffold accidents attributed the accident to the planking or support giving way or the employee slipping or being struck by a falling object. All of these can be controlled by compliance with regulatory standards.
What is a Scaffold?
A scaffold is a temporary structure used in construction to support people and materials while work is being carried out on a building or other tall structure. Scaffolding is often used to allow workers to reach higher levels of a building or structure, and it must be used correctly to prevent accidents and injuries.
A supported scaffold (typically a frame scaffold) is the most commonly used. It has one or more platforms supported by outrigger beams, brackets, poles, legs, uprights, posts, frames, or similar rigid support. In addition, supported scaffolds include system scaffolds (fixed connection points at predetermined levels) and mobile scaffolds. Unfortunately, workers fall daily when working on scaffolds, often resulting in either fatalities or permanent injuries. These tragedies are sometimes caused by faulty design or poor construction, but in most cases, the cause is preventable: poor scaffold maintenance or improper use are the most common causes.
A supported scaffold system is shown.
Let’s Start with the Base–Solid Foundation
Scaffolding is only as good as its foundation. Scaffolds are temporary platforms used in the construction industry, allowing workers to access higher levels. A supported scaffold is a scaffold system set on ground level with built-in levels to increase its height. However, no matter how high the scaffold is set, it must be on a good foundation. According to the WA Division of Occupational Safety and Health (DOSH) “supported scaffold poles, legs, posts, frames, and uprights shall bear on base plates and mud sills or other adequate firm foundation.”
Base Plate: A base plate is a device that spreads the point load of the scaffold frame over a larger area, keeping the structure from sinking into the ground.
Mudsill: A mud sill is a device that further extends the point load of the base plates. The mudsill under the scaffold base plate uniformly distributes the scaffold load over a larger area than that distributed by the base plate alone, thereby reducing the loading on the ground beneath the base plates.
Adequate Firm Foundation: An adequate foundation, like base plates on mud sills, will prevent the scaffold from settling into the ground. A firm foundation, such as a flat, level concrete slab, is an adequate surface for a base plate.
Scaffold Platform Safety
Scaffold platforms should be fully planked as possible, secured, and guard-railed to ensure the safety of any occupants. Workers should not stockpile materials on the scaffolds, and all materials and tools should be removed at the end of the day. Overloading the scaffold should be avoided, and workers should not work on scaffolds during high winds or adverse weather.
Scaffold Access / Egress
Workers are vulnerable to fall hazards when climbing on or off a scaffold. Therefore, employers are required to provide safe scaffold access. The four most common types of scaffold access include the following:
Ladders
Integral (built-in) access
Stair towers
Direct access – ramps and walkways (only if the scaffold is not more than 14 inches horizontally and 24 inches vertically from other surfaces).
A construction worker is shown carrying materials while walking on a scaffold.
Note: Climbing the structural cross-bracing of a scaffold is unsafe and prohibited.
Scaffold Hazards
Falls from elevation due to lack of fall protection: Falls are attributed to the lack of guardrails, improper installation of guardrails, and failure to use personal fall arrest systems when required. WAC 296-880-30030 states that fall protection must be used when work heights reach 10’ or more.
Collapse of the scaffold, caused by instability or overloading: The proper erection of a scaffold is essential in preventing this hazard. Before erecting the scaffold, several factors must be accounted for. The weight the scaffold will be required to hold, including the weight of the scaffold itself, materials, and workers, shall be considered. Foundation stability, placement of scaffold planks, distance from the scaffold to the work surface, and tie-in requirements are just a few of the other items that must be considered.
Being struck by falling tools, work materials, or debris: Workers on scaffolds are not the only ones exposed to scaffold-related hazards. Many individuals have been injured or killed due to being struck by materials or tools that have fallen from scaffold platforms. To protect against this hazard, install toe boards or netting on work platforms to prevent these items from falling to the ground or lower-level work areas. Another option is to erect barricades that physically prevent individuals from walking under work platforms and dangerous areas.
Electrocution due to the proximity of the scaffold to overhead power lines: A minimum of 10’ (might be more depending on voltage) must be maintained between the scaffold and electrical hazards. The power company must de-energize or adequately insulate the hazard if this distance cannot be maintained. Coordination between the power company and the company erecting/using the scaffold cannot be overstated.
Inspecting the Scaffold
Inspecting scaffolding before each use is crucial to ensure it is safe and secure. A daily inspection should be performed to check the guardrails, connectors, fastenings, footing, tie-ins, and bracing. If any component is damaged, it should be repaired or replaced immediately. A competent person with experience in scaffolding safety should perform the inspection. Use Daily Scaffold Inspection tags. The tag should be hung where the employees access the scaffold. In addition, scaffolding must be inspected after an event that may have compromised the scaffold system’s structural integrity.
A worker is shown looking upwards with a clipboard and pen.
