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Temporary structure, permanent safety

Help keep employees safe during all stages of scaffolding work

February 1, 2014

Key points

  • Fall protection should be used on scaffolds at all times, regardless of height, experts recommend.
  • Falling objects can take unpredictable paths to the ground, so workers should take every precaution to prevent objects from being dropped or knocked off a scaffold platform.
  • Different types of scaffolds present different types of hazards.

On a November day in 1994, a 60-year-old painter foreman with 20 years of experience was standing more than 35 feet above the ground on a scaffold, working on the window frames and roof eaves of a church in Tennessee.

A NIOSH report on the incident states that while standing on two 12-inch-wide unsecured boards that left one-third of the scaffold floor uncovered, the worker fell between the boards and the outside rail of the scaffold, plummeting to his death.

Scaffolds are common structures on many jobsites, and the hazards of working on them are as prevalent today as they were 20 years ago. In 2012, 57 workers fell to their deaths from scaffolds or staging platforms, according to preliminary data from the Bureau of Labor Statistics, and thousands more are injured every year during scaffolding activities.

However, such incidents are preventable.

“It’s important that users understand the risks involved with working at elevation,” said John Palmer, director of the Scaffold Training Institute based in League City, TX.

Experts say employees need to understand that scaffolds are not permanent structures and care must be taken when working on all stages of scaffolding – from their construction to the work that takes place on them.

Setup and use

During the set-up phase, the structure must be placed on a solid, level base, the Silver Spring, MD-based Center for Construction Research and Training (also known as CPWR) states.

The footing of a scaffold typically consists of a wooden pad (known as a mud sill) that goes directly on top of the floor material – usually dirt or concrete. On top of the mud sill is a base plate, which is a 6-inch square steel footing component that goes under the scaffold post. Both the base plate and mud sill help spread out the load of the scaffold so the pressure of pounds per square foot on the scaffold legs is reduced, Palmer said.

The designer of a scaffold needs to communicate with workers before the structure is designed and built, Palmer added, to ensure the erected scaffold meets the requirements for how it will be used.

CPWR also states that before scaffolds are used, a competent person – defined by OSHA as someone who is able to identify hazards and has the authority to eliminate them – must check four points:

  • Access on and off the scaffold meets OSHA requirements.
  • All work areas are fully planked or decked.
  • All guardrails are installed properly, or alternative fall protection is provided.
  • Scaffolds are guyed and tied to the building correctly, and the guys and ties are in good condition.

Planking should extend all the way across, Palmer said, and OSHA’s maximum allowable gap between planks is 1 inch. Workers should not climb up levels on the scaffold components – a proper ladder should be used, whether it is a ladder placed next to the scaffold or one built into the scaffold’s frame.

At times, work can be constrained because of the scaffold’s structure. However, Palmer warned against removing bracing from the scaffold, as doing so can affect the structural integrity of the whole system – and could even bring the scaffold down. “It’s unlikely that removing one piece at a time will cause a failure, but if they remove too many pieces simultaneously, then of course that could happen,” he said.

Guarding against falls

One of the biggest hazards of working on scaffolding is falls. OSHA’s trigger height for mandated fall protection is 10 feet above a lower level, but Palmer stressed that employers should provide fall protection for workers at any height above the ground.

“One of the common misconceptions with new workers is that they’re not going to get hurt if they don’t fall very far,” Palmer said. However, he added, these workers should be made aware that falls from heights as low as 6 feet can result in a serious injury or fatality. Falls on the same level can lead to injury as well.

Compliance with fall protection requirements on a fully planked or decked scaffold – in which the entire standing surface has been laid down with no large gaps – can be achieved with a guardrail. But Paul Amedee, vice president of safety at the Waukesha, WI-based scaffold service and training company Safway Group, suggested that all workers on any type of scaffold use a personal fall arrest system. Although some may consider that excessive, Amedee said it is a best practice because work on a scaffold often requires an employee to reach out past the protection of a platform, whether to grab equipment or perform a task. When workers do that, they are putting themselves at risk of a fall, according to Amedee.

Additionally, Amedee stressed that the scaffold is a temporary structure. “The biggest mistake people make on scaffolds is they don’t always pay attention to the importance of fall protection because the scaffold feels solid,” he said. “They don’t tie off, and then find themselves walking near an opening that could create a fall to the next level; they expose themselves to serious hazards.”

Certain scaffolds, such as swing scaffolds, require a guardrail and personal fall arrest system for the worker. Likewise, although OSHA does not require tying off in some situations during erection or dismantling of scaffolding, many companies have instituted a 100 percent tie-off policy, Amedee said.

(See Different types, different hazards for more information on the various hazards different scaffolds can present.)

Workers who use a personal fall arrest system – or tie off – need to know where to set their anchors, Amedee said. Depending on the scaffold type, there may be different points on which an anchor can or cannot be attached. Scaffolds can be used only as an anchorage if the scaffold meets the requirements and is built to withstand the forces applied when someone falls.

OSHA, SAIA renew alliance

On Dec. 18, OSHA and the Scaffold and Access Industry Association renewed their alliance aimed at providing information and training to protect workers around scaffolds.

The alliance will focus on falls, caught-in-betweens, and a variety of other hazards associated with scaffolds and lift equipment.

“By renewing our alliance with SAIA, we will expand our outreach to employers and workers and provide important training to protect workers in the scaffold and access industry,” OSHA administrator David Michaels said in a press release.

Go to OSHA's website for more information on the alliance.

Struck-bys and material handling

Workers on all levels of a scaffold, as well as those on the ground, are exposed to possible falling objects, according to Palmer. Although workers on lower levels of a scaffold have overhead protection – the scaffold planks above them – that does not mean they are safe from falling objects.

Amedee suggested workers learn to “stay out of that line of fire” while on or around scaffolds. Employees can become injured by falling or dropped objects whenever they lean or reach outside the scaffold structure.

However, that is not the only way a worker can be injured. When an object – particularly a tool – drops from a scaffold, it may collide with other objects or part of the scaffold itself, and its path may change direction.

“A few of us call this the pinball effect,” Amedee said. “It kind of bounces around. You really don’t know where it’s going to go.”

Depending on the size or dimensions of the object and how it falls or bounces, workers as far as 30 horizontal feet away could be struck. Even people under the decking of a scaffold could be at risk. To prevent objects from falling, ensure toeboards are in place. When tools or equipment are piled higher than the top of a toeboard, OSHA requires paneling or a screen extending up to the guardrail to stop objects from falling.

Although not an OSHA requirement, using nets and tethered tools is considered a best practice for preventing falling equipment, Amedee said. Additionally, keeping a clean workspace is necessary so workers do not inadvertently knock a tool or building material off the scaffold. A clean workspace also minimizes the risk of a tripping hazard, Palmer said.

Similar to struck-bys and drops, basic material handling is important while working on a scaffold. Improper handling of materials can lead to ergonomics-related injuries, Palmer warned, so workers should be familiar with proper lifting techniques.

Scaffold erectors have to move large, bulky pieces of material, so a good grip in the center of the material should be used, Palmer said. Hands should be spread apart for maximum control. When moving very large pieces of material, co-workers should help.

Many employers are considering the use of mechanical devices to haul equipment up and down a scaffold instead of the old daisy chain method, in which erectors form a line and pass material to each other. However, Amedee cautioned that workers can be injured even if using mechanical lift devices. When hauling equipment, areas should be barricaded to keep people away, Amedee said.

Additional hazards

Falls and struck-bys are the biggest hazards on and around a scaffold, but they are not the only ones.

On higher elevated scaffolds, wind can be a serious issue. OSHA requires workers to use a personal fall arrest system in addition to the guardrail, or install a wind screen, in high-wind situations. Although the agency does not define a specific wind speed limit, Palmer suggested 25 mph.

Wind also can cause workers to drop large objects from a scaffold. “The wind might just take it right out of your hands,” Palmer said.

Being on a scaffold brings workers closer to overhead power lines. Because of the risk of electrical injuries, OSHA requires 10 feet of clearance between power lines and everything on the scaffold. This includes all workers and materials.

For example: If a scaffold decking is 20 feet away from power lines and a 6-foot-tall worker holds a piece of material 10 feet long above his head, this scaffold would not ?be in compliance because the material would be about 4 feet away from the power lines – less than the required clearance.

All workers should know the load limit of the scaffold they are working on. This may require a bit of math on the worker’s part – scaffold platforms come in three categories of uniform loading, and each category has a weight limit per square foot. Workers will need to know their weight, as well as the weight of all the material and tools they plan on bringing onto the scaffold.

Some workers – such as bricklayers or masons – commonly overload the scaffold by bringing up a lot of material all at one time, according to Amedee. When workers overload the scaffold and exceed its weight limit, the scaffold has the potential to collapse.

Instead, Amedee said, workers should stay under the scaffold’s weight limit and retrieve supplies as needed.


Perhaps above all else, workers on scaffolds need to keep in mind where they are – on a temporary, elevated platform with exposure to a number of hazards. Palmer recommended workers on scaffolding be extra cautious by moving a bit slower and being more aware of the various width and length constraints of the structure.

“They need to understand they’re not just working on the ground. They’re at elevation,” Palmer said. “Even if the scaffold is completed and all the guardrails are installed, they need to have some respect for the potential hazard of working at heights.”

Different scaffolds