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K-State Today

August 18, 2011

Scaffold safety

By Lisa Linck

Each year more than 60 workers are killed by falls from scaffolds in the U.S., with around one in five of the fatal falls happening in construction.

A construction worker recently fell to his death at the Bill Snyder Family Stadium construction site. A plank slid out of place when the worker stepped onto the scaffold. Besides problems with planks and guardrails, the main causes of injuries and deaths on scaffolds include poor planning for assembling and taking them apart, missing tie-ins or bracing, loads that are too heavy and being too close to power lines. Also, falling objects can hurt people below scaffolds.

Protect yourself

Scaffolds are supported by posts/beams and legs or suspended by ropes. A qualified person  -- terms in italics defined below -- must design a scaffold. Supported scaffolds must be able to support their own weight and at least four times the maximum intended load.

A competent person must inspect a scaffold before each work shift and after anything happens that could affect the structure. The competent person should be trained in scaffold safety. A competent person must supervise if a scaffold is assembled, changed, moved or taken apart.

Keep scaffolds 10 feet or more from power lines -- or 3 feet away if lines are less than 300 volts -- unless you are sure the power lines are de-energized. You cannot work on a scaffold in high winds or a storm unless a competent person says it is safe and you use personal fall-arrest or a windscreen. You must not work on a scaffold that has ice or snow on it -- except to get ice or snow off the scaffold.

Guidelines for checking a scaffold

If a scaffold is more than 2 feet above or below a level, there must be a way to get on or off, such as a ladder, ramp or personnel hoist. The access must not be more than 14 inches from the scaffold.

Put a standing scaffold on a firm foundation with base plates attached to feet -- for instance, with one piece of wood under each pair of legs across the shortest distance, extending at least 1 foot past each leg. Uprights must be vertical and braced to prevent swaying; platforms must be level.

A scaffold that is more than four times higher than its base is wide, must be tied to supports. Most scaffold platforms and walkways must be 18 inches wide or more. If a work area is less than 18 inches wide, guardrails and/or personal fall-arrest must be used.

Also, 10-foot planks must extend at least 6 inches past the end supports, but not more than 12 inches. There should be no more than 1 inch between planks or between planks and uprights. Wood planks must be unpainted, so any cracks will show. For supported scaffolds, check at least these points:

1. Completely planked platforms

2. Proper access

3. Complete guardrails

4. Proper ties to buildings, where required

Suspended scaffolds

Supporting outrigger beams must be able to support at least four times the intended load. To keep a scaffold from falling to the ground, it must be attached to the roof, tied to a secure anchorage or secured with counterweights. The suspension ropes and rigging must support at least six times the intended load. Counterweights must be attached to secure and strong places on a building so they won't move. Do not use bags of sand or gravel, masonry blocks or roofing materials that can flow or move. Do not use gas-powered equipment or hoists. Hoists must have automatic brakes for emergencies. A one-point or two-point suspended scaffold must be tied or secured to prevent swaying.

Fall protection

If a scaffold is more than 10 feet above a level, workers must be protected from falls by guardrails or a fall arrest system -- except those on single-point and two-point adjustable suspension scaffolds. Both a personal fall arrest system and a guardrail must protect each employee on a single-point and two-point adjustable suspended scaffold. A competent person must decide if fall protection is feasible when you assemble a scaffold or take it apart.

On most scaffolds, guardrails must be on all open sides and ends. On supported scaffolds and some other scaffolds, guardrails or personal fall protection is enough. On most suspension scaffolds, both are needed. Use a harness, not a body belt, for personal fall protection. You do not need a guardrail on the working side when the platform is less than 14 inches from the work or 18 inches for plastering and lathing. The open side of an outrigger must never be more than 3 inches from the face of the building.

On supported scaffolds most of the time, the top rail must be 38 inches to 45 inches above the platform. A top rail must be strong enough to hold 200 pounds or 100 pounds on single-point and two-point suspension scaffolds. A mid-rail must be about halfway between the platform and the top rail; most mid-rails must be able to hold 150 pounds. If mesh, screens or panels are used, a top rail is needed -- unless mesh was designed and installed to meet guardrail requirements.

Scaffold walkways must have no more than a 9.5 inches gap between planks and a guardrail. Don't let junk collect on the scaffold. You can trip and fall.

Protection for people below a scaffold

There must be a 3½ inches-high toe board to prevent things falling off a scaffold. If things on the scaffold are taller than 3½ inches -- above the toeboard -- other systems, such as debris nets, can be used to catch falling tools or materials. If things can fall off a scaffold, people must be prevented from walking under or near the scaffold.


The employer must have a qualified person provide safety training for each worker who uses a scaffold. A competent person must give safety training to any worker who assembles, takes apart, moves, operates, repairs, maintains or inspects scaffolds. If the worksite changes or the type of scaffold or safety equipment changes, workers using scaffolds must be retrained.

* The Occupational Safety and Health Administration defines a qualified person by having extensive knowledge, training and experience who can solve problems related to the subject matter. A competent person is capable of identifying existing and predictable hazards and has authorization to take prompt measures to eliminate them. More information on scaffold safety is in the OSHA Construction Standards in the Code of Federal Regulations, 29 CFR 1926.450-454.