Supported Scaffold Safety. An Overview of Scaffold Safety. May, 2011. Topics Covered. Scaffold hazards Duties of a “competent person” Basic scaffold requirements Fall protection and guardrails Employee training. Supported Scaffolds Examples. Ladder jack scaffold.
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An Overview of Scaffold Safety
Duties of a “competent person”
Basic scaffold requirements
Fall protection and guardrails
Ladder jack scaffold
Fabricated frame scaffold
Supported scaffolds are scaffolds that are in contact with the ground rather than being suspended by cables.
The safety of a scaffold is highly dependent upon being built right in the first place. When scaffolds fail, they fail in a catastrophic way and can cause many serious injuries or deaths depending on who is on or around it when it fails.
Damaged or weakened parts must immediately be:
Must be supervised and directed by a competent person
Must be done by trained employees selected by a competent person
A competent person is able to:
A competent person must:
A “competent person” determines feasibility of fall protection, and
the employer must provide the maximum feasible fall protection.
Cross bracing or “X” brace can substitute for top rail or mid rail but not both.
Cross bracing is acceptable in place of a midrail when the crossing point of two braces is between 20 inches and 30 inches above the work platform.
Cross bracing can be used as a top rail when the crossing point is between 38 inches and 48 inches above the work platform.
The end points at each upright must be no more than 48 inches apart.
For platforms more than two above or below a point of access
In the picture on right, the worker is climbing the scaffold frame, which is in violation of the rule.
Examples of scaffolds too close to power lines
You can get closer than these distances if you contact the power company and they deenergize the lines and visibly ground them or install protective shields.
Support the load without settling or displacement
A mud sill isn’t needed on a concrete surface or dry compacted soil. You always need the base plate.
Cardboard, sticks, blocks, rocks or bricks aren’t a sound method of leveling
Scaffold platforms must be fully planked with no gaps greater than one inch.
(and this employee needs fall protection)
Gaps too wide between planks
If it’s not adequately secured, it can tip if you walk out past the support.
If a plank extends too far past the support because it’s too long, you can barricade access to the hazardous area.
Damaged wood planks include:
Rot- "squishy" feel, or powdery appearance from termite damage
Cupping of 3/8" or more on a 10" wide or 1/2" or more on 12" wide plank.
Crook of more than 5/16”, bow of more than 7/16” or twist of more than ¾” on a 10’ long 10” board.
Wane of more than ¼ the width and ¼ the thickness for more than ¼ the length of the plank.
A splitthat has a length of 1 ½ times the board width or more.
Knotsthat are more than 1 ½” diameter if loose or 2” diameter if tight on a 10” plank.
A notch cut into a plank more than 1/3 the plank width.
Any saw kerf cut across the plank weakens the plank by the depth of the cut. The problem may not be noticed if the plank is later laid with the cut side down.
4 times the intended load + scaffold weight
Planks must not deflect more than 1/60 of span when loaded
Angled plank is not on the bottom
Not fully planked at transition
No guardrail at transition
On a corner, planks that don’t come in at a right angle to the support must be on the bottom and then overlapped by the planks that are at a right angle.
Forklifts and front-end loaders are not designed by the manufacturer for such use.
If the ratio of height to base is more than 4:1, then:
Install guys every 26’ above this tie point for scaffolds more than 3’ wide.
Install these guys at each end of the scaffold and space additional middle guys no more than 30’ apart.
If you use a cantilevered work platform (outside the framework of the scaffold), then you must use some type of bracing such as tying or outriggers to prevent the scaffold from tipping.
Do clean up debris on platforms before it accumulates.
This is an example of a lean-to scaffold. In this picture, the workers have a shore scaffold on top of another shore scaffold. Access is unsafe both from above and below. The only thing holding this scaffold up is the DUMPSTER!
Employees need training so they don’t misuse the scaffold or do things that will cause it to lose its integrity, such as removing cross bracing so they can do their work. Training needs to be specific to the scaffold the workers will be using. Job-specific issues would include power line clearances, surface conditions.
DOSH Scaffolds Rules: WAC 296-874, Scaffolds
Scaffold Accident Video – A Life-Changing Moment
OSHA – Scaffolding eTool
YouTube – Scaffold Safety
CPWR – Scaffold Safety Hazard Alert
Oregon OSHA – Supported Scaffolds in Construction
Oregon OSHA – Scaffold Safety (Spanish)