1. Supported Scaffold Safety
An Overview of Scaffold Safety
May, 2011

2. Topics Covered Scaffold hazards Duties of a “competent person”
Basic scaffold requirements
Fall protection and guardrails
Employee training

3. Supported Scaffolds Examples
Ladder jack scaffold
Fabricated frame scaffold
Mobile scaffold
Supported scaffolds are scaffolds that are in contact with the ground rather than being suspended by cables.

4. More Supported Scaffold Examples

5. Hazards of Scaffold Work
According to the scaffold industry association, the five most serious scaffold hazards are:
Falls
Unsafe access
Falling objects
Electrocution
Scaffold collapse
Falls, scaffold collapse and electrocution account for most scaffold related fatalities.
A combination of regular inspection and consistent training of workers can go a long way to reducing these risks.

6. Scaffold Collapse Can Happen
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.

7. Damage Scaffold Parts Damaged or weakened parts must immediately be:
Repaired, replaced, braced to meet minimum strength OR
Removed from service until repaired.

8. Erecting, moving, altering or dismantling scaffolds
Must be supervised and directed by a competent person
Must be done by trained employees selected by a competent person

9. What is a “Competent Person”?
A competent person is able to:
Identify existing and predictable hazards,
Identify working conditions that are unsanitary, hazardous or dangerous and:
Has authority to eliminate hazards.
A competent person must:
Have knowledge of what the scaffolding standard requires for workplace safety training and experience in erecting and inspecting scaffolds,
know about the kinds of hazards that can exist around scaffolds,
be designated by management as the competent person,
have authority to take action to stop unsafe activities and eliminate hazards identified.

10. Erecting and Dismantling Scaffolds
While scaffolding is being erected or dismantled:
A “competent person” determines feasibility of fall protection, and
the employer must provide the maximum feasible fall protection.
Questions to ask are:
Is there a nearby structure from which a lifeline can be dropped that the worker can tie off to?
Can we install guardrails immediately after installing the fabricated frames and before moving to the next level?
Can we sequence disassembly to keep the worker protected for the maximum feasible time?
Whatever is feasible to do must be done during the assembly/ disassembly stages.

11. Fall Protection on Scaffold
Employers must provide fall protection on a scaffold more than 10 feet above a lower level by one of these methods:
Guardrails, which must be:
Installed along open sides and ends and
In place before employees use the scaffold OR
Personal fall arrest system
In accordance with WAC Part C-1 and WAC
Must be attached to the structure or a lifeline and not the scaffold

12. Examples of Lack of Fall Protection

13. Requirements for Guardrails
Guardrails consist of toprail, midrail and falling object protection, such as a toeboard
The toprail must be between 38” – 45” high and withstand a 200 lb. force
The midrail must be installed midway between the top edge and the platform surface and withstand a 150 lb. force
A toeboard, when used, must be 3 ½ inches tall and able to withstand a 50 lb. force. Barricades at base of scaffold can be substituted for toeboard
Toeboard (2 X 4 50 lb strength), screen or nets if employees walk or work below.
An alternative is to barricade the area around the base of the scaffold.
Top surface smooth to prevent puncture or snagging of clothes.
Manila or plastic rope rails must be inspected frequently to assure that it doesn’t deteriorate below strength requirements.
Don’t use steel or plastic banding as a top rail.
Don’t let ends of rails overhang the terminal post unless there isn’t a hazard.
You can only use cross braces in lieu of a top rail or mid rail but not both if a 19” sphere won’t pass through the resulting openings.
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.
Install the top rail between 38” and 45”
Cross bracing can be used as a top rail when the crossing point is between 38 inches and 48 inches above the work platform.
Install the midrail ½ way between the cross point and the platform
The end points at each upright must be no more than 48 inches apart.

14. Guardrails
Cross bracing or “X” brace can substitute for top rail or mid rail but not both.
You can only use cross braces in lieu of a top rail or mid rail but not both if a 19” sphere won’t pass through the resulting openings.
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.
Install the top rail between 38” and 45”
Cross bracing can be used as a top rail when the crossing point is between 38 inches and 48 inches above the work platform.
Install the midrail ½ way between the cross point and the platform
The end points at each upright must be no more than 48 inches apart.
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.

15. Provide a Ladder, Ramp or Direct Access
For platforms more than two above or below a point of access
Stairs must have a rest platform every 12 feet.
Slip resistant tread minimum 18” wide.
Ramp: Max 20 degree slope with non-slip or cleats
Min 18” wide, guardrails if more than 4 feet above adjacent surface.
Direct access: Max 14” step across distance.
In the picture on right, the worker is climbing the scaffold frame, which is in violation of the rule.

16. Power Line Clearance Insulated power lines Uninsulated power lines
Less than 300 volts – 3 feet
Less than 300 volts – 10 feet -
300 volts – 50 kilovolts = 10 feet
Over 50k Volts, add .4” per KV
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.

17. Footings Support the load without settling or displacement Level Sound
Rigid
A mud sill isn’t needed on a concrete surface or dry compacted soil. You always need the base plate.

18. Unstable Footing Examples
Cardboard, sticks, blocks, rocks or bricks aren’t a sound method of leveling

19. Platform Specifications
Each working level fully planked; no more than 1” gaps
Minimum platform and walkway width of 18”
Overlap planks between scaffold sections by at least 12”
Extend end over support 6” min. (Maximum end extension 12”)
Don’t paint planks since they will hide defects
Front edge within 14” of the work, or guard rails or fall protection must be used.
Fully decked between uprights and guardrails supports.
Platforms must be at least 18” wide
Except Ladder jack, pump jack, top plate bracket or roof bracket type scaffold must be at least 12” wide.
Except when the area is too narrow to allow 18” width guardrails or fall protection must be used.
The intent is that there be no more than 1” space between planks and uprights.
However planks can be up to 9 ½” away from the upright if you can show that the scaffold requires additional space (such as to fit around the uprights when side brackets are used to extend the width of the platform.)
Extend planks over the supporting members at least 6” unless you have tied the plank or use cleats or hooks on the underside.
Don’t extend the plank more than 12” (10’ or less plank) or
18” (longer than 10’ plank) or you could flip the plank up if you step on the extension.
Overlap planks between sections of scaffold by at least 12”.
You can only overlap over a supporting bearers.
Overlap can be less if planks are secured with cleats or tie wires
You can butt planks if each has their own support and are tied or hooked.
Overlaps can only be made above supporting bearers
Don’t paint planks since this will hide defects or damage that may only become apparent if someone falls through the plank.
Wood preservatives and non-slip finishes ok if they don’t obscure the top and bottom surfaces.
If the scaffold front edge isn’t within 14” of the wall then you must use guardrails
Except that plaster and lathing operations can be 18” away.

20. Examples of Improper Scaffold Planking
Scaffold platforms must be fully planked with no gaps greater than one inch.
(and this employee needs fall protection)
Gaps too wide between planks

21. Planks can’t extend more than 18” beyond their support
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.

22. Plank Specifications Scaffold grade or equivalent
1,500 lb-f/in2 (stress grade) construction lumber
Manufactured planks used according to manufacturer’s recommendations
The standard does not specifically require scaffold grade planks.
However, the platform material you use must be able to support 4X the intended load.
If you use a manufactured plank then you need to follow the manufacturer’s instructions in terms of weight limit and distribution of that weight (uniformly over the entire span)
e.g.: three person plank has max 250 lbs at center and additional 250 lbs at 18” to the right and to the left of center.

23. Wood Plank Inspection 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 split that has a length of 1 ½ times the board width or more.
Knots that 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.
Damaged manufactured planks:
Bent or cracked in hooks (DON’T repair by re-bending hook.)
Cracked rails Damaged decking
Corrosion to metal supports Loose fasteners

24. Plank Load Capacity 4 times the intended load + scaffold weight
Planks must not deflect more than 1/60 of span when loaded

25. Examples of Overloaded Scaffolds

26. Overlaps 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.

27. Example of Unstable Support
Forklifts and front-end loaders are not designed by the manufacturer for such use.

28. Guying, Tying or Bracing
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.
If the height of a scaffold is more than four times the width of the base of the scaffold
Including any outriggers, if used
You must install guys, ties, bracing or the equivalent at the closest horizontal member:
that supports both the outer and inner legs and
that is nearest the point where the scaffold height is 4 times its base width – as shown in the illustration <Click>
Install guys every 26’ above this tie point for scaffolds more than 3’ wide
(20’ above the tie point for scaffolds 3’ wide or less)
The last guy must be within the 4:1 ratio distance from the top.
Install these guys at each end of the scaffold and space additional middle guys no more than 30’ apart (as measured from one end).
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.

29. Other Scaffold Use Rules
Don’t
Move a scaffold when someone is on it.
Work on a scaffold covered with snow or ice.
Work on a scaffold during a storm or high winds.
Use boxes, barrels or a ladder on top of a scaffold to increase its height.
Do clean up debris on platforms before it accumulates.

30. Unacceptable Scaffold Example
Shore or “lean to”
Also, a competent person must approve the use of dissimilar metals
Intermixed scaffold components must fit together without force and not effect the structural integrity of the scaffold.
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!

31. Worker Must Be Trained On:
Recognizing hazards of the type of scaffold they’ll be using
Understanding the procedures to control or minimize hazards
How to erect, maintain and disassemble the fall protection and falling object protection systems
Using the scaffold and handling materials on the scaffold
Maximum intended load and capacity
Other information as needed
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.

32. Worker Must Be Retrained When:
You believe an employee lacks the skill or understanding to safely erect, use or dismantle a scaffold
If an employee's work is inadequate
If there is a change in any of the following that presents new hazards:
Worksite
Type of scaffold
Fall protection
Falling object protection
Other equipment

33. Additional Information
DOSH Scaffolds Rules: WAC , 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)