Chapter 3: Scaffold Safety

What Are The Hazards Of Using Scaffolding?

• Falls from elevation—caused by slipping, unsafe access, and the lack of fall protection. Scaffolding over 10 feet in elevation must have guardrails, or other fall protection measures.

• Struck by falling tools/debris • Electrocution—from overhead power lines• Scaffold collapse—caused by instability or

overloading • Bad planking—giving way

Tubular welded frame

SuspendedAerial Lift

Scaffolding in Residential Construction

Ladder Jacks

Pump Jacks

The Competent Person

• Required on all sites where scaffolding is used

• Must be qualified by training and experience

Duties of the Competent Person

• Select and direct employees to erect, dismantle, move, or alter scaffolds.

• Determine if it is safe to work on or from scaffolding during storms, high winds.

• Ensure personal fall arrest system or wind screens protect employees.

• Train employees involved in erecting scaffolds.• Inspect for visible defects.

Base Plates

• All scaffolds require base plates

• Base plates are often combined with screw jacks to adjust height

• On open ground, use mud sills in addition to base plates

Plumb and Level

• Check that initial row of scaffold frames are plumb

• Use screw jacks on base plates to raise or lower frames

Examples of improper foundations

Scaffold Height

The height of the scaffold should not be more than four times its minimum base dimension unless guys, ties, or braces are used

20’

5’ 41

TIES WIDE BASE

ANCHORS & GUYS

Brace scaffold using ties & guys

• It is the responsibility of the competent person to– use the necessary ties, guys, braces or outriggers to

prevent a supported scaffold from tipping.– assure that the supported scaffold poles, legs, post

frames and uprights are plumb and braced to prevent swaying and displacement.

De-energized?

Prior to setup: Inspect the site for electrical lines

OSHA minimum clearance distances from overhead power lines:

• Less than 300 volts—clear by 3 feet

• 300 volts to 50,000 volts—clear by 10 feet

• More than 50,000 volts—10 feet plus 4 inches for every 10,000 volts over 50,000 volts

Guardrails and Crossbracing• Toprail—Must be between 38 to 45 inches.

– when the crosspoint of the crossbracing is used as a toprail, it must be between 38 and 48 inches.

• Midrails—Must be halfway between top rail and platform.– when a cross point of crossbracing is used as a midrail it must

be between 20 – 30 inches above the work platform.

• Install along open sides & ends before releasing the scaffold for use to employees.

Laborer was working on the third level of a tubular welded frame scaffold which was covered with ice and snow

The scaffold was not fully decked, there was no guardrail and no access ladder

The worker slipped and fell head first 20 feet to the pavement below

Fatal Fact – Ice & No Guardrails

Proper Scaffold Access• Provide access when

scaffold platforms are more than 2 feet above or below a point of access.

• Permitted types of access:• Ladders, such as portable,

hook-on, attachable, stairway type, and built-ins

• Stair towers• Ramps and walkways• May use building stairs and

come out window

Scaffold Access• Never access by

crossbraces

• May use end frames if designed for access

Scaffold Access Prohibited

• Rungs on this tubular frame scaffold can NOT be used for access

Scaffold Platform Construction

Platforms must:• be fully planked or decked with no more than 1 inch gaps• be able to support its weight & 4 times maximum load• be at least 18 inches wide

Decking

Planking

• Overlap planks at least 12 inches

Scaffold Platform Construction

• Each abutted end of plank must rest on a separate support surface

• Overlap platforms at least 12 inches over supports, unless restrained to prevent movement

Plank ends are not properly overlapped

• Distance limits: platform edge to working face of wall • No more than 14" from the face of the work • 3" from the face for outrigger scaffolds • 18" from the face for plastering and lathing operations

Ladder Jack Scaffolds

• Height of ladder jack platforms must not exceed 20 feet;

• All ladders used to support ladder jack scaffolds must comply with 29 CFR 1926.452 subpart X—Stairways and Ladders, except:– Job made ladders can NOT be

used to support ladder jack scaffolds;

Ladder Jack Scaffolds – cont.

• The ladder jack shall be designed and constructed such that it will bear on the side rails and ladder rungs alone. If bearing on rungs only, the bearing area must include a length of at least 10 inches on each rung;

• Ladders used to support ladder jacks must be placed, fastened or equipped with devices to prevent slipping; and

• Scaffold platforms shall not be bridged one to another.

Ladder Jacks:Fall Protection > 10 feet

Pump Jack Scaffold

• Erected no higher than 30 feet

• Tie off onto building• Plank width minimum

12 inches• Fall protection• Guardrail set up

Pump Jack Scaffold

Pump Jack ScaffoldGuardrails are required at all open sides and ends of scaffolds.

Violation: Ends are not guarded on this narrow scaffold.

Aerial lifts and fall protection

• Use fall protection (guardrails or a fall arrest system) when moving between the lift and an elevated work surface.

• Stand on the floor of the basket, and never on the edge of the basket

• Do not combine the aerial lift with planks, ladders, or other devices

Aerial lifts: Tie-off

Employees working from aerial lifts must be tied-off.

• Wear personal fall protection equipment, connecting directly or indirectly to an anchorage.

• Lanyards, vertical lifelines, and anchorage points must support 5,000 pounds per employee

• A body belt is permitted only if it is part of a restraint system.

Employee was operating an aerial lift, with an extendable boom rotating work platform

The boom was fully extended and the machine apparently ran over some bricks, causing the boom to flex or spring, throwing the employee from the basket

The employee fell 37 feet to a concrete surface

Fatal Fact – Moving a Lift

Summary

• Assign Competent Person• Use proper scaffold construction methods• Ensure stable access• Avoid electrical hazards• Ensure fall protection/guardrails• Secure decking• Apply protections to ladder, pump jack scaffolds,

and aerial lifts