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
•
Scaffolding in Residential Construction
Ladder Jacks
Suspended
Tubular welded frame
Aerial Lift
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
20’
5’
1
4
The height of the
scaffold should not
be more than four
times its minimum
base dimension
unless guys, ties, or
braces are used
Brace scaffold using ties & guys
TIES
WIDE
BASE
ANCHORS &
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.
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.
Fatal Fact – Ice & No Guardrails
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
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 Scaffold
Guardrails 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.
Fatal Fact – Moving a Lift
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
Summary
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•
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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