Getting Pipe Staging Right - Continued
Engineered (laminated) lumber scaffold planks and proprietary
system platforms cost more than regular framing lumber, but are
well worth the extra money. Work platforms manufactured from
aluminum or plywood and steel use integral hooks to connect to
the frame, helping to hold it square. The hooks typically
include an additional means of locking to prevent wind uplift,
a real concern. Strong winds can cause stacked frame sections
to separate vertically, which is why you never want to omit the
toggle pins that secure the coupling pins on both sides of
connected frames (Figure 8). No component in the system should
be thought of as optional or unnecessary.
Figure 8Wind uplift and frame separation are
serious concerns. Never omit the toggle pins that secure both
ends of the couplers between frames.
Safety guidelines require that every working level be fully
planked from one side of the scaffold to the other, with no
gaps greater than 1 inch. Proprietary planks and platforms are
sized to conform to this standard when used in multiples.
Toeboards prevent loose materials from falling off the work
platform and have to be at least 4 inches high. You can buy or
rent a metal version, but we simply lean staging planks on edge
along the frames' uprights and wedge them against the last
plank on the platform (Figure 9).
Figure 9.Falling objects present a huge safety
hazard on the job site. Toeboards prevent tools and materials
from being knocked off the scaffold and should always be
installed before loading and using the platform. Full-width
planking prevents both drops and falls.
Side arms and end arms extend the width and length,
respectively, of the work platform. We regularly use side arms
to offset workers toward the wall and we use the main platform
to stage materials and mortar trays (Figure 10). Side arms can
be set in 16-inch intervals, hooking on to the frame ledgers at
a point lower than the platform to place tools and materials at
a convenient working height. When setting up, keep in mind that
the wall surface should be no more than 14 inches from the
open, working side of the scaffold. Any farther, and you have
to provide guardrails. And remember that side arms should be
used to support only personnel, not materials.
Side arms (top) extend the width of the
platform and may be offset from the main platform for working
convenience. Frame ledgers provide height adjustment in 16-inch
Also keep loading in mind when designing your scaffold.
Light-duty scaffold planks top out at 25 pounds per square
foot, medium-duty at 50 pounds per square foot, and heavy-duty
at 75 pounds per square foot, applied uniformly over the entire
span area. Proprietary planks are rated accordingly. As a rule,
plank deflection must not exceed 1/60 of the span when loaded,
which equates to 1 3/8 inches over 7 feet.
Water and fungal rot can degrade even approved planking, so we
keep our planks dry when they're not in use. We store them
indoors in such a way that air can circulate freely around
them. We also inspect the planks before every use for any signs
of decay or damage. When I find a suspect plank, I don't leave
it lying around; I cut it up into scrap.
Guardrails. Work platforms higher than 10 feet above the base
level must have two parallel guardrails placed approximately 19
inches and 42 inches above the work platform (Figure 11).
Actually, we're even stricter than that: In our company, any
staging more than 6 feet above the ground must have a
guardrail. Cross braces are not guardrails, so at every working
level of a multilevel scaffold, we install proprietary metal
railings or 2x4s held in place with #18 tie wire. Around the
top platform level, clamp-on tubular steel mounting posts adapt
the guard railings.
Don't forget the open platform ends, which also require
Figure 11.Work platforms higher than 10 feet above
the base level must have two parallel guardrails placed
approximately 19 and 42 inches above the work platform to
prevent falls (far left). Even platform ends must be closed
(left). The full platform and high railings on this slate
roofing job supply an unbeatable degree of comfort,
convenience, and efficiency.
How Much Is Enough?
If I can't fit the staging I need for a job in my pickup truck,
I turn to a scaffolding rental company for the equipment. These
outfits deliver and pick up for short money and provide
components that are properly stored and inspected for continued
use. A rental company can also provide occasional specialty
equipment that you don't use often enough to justify
Estimating scaffold needs. Although the basic assembly in a
frame scaffold system consists of two frames and two cross
braces, a 1:1 ratio, the ratio shifts in favor of the cross
braces in multiple assemblies, to 1:1.8. That's a good general
ratio to apply when calculating scaffolding. Never skimp on
Sometimes bracing can create a barrier between you and the work
surface, or it can't be installed because of a structural
obstacle. In such cases, plan to use straddle braces or
straddle frames instead, which are specifically designed to
provide access and clearance around obstructions (Figure 12).
Putlogs — trusslike staging beams used to bridge over
projecting obstructions and to keep passageways open below the
staged area — must be firmly attached to the staging
frame with proprietary hangers or clamps. Putlogs give a frame
scaffolding system an enormous amount of adaptability (Figure
Don't submit to the temptation to remove
or simply not install braces on the working side of a scaffold.
Instead, use straddle frames, which replace the brace function
while still providing good access to the work surface. These
walk-through frames allow unimpeded traffic flow beneath the
13. Putlogs — essentially
tubular steel trusses — allow you to scaffold around
structural obstacles like this projecting roofline (top left),
or to maintain clear passage beneath a work platform (below).
Special brackets connect the putlogs to the frame (top
Things To Watch For
I have worked as a consultant on a number of lawsuits related
to scaffolding tragedies. I've seen nearly everything go wrong
that can, including overload failure, a wall that fell on its
staging and caused it to fail, faulty erection, component
failure due to rust and mishandling, and improper use of
Remember: When you erect staging, you're not the only one who's
going to use it. You have to be aware of traps like poor
access, planks without proper overlap, open ends of work
platforms, unstable anchoring points, and missing bracing. Work
platforms must be completely decked in; they should not consist
of just one or two planks (Figure 14). Even where restricted by
stair penetrations or obstacles, walkways should never be
narrower than 18 inches.
Figure 14.Full planking prevents sideways shifts
and treacherous gaps in the platform.
Inspecting components. You
never want to use the rusty staging lifted out of the mud and
weeds behind your uncle's garage. Advanced corrosion reduces
the tube-wall thickness to an unknown and therefore unsafe
level of performance. It takes ultrasonic testing to accurately
determine whether the wall thickness is compromised, so I keep
it simple: If the tubing shows deep pits and flaking rust, I
cut it up and say goodbye.
Other things my crew is trained to watch for include cracked or
broken welds; broken, missing, or inoperable cross-brace lock
devices; splits in the tubing; voids or holes in the tubing
from accidental impact, cutting, or abrasion; out-of-round
tubing (a forced fit between proprietary frames is a good
indicator); bent legs; bent crossmembers; and out-of-square
frames (Figure 15).This bent crossmember could compromise
the structural integrity of the entire frame, so it was removed
from service (left). The author points to tubing dented by an
attempt to force-fit together unlike or damaged frame units
Don't mix staging frames from different manufacturers unless
they fit together without forcing and all connecting points
provide an exact match. Tube diameter can vary just enough from
one maker to another to prevent common use of the coupler pins.
Some tubes are drilled to receive coupler toggle pins at 30
degrees and others at 90 degrees, an obvious and unacceptable
mismatch (Figure 16).
Figure 16.Unlike frames must not be combined unless
they provide an exact match between coupler and toggle pins,
braces, tube diameter, and, most important, structural load
ratings. In the photo at right, one maker's walk-through frame
is compatibly stacked on the ledger frame of another.
Sometimes, though, brace mounting locks are welded to the frame
at different spacings from one maker to the next, making the
two brands incompatible. In the photo at far right, the wire
tying this brace between two unmatched frames is a real
Furthermore, the vertical spacing between brace locks may not
be equal or in the same location from one brand of frame to the
next. This makes it difficult or impossible to level the frames
and hook up the cross braces.
Most important, the duty rating may not be the same from one
make to the next. All manufactured scaffold components must be
capable of supporting four times the maximum intended load, but
since different frames may have different ratings, the odd
frame in the assembly could become a weak link.
Words to the Wise
When it comes to scaffolding, there are no stupid questions and
you can't be too careful. So I will close with a few final
Beware of electrical service drops and power lines. Refer to
the chart published in OSHA's guide and elsewhere for proper
safe clearances for staging and personnel. Your power company
will come out and sleeve the lines, usually at no charge.
Start with a good foundation. Check the soil condition: Is it
compacted cut or loose fill? In urban work, the sidewalk may be
hollow. Don't take a chance by assuming a slab is solid; we use
a minimum 2x10 mudsill, 18 to 24 inches long, beneath screw
jacks or base plates.
Never use concrete block or wood shipping pallets to build up
your base. Concrete block on edge can fold over or be punched
through and pallets can collapse.
Always use screw jacks on the base frames to level and plumb
Pull a string line across multiple frame assemblies to
establish a common level.
is a masonry contractor in Littleton,
Mass. Thanks to Alan Kline of Lynn Ladder & Scaffolding for
assisting with this article.