suspended scaffolds cut high-rise masonry costs_tcm68-1374803

7/27/2019 Suspended Scaffolds Cut High-Rise Masonry Costs_tcm68-1374803

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Scaffolds are essential to ma-sonry construction, provid-ing masons with safe and

convenient access to their work.On tall buildings, though, the costof scaffolding can be a significantportion of the contract price. Thiscost can be reduced by using sus-

pended scaffold systems de-signed specifically for masonryconstruction.

These systems eliminate thecost and labor needed to erectmultiple levels of conventionalscaffold framing. Because theplatform height of a suspendedscaffold can be constantly adjust-ed, masons always work at theirmost comfortable, productive lev-el. And if weather enclosure andheat are required, suspended

scaffolds have only one level toenclose.

How they workSuspended scaffolds for mason-

ry construction are work plat-forms, suspended by wire ropes

from outrigger beams thatare anchored above. Theseoutrigger beams may bemounted on the roof or at anintermediate floor above theworking level. The wireropes that support the scaf-fold wrap around drum

winches or pass throughtraction hoists that are oper-ated manually to raise orlower the platform.

In one commonly usedsystem, the wire ropes,winches, and scaffold framesare 7 feet on center, as in aconventional built-up scaf-fold. The masonry contrac-tor planks the work surfacewith 2x10x16-foot scaffold-grade wood plank that span

three supports. The top ofthe scaffold must be plankedas well, to protect against in-

juries from falling objects.Other systems come com-

plete from the manufacturer withaluminum decking and overhead

protection, as well as all neces-sary guard rails and screening, al-ready in place. Some also allowfor two-level platforms so thatmasons can reach stocked materi-als comfortably.

Masonry scaffolds typically usemultipoint suspension, with awire rope and hoist on the build-

ing side and the outside of eachframe. Multipoint suspension in-creases the load capacity and thestability of the scaffold.

Depending on the building con-figuration, the scaffold sectionsmay be connected end to end orkept separate so they can moveindependently.

The distance scaffolds may be

Suspended scaffolds c ut

high-rise masonry c ostsOn tall buil dings, suspended scaffolds elimi nate mul tip le tiers of frame

scaffolding and keep masons work ing at their most comfor table level

By Kenne th A . Hoo ker

Suspended sca ffolds are supp orted bywire rop es hung from outrigger be am s an-chored to a higher floor or roof slab . Stopbo lts through the outrigge r bea ms limit themove ment of the w ire rope s.

The suspe nded sca ffold supp ort system is com plex a nd m ust be spec ifica l-ly eng ineered for eac h job. Design, installation, and rem ova l services nor-ma lly a re provided b y the scaffold supplier as pa rt of a rental agreem ent.


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suspended has no specific limit.However, on taller projects, thescaffold usually is first hung froman intermediate floor, so that ma-sons can begin work on lowerfloors before the building istopped out. The scaffold com-monly is installed once the mainstructural frame is up about 10stories. When the 10th floor slab

is poured, the scaffold supplierarranges for anchors or sleeves tobe embedded in the concrete tohold the outriggers.

Heavy-duty masons multipointsuspended scaffolds are rated for50-psf loading and are available ineither 5- or 8-foot widths. The 5-foot width is less expensive andworks well when only limitedamounts of material need to bes t o red or transported on the scaf-fold. The wider platform allows

space for brick, block, and mor-tar to be wheeled along the scaf-fold to supply masons working onthe wall.

Narrower platforms rated for25-psf loading may sometimes beused when all materials arestocked from the building floors.

Suspe nded sc affoldsusually are rented

Suspended scaffolds for mason-ry work are rarely, if ever, pur-chased from a supplier. Rentalagreements are far more common.In fact, some suppliers will onlyrent, not sell, the systems. Therental agreement usually includesnot only the scaffold, hoists, andwire rope, but also the outriggerbeams and anchoring system. Thescaffold supplier installs theequipment, moves the outriggerbeams to higher floors as neces-sary during the job, and removesthe equipment when the projectis completed.

Renting is pre f e rred for two re a-sons. First, methods of configuringand anchoring suspended scaff o l d-ing vary from job to job, depend-ing on the building design. In fact,each installation needs to be engi-n e e red individually to perf o rmp ro p e r l y. Suppliers employ staffengineers to handle this designwork and qualified crews to install

the system and make sure its func-tioning smoothly and safely.

Second, since many masonrycontractors dont routinely workon high-rise buildings, their needfor suspended scaffolding is spo-radic. Maintaining the equipmentin inventory for only occasionaluse is hard to justify, especiallywhen each projects requirements

are likely to differ.

When to use themOpinions vary on the height a

building needs to be to make sus-pended scaffolds cost-effective.One manufacturer claims that theequipment cost for suspendedscaffolds beats the cost of con-ventional scaffold framing atabout seven stories. Others say asuspended scaffold is worth con-sidering on any building taller

than about 100 feet or 10 stories.One manufacturer that handles

both types of equipment says thata suspended system costs aboutas much to rent as 500 conven-tional scaffold frames. A masonrycontractor who already has alarge supply of frames in stock,and simply needs to supplementthem, may find it less expensiveto rent more frames and build thescaffold tall enough to serve theproject.

For buildings 100 to 150 feethigh, the contractor should con-sider both types and decidewhich is better. The added conve-nience derived from working on afully height-adjustable platformmay make up for some of the in-creased installation cost.

Above 150 feet, using a suspend-ed scaffold is almost always morec o s t - e ffective. Since scaffold equip-ment is rented on a monthly basis,it becomes expensive to re n tframes to support scaffolds for

work on high floors, long after thework on lower floors is completed.

On some low-rise buildings spe-cial conditions at ground levelmay make it desirable to use sus-pended scaffolding. For example,an adjacent building may preventinstallation of scaffold framing atthe base of the building. In remod-eling projects where upper stories

are added to an existing building,the owner may not want the lower

stories obstructed by scaffoldframing.

Contrac tors view sDan Macario, president of Gen-

co Inc., Bethesda, Maryland, saysthat his company has used sus-pended scaffolds on high-rise pro-

jects for more than 45 years.The costs for tubular-frame

and suspended scaffolds breakeven at six or seven stories, saysMacario. We use medium- or

heavy-duty suspended scaffoldsfor projects taller than that, de-pending on how the job is to bestocked. We rent the componentsand follow the engineering draw-ings provided by the supplier, butwe have a crew thats trained toinstall the support beams, con-struct the platforms, and rig thehoists. Suspended scaffolds re-duce our costs on high-rise jobsand also keep the base of thebuilding accessible when wereworking above the first floor.

Ed Smith of Hansen & Hempel,Elmhurst, Illinois, says that hiscompany uses suspended scaf-folds on projects nine or morestories high. The masons like be-ing able to adjust the scaffoldheight in small increments sothey can keep working at a com-fortable level.

Jacob Bros. Inc. of Cincinnati

Scaffolds are raised or lowe redma nually using trac tion hoists ateac h vertica l supp ort. Thoughmany suspended scaffolds are 5feet wide , wider platforms providespa ce for palletized brick.


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used a suspended scaffold on itsfirst high-rise job a couple of yearsago, partly to reduce costs andp a rtly to improve access to thelower floors on the tight buildingsite. Although the suspended scaf-fold accomplished those goals,f o reman Rick Davis found severallimitations to its perf o rm a n c e .

The building had a number of

inset bays, which created gapsbetween the work platform andthe wall that the scaffold we usedcouldnt be modified to elimi-nate, says Davis. The gaps werehard to work across and, in fact,led to an OSHA citation. The jobwas stocked from the floors, butas the scaffold moved to the up-per wall sections on each floor, la-borers couldnt easily pass mate-rials to the masons.

Although their potential advan-

tages are affected by the specificbuilding design, suspended scaf-folds can be an economical altern a-tive to tubular-frame scaffolds forhigh-rise masonry construction.

PUBLICATION #M910111Copyright 1991

The Aberdeen GroupAll rights reserved

suspended scaffolds cut high-rise masonry costs_tcm68-1374803

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