WORKING AT HEIGHTS
SCAFFOLDS
SCAFFOLDS
All scaffolds must be designed, erected, inspected, maintained by suitable competent persons.
A safety harness and lifeline secured to a suitable anchorage point must be used when working on a tower or mobile access platform.
SCAFFOLDS Check that all scaffolds: •
Are planned, installed, altered and dismantled by a competent person and that the work is supervised.
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Are capable of supporting the imposed loading.
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Have boards which are wide enough to carry out the work and are properly fitted.
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Have safety ladder or other means of access to the platform.
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Are appropriate to the task before using them.
SCAFFOLDS
FOUNDATIONS: •
All free standing structures must be built on solid foundations and must be vertical.
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If on sloping ground, they must be prevented from slipping
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Towers inside buildings must be on level floors or adequately compacted sub-bases.
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When the ground is soft foundations, a sole base must be mounted and the tower must be firmly fixed.
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When the ground is sloping, the sole plates must be dug in flat.
SCAFFOLDS
Bracing: • The towers must be adequately stiffened on all sides and in plan at every alternate lift. Access: • there must be a safe method of getting to and from the work platform. • It is not safe to climb up the end frames of the tower, except where the frame has an appropriately designed built-in ladder. • Access to the top of towers must be by ladders either built into the framework or attached to the top of the tower and preferably inside the base area.
SCAFFOLDS
Deck: • • •
•
The working surface must be fully boarded. The supports for the boards must be fit for the purpose. If the boards are short, they must be prevented from sliding. The deck must be provided with guard rails and toe boards
Operation: •
The user must apply no horizontal force at any of the working decks either by hauling heavy ropes and cables or lifting significant loads.
SCAFFOLDS STABILITY •
Make sure the tower is on firm level ground with the wheels or feet properly supported.
•
Do not use bricks or building blocks to take the weight of any part of the tower.
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H RIG
SCAFFOLDS STABILITY
•
The taller the tower, the greater its instability.
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As a simplified rule, if the tower is to be used in exposed conditions, the height of the working platform must be no more the minimum base dimension.
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If the tower is to be used inside, on firm, level ground, the ratio may be extended to 3.5.
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Mobile access towers must be fitted with lockable castors in good conditions at the bottom of the uprights.
SCAFFOLDS STABILITY
The stability of any tower may be affected by: •
Exposure to strong winds
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Loading of heavy equipment
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Hoist of heavy materials
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Use of tower for heavy or complex operations
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Climbing from outside Use a support for ladders: never place a ladder on the top platform •
in order to extend the height of a tower scaffold. •
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SCAFFOLDS EDGE PROTECTION
Suitable edge protection (toe boards and guard rails) should be provided on all platforms. Guard rails must be, at least, 910mm high and toe boards at least 150mm high. An intermediate guard rail (or suitable alternative) must be provided so the unprotected gap does not exceed 470mm.
SCAFFOLDS INSPECTION •
Scaffolds must be inspected at a maximum of 7 working day intervals, always before use and after inclement weather or movement.
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When dismantling a tower do not throw rope, if necessary.
SCAFFOLDS ERECTION AND DISMANTLING
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Helmets must be worn at all times during the erection or dismantling of towers and when the tower is in use.
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When dismantling a tower, do not throw materials down; lower them down by rope, if necessary.
DUTIES
SCAFFOLDS
As guidance, reference can be made to Table 1. Taken from British Standard BS 5793 : 1993 Tubular steel scaffolds TABLE 1. ACCESS AND WORKING SCAFFOLDS OF STEELTUBE Distributed loads on platform KN/m2
Max. N.º of platform
Commonly used widths (using 225mm boards)
Max. Bay length
1 working platform
3 boards
2,7m
4 boards
2,4m
5 boards or 4 boards + 1 board inside
2,1m
Duty
Use of platform
Inspection and very light duty
Inspection, pointing, stone cleaning, light cleaning and access
0,75
Light Duty
Plastering, painting stone cleanings glazing
1,50
2 working platforms
General purpose
General building work including brickwork, window and mullion fixing
2,00
2 working platform +1 at very light duty
SCAFFOLDS DUTIES As guidance, reference can be made to Table 1. Taken from British Standard BS 5793 : 1993 Tubular steel scaffolds
TABLE 1. ACCESS AND WORKING SCAFFOLDS OF TUBES AND COUPLERS
Duty
Heavy duty
Masonry or special duty
Use of platform
Distributed loads on platform KN/m2
Block work, brickwork, heavy cladding
2,50
Masonry work, concrete block work and very heavy cladding
3,00
Max. N.º of platform
Commonly used widths (using 225mm boards)
Max. Bay length
2 working platform + 1 at very light duty
5 boards or 5 boards + 1 inside or 4 boards + 1 inside
2,0m
6 to 8 boards
1,80m
1 working platform + 1 at very light duty
SCAFFOLDS
Ladder access to scaffolds •
Ladder access to scaffolds are usually built and supported by the stiles.
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Every sloping ladder must stand on a firm and level base.
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Ladders must not be extended by lashing two length together.
SCAFFOLDS
Ladder access to scaffolds •
Ladders access to scaffolds must be provided with toe boards and guard rails.
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If it is not possible to have toe boards adjacent to the rungs, use double guard rail.
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Where practicable, it should be set at an angle of 4 vertical to 1 horizontal
H
D=
H/4
TYPES OF SCAFFOLDS PUTLOG SCAFFOLDS • They consist of a single row of uprights, parallel to the face of the building. • The inner edge of the platform is as close to the wall as practicable. • The scaffold uses the wall the building to support the inside edges.
Bay le
Longitudinal bracing in zig-zag patern
ngth
Guardrails and toeboards fixed to the standards
Through tie Bridle
Joint pin
Putlog or right angle coupler Putlog adaptor or head Flat ended putlog
Joint pin or sleeve coupler
TYPICAL PUTLOG SCAFFOLD
Ledger fixed with right angle couplers
Longitudinal or focade bracing
38x225 mm timber sole plate when standing on soil
TYPES OF SCAFFOLDS PUTLOG SCAFFOLDS • The scaffold is fixed to the wall by a tie member, normally a tube or an anchorage. • Suppliers’ information about tie methods must be followed.
Secured packing
• Where no specific information is supplied, the requirements of the relevant national standards must be followed. • The type of tie must be selected to suit the typing requirements and the nature of facade.
Bridle tube
• Building structure integrity must be established by test, if necessary. Tie
• The structure must be adequate to sustain the loads which will be transferred to it.
TYPES OF SCAFFOLDS INDEPENDENT SCAFFOLDS • An independent scaffold consists of a double row of uprights, with each row parallel to the building. • The inner row is set as close to the building as practicable. • The transoms are not built into the wale of the building. • The scaffold must be tied to the building. • Longitudinal (diagonal) bracing is generally fixed to alternate pairs standards. TYPICAL INDEPENDENT SCAFFOLDS
TYPES OF SCAFFOLDS TOWER AND MOBILE ACCESS SCAFFOLDS
TOWER
MOBILE TOWER
TYPES OF SCAFFOLDS TOWER AND MOBILE ACCESS SCAFFOLDS BEFORE USING ANY SCAFFOLD, CHECK:
• You have the correct quantities of all the components for the proposed height of the tower, including a rope, if necessary, to assist erection/dismantling • Precautions against collision of persons or vehicles were taken. •
In mobile access scaffolds, castors are locked as well as fitted
TYPES OF SCAFFOLDS TOWER AND MOBILE ACCESS SCAFFOLDS When assembling the scaffold: • Fit all components in the exact sequence shown in the manufacturer’s manual. • Fit stabilisers as soon as possible when erecting the scaffold. • Check that the tower is vertical, in both planes. • Fit two guard rails on each side of the platforms and toe boards to all platforms, except where the manufacturer’s manual indicates otherwise.
X Wrong
Right Remember all manufacturer’s instructions are given taking into account that the tower has all precaution to ensure that it is stable.
TYPES OF SCAFFOLDS TOWER AND MOBILE ACCESS SCAFFOLDS • In order to move the tower, follow these steps: - Check that materials and people are removed - Unlock the tower castors.
X Wrong
- Ensure that the ground level path is firm and level without obstructions, bumps, hollows, power cables, phone wires…etc
Right
- Move the tower by manual effort from ground level only. - Re- lock the tower castors and replace stabilisers of the equipment.
X Wrong
TYPES OF SCAFFOLDS TOWER AND MOBILE ACCESS SCAFFOLDS BEFORE USING ANY SCAFFOLD, CHECK: • That the manufacture’s instruction manual is available. • All components for damage or corrosion. • That equipment is in compliance with local bye-laws and all regulations. • That the ground is firm and level.
X Wrong
Right