Scaffolding by chakamba j

BY CHAKAMBA JSCAFFOLDS

SCAFFOLDS

SCAFFOLD

• A scaffold is any temporary elevated platform (supported or suspended) and its supporting structure (including points of anchorage), used for supporting both employees and the materials to be used.

• A temporary frame usually constructed from steel or aluminum alloy tubes clipped or coupled together to provide a means of access to high-level working areas as well as providing as a safe platform from which to work

FUNCTIONS

• As a working platform - so that the worker can stand on the platform do the work easily and safely.

• As a platform for placing material and logistic needed by the workers to carry out their job.

• As a platform and walking passage - scaffolding support the platform that been used by the worker as their walking path to transport the material and logistic.

TERMINOLOGY USED IN SCAFFOLDS

• Standards -are the vertical tubes that transfer the entire mass of the structure to the ground where they rest on a square base plate to spread the load.

• Transoms -are placed next to the standards, they hold the standards in place and provide support for boards.

• Ledger- is a horizontal member that joins or connect the standards in a row .

• Double Coupler - the only real load bearing fitting used in scaffolding - used to join ledgers to standards .

• Swivel Coupler - Composed of 2 single coupler riveted together so that it is possible to rotate them and use them for connecting 2 scaffold tubes at any angle.

TERMS CONTI• Putlog Coupler - use solely for fixing putlogs/transoms to the

horizontal ledgers.• Base Plate - It is used to distribute the load from the foot of

a standard on to a sole plate or firm ground. • Split Joint Pin - a connection fitting used to joint scaffold

tubes end to end. A centre bolt expands the two segments that grip on the bore of the tubes.

• Reveal Pin - fits into the end of a tube to form an adjustable strut.

• Putlog End - a flat plate that fits on the end of a scaffold tube to convert it into a putlog.

TERMS CONTI..

• Guard rail-metal/wood/rope placed 750mm above the toe board to prevent workmen from falling off the platform.

• Toe board-scaffold board put on edge of the platform to prevent tools and materials from falling down.

• Brace-diagonal member from standard to standard to stabilize the scaffolding.

• Putlog-the horizontal member from standard to wall on a dependent scaffolding.

TERMS CONTI..• Sole plate-a flat and wide wooden plate onto

which the base plate will be fixed.

GUARDRAIL• Falls from scaffolds are one of the leading causes of injuries to construction

workers .

• All scaffolds 3 m (10 ft.) or more above grade must have standard guardrails on their open side.

• A standard guard consists of:• A top rail approximately 1.1 m (42 in.) above the platform• An intermediate rail centered at approximately the midpoint of the space

between the underside of the top rail and the upper edge of the platform• Vertical guardrail supports spaced not more than 3 m (10 ft.) apart for wooden

scaffolding• Standard guardrails must be designed to withstand a static load of 550 N (125

lb.) applied laterally at any point of the top rail.

GUARD RAIL

CATEGORIES OF SCAFFOLDS

1.SUSPENDED-these consist of a working platform suspended from supports such as outriggers which cantilever over the upper edge of a building and in this form are a temporary means of access to the face of a building for the purposes of cleaning and light maintenance work.


SUSPENDED SCAFFOLDS• It is platform that is suspended by rope or other

non-rigid means, from an overhead structure There are many types of suspended scaffolds such two point (swing stage), multipoint adjustable, catenary and others.

• Two Point (Swing Stage) is hung by ropes or cable connected to stirrups at each end of the platform. It is used by window washers or skyscrapers

SUSPENDED SCAFFOLD

2. Supported Scaffolds

Supported scaffolds are scaffolds that are have an attachment to the ground rather than are suspended by cables.


3.Rolling/Mobile tower scaffold • The mobile scaffold would have small tires

under the standards. Designed to be easily moved .Commonly used for things such as painting and plastering, where workers must frequently change position. Used mainly by painters and maintenance to gain access to ceilings.

ROLLING/MOBILE SCAFFOLDS

• Constructed standard tubes and fittings• Refers to as mobile because it is mounted on

wheels fitted with brakes.• It is used for short duration light work, for

example, painting and cleaning, to a height not exceeding 12m, an gain access to ceilings.

ROLLING SCAFFOLD

ROLLING SCAFFOLD

• Do not move while occupied unless specifically designed for such movement.

• Before moving inspect for pits, holes, or obstructions on the floor.

• Push the base on or near the bottom when moving.

Caster wheels must be locked to prevent movement of the scaffold when stationary

.

COMMON TYPES OF SCAFFOLDS

1. PUTLOG SCAFFOLDS• It consists of a single row of uprights or standards set

away from the wall at a distance that will accommodate the required width of the working platform. The standards are joined together with horizontal members called “ledgers” The ledgers are tied to the building with cross members called putlog. It is erected as the building rises and mostly used for buildings of traditional brick construction

• Putlog Scaffold tied into the brickwork using putlogs or tubes with putlog adaptors

PUTLOG SCAFFOLD

COMMON TYPES CONTI..

2. INDEPENTENT SCAFFOLD• this form does not rely on the adjacent

structure to provide support, however, it should be tied back to the structure at intervals in order to provide additional horizontal stability

INDEPENDENT TIED SCAFFOLD


3. BIRDCAGE SCAFFOLDS• Consists of a two directional arrangement of

standards, ledgers and transoms to support a close boarded working platform at the required height.

• Used to provide a complete working platform at high level over a large area.


4. SYSTEM SCAFFOLDS• These are based upon the traditional

independent steel tube scaffold but instead of being connected together with a series of loose couplers and clips they usually have integral interlocking connections.

• Easy to erect, adaptable and assembled and dismantled by semi-skilled labour.


5. GANTRY SCAFFOLD• Basically a loading and unloading platform over a

path or public foot path.• It is a mandatory to seek permission from the local

authority which will specify walkway dimensions, how wide and high it be. For lighting, and when to load and unloading.

• Can also serve as a storage and accommodation area as well as providing the staging from which a conventional independent scaffold to provide access to the face of the building can be erected.

COMMON TYPES CONT..

6. TRESSLE SCAFFOLDS• They vary in type and pattern and useful in confined

spaces, or where a platform has to be quickly erected and dismantled, when painting walls and ceilings, and on partitions and passages.

• Scaffold platforms shall not be used above the second to top rung.

• Job built ladders cannot be used in a trestle scaffold system.

• Ladders must be secured to prevent displacement.

TRESSLE SCAFFOLD

TRESSLE SCAFFOLD


7. Slung scaffolds • these are scaffolds which are suspended by

means of wire ropes or chains and are not provided with a means of being raised or lowered by a lifting appliances.

• Main use is for gaining access to high ceilings or the underside of high roofs

LEGISLATION GOVERNING THE USE OF SCAFFOLDS

• Scaffold erection and dismantling must be done by, or supervised by, qualified workers.

• The vertical supports of scaffolds must be placed on a firm base or sill capable of withstanding superimposed weight from the scaffold and anything placed on the scaffold

• Do not use pallets, boxes, concrete blocks, bricks, or other unstable materials to support scaffolds.

• All scaffolds must be erected plumb and level, and be designed for the intended use.

LEGISLATION GOVERNING USE OF SCAFFOLDS

HEALTH AND SAFETY AT WORK ACT 1974• Protect the health, safety and welfare of employees

and to safeguard the public who may be exposed to risks from work activities.

• It sets out the general duties which employers have towards employees and members of the public and employees have to themselves and to each other.

• Also requires good management and common sense which lead to employers to look at what risks are and take sensible measures to tackle them.

FACTORIES ACT 19748 SECTION 32

• Any employee to work at a height from where he/she is likely to fall there should be a provision of a fence or otherwise to ensure the safety of the person.

PROVISION AND USE OF WORK EQUIPMENT REGULATIONS OF 1998

• The employer must ensure that the work equipment he/she provides meets requirements of ( PUWER) in respect of suitability, maintenance and regular inspection.

• Must ensure that risks created by using the equipment are eliminated where possible or controlled as far as reasonable by taking appropriate hardware measures and software.

WORK HEIGHT REGISTRATION OF 2005

• All work at height is covered regardless of what height it is performed at.

• Precautions need to be taken where there is a risk of injury.

• Use risk assessment to decide whether precautions are needed and in what form.

• Precautions are expected with work above 2 meters but also assess risks from fall below this height and take sensible precautions which reflect the risks.

REGULATIONS GOVERNING USE OF SCAFFOLDS

• Never overload a scaffolding.• Timber should not be painted as this will hide the

defects.• Never work under a scaffolding in use.• Always use a ladder to climb up the and down the

scaffolding.• Always install a guard rail/hand rail/guard net and toe

boards.• Metal parts must be free from rust. • All joints must be securely fixed and rigid.

REGULATIONS CONTI.. It is vital that after erection, a scaffold must be

inspected by an independent competent person before use and at regular intervals thereafter to enhance safety.

Put on safety gear, for example helmets, safety chains and belts, hard soled boots, etc.

All scaffolds must be inspected before use by those who will use them, regardless of who erected them. No damaged or weakened scaffold may be used until it has been effectively repaired

REGULATIONS CONTI.. Standard must be on the same level and

vertically straight on the base plate. The supporting platform wood must be

supported properly. Working platform must been equipped

with safety elements such as hand rail. Scaffold must be inspected at certain

times.

REGULATIONS CONCL..

• Badly assembled and neglected scaffold have

been a significant contributory factor to the high accident rate associated with the construction industry. It is imperative that the erection of the scaffolds be done following the laid out regulations in the building industry.

SCAFFOLD INSPECTION POINTS.• Supervision of scaffold erection and progress /safety reports

are undertaken by a suitable experience and qualified person. Must be inspected:• before use.• within the preceding 7 days • after adverse weather conditions that may have affected the

scaffold’s strength or stability. • whenever alterations / additions are made to the scaffold.• Scaffold registers must be kept on site and be available for

inspection at all times and must be signed

INSPECTION TO INCLUDE

• Access• Full planking• Guard rails• plumbness

INSPECTION MUST BE CARRIED OUT BY

• A competent person such as a registered engineer.

• A certified scaffolder with the appropriate class.• Inspection entries in the register must be made

and signed by the person who carries out the inspection.

• Should any defect be found, during inspection, it must be rectified before use.

• All scaffold must be protected against damage from traffic and other causes.

REASONS WHY SCAFFOLDS COLLAPSE

• Overloading cause tilting of scaffolds• Platforms breaking• Use of insufficient braces and ledgers• Base plates not standard or improperly

secured to the sole plate.• High and unstable scaffolds not secured with

ties, guys, and braces.• Small scaffolds are also commonly involved

REPORTS

• Reports must be made in the prescribed register which shall show the following:

• The location and description of the scaffold or equipment.

• Date of inspection.• Results of inspection ( if the scaffold is in good

order then this must be stated).• The signature of the person making the

inspection.

LADDERS

• All ladders must be of good construction and of adequate strength for the purpose they are to be used.

• They must be properly maintained.

REGULATIONS GOVERNING THE USE OF LADDERS.

• No ladder shall be used in which there is a rung.

• A ladder shall not stand on loose bricks or other loose packing.

• Every rung shall be properly fixed to the stiles.

A ladder must be secured where necessary to prevent undue sagging or swaying

Every ladder shall have a firm and level footing.

REGULATIONS ON THE USE OF LADDER CONTI..

• Do not use a stepladder that is folded or in a leaning position.

REGULATIONS CONTI..

• Face the ladder when ascending or descending.

• Maintain three points of contact at all times.• Keep your body centered on the ladder.• Never let your belt buckle pass either side rail.

REFERENCE• Chudley R. and Greeno R. (2005), Building Construction.

Handbook incorporating current Building and Construction regulations. Fifth Edition. Elsevier Butterworth Heinemann. London.

• Grundy, J. T. (1981), Construction technology, vol. 3. Edward Anold (Publishers) Ltd. London.

• Nash, W. G. (1990), Brickwork 2. Stanley Thornes (Publishers) Ltd. London.

• Nhira C. Dhafana L and Ali M. (2005) Step Ahead Building Studies. Students’ Book 2. Longman. Zimbabwe (Pvt) Ltd, Harare.

Engineering

Scaffolding by chakamba j