SCAFFOLDING IN NEW ZEALAND RESEARCH

 

 

1.1.1 Scaffolding

For the purposes of this document scaffolding is defined as:

Any structure or framework, swinging stage, suspended scaffolding, or boatswain's chair, of a temporary nature, used or intended to be used for the support or protection of workers for the purpose of carrying out their work or for the support of materials used in connection with any such work. Scaffolding includes any scaffolding erected as such and not dismantled, whether or not it is being used as scaffolding; and also includes any plank, coupling, fastening, fitting, equipment, item or device used in connection with the construction, erection, dismantling or use of scaffolding.

Note that the definition of scaffolding in the Health and Safety in Employment Regulations 1995 under clause 1.3.2 has in view the interpretation of the levels of scaffolding contained in its umbrella legislation, the Health and Safety in Employment Act 1992 and is therefore a little different from that given above.

1.1.2 Scaffolding process

Scaffolding process is defined as:

The planning for and/or the design, erection, inspection, alteration, use or dismantling of any scaffolding and/or related components. This includes all structures constructed using scaffolding components, such as falsework, temporary grandstands, lighting towers and stair access towers. [These have been included in the scope of the BPG if scaffolding components are being used.]

1.2 Design requirements

1.2.1 Principles of design

The design of scaffolds should take into account the following:

• The strength, stability and rigidity of the supporting structure.
• The handling normally associated with scaffolding.
• The safety of persons engaged in the erection, alteration and dismantling of the scaffold.
• The safety of persons using the scaffold.
• The safety of persons in the vicinity of the scaffold.
• The scaffolds fitness for its intended purpose.

1.2.1.1 Standards applicable to scaffolding, scaffolding components and related activities

Relevant standards are those related to:

1. The design and erection of scaffolding.
2. The nature and integrity of structural members.
3. Scaffold components.

This includes but is not limited to the following:
AS 1577 Scaffold planks
AS 1664.1 Aluminium structures (Limit state design)
AS/NZS 1170.0 Structural design actions - General principles
AS/NZS 1170.1 Structural design actions - Permanent, imposed and other actions
AS/NZS 1170.2 Structural design actions - Wind actions
AS/NZS 1170.3 Structural design actions - Snow and ice actions
NZS 1170.5 Structural design actions - Earthquake actions-New Zealand
AS/NZS 1554.1 Structural steel welding - Welding of steel structures
AS/NZS 1554.2 Structural steel welding - Stud welding (steel studs to steel)
AS/NZS 1554.2 Structural steel welding - Welding of high strength quenched and tempered steels
AS/NZS 1576.1 Scaffolding - General requirements
AS/NZS 1576.2 Scaffolding - Couplers and accessories
AS/NZS 1576.3 Scaffolding - Prefabricated and tube-and-coupler scaffolding
AS/NZS 1576.4 Scaffolding - Suspended scaffolding
AS/NZS 1576.5 Scaffolding - Prefabricated splitheads and trestles
AS/NZS 1576.6 Scaffolding - Metal tube-and-coupler-Deemed to comply with AS/NZS 1576.3
AS/NZS 1665 Welding of aluminium structures
AS/NZS 1892.1 Portable ladders-Metal
AS/NZS 1892.3 Portable ladders-Reinforced plastic
AS/NZS 1892.3 Portable ladders-Selection, safe use and care
AS/NZS 3012 Electrical installations-Construction and demolition sites
AS/NZS 4576 Guidelines for scaffolding
NZS 3603 Timber structures standard

NZS 3608 Specification for timber ladders

NZS 4711 Qualification tests for metal-arc welders

NZS 4781 Code of practice for safety in welding and cutting

Standards relating to the design use and maintenance of industrial fall-arrest systems and devices include, but are not limited to:

AS/NZS 1891.1 Industrial fall-arrest systems and devices - Harnesses and ancillary equipment

AS/NZS 1891.2 Industrial fall-arrest systems and devices - Horizontal lifeline and rail systems

AS/NZS 1891.2 Supp1 Industrial fall-arrest systems and devices - Prescribed configurations for horizontal lifelines

AS/NZS 1891.3 Industrial fall-arrest systems and devices - Fall-arrest devices

AS/NZS 1891.4 Industrial fall-arrest systems and devices - Selection, use and maintenance

1.2.1.2 Task analysis

It is becoming generally accepted that on larger sites clients want a task analysis completed as part of the design process. This is generally provided in conjunction with hazard identification.
A task analysis shows the step by step requirements to erect, alter or dismantle a scaffold for a particular site. A task analysis form is appendixed in the last section of this document.

1.2.2 Loads in scaffolding

1.2.2.1 Load combinations

Scaffolding foundations must be able to carry and distribute all the weight of the scaffold, including any extra loads placed on the scaffold. To facilitate this, when scaffolding is designed particular attention should be given to ground conditions (subsidence, water courses, level, the nature of ground materials etc.) and to the loadings on the scaffold.

Scaffolding should be designed for the most adverse combination of dead loads, live loads and environmental loads that can reasonably be expected during the period that the scaffold is expected to be in service.
Load combinations for strength limit states should be in accordance with AS/NZS 1170.0 and its supplements, except that dead and live load combinations need to be as follows:

2.0G + 2.0Q [Where G = dead load and Q = live load (including impact, if any)].

Where environmental loads will be such that work is unlikely to proceed under those conditions, then the loading calculation at that point in time may be restricted to dead loads, expected live loads from stacked materials and environmental loads. When work resumes the loading will change.
For permissible stress design, the sum of the dead and live loads applied shall be increased by 15 percent, to allow for re-use of materials.

1.2.2.2 Dead loads

The dead load (G) is the self-weight of the scaffolding. That is, all structural components and equipment that form the scaffold. It is generally a static load.

1.2.2.3 Environmental loads

Where appropriate, the environmental loads shall include the following:

• Wind loads in accordance with AS/NZS 1170 (and supplements) imposed on the scaffold, including any guardrails, toeboards, stacked materials, screens, sheeting, platform ropes, guy wires and other attachments.
• Snow loads in accordance with AS/NZS 1170 (and supplements).
• Rain and ice loads, where it is considered likely that the scaffold and claddings will be subjected to rain or a build-up of ice.
• Earthquake loads in accordance with AS/NZS 1170 (and supplements).

1.2.2.4 Live loads

The live load (Q) is the temporary loads imposed on a scaffold. These include but are not limited to:

• Duty loads (light, medium, heavy, special) such as persons and/or materials.
• Environmental loads (wind, snow etc).
• Impact loads through short, sudden loadings such as loading materials in/out from a platform and mechanical hoist operation.

Scaffolds should not be used to support formwork and plant, such as hoist towers and concrete pumping equipment, unless the scaffold is specifically designed to do this.

Duty live loads
The live load applied to a working platform is categorised by the following duty conditions:

• Light-duty - a load of 2.2 kN (225 kg) per bay that includes a single concentrated load of 1 kN (100 kg).
• Medium-duty - a load of 4.4 kN (450 kg) per bay that includes a single concentrated load of 1.5 kN (150 kg).
• Heavy-duty - a load of 6.6 kN (675 kg) per bay that includes a single concentrated load of 2.0 kN (200 kg).
• Special-duty - the largest intended load but not less than heavy-duty.

For design purposes the single concentrated load should be assumed to be in the most adverse position within the bay.
AS 1576 elaborates on loads in scaffolding.

1.2.2.5 Load calculations

Calculation used for live loads

Live loads on standards will vary for different bays and platforms. The explanation below relates to calculations for any one particular bay on one platform level.
To calculate the live load on a standard, assume that each standard in that bay supports one third of the duty live load on each platform in each adjoining bay. This is to allow for off centre loading of platforms and concentrated loads placed closer to a standard.
For example, consider a medium duty scaffold.
The live load on any one standard (between two bays each of 4.4 kN - 450kg) based on the worst possible loading in adjacent bays
= 4.4 kN (450kg) X 2 ÷3 = 2.9 kN (300kg)
Assume that the dead load of the scaffold supported by the standard is 3.5 kN (350kg).
Then the design load for this standard
= 2.9 kN (300kg) + 3.5 kN (350kg) = 6.4 kN (650kg)

Calculation used for non standard soleboard lengths

Now that the design load on the standard is known i.e. 6.4 kN (650kg), the minimum length of the soleboard can be determined for a known ground or floor load capacity.
Assume the ground load capacity is 2500kg/m² and a typical timber plank 225mm wide will be used.
Therefore, the minimum acceptable length of the soleboard is:
650kg ÷ 2500kg/ m² ÷ 0.225m = 1.16m.
The minimum length soleboard required for the above conditions is thus 1.16m long.

1.2.2.6 Mass of persons and general material

The following table gives the approximate masses of persons and general materials likely to be supported from scaffolds.

Table 1: Mass of persons and general materials for use when scaffolding

Items	Approximate Mass
Bricks	4.0 kg per brick
Cement	40.0 kg per bag
Concrete block 400 x 200 x 200mm hollow	19.0 kg per block
Concrete block 400 x 200 x 150mm hollow	16.0 kg per block
Concrete block 400 x 200 x 100mm hollow	13.0 kg per block
Concrete block 400 x 200 x 100mm solid	16.0 kg per block
Concrete ready mixed wet	2550.0 kg per cubic metre (m³)
Concrete in wheelbarrow	140.0 kg
Drums empty 200 litre	13.0 kg
Marble	2700.0 kg per cubic metre (m³)
Paint (except red and white lead) 5 litres	10.5 kg
Paint red and white lead 5 litres	15.0 kg
Persons single	100.0 kg
Persons plus wheelbarrow with concrete	220.0 kg
Plaster fibrous	1.6 kg per square metre (m²)
Plaster bag	38.0 kg
Plywood 17.0mm	10.0 kg per square metre (m²)
Sand	2000.0 kg per cubic metre (m³)
Shale	2600.0 kg per cubic metre (m³)
Steel rods 6.5mm diameter	25.0 kg per 100.0m
Steel rods 10.0mm diameter	67.0 kg per 100.0m
Steel rods 12.0mm diameter	89.0 kg per 100.0m
Steel rods 16.0mm diameter	158.0 kg per 100.0m
Steel rods 20.0mm diameter	247.0 kg per 100.0m
Steel rods 25.0mm diameter	358.0 kg per 100.0m
Tiles terra cotta	3.5 kg per tile
Tiles concrete	3.75 kg per tile
Timber hardwoods	1100.0 kg per cubic metre (m³)
Timber softwoods	640.0 kg per cubic metre (m³)
Water (excluding container)	1.0 kg per litre
Double coupler	1.0 kg
Single coupler	0.6 kg
Joiner	0.8 kg
Swivel coupler	1.2 kg
3.0m laminated timber plank	18.0 kg
48.3mm galvanised scaffold tube 1.0m	4.4 kg per metre

1.2.3 Structures supporting scaffolding

The supporting structure should be capable of supporting the most adverse combination of loads applied by the scaffold during the period of its service. Where the supporting structure is not capable of supporting the most adverse combination of expected loads it may need to be strengthened by propping or other means.
Soleboards and baseplates can also be used to evenly distribute the load from the scaffold to the supporting surface. Both soleboards and baseplates may be required for use on less stable surfaces, such as soil or gravel. The use of soleboards and/or baseplates should be considered in the design of the scaffold.

1.2.3.1 Stability

Scaffold stability may be achieved by:

• Tying the scaffold to a supporting structure.
• Guying to a supporting structure.
• Increasing the dead load by securely attaching counterweights near the base.
• Adding bays to increase the base dimension.

1.2.3.2 Brackets

Prefabricated scaffold brackets

Prefabricated scaffold brackets that are attached to a structure to provide support for a working platform must:

1. Have adequate and suitable means of attachment to provide vertical support and to resist accidental sideways movement.
2. Be stable in the longitudinal direction of the platform under the applied horizontal force and have a factor of safety of not less than 1.5.
3. Be fitted with guardrails, midrails and toeboards on all platforms.

Ladder brackets

Ladder brackets that are used for supporting a working platform for the purpose of painting only must satisfy the following requirements:

1. Brackets are attached to ladders not inferior to the requirements set out in NZS: 3609 Timber ladders or NZS 5233 Portable ladders (other than timber ladders).
2. The ladders used for attaching the brackets do not exceed a maximum working length of 7.8m.
3. The top rung to which each bracket is attached is not more than three-quarters of the ladder's working length from the foot of the ladder.
4. Precautions are taken to ensure that the feet and tops of ladders are so supported that the ladders will not slide sideways or outwards.
5. Only one person works on the platform at one time and, if the platform is being used in a public place, a second worker is on hand to assist if mishaps occur and in setting up and moving ladders, brackets and scaffold planks.
6. The span and quality of the plank used complies with the provisions relating to light-duty working platforms.
7. As a working platform edge protection is required. While this is not impossible to achieve it is suggested that alternative, more practicable and safer methods be utilised such as scissor hoists, tube and clip or proprietary scaffolding.

1.2.3.3 Trestles and tripods

Definitions

A trestle is a self supporting metal or timber stand, incorporating one or more horizontal member, on which a working platform may be laid. Steel trestles are often telescopic and of the folding type.
A tripod is a three-legged stand for supporting one end of a horizontal beam on which a working platform may be laid.

Special requirements

1. The design and construction of steel trestles needs to be to a recognised standard. Refer to AS/NZS 1892.1 Section 6 Particular requirements for trestle ladders and to AS/NZS 1576.5 Prefabricated splitheads and trestles.
2. The loading of working platforms is generally restricted to light duty (225kg). Loadings for planks and manufacturer's instructions must be adhered to.
3. The ratio of height of trestle to spread of legs should not exceed 3. For safe erection and use refer to manufacturer's instructions.
4. The maximum span of timber scaffold planks able to be used on trestles is 2.4m.
5. Trestles should be erected on firm and level ground to provide maximum support.
6. As a working platform edge protection is required. While this is not impossible to achieve it is suggested that alternative, more practicable and safer methods be utilised such as scissor hoists, tube and clip or proprietary scaffolding.

1.3 Legislative and regulatory context

1.3.1 The Health and Safety in Employment Act 1992

Object of the Act

The object of the HSE Act is the prevention of harm to all persons at work and other persons in, or in the vicinity of, a place of work. To do this, it imposes duties on employers, employees, principals and others, and promotes excellence in health and safety management by employers. It also provides for the making of regulations and codes of practice.

Employers' duties

Employers have the most duties to perform to ensure the health and safety of employees. Employers have a general duty to take all practicable steps to ensure the safety of employees at work. In particular, they are required to take all practicable steps to:

• Provide and maintain a safe working environment.
• Provide and maintain facilities for the safety and health of employees at work.
• Ensure that the machinery and equipment is safe for employees.
• Provide protective clothing and equipment.
• Ensure that working arrangements are not hazardous to employees.
• Provide procedures to deal with emergencies that may arise while employees are at work.

Taking "all practicable steps", means taking all steps to maintain health and safety that can reasonably be expected in the circumstances, having regard to the:

• Nature and the severity of the harm that may be suffered if the duty of care is not performed.
• Current state of knowledge about the likelihood that harm of that nature and severity could occur if health and safety is not maintained.
• Current state of knowledge about harm of that nature.
• Current state of knowledge about the means available to achieve safe and healthy results, and about the likely efficacy of taking such action.
• Availability and cost of each of these means, to ensure safety.

Hazard management

Employers must identify and regularly review hazards in the place of work (existing, new and potential) to determine whether they are significant hazards and require further action.
Employers are required to record details of harm or situations that could have caused harm in their place of work. Employers are also required to investigate incidents where serious harm occurs to determine if it was caused by or arose from a significant hazard.
This is particularly concerned with:

• Serious harm; or
• Harm (being more than trivial) where the severity of effects on any person depends (entirely or among other things) on the extent or frequency of the persons exposure to the hazard; or
• Harm that does not usually occur, or usually is not easily detectable, until a significant time after exposure to the hazard.

Where the hazard is significant the HSE Act sets out steps for employers to take, namely:

• Where practicable, eliminate the hazard.
• If elimination is not practicable, isolate the hazard.
• If it is impracticable to eliminate or isolate the hazard completely, then the employer must minimise the hazard to employees.

Where a hazard cannot be eliminated or isolated employers must in addition, where appropriate:

• Ensure that protective clothing and equipment is provided, accessible and used.
• Monitor employees' exposure to the hazard.
• Seek the consent of employees to monitor their health.
• With informed consent, monitor employees' health.

Information for employees

Before employees begin work, they must be informed by their employers of:

• Hazards they may be exposed to while at work.
• Hazards they may create that could harm other people.
• How to minimise these hazards becoming a source of harm to themselves and others.
• The location of safety equipment.
• Emergency procedures.

Employers are also required to inform employees of the results of any health and safety monitoring. In doing so, the privacy of individual employees must be protected.

Employers to involve employees in developing health and safety procedures

Employers must provide reasonable opportunity for their employees to participate in ongoing processes for the improvement of health and safety in their place of work.

Training for employees

Employers must ensure employees are either sufficiently experienced to do their work or are adequately supervised by an experienced person. In addition employees must be adequately trained in the safe use of equipment in the workplace, including protective clothing and safety equipment.

Safety of people who are not employees

Employers are also responsible for the health and safety of people who are not employees. Employers must take all practicable steps to ensure that employees do not harm any other person while they are at work, including members of the public or visitors to the place of work.

Duties of employees and self employed persons

Employees and self-employed persons are responsible for their own safety and health while at work. They must also ensure that their actions do not harm anyone else. However, their responsibilities do not detract from those of the employer or principal.

Duties of principals, contractors, scaffolding erectors and users of scaffolds

All those involved in the erection, alteration, use and dismantling of scaffolding have responsibilities under the HSE Act, both for the scaffolding process and for the protection of those who use the scaffold in the course of their work. While the actual scaffolding process can vary from project to project, it is up to those involved to clarify their various responsibilities.
Note that a party can have responsibilities simultaneously as both a principal and an employer.
Specific duties of each party to the scaffolding process may include the following.

A. Property developers, project management consultants, owners, and persons who control the workplace need to ensure that:

• Adequately qualified contractors and consultants are employed on the project.
• Sufficient monies are available to fund the works and the temporary works so that provisions can be made to protect employers, employees and others against the various hazards that may arise.

B. Main contractors, project management consultants or subcontractors who engage others or contract for the erection of a scaffold need to:

• Plan the work to be carried out from the scaffold and specify any special requirements for the scaffold, e.g. any loads the scaffold may be expected to carry.
• Coordinate the erection, use and dismantling of the scaffold.
• Ensure the safety of others who may be in the vicinity of the scaffold, including members of the public.
• Provide for public protection, including gantries and screening. This may include coordination with local authorities and obtaining permits as necessary.
• Provide information about foundation conditions for the scaffold including, if necessary, information about the strength of verandahs and suspended slabs upon which the scaffold is to be erected.
• Provide information about the proximity of powerlines and protective methods.
• Clearly communicate to the scaffolding erector via specifications, drawings, or other information, the scope and all requirements for the scaffold.
• Coordinate/delegate all subsequent inspections and alterations needed to ensure the safety of the scaffold and those using it. This includes the need to ensure that a scaffold register or scaffold record system is kept up to date.
• Ensure protection of the scaffold from construction vehicles or other vehicles in the vicinity, including coordination of crane activities over the scaffold.

C. Scaffolding erection companies must:

• Develop a clear understanding of the scaffold required and the work that is to be carried out from the scaffold, including the need for protective gantries, screening, foundation conditions, power cables, etc.
• Design and plan the scaffold and the erection process, including coordination with other employers who are in the vicinity, to ensure safety during construction, use, alteration and later dismantling of the scaffold.
• Provide a scaffold that complies with the manufacturer's specification and the BPG.
• On completion of the erection of the scaffold, inspect and certify that it is safe for use and hand over the scaffold to the principal. The hand over must include any information that could affect subsequent users of the scaffold and any limitations on the scaffold.
• Coordinate with the principal on the need for subsequent inspections and alterations as work proceeds on the project e.g. alteration of working platforms, increasing the height of the scaffold, etc.

D. Users of the scaffold must:

• Understand any limitations of the scaffold that could affect their work, e.g. load limits.
• Not alter the scaffold in any way.
• Liaise with the main contractor or the scaffold erector to have ties, working platforms, etc relocated or altered as necessary.
• Carry out their own work so as not to endanger others in the vicinity.

Accidents and serious harm (records and notifications)

The HSE Act requires employers, principals and self-employed people to keep a register of all work-related accidents and serious harm. This includes every accident that harmed or might have harmed a person.
Employers, principals and self-employed people are also required to investigate all accidents, harm and near misses to determine whether they were caused by a significant hazard.
Employers, principals and self-employed people are required to notify serious harm that occurs to employees while at work to the Secretary of Labour (in practice, the nearest office of the Department of Labour - DOL), as soon as possible. The DOL office will advise whether it wishes to investigate the accident and what action may be taken in the meantime.

1.3.2 The Health and Safety in Employment Regulations 1995

Regulations are promulgated from time to time under the HSE Act. Legally, the requirements of both the Act and its regulations must be complied with.
Regulations may, among other things, impose duties on employers, employees, designers, manufacturers, and others relating to health and safety. These regulations may apply with respect to places of work, plant, processes or substances and may deal with particular problems that have arisen.
The main regulations applying to scaffolding are the Health and Safety in Employment Regulations 1995.
The Health and Safety in Employment Regulations define scaffolding as:

Any advanced scaffolding, basic scaffolding, or suspended scaffolding or any framework or structure, of a temporary nature, used or intended to be used for: the support or protection of persons carrying out construction work or work connected with construction work, for the purpose of carrying out that work or; the support of materials used in connection with any such work. This includes any scaffolding constructed as such and not dismantled, whether or not it is being used as scaffolding, and also includes any coupling, device, fastening, fitting, or plank used in connection with the construction, erection, or use of scaffolding.

1.3.3 Scope of scaffolding work in the HSE Regulations

Basic scaffolding includes:

• Fall arrest systems.
• Free standing modular scaffolding systems.
• Gin wheels.
• Ropes.
• Static lines.

Suspended scaffolding includes:

• Boatswain's chairs, whether hand hauled or mechanical.
• Swing stages, whether hand hauled or mechanical.

Advanced scaffolding includes:

• Basic scaffolding.

• Suspended scaffolding.

• Barrow ramps.

• Bracket scaffolds for tank work and formwork.

• Cantilevered scaffolds.

• Catch nets.

• Hung scaffolding, including scaffolding hung from a chain, tube or wire rope

• Mast climbers.

• Safety nets for public protection.

• Scaffolding associated with perimeter safety screens or shutters.

• Sloping platforms.

• Spurred scaffolds.
• Tube and fitting scaffolding, including covered ways or gantries made of tube and fitting scaffolding.
• Boatswain's chairs, whether hand hauled or mechanical.
• Swing stages, whether hand hauled or mechanical.

Duty in relation to scaffolding under the HSE Regulations

Scaffolding must be:

• Suitable for the purpose for which it is to be used.
• Properly constructed of sound materials.
• Constructed with sufficient reserve of strength having regard to the loads and stresses to which it may be subjected.
• Sufficient in amount for the purpose for which it is to be used.

Requirements of the scaffolder:

• Have a thorough knowledge of the use or uses in regard to the type or types of scaffolding being erected, altered or dismantled.
• Have a thorough knowledge of the erection, maintenance, repair and dismantling in regard to the type or types of scaffolding being employed.
• Have a thorough knowledge of the practices that must be followed in regard to the type or types of scaffolding being erected, altered or dismantled.
• Have suitable training, including recent experience, in the use, erection, maintenance and dismantling of scaffolding in regard to the type or types of scaffolding being employed.

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