Scaffolding

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Scaffolding includes providing a temporary safe working platform for:

• Erection.
• Maintenance.
• Construction.
• Repair.
• Access.
• Inspection.

It is formed from individual tubes and joints or, proprietary components.

There are two main types of scaffolding:

• Freestanding scaffolds, such as Independent towers,
• Independent tied scaffolds, such as independent towers tied to an adjacent structure.

The most common piece of structure used in scaffolding is the scaffold tube. The tube generally comes in two thicknesses, 3.2mm or 4mm. The tubes are galvanised due to their exposure to the elements and axial capacity loads are given either ‘as new’ or ‘used.’ Capacities of tubes used in tension are usually limited by the safe slip load capacity of the coupler, which is far lower than the actual tensile resistance of the tube.

Scaffolding is designed for its self-weight, ie. the weight of the boards, tubes, guardrails, toeboards etc. and imposed loads such as wind. The imposed load applied to the scaffolding depends on its use.

Four classes of loading are available:

• Service Class 1 - 0.75 kN/m2 – Inspection and very light duty access
• Service Class 2 - 1.50 kN/m2 – Light duty such as painting and cleaning
• Service Class 3 - 2.00 kN/m2 – General building work, brickwork, etc.
• Service Class 4 - 3.00 kN/m2 – Heavy duty such as masonry and heavy cladding

The wind load applied to scaffolding will change depending on whether sheeting or debris nets are used. The magnitude of the wind load will alter the required capacity of the ties and may affect their frequency.

When scaffolding is tied to a building it uses the permanent structure of the building to provide stability. The selection of tie positions should be tested and checked before use and the suitability of the permanent structures composition to carry the ties should be analysed.

Scaffolding is also braced laterally using façade and ledger bracing.

Workmanship and inspection is vital for the erection and dismantling of scaffolding and must be undertaken by competent personal under supervision.

The National Access and Scaffolding Confederation (NASC) has published TG20:13, a suite of guidance for scaffolding design and operation, supported by the UK Contractors Group (UKCG), the Health and Safety Executive (HSE) and the Construction Industry Training Board (CITB).

This includes a software application TG20:13 e-Guide '...making it extremely easy to check scaffolds for TG20:13 compliance digitally, with user-friendly software which will facilitate printing and circulation of details of TG20:13 compliant structures by email.' It has been reported that this could reduce the cost of scaffolding design by 50% (ref Construction Enquirer 26 February 2014).

At the end of 2013 there were over 14,000 scaffolders in the UK.

The NASC incorporates Company membership only which requires:

• Two years of trading.
• 75% direct employee operatives.
• 50% fully qualified operatives.
• 90% operatives must hold a current CISRS card.
• Registration with CITB for training levy purposes.
• £5m public liability insurance.

[edit] Find out more

[edit] Related articles on Designing Buildings Wiki

• Bituminous mixing and laying plant.
• Building wraps.
• CDM.
• Concreting plant.
• Crane supports.
• Crane regulations.
• Debris netting.
• Deleterious materials.
• Design liability.
• Demolition.
• Dynamic self-retracting lanyard.
• Earth-moving plant.
• Excavating plant.
• Facade retention.
• Falsework.
• Formwork.
• Railings.
• Rubble chute.
• Shoring.
• Temporary works.
• Trench support.
• Types of crane.
• Work at height regulations.
• Working platform.
• Working platforms for tracked plant: good practice guide to the design, installation, maintenance and repair of ground-supported working platforms.

[edit] External references

• BS5975:2008 + A1: 2001 Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework (BSI 2011).
• The National Access And Scaffolding Confederation (NASC).