03.02 Access

Categories: Buildability

Introduction
Erection of cladding usually requires working at height and is therefore potentially hazardous. Safe erection of cladding requires the provision of suitable access facilities to reach fixing locations. Access may also be required for glazing and sealing. Traditionally the responsibility for provision of safe methods of work has been the responsibility of the contractor however the CDM regulations place a duty on the designer to consider the risks associated with construction.

The designer may reduce risks by:

• Increasing the amount of prefabrication and hence reducing the amount of work which must be carried out at height.
• Ensuring that fixing details are simple to operate and readily accessible thus minimising the time required to complete the work.
• Using fixing, glazing and sealing methods which can be carried out from within the structure.

For example panellised curtain walls can be erected entirely from within the building. Joints between panels can be constructed as open joints with only an inner air seal, installed from the inner face of the wall. The glazing can be installed before erection or designed to be fitted from the inside. Installing the glazing from inside also avoids the need for external access for replacing the glazing following breakage.

This section provides a summary of the methods of providing access to the outside of the façade and highlights considerations applicable to its use in cladding. It should be noted that the provision of access requires compliance with safety legislation which is supported by Approved Codes of Practice and guidance documents issued by the Health and Safety Executive. For many forms of access additional guidance is given in British Standards. CIRIA Special Publication 121 gives a more detailed description of the methods of access and safety requirements and the Architectural Cladding Association has issued a code of practice for the safe erection of precast concrete cladding which includes a section on access.
 

Choice of access equipment
In some cases suitable access may be provided by the main contractor for other purposes however in many cases the main access requirement will be for installation of the cladding and the cladding contractor will be responsible for its provision.

There are various methods of gaining access to the outside of the façade which are described below. The appropriate choice for a given situation depends on the nature of the work to be carried out, whether access is required for other purposes and financial considerations. It should be noted that although stick curtain walling may be thought of as using relatively light components which could be erected from a mobile elevating work platform, it may use glazing units 1800mm x 1200mm comprising a pane of toughened glass and a pane of 7.3mm laminated glass which weigh 70 kg and would be difficult to handle in the bucket of a platform.
 

Ladders
Ladders are generally restricted to providing access to other working platforms and for inspection. They are also restricted in the heights that can be reached.
 

Scaffold towers
Scaffold towers may be built up from scaffolding components but prefabricated towers are more commonly  used. Towers need a firm level surface and have limited height which depends on the base dimensions. They may be useful where cladding connections are required at soffit level.
 

Scaffolding
Scaffolding provides a good working platform and can be adapted to accommodate most situations however it is time consuming to erect and hence other methods may be preferred where access is only required for a short time. The presence of scaffolding restricts access for positioning cladding panels by crane. Scaffolding is particularly suitable for masonry construction which is relatively slow, requires continuous access over the length of the façade and requires provision for substantial material loads.

Scaffolding may only be erected, altered and dismantled by experienced operatives under the immediate supervision of a competent person.
 

Mobile elevating work platforms
Mobile elevating work platforms (MEWPs) include scissor lifts, image, articulated booms and telescopic booms although some machines have booms with both telescopic and articulated elements, image. The working platform may range from a small bucket capable of carrying a single person on small machines to a platform several metres in each direction on some scissor lift machines. Some machines require a level site whereas others can accommodate rough terrain. The maximum height and outreach also vary with a maximum of 30m or more. Trained operators are required.
 

Mast climbers
Mast climbing work platforms (MCWPs) can be arranged to provide continuous access to a length of the façade and the height can be adjusted as work proceeds, image . In some cases two working levels are provided. The platform also allows men and materials to be transported from the ground to the work site. MCWPs may be used free standing but may be tied to the structure when used at greater heights.

MCWPs must be installed by competent specialists and operated by trained staff.
 

Suspended work platforms
Suspended work platforms include slung scaffolds and bosun’s chairs but the most common type  for use in cladding is cradles image. Cradles may be permanent installations or temporary and may be fixed so that they can only move up or down or travelling so that horizontal movement is also possible.

Suspended access systems must be installed by competent specialists and used by trained staff.
 

Abseiling
Abseiling can provide a safe and cost effective means of access to difficult areas however it is only suitable for light work and inspection, image. Abseiling should only be undertaken by trained specialists.
 

Main structure
Some operations can be carried out from within the structure however this does not eliminate risk as it will require working near the edges of the floors. The edges of the floors should normally be provided with edge protection to prevent falls but this may have to be removed to allow cladding operations to proceed. If this is necessary alternative methods of protection such as harnesses attached to suitable anchorages must be used by those erecting the cladding. Protection for operatives not engaged in the cladding erection must also be provided preferably by restricting access to the immediate area.
 

Maintenance and inspection
All access equipment should be inspected regularly and maintained at the recommended intervals. For some equipment there are statutory requirements for the frequency of inspection and qualifications of the inspector.
 

Training of staff
All work at height is potentially hazardous and should only be carried out by competent staff. However, while awareness of basic site safety may be sufficient for work on a fixed scaffold, some other equipment may require specially trained staff. The abilities of the proposed staff and the need for training should be considered when the choice of access method is made.