Scaffolding
Description
Scaffolding may be used to provide a temporary or semi-permanent means of access, working platforms, spectator terraces (also refer to demountable structures), or as stability to structures under construction or demolition.
General considerations
Scaffolding, from the perspective of construction or demolition activities, is predominantly a system designed to enable safe working at height, but can be used as a means to provide stability to buildings or structures and not for use as access. There are two generic types of scaffolding systems:
Tower scaffold - this is an independent scaffold, which is standalone and is often moveable with provision of outriggers for stability. However, these scaffolds may be tied to the building if outriggers cannot be used or if there are issues regarding prevailing wind speeds.
Fixed scaffold - this is formed of tube and fittings or modular systems that lock together and is normally tied or anchored to the structure under construction or demolition. Tie methods will be via window openings or eye-bolts drilled and fixed using nylon plugs.
Commonly the structural components are steel or aluminium with metal or timber access platforms (planks). There is normally no additional fire resistance afforded to the system. Aluminium is particularly used to span openings such as shop fronts or across fragile roofs due to its reduced weight. However the low melting point of aluminium (660°C) means it will rapidly lose its strength when exposed to fire.
Scaffolds should be continually boarded with no gaps or openings, and have toe boards and guard rails.
Scaffolds may contain staircases to provide emergency escape. These may be constructed from scaffolding with timber treads or purpose-made all-metal escape stairs. These may provide suitable access and egress, subject to an appropriate risk assessment.
Technical guidance for the erection of scaffolding is available and should be followed - refer to the Health and Safety Executive guidance for scaffolding. This guidance includes information about certification of any system designed and installed for use on a construction or demolition sites.
Incomplete scaffolding systems (that have not been certified for use) should be clearly marked to prevent their use.
It is possible for scaffolding systems to be designed to provide stability to the structure under construction or demolition. These will not necessarily provide support to the structure as they will not take the load of the structure, and they may not provide access. A system that is not designed to provide access should be marked accordingly.
Scaffolding systems commonly incorporate netting or sheeting to prevent items falling from them or to provide protection from the weather. These can present risks to firefighters as they can obscure vision, facilitate firespread or can be a entanglement hazard. There are systems available which are fire retardant and can reduce firespread up the façade of the building - these will have a certification mark as shown in the figure below.
Scaffolding, when used as a working platform, may also be used for storage of materials (such as bricks or blocks) and plant machinery. They may have lighting systems for illuminating work areas.
Systems may incorporate vertical motorised lifts for access and/or transport of material, although these are normally anchored to a structure rather than to the scaffolding system. These lifts should not be used during a fire and may be designed to only transport equipment or building materials.
Inherent benefits
- Completed systems will generally be certified for use and this information should be available via the site's competent person
- Can provide a means of access for fire and rescue service personnel - subject to an appropriate risk assessment
- Scaffolding should have weekly written inspections
- Scaffolding tags may provide information about the structure and the scaffolding provider
Inherent hazards
- Scaffolding systems may collapse rapidly and independently of the building, depending upon the severity of the fire
- Collapse may occur beyond the site boundary, hoarding or fencing
- Collapse may pull down other elevations of the building to which it is attached
- The behaviour of aluminium and nylon plugs should be considered
- Not all scaffolding systems are load-bearing
- Presence of scaffolding systems can worsen the fire, particularly where there is non-fire retardant sheeting or netting
- Netting can become loose during a fire and may present an entanglement hazard
- The behaviour of scaffolding in fire is unpredictable and its use during a fire must be subject to an appropriate risk assessment
Further information