Which Scaffolding Requires A Design

Scaffold design

Uncovering the Importance of Design in Scaffolding: Why Proper Planning is Key to Success

When it comes to scaffolding arrangements for both domestic and commercial properties, clients often have concerns about whether a design is necessary. The Health and Safety Executive (HSE) has provided a list of scaffold arrangements that require a design before work can begin, but there can still be confusion surrounding this topic. This is due to conflicting information from historical practices in the scaffolding industry and documents such as the TG20:21 guidance literature, which outlines when a design is needed. While TG20:21 does provide specific and prescriptive guidelines for scaffolding that can be erected without a design, factors such as wind load, netting/sheeting, and location must be taken into account. Ultimately, the customer’s preferences and requirements should be the deciding factor in whether a design is needed. While some scaffold configurations may comply with the British Standard/TG20, a design may still be necessary if the customer requests one. This is often the case with large-scale contractors who prioritise health and safety and require a design for their management and coordination of tradespersons using the scaffold.

What Scaffolds Require A Design?

Essentially any scaffold where Tube & Fittings have been used and a TG20:21 compliance sheet cannot fully cover all aspects of the scaffold, should be designed. The following is a list of the more common scaffold arrangements that DO require a design, although there may be some caveats (listed in brackets):

  • Cantilevered / truss out scaffolds
    (outside of TG20’s limited range)
  • Shoring / retention scaffolds
  • Independent scaffolds higher than 50m
  • Independent access scaffolds wider than 5  main and 3 inside boards wide
  • Independent access scaffolds with lift heights greater than 3m
  • Independent access scaffolds loaded to greater than 3kN/m²
  • Free standing scaffolds
    (apart from TG20 free standing towers)
  • Bridged scaffolds
    (with bridge span greater than 6m)
  • Temporary roofs
  • Support scaffolds
  • Complex loading bays
    (outside of TG20’s limited ‘standard’ loading bay)
  • Storage racks
  • Mobile tower scaffolds
  • Ramps and roadways
  • Staircases
  • Pedestrian walkways
  • Drop scaffolds
  • Pavement gantry
  • Lifting gantry / lifting tower scaffolds
  • Radial / splayed scaffolds
  • Temporary screens / hoarding
  • System scaffolds installed outside of manufacturers’ guidance

Which Scaffolds Don’t Require A Design?

The following configurations can be erected without the need for a design by a competent person, although a TG20:21 compliance sheet should be used instead:

  • Independent tied access scaffolds
    (up to 50m high)
  • Interior birdcage scaffolds
  • Lift shaft scaffolds
    (butted in all sides, up to 2.7m * 2.7m wide)
  • Chimney stack scaffolds
    (ridge, gable end and eaves chimneys)
  • Free standing towers
    (up to 10m high internal or 8m high external)
  • Tied tower scaffolds
    (up to 50m high)
  • Independent access scaffolds with pavement lift
  • Standard TG20 loading bays
  • Independent access scaffolds with bridge spanning up to 6m
  • Independent access scaffolds with cantilevered spurred platform

scaffolding design

What should be included in a scaffold design?

According to the Work at Height Regulations (2005), scaffolding must be assembled according to a recognised configuration, like TG20, or designed by a competent person through custom calculations. This is necessary to ensure that the scaffold is rigid, strong, and stable throughout the entire process of assembly, use, and dismantling.

During the initial planning stage, it is crucial for the user to provide all necessary information to the scaffolding contractor to ensure a proper design process. This includes the location of the scaffold, the expected duration of use, its intended purpose, dimensions and critical measurements, the number of boarded lifts, maximum load and worker capacity, and access methods (such as ladders or staircases). Additionally, any requirements for sheeting, brickguard, or netting should be communicated, as well as any specific provisions or restrictions for the scaffold’s placement, such as on a pedestrian walkway or the need for hoists or mechanical handling.

The contractor or scaffold designer should then provide relevant information about the scaffold, such as the type (e.g. tube and fitting), maximum bay lengths and lift heights, platform boarding arrangement and maximum boarded lifts, load class, safe working load, maximum leg loads, and tie spacing. Any additional elements involved in the scaffold, such as fans or loading bays, should also be noted. It is important to specify whether these elements fall under standard TG20 configuration or if they require specific design for the task at hand. Other pertinent information, including installation details, design specifications, and usage guidelines, should also be provided. Finally, reference numbers and dates should be recorded for future use and reference.

Legal Requirements For Scaffolding

All scaffolds must be erected, altered and dismantled in a safe manner. This can be achieved by referring to the guidance given by the NASC (National Access & Scaffolding Confederation) in a document called SG4: Preventing Falls in Scaffolding. Contractors should also follow similar guidance provided by the manufacturers of their scaffolding system.

Contractors should also be aware that any proposed alterations or modifications which take a scaffold outside of a generally recognised TG20 configuration must be designed, checked and proven via calculation by a competent person.

Competence & Supervision Guidelines

Employees must be competent for the scaffolding work they undertake and must receive appropriate training which is relevant to the complexity of the scaffolding they are working with. Employers are expected to provide appropriate supervision and should take into account the complexity of the work involved when considering the level of training/competence required by its scaffolders.

At the very minimum, each scaffold team should contain a competent person who has received appropriate training for the type of scaffold the team are working with, which covers how to erect, alter and dismantle the scaffold. Any trainee or apprentice scaffolders should always be directly supervised by a competent person. All operatives who have yet to complete approved training methods and assessments should be considered “trainees” with COTS training.

Supervision Criteria For Scaffolds That Require A Design

Proper supervision is crucial for the safe erection of complex scaffolding structures that require a design. These structures should only be erected under the direct supervision of an advanced scaffolder, who has received specialised training for specific systems or complex configurations. It is essential that the advanced scaffolder is knowledgeable about the latest HSE guidelines and adheres to industry best practices. They should also be able to effectively communicate potential risks to all employees through pre-job briefings and regular “toolbox talks” during the project. This ensures that everyone is aware of the potential hazards associated with each task and can take necessary precautions to prevent accidents.

Inspecting A Scaffold

It is crucial to understand that whether a scaffold requires a design or not, it is the responsibility of the user to ensure that it has been thoroughly inspected. This should be done before its first use, immediately after installation, at regular intervals of no less than every seven days (typically at the beginning of the working week), and after any unforeseen circumstances that may compromise the safety of the scaffold, such as high winds or inclement weather. These inspections should be carried out by a worker who has the appropriate training, knowledge, and experience to comprehend both simple and complex scaffolding designs. The competence of the worker can be evaluated under the CISRS (Construction Industry Scaffolders Record Scheme), or they may have acquired the necessary knowledge through attending a training seminar conducted by the manufacturer of the scaffolding set being used. Additionally, individuals who have attended a relevant scaffold inspection course, such as a project manager, can also be considered competent enough to inspect basic scaffold structures. However, advanced scaffolders should ideally inspect complex structures falling under the category of “require a design.” The inspection reports should clearly outline any potential risks or defects, along with a list of corrective actions that have been implemented, even if they were done promptly as soon as they were noticed. Scaffold Inspections is a service Safety and Access can carry out  on all types of scaffold structures.

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