Roof Trusses

WorkSafe ACT was recently notified of a worker who had fallen from heights whilst installing roof trusses at a residential construction site. The worker was not provided with the appropriate control measures to do their job safely.

Under the Work Health and Safety Act 2011 (WHS Act), it is the responsibility of persons conducting a business or undertaking (PCBUs) to manage all risks to work health and safety posed by the risks associated with workings at heights.

Managing the risks

Working at heights is an integral part of installing roof trusses.

At no time is any person to stand on or work from an external wall top plate when installing roof trusses without a suitable fall prevention device. The erection of trusses may be undertaken from internal wall top plates or from scaffold planks supported on internal wall top plates provided:

  • no person works closer than 1.5 metres to an external wall, including gable end walls
  • all persons are adequately protected against the risk of a fall, for example into a stairwell or other void, and
  • planks are adequately supported across their spans.

For persons erecting wall frames above 2 meters or more, edge protection must be provided.

When trusses are erected at up to 600 mm, persons working between the trusses to fix or brace them can use the erected trusses as a form of fall prevention device under controlled conditions as described within the Code of Practice: Managing the Risk of Falls in Housing Construction (the Code). If trusses are erected at greater than 600 mm, please refer to Chapter 10 of the Code for suggested methods of working safely at heights.

Another great resource on suitable fall protection is this SafeWork NSW video: Safe erection of roof trusses.

What is a safe working area?

A truss bottom chord is more likely to provide a safe working area if all the conditions below are met:

  • trusses are adequately braced to stabilise the structure. Bracing should be at a maximum of 3000 mm apart if the bottom chord is used to support the person erecting trusses
  • only a competent person works at heights
  • suitable footwear that provides good foothold is worn
  • a competent person or the truss manufacturer/supplier has provided the necessary detail and instructions, including advice regarding installers standing on the bottom chord
  • the bottom chord is visually checked by a nominated competent person for defects that may compromise the material’s structural integrity (that is knots, splits, cracks and rotting timber) before walking on it, and
  • in cases requiring a competent person to undertake the above specific activity, it is a matter for the PCBU to take reasonably practicable steps to determine if the person engaged to do the work has acquired through training, qualification or experience the knowledge and skills to carry out the task.

As the PCBU you must implement appropriate safe systems of work in accordance with the hierarchy of controls to eliminate or minimise the risks to the health and safety of workers.

Further information

Visit following pages to get further information:

On this page