3.1.2 Roof framing
Delivery and placement of roof trusses

Where practicable, roof trusses need to be placed by crane on the wall top plates at the time of delivery. The truss erector, supplier and transporter should liaise to confirm the order in which the trusses are to be loaded onto the truck. The trusses should be unloaded at the site in the order that minimises the amount of handling needed by the truss erectors. When working at height, the erectors should be able to access the next required truss from the top of the truss stack.

The builder, in consultation with relevant sub-contractors, needs to ensure that the trusses, when landed, do not overload the wall frames.

If the trusses have not landed directly onto the top plates, you must develop a safety system for lifting the trusses to the upper level. Employers need to ensure that employees do not stand on the top plate to receive roof trusses passed up from below.

Employees locating and fixing trusses at the perimeter of a building should work from an external scaffold or from trestle scaffolds set up on the floor.

If work is to be carried out from trestle scaffolds near window and door openings an additional guardrail may be necessary. Standard height guardrails will be too low to prevent a person falling from the trestle scaffold, from falling through the window or door opening.

Reducing the risk of falls

As established, the main risk when working on framing, especially roof framing, is the risk of falling. At best, falls can result in a delay of the build; at worst it can lead to serious injuries or even death. As such, ensuring that work which is undertaken at heights is properly controlled needs to take the utmost priority when planning for work at a construction site.

Examples of tasks associated with the risk of falling from roofs include:

  • Installation of roof framing where trusses and rafters exceed 600mm centres
  • Installation of roof bracing
  • Measuring of top chord for batten set out
  • Installation of battens and sarking
  • Installation of metal or tile cladding
What are your responsibilities?

There are a number of control measures that can be used to prevent a person falling when working with roof framing and associated tasks. The control measure you choose will depend on your particular situation and the hazards and risks present at your worksite. The following four control measures are options that you might find helpful, depending on what you have identified in your risk assessment. 

Spacing your roof members at 600mm means that the members are within reach for workers, whilst also allowing for movement for installation and cladding.

If you are renovating an existing roof, and the framework have rafters or trusses at centres greater than 600 mm, it is likely going to be impractical - and associated with its own risks - to install additional trusses. Here, it is more appropriate to use options 2, 3 or 4. 

Roof framing members installed at spacings greater than 600mm result in significant openings that make it difficult for workers to move around safely. In these cases, control measures will have to be put in place to prevent falls.

Once the truss frames are in position, roof battens must be installed at centres not exceeding 450mm to significantly reduce openings. The battens must be strong enough to span the top chords of trusses or rafters and prevent a worker from falling through the spacing of the roof members during the installation of the battens.

Note that the installation of the roof battens is associated with a degree of risk on its own. For this reason:

  • A control measure must be in place to protect the worker installing the battens from both internal and external falls, 
  • Roof battens must be installed from the roof edge up the pitch of the roof,
  • Workers must not be located above the height of the battens prior to batten installation,
  • Perimeter battens to ridges, hips and valleys must not be installed before the battens to the body of the roof have been installed.

Finally, ceiling battens are not an acceptable control measure to arrest a worker's fall.

If your roof members are installed at greater spacing than 600mm, you might want to consider installing a barrier (e.g. safety mesh) on the top chords of the trusses to prevent workers from falling.

Again, due to the increased spacing between roof framing members, the installation of the barriers itself poses a risk of falling. During installation of the barrier:

  • A control measure must be in place to prevent both an internal and external fall to the person installing the barrier
  • The barrier must be fixed and joined in accordance with the manufacturer's instructions
  • The barrier must be suitable and capable of controlling the risk of falls

A final option is to provide a fall arresting platform on the bottom chord of the roof trusses to arrest a worker's fall.

Note, a fall arrest platform is only as strong as the members that support it. Where the platform is supported by a bottom chord of a truss, there must be confirmation from the truss manufacturer that the member can sustain the additional loads it may be subject to in the case of a fall.

Key legislation
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