Domestic construction - controlling falling risks while working on roof framing

Issued: 19 July 2005

Purpose

To inform workers, principal contractors and employers of the hazards of falling through roof framing structures during construction and installation of roofs in the housing construction industry.

Background

Workers who install roofs and work on roof framing will be exposed to the risk of falling through the roof framing where there are no appropriate control measures in place to prevent the fall. These falls can result in serious injuries that have a significant impact on the ability of the worker to continue in this type of work activity. In some situations, fatalities have occurred.

The nature of roof frame design and the work methods adopted for their construction present a falling risk to workers who will be installing the framing and its cladding. The greater the openings in the roof frame during construction, the greater the risks for a worker to fall through those openings.

Examples of workers at risk of falling through roof framing can include:

workers installing roof framing where trusses and rafters exceed 600mm centres
workers installing roof bracing
workers measuring the top chord for batten set out
workers installing battens and sarking
workers installing metal or tile cladding.

Workplace health and safety legislative requirements

In recognition of this hazardous work activity, the Work Health and Safety Regulation 2008 (the Regulation) contains specific provisions that apply to employers who are responsible for themselves and others when this type of work is performed:

Section 317 of the Regulation requires the employer or self employed person in housing construction work to ensure before the worker is on the roof that:
- each hazard that may result in a fall of less than three metres, or could cause death or injury, is identified
- the risk of death or injury that may result is assessed
- the control measures necessary to prevent or minimise the level of exposure to the risk are implemented.

Section 318 of the Regulation requires the employer or self employed person in housing construction work to ensure before the worker is on the roof that:
- control measures are implemented to prevent a person falling or to arrest a person's fall where the fall is at least three metres, if prevention of the fall is not practicable.
Section 294 of the Regulation requires the employer or self employed person to provide a Work Method Statement for 'high risk construction activity' before the activity commences. A 'high risk construction activity' is where the height of the work to be performed is three metres or more and where the work is housing construction work (as defined in section 259 of the Regulation).

The Work Method Statement must state, amongst other things:

the way the employer or self-employed person proposes to perform the activity
how the control measures will be implemented.

For further information about work method statements refer to Section 260 of the Regulation.

Suggested control measures

It is accepted that one control measure nominated for one housing site may not be relevant for another site. For this reason, all jobs need to be approached individually and a risk assessment, as outlined in Section 317 above, must be undertaken to allow the employer or self employed person to decide on the most appropriate control measures.

There are a number of control measures that can be used to prevent a person falling. The control measure adopted would be determined by the particular hazards and risks present at the time. The following control measure options, although not comprehensive, give an insight into what could be used, depending on the outcome of the risk assessment.

Option 1: Roof trusses installed and secured at spacings not exceeding 600mm

Spacing of 600mm, although not totally ideal, can result in roof members that are within reach and thus allow some degree of movement around the framework during their installation and cladding of the roof.

Note: On existing roofs, where the roof surface is being replaced, it is acknowledged that the existing framework may have rafters or trusses at centres greater than 600mm centres. The installation of additional rafters or trusses to reduce the spacing will generally be impractical and the risk associated with installing additional trusses will outweigh the advantages achieved. In these circumstances, options 2, 3 or 4 would be more appropriate.

Option 2: Roof framing members at greater than 600mm spacings and control measures in place

Where it is decided to build the roof framing members at greater than 600mm spacings (i.e. 900mm, 1200mm, etc), the resulting openings will be significant and it will be difficult for the worker to move around safely. A control measure must be in place that will prevent the worker from both an internal and external fall during the truss installation.

Where roof batten installation is to occur once the truss frames are in position, roof battens must be installed at centres not exceeding 450mm. Ceiling battens are not roof battens. The 450mm centres of the roof battens significantly reduce the openings due to the increased truss spacings. The battens must be strong enough to span the top chords of trusses or rafters and prevent a worker falling through the spacing of the roof members during the installation of the battens.

Note: The installation of the roof battens themselves present a degree of risk because of the framing member spacings that the worker will be moving around on. Therefore:

a control measure must be in place to prevent both an internal and external fall to the person installing the battens; and
roof battens must be installed from the roof edge up the pitch of the roof; and
workers must not be located above the height of the battens prior to batten installation; and
perimeter battens to ridges, hips and valleys must not be installed before the battens to the body of the roof have been installed.

Ceiling battens are not an acceptable control measure to arrest a worker's fall. While some parties claim that ceiling battens will not fail when a falling worker strikes the batten, they have been unable to demonstrate that injuries will not be substantial.

Option 3: Roof framing members at greater than 600mm spacings and a barrier installed

Where the roof framing members are greater than 600mm spacings, a barrier (e.g. safety mesh) can be installed on the top chords of the trusses that will prevent workers falling.

Note: Again, due to the increased spacing between roof framing members, there will be a risk of falling for the worker who is installing the barrier mesh etc. 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 capable of controlling the risk of falling for workers who are required to work on top of the roof framing.

Option 4: Provision of a fall arresting platform

Another 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. The obligation holder must ensure the platform complies with the regulatory requirements for Fall Arresting Platforms (see section 322 of the Regulation).

Important note:

Workplace Health and Safety Queensland provides this alert to improve public access to occupational health safety information on the issue of controlling falling risks while working on roof framing. The information provided in this alert can only assist you in the most general way. Before relying on any of the suggested options outlined in this alert, users should carefully make their own assessment as to the relevance for their purposes.