Ensure roof anchors are secure
Concerns have been raised over the safety of roof anchors – eye bolts attached to roofs and walls for fixing safety lines for workers. The concerns relate mainly to light steel construction.
Although roof anchors will be adequate in many situations, the Department recommends that a structural engineer be consulted if there are any concerns about their safety.
Concerns over roof anchors relate to:
- weakened structures that could result in roof failure
- connections that are not strong enough to save a falling worker
- roof leaks that could lead to deterioration of both the attachment and the structure of the building
- inadequate inspection and repairs after the emergency use of a roof anchor.
Modern lightweight construction often has very little reserve strength, and drilling holes in some members to attach anchors may weaken them to an unacceptable level. The size and position of the holes are critical. Attaching an anchor may reduce purlin strength by up to 36 percent, depending on the anchor type and the size of the purlin.
A structural engineer may be needed to assess the effect of adding anchors and determine whether other strengthening is needed.
Installation guidelines are vague
Technical literature provided by manufacturers does not adequately address the strength of the member that roof anchors are attached to. Stopping the fall of a worker can result in large forces on the roof structure, which may weaken it against future high winds or carrying maintenance workers.
There are also vague requirements for checking that a building can carry the anchor loads. This is despite AS/NZS 1891.4: 2000, Industrial Fall-Arrest Systems and Devices - Selection, Use and Maintenance, requiring that in each industrial fall-arrest system 'the building or structure shall be assessed by an engineer'. This Standard represents industry best practice but is not mandatory.