Diversion anchors and re-anchoring are two important parts of using common fall protection systems.
Roof anchor points are probably the most common item found in fall protection systems. They generally have a low visual profile, can be installed quickly and are easy for workers to connect to and use.
Understanding how diversion anchors and re-anchoring techniques are used is an important piece of knowledge workers need to have in order to protect themselves from falls while using these systems.
What is a roof anchor system?
A roof anchor system is a common type of fall protection system. They are generally installed in environments where access to a roof (or other work area) is required a handful of times per year for maintenance work.
With these systems, a number of permanent anchorage points are installed onto the roof. These can either be surface mounted points (riveted/screwed into metal roof sheets) or fixed into the structure (for example, chemical adhesive into concrete roofs).
A worker attaches to each anchor point in sequence to safely access a particular area of the roof.
Typically, these anchor points are installed in straight lines. This allows the worker to easily connect from the first to the second to the third in sequence.
However, to access corners and other areas of a workspace, a diversion anchor may be required.
Diversion anchors
Diversion anchors are used to reduce the potential for a swing fall when using an anchor-based fall protection system (refer to s3.3.2 in AS/NZS 1891.4:2025).
Provided the worker is correctly implementing fall restraint technique, diversion anchors provide additional connection points for workers to access corners and other areas of a roof without placing themselves in a situation where a swing fall can occur.
Physics of a fall
When designed and used correctly, a roof anchor system should mean a worker does not place themselves in a position where they can fall over an edge. However, it is very easy for a mistake to occur while using these systems. The worker can be focussed on their task and forget to correctly adjust their rope line or connect to the wrong anchor relative to the area they are attempting to access.
Should a fall occur most roof anchors are designed to deform and bend. This assists in reducing the forces placed on both the body of the worker and the structure as the fall is arrested. But this process will only work as intended if the loads applied to the anchor are within its designed load ratings.
For fall arrest anchors, typically this load rating is 15kN (kilonewtons). This minimum load rating requirement is based on arresting the fall of a 100kg mass (the worker) with a safety factor of 2.5.
In situations where a worker is diverting off what would otherwise be a straight line, the forces applied to pass-through (or intermediate) anchors, can exceed the anchor’s designed load ratings.
Re-anchoring
Re-anchoring is a procedure by which the worker creates a new primary anchor point in their fall protection system.
As shown above, in situations where a worker is diverting more than 60° through an anchor, the forces exerted in a fall will exceed the design load rating of the pass-through anchor. A load such as this would render the anchor, and the fall protection system, non-compliant.
By re-anchoring at the pass-through anchor, a new re-anchored primary anchor is created. Now, should a fall occur, the load forces being applied will be directly on the primary anchor. This ensures, if used correctly, the anchor is not exposed to forces beyond its designed load rating.
Re-anchoring can be achieved by connecting an alpine butterfly knot (tied in the rope-line) to the anchor prior to the diversion, as recommended in AS/NZS 1891.4:2025, s3.3.2.
Partners in protecting people
Height Safety Engineers are dedicated to ensuring that everyone working at height and in high-risk environments is protected against the risk of a fall from height.
Understanding how anchor point systems are to be used is a critical skill every worker should have. Our team offers a range of nationally accredited training courses and can build a bespoke course for your site or team. Start your safety journey with us today.
Contact us today on 1300 884 978, enquiries@heightsafety.net or click here to drop us a line.
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