Ladders, steps and stairs – what to use and when

A bewildering choice of ladders, steps, staircases will all help you climb but the right system or design depends on the pitch or gradient to be scaled. The best guide is a chart in AS 1657-1992: Fixed platforms, walkways, stairways and ladders - Design, construction and installation, which covers surfaces ranging from flat to 90 degrees (see above chart).

0 to 7 degrees
A walkway is needed for safe access to a roof inclined from 0 to 7 degrees. Normally, the walkway is a 600mm wide steel or aluminium grating mounted on support brackets.
 
Follow the spans recommended by manufacturers carefully to avoid flexing that can dislodge fixings and cause roof leaks.

From 7 to 20 degrees
The Standard calls for a “cleated” or “grated” walkway when the gradient reaches up to 20 degrees. This consists of a square bar fitted across the walkway to gain a foothold. The spacing between the cleats depends on the incline angle of the walkway.

It is also good practice to install a guardrail/handrail on severe inclines. While guard rails are not specified by the current Standard, their use is consistent with state prevention of falls regulations and working at heights legislation, and would normally be consistent with the outcome of a risk assessment.

Guard rails are invaluable when, for example, you walk up a saw tooth roof (typically between 14 and 16 degrees) and sense the need for support – with good reason. Even if you were 5 metres from the roof's edge and inadvertently stepped off a 600mm wide walkway on a 14 degree pitch, you would be injured and likely to fall off. A guardrail keeps you on the walkway and provides good hand support.

From 20 to 26.5 degrees
In this range, steps with landings are required because the gradient is too steep for a simple cleated walkway but not quite steep enough to accommodate a staircase.

From 26.5 degrees to 45 degrees
A staircase should always be built in this range if practicable because it is a safer means of access than any ladder but space constraints often present a problem for architects and designers.

From 45 Degrees to 60 degrees
Referred to as the “danger zone” in AS1657, this range is considered to be dangerous, and access equipment should not be installed.

From 60 to 70 degrees
Step type ladders consisting of treads and handrails are generally installed in the range. Referred to in industry as “step ladders”, step type ladders closely resemble the design of a staircase.

From 70 to 90 degrees
In this range rung type ladders are installed. The preferred angle for a rung type ladder is 75 degrees if it is practicable, and intermediate landing platforms are required if the height exceeds specific parameters.
Cages are also required under certain conditions to be used to rest against during access and egress.

The case for step type ladders
Two factors make step type ladders safer than rung type ladders: stability and balance. The broad treads of a step type ladder offer much more stability than 20mm rungs. The step type ladders also position a person's bodyweight forward, making a backwards fall unlikely. Instead, the risk is falling to the side, which is effectively excluded by complying with AS1657-1992 and installing a ladder enclosure.

Ladder hazards
Of course, apart from dealing with space constraints, designers must take the inherent risks posed by different ladder types into account - the injury sustained from falling from a height of 3 metres is likely at best to be severe and at worst, fatal.

While all ladders are more risky than staircases, it is less risky to use a step type ladder than a rung type ladder that introduces a significant risk of falling backwards.

Ladder lines
“Ladder safety lines” have become a popular way to deal with the risk of falls from rung type ladders. Generally, steel cables attached to the stile carry a shuttle incorporating a locking mechanism that connects to the user's safety harness.

Unfortunately, they are far from a safety panacea. Ladder lines involve personal protective equipment and are one of the last options available according to the OHS Act's hierarchy of control. Users need to be skilled and equipment must be suitable, compatible, carefully maintained and regularly tested. Training and administrative procedures must be put in place and constantly reviewed. Finally, a fall arrested by a ladder line can also lead to suspension trauma, so rescue plans are essential and users cannot work alone.

Ladder lines are a good option only when severe space constraints preclude the use of a safer means of access (such as a step type ladder) or midway landing platforms or when compliance with AS1657-1992 is not practicable.

The most common problems using ladders
The implications of non-compliance with AS1657-1992 are far-reaching. The Standard is referred to in the national Building Code of Australia (BCA), Victoria's OH&S Prevention of Falls (Regulations) 2003 and the Code of Practice for Safe Work on Roofs (Part 2) in NSW. A breach of AS 1657 is therefore effectively a breach of a host of regulations.

In addition to any final inspections carried out by the builder or others, the controller of the workplace must conduct a risk assessment to ensure compliance.

The bottom line
Dangerous ladders, particularly those at roof level, are a tragedy waiting to happen. The stakes are high and the margins between "safe" and "dangerous" are slim: just 10mm of clearance can be the difference between getting enough grip and failing to hold on.

The answer is to develop a practical action plan in accordance with the hierarchy of controls, budget for it and implement it. A great starting point (and one prescribed in the OH&S Act) is a height safety risk assessment of your workplace. Thoroughly inspect the access equipment to AS1657-1992 and consult with the people using the equipment.
 
Your liability will be reduced and, more importantly still, you will be responsible for a safer workplace.