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Don’t fall for second rate roof systems

Miller sets new benchmark in fall arrest products

Designing a safe system for working on domestic or other small scale buildings is one of those activities that architects and engineers are regularly called upon to do.

Like all construction projects this has to be done in the minimum of time with the minimum of cost.

But there is a lot to be considered and new products making this easier and safer have recently been launched.

In most cases the aim of a Fall Arrest system is to provide safe access for staff to distinct points on the roof to enable the cleaning of gutters and the like.

In all but the most utilitarian of the buildings owners are not keen to have the appearance of buildings downgraded by the appearance of walk ways or horizontal life lines.

The first step is the provision of safe, easyto-use access.

If regular roof access is required, a range of fixed ladder systems can be permanently installed.

These range from conventional ladders, to ladders like the Miller Pivotloc – a folding ladder.

This effectively makes the ladder invisible when not in use.

For situations where a temporary ladder is used there are also surface mount brackets that will secure the ladder while the climber ascends and in the case of some of the newer models provides a rated fall arrest anchorage point.

As the worker reaches the roof edge they should be able to reach the next anchorage point. That is, as they climb onto the roof they should remain connected through the entire movement.

The development of surface mount fall arrest anchorage points for metal roofs, has resulted in a very compact and low profile unit that can comply with AS/NZS 1891 Part 4 as anchorage points.

Some units can be used as simple individual fall arrest points, bases for permanent horizontal life line intermediate supports or end anchorages for temporary horizontal life lines.

When specifying these units it is necessary to make sure that they are compatible with the roofing profile.

Technical files for surface mount anchorage points such as the Millerfix are available from the manufacturer.

These surface mount units come with a closed cell neoprene weather proofing seal.

They are usually also fitted by using heavy duty mandrel style rivets (also fitted with a weather proof seals).

The positioning and orientation of the rivet lines will be set out in the instructions and should be closely followed.

If there is a risk of free fall, usually the safest method of connection between the operators harness and the anchorage point is a compact fall arrester.

The reason for this is that the compact fall arrester (such as the Miller TurboLite or the Miller Scorpion), will continuously monitor the amount of material that is laid out, minimising the amount of slack material in the connection.

This will minimise the degree of the freefall.

If there is a risk that during the fall the connection part of the fall arrester may come in contact with sharp edge, a range of compact fall arresters have been designed to sustain the impact.

These have been tested against the new European Standard for Fall Arresters.

If there is a need for the roof worker to walk along the roof consideration should be given to installing a permanent horizontal lifeline.

This is a 8mm stainless steel wire that is supported along its length, usually just off the roof surface.

The operators can connect to the line and walk along next to it.

Permanent lines like this have the advantage of being very low profile, and will not be an eyesore.

There is some engineering involved in establishing the required strength of the structure supporting the line, typically the intermediate supports need to be able to sustain a force of 12kN, the end posts and the corners twice the in line force.

Each system manufacturer can provide either a program or a spread sheet to allow the calculation of the in-line force.

System variables that effect the calculation of the in-line force are the number of people, system overall length, length of intermediate spans and numbers of corners.

Most lines require an in line energy absorber, to make sure the line is installed with to the appropriate pretension and that in the event of a fall that the peak force in the system will not go above a safe level for the system as a whole.

Selecting the right system and parts to provide a safe and secure working environment for working on roofs is important.

Manufacturers of fall arrest and other safety equipment are keen to supply, technical files and other information to assist.

Sperian Protection
Ph: 1300 139 166
www.sperian.com