Guttering is a narrow pipe through which collects a rain water from rooftop of a building, typically in to drain or stores the water in a tank. The roof drainage system has gutters and downpipes should be connected to a rooftop storm water drainage system and should be designed so that any overflow during heavy rain periods is prevented from flowing back into the building.
Australia is familiar with Colour bond Steel. It is an iconic Australian product. And it is good. It was not however meant to be used for gutter guards.
Under the Environmental Planning and Assessment Act 1979 and its Regulations, all building work must be carried out in accordance with the Building Code of Australia (BCA). In addition to referring to Australian Standards, the BCA also contains requirements for the disposal of surface water in Volume One, in Performance Requirements FP1.2 and FP 1.3, and in Volume Two, in Part 3.5.2, namely, Performance Requirement P2.2.1 and Clauses 184.108.40.206.and 220.127.116.11.
The most common means to satisfy these requirements for roof drainage (ie. guttering) installations is via compliance with the National Plumbing and Drainage Code AS/NZS 3500.3 - 2003.