High front guttering advisory committee report - NSW Fair Trading ...

Figure 1: BCA Hierarchy
Of the above, the 3 rd and 4 th levels are the only ones of primary interest to this report. Here, the 3 rd
level (Performance level) is the only mandatory level in the entire hierarchy whilst the 4 th level
allows for multiple “building solutions” to meet the mandatory performance requirements.
Importantly, the performance requirements aim to be non-prescriptive – they tell designers the
outcome that must be achieved (which of note excludes comment on durability issues). The
requirements purposely avoid prescribing how to actually achieve it as this is reserved for the
Building Solutions level. In a combined sense, performance requirements and building solutions aim
to provide a flexible and progressive means for managing compliance.
Performance requirements are particularly important to consider when assessing the presence or
otherwise of a “systemic problem” in the function of high fronted guttering. With regard to this, the
performance requirements for guttering are contained in Part 2 of the BCA (Volume 2) under P2.2.1
and include:
I. Surface water, resulting from a storm having an average recurrence interval of 20 years and
which is collected or concentrated by a building or site work, must be disposed of in a way
that avoids the likelihood of damage or nuisance to any other property
II. Surface water, resulting from a storm having an average recurrence interval of 100 years
must not enter the building
III. A drainage system for the disposal of surface water must –
a. Convey water to an appropriate outfall; and
b. Avoid the entry of water into a building; and
c. Avoid water damaging the building.
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