National Construction Code (Australia)

The National Construction Code (NCC) is Australia's primary set of technical design and construction provisions for buildings and plumbing. It is maintained and published by the Australian Building Codes Board (ABCB), a joint body of the federal, state and territory governments, and is given legal effect through state and territory building legislation. The NCC is revised on a three-year cycle; NCC 2022 replaced NCC 2019.

Structure

The NCC has three volumes:

• Volume One – mainly commercial, multi-residential and public buildings (Class 2 to 9 buildings).
• Volume Two – mainly houses and small domestic buildings (Class 1 and 10 buildings).
• Volume Three – the Plumbing Code of Australia, which includes roof drainage.

Volumes One and Two together form the Building Code of Australia (BCA).

How compliance works

The NCC sets performance requirements. They can be met by:

• a Deemed-to-Satisfy (DTS) solution, the most common route, which follows prescriptive provisions and referenced Australian Standards; or
• a Performance Solution (formerly "alternative solution"), which shows by analysis, testing or expert judgement that the performance requirements are met.

Roofing provisions

Roofs are affected by several parts of the NCC, including structure (wind, snow and other loads), weatherproofing, fire, energy efficiency, condensation management and bushfire protection. The NCC calls up Australian Standards for detailed rules. Among those commonly used for roofs are AS/NZS 1170 for structural design actions (with Part 2 covering wind), AS 1562 for the design and installation of sheet roof and wall cladding, and AS 3959 for construction in bushfire-prone areas, which sets requirements by Bushfire Attack Level (BAL).

NCC 2022 also increased energy-efficiency requirements and introduced more detailed condensation management provisions, which affect roof ventilation and sarking, and raised the minimum freeboard for valley gutters to 15 mm (0.6 in).

Roof drainage

The Plumbing Code (Volume Three) and its referenced standards govern the sizing of gutters, downpipes and overflow provisions. Overflow from box and valley gutters into buildings has been a recurring cause of damage, which is reflected in tighter provisions.

Related schemes

Product conformity can be demonstrated through evidence such as test reports, certificates and, historically, the CodeMark certification scheme. Building surveyors (certifiers) in each state check compliance.