NCC structure: BCA, PCA, volumes and building classes explained

TL;DR

The National Construction Code (NCC) has three volumes: Volumes One and Two form the Building Code of Australia (BCA) covering building work, while Volume Three is the Plumbing Code of Australia (PCA) covering plumbing and drainage. For residential builders, Volume Two (Class 1 houses, Class 10 garages and sheds) is the daily reference, read alongside the ABCB Housing Provisions Standard which holds the DTS numbers. Getting a building’s class wrong at the design stage flows through to the certifier, the DA, and the insurer, so locking in the class before you price is not optional.

In plain English

The National Construction Code (NCC) is the single technical code governing building and plumbing work across Australia. Every state and territory adopts it (with state-specific variations appended), and it’s the document your Principal Certifying Authority (PCA) uses to assess whether your design complies (verified 2026-05-07: ABCB, NCC overview).

The NCC has three volumes. Two of them together form the Building Code of Australia (BCA):

Volume One (BCA): Class 2 to 9 buildings. Multi-residential (apartments), commercial, industrial, and public buildings.
Volume Two (BCA): Class 1 and 10 buildings. Houses, duplexes, townhouses, and non-habitable structures (garages, sheds, pools, fences).

The third is the Plumbing Code of Australia (PCA):

Volume Three (PCA): Plumbing and drainage requirements for all building classes. Governs design, construction, and maintenance of plumbing systems across the country.

For residential builders, Volume Two is your primary reference. Volume Three governs every licensed plumber working on your site, regardless of building class.

What it requires

Building classes (A6)

Every building or part of a building is assigned a class under NCC 2022 Part A6. The class determines which volume applies and what compliance obligations attach. Getting the class right is non-negotiable: it drives the certifier’s inspection regime, the fire safety requirements, and the energy compliance path (verified 2026-05-07: NCC Building classifications).

Class	Description	Volume
1a	Detached houses, townhouses, terrace/row houses attached by fire-resistant walls	Two (BCA)
1b	Boarding/guest houses not over 300 m², not more than 12 persons; OR four or more holiday dwellings on one allotment	Two (BCA)
2	Multi-residential: two or more separate dwellings stacked (apartments, flats)	One (BCA)
3	Group residential: long-term or transient accommodation for unrelated persons (hostels, boarding houses over Class 1b limits, aged care hostels, staff quarters)	One (BCA)
4	Single dwelling within a Class 5 to 9 building (caretaker’s flat above a shop, accommodation in a school)	One (BCA)
5	Office buildings for professional or commercial purposes	One (BCA)
6	Retail or service buildings: shops, restaurants, hairdressers, service stations	One (BCA)
7a	Carparks	One (BCA)
7b	Warehouses, wholesale display buildings	One (BCA)
8	Industrial: factories, workshops, food processing, laboratories	One (BCA)
9a	Health-care: hospitals, day surgery facilities where patients may be unable to self-evacuate	One (BCA)
9b	Assembly: schools, childcare centres, theatres, sports facilities, places of worship	One (BCA)
9c	Residential care facilities: buildings where 10% or more of occupants need daily assistance	One (BCA)
10a	Non-habitable buildings: private garages, carports, sheds	Two (BCA)
10b	Structures: fences, masts, antennas, retaining walls, free-standing walls, swimming pools	Two (BCA)
10c	Private bushfire shelters for Class 1a dwellings	Two (BCA)

Volume Three (PCA) applies across all classes for plumbing and drainage work.

The four volumes you actually use day-to-day

For residential work, most compliance sits in two documents read together:

NCC 2022 Volume Two: Performance Requirements and Deemed-to-Satisfy provisions for Class 1 and 10 buildings. Section H has eight parts: H1 Structure, H2 Damp and weatherproofing, H3 Fire safety, H4 Health and amenity, H5 Safe movement, H6 Energy efficiency, H7 Ancillary provisions, H8 Livable housing design.
ABCB Housing Provisions Standard 2022: The actual DTS numbers. Most of the prescriptive detail (footing dimensions, framing bracing tables, fire separation specs, balustrade heights, accessibility minimums) lives here, not in the front of Volume Two. Free download from the ABCB site.
NCC 2022 Volume Three (PCA): Your licensed plumber’s reference. Governs water supply, drainage, stormwater, and gas, backed by AS 3500. If you’re checking a plumbing inspection or disputing a rectification scope, this is where the rules sit.
NCC 2022 Volume One: Needed when you have a Class 2 to 9 element on a residential site (a caretaker’s flat, a Class 3 short-stay complex, a common corridor in a duplex that triggers Class 2). Most residential builders won’t open Volume One often, but Class 2 (apartment) work sits here entirely.

Compliance pathways: DTS vs Performance Solution

Both volumes give you two routes to compliance:

Deemed-to-Satisfy (DTS): Follow the prescribed numbers and methods. Automatically meets the Performance Requirement. The certifier checks you’ve followed the recipe; no engineering report needed.
Performance Solution (Alternative Solution): An expert (engineer, fire-safety consultant) prepares a report showing the design meets the Performance Requirement another way. Normal for heritage retrofits, awkward sites, novel materials, or where DTS isn’t possible. The certifier (PCA) reviews and accepts the report.

For a standard Class 1 house, DTS via the Housing Provisions is the default. Performance Solutions are the exception.

What it doesn’t cover

The NCC sets technical standards for building and plumbing work. It doesn’t cover:

Planning and zoning: Setbacks, height limits, FSR, heritage overlays, bushfire planning zones, flood overlays. These sit under state planning legislation and local LEPs/DCPs assessed at the DA stage.
Licensing of who can do the work: State licensing acts (Fair Trading NSW, VBA Victoria, QBCC Queensland, etc.) set who must hold a licence to do building or plumbing work. The NCC is silent on this.
Site safety and WHS: The WHS Act and SafeWork regulators run in parallel. Compliance with the NCC doesn’t mean your site is WHS-compliant.
Demolition: State demolition codes and regulations apply separately.
Electrical wiring: AS/NZS 3000 (the Wiring Rules) govern electrical work. State licensing rules govern who can do it.

Practical implications

Know your class before you price

A Class 1a detached house and a Class 2 apartment building look similar on the outside. Inside the NCC, they sit in different volumes with different fire separation requirements, energy paths, and inspection regimes. Misclassifying a project (e.g. treating a four-unit development as four Class 1a houses when it should be Class 2) creates a compliance gap that surfaces at certifier stage, not at design stage, and by then the fix is expensive (verified 2026-05-07: NCC Building classifications).

Mixed-use and multiple classifications

A building can have more than one class. A shop (Class 6) with a flat above (Class 4) is classified as both. A Class 1a house with an attached private garage (Class 10a) sits across two classes. The governing requirements apply per part, so fire separation between a Class 1a and Class 10a garage (H3 in Volume Two) is a real compliance obligation, not optional.

NCC 2025: the next edition

NCC 2025 was released on 1 May 2026. Adoption is staggered by state. As at 1 May 2026: ACT, Tasmania, Victoria and Western Australia have adopted NCC 2025; South Australia adopted Volume Three (PCA) with Volume One and Two to follow on 1 May 2027; NSW and Queensland are scheduled to adopt on 1 May 2027; the Northern Territory has not adopted NCC 2025 (verified 2026-05-07: NCC 2025 state and territory adoption information).

Until your state adopts NCC 2025, NCC 2022 remains the operative edition for new work. Always confirm against the ABCB adoption page and your state regulator before quoting.

Volume Three (PCA): what it means for the builder

You’re not the licensed plumber, but the PCA governs inspections on your site. Volume Three sets minimum standards for water supply, sanitary drainage, stormwater, and gas. The PCA’s plumbing inspection sign-offs rely on it. If a plumber’s work is defective, the standard for rectification is the PCA plus the referenced Australian Standards (primarily AS 3500 series). Knowing the structure means you know where to point disputes.

State variations

VIC

Victoria adopted NCC 2025 on 1 May 2026 with no transition period, given legal force through the Building Act 1993, the Building Regulations 2018 and Plumbing Regulations 2018. The Victorian Building Authority (VBA) administers building and plumbing regulation, including practitioner registration and the issue of plumbing compliance certificates by licensed plumbers. The Victorian Appendix to NCC 2025 trims state variations from 115 to 60 across the three volumes, retaining residential bushfire variations and Victoria’s earlier lead-free plumbing start (1 May 2026, ahead of the national date). On reactive sites, the VBA practice note on drainage in reactive soil requires Class P sites to be designed by an appropriately qualified engineer rather than a plumber acting as recognised expert, and AS 2870 site classification still drives footing design under NCC Volume Two H1 (verified 2026-05-09).

QLD

Queensland is still on NCC 2022 Amendment 2 and is scheduled to adopt NCC 2025 on 1 May 2027 (verified 2026-05-09). The NCC takes legal effect through the Building Act 1975 and Building Regulation 2021, administered by the Queensland Building and Construction Commission (QBCC). Coastal North Queensland sits in cyclonic wind Regions C and D under AS/NZS 1170.2, with NCC 2022 Volume One Specification 4 layering extra design rules over AS 4055 site wind classifications C1 to C4, including QBCC standards and tolerances rules that all cut roof tiles in C2/C3 must be clipped or screwed (flexible pointing alone does not satisfy). Plumbing licensing is split: the QBCC licenses contractors and the Plumbing Industry Council registers plumbers and drainers under the Plumbing and Drainage Act 2018, with a Form 4/Form 9 compliance certificate required for notifiable work.

WA

Western Australia adopted NCC 2025 on 1 May 2026 with a 12-month transition period running until 30 April 2027 (verified 2026-05-09). The NCC is given force by Part 3 of the Building Act 2011 and Part 4 of the Building Regulations 2012, with Building and Energy inside DEMIRS administering builder, plumber and gas-fitter licensing through the Building Services Board and the Plumbers Licensing Board. WA’s signature variation is wind Region D, the 50 km coastal band from Carnarvon to Port Hedland (Karratha, Onslow, Exmouth) where buildings must withstand around 69 m/s winds, with a WA-specific table varying AS 4055 Table 2.2 to add C5 to C8 site classifications above the standard C1 to C4. Class 1 work in Region D effectively requires structural engineering for footings, framing, tie-down and cladding rather than DTS-only design.

SA

South Australia adopted Volume Three (PCA) of NCC 2025 on 1 May 2026 and will adopt Volumes One and Two on 1 May 2027; until then NCC 2022 Amendment 2 remains the operative Building Code (verified 2026-05-09). The NCC sits inside the Building Rules under the Planning, Development and Infrastructure Act 2016, and the Minister gazettes amendments via Ministerial Building Standards including MBS 007 (Modifications to the BCA, currently at Amendment 6 gazetted 23 April 2026) and MBS 008 (designated bushfire prone areas). Consumer and Business Services (CBS) licenses building work contractors and plumbing, gas-fitting and electrical (PGE) workers; PGE work is treated as building work but sits under separate technical schemes administered by the Office of the Technical Regulator. SA-specific structural variations focus on small-allotment and additions-and-alterations concessions in MBS 007 rather than wind or cyclonic uplifts, since SA sits entirely in non-cyclonic wind Regions A and B under AS/NZS 1170.2.

TAS

Tasmania adopted NCC 2025 on 1 May 2026 with no transition period, given force by the Building Act 2016 and Building Regulations 2016 (verified 2026-05-09). Consumer, Building and Occupational Services (CBOS) inside the Department of Justice administers the Act, with the Director of Building Control issuing Determinations that set the categories of building and plumbing work, accreditation rules and which trades require a Certificate of Likely Compliance before work starts. CBOS has flagged state variations that disapply some NCC 2025 changes, and Tasmania remains the only state where parts of the alpine area sit in non-trivial snow loading territory under AS/NZS 1170.3 (factored into AS 1684.2 framing for Class 1 work). Plumbing is licensed by CBOS, work must be done by a licensed plumber, and the council Permit Authority issues plumbing approvals with a Form 80 Certificate of Completion at finish.

NT

The Northern Territory has not adopted NCC 2025 and continues to operate under NCC 2022 (verified 2026-05-09). The NCC is given force by the Building Act 1993 (NT) and Building Regulations 1993, with the Building Practitioners Board registering builders, building certifiers, designers, engineers and plumbers. Most NT residential work sits in cyclonic wind Region C (the coastal 50 km band including Darwin, Palmerston and the Top End), with Region D applying offshore, and NCC 2022 Volume One Specification 4 plus NT minimum design standards layering extra structural, tie-down, cladding and roof-fixing requirements over AS/NZS 1170.2 and AS 4055. Termite risk is treated as Area H (high) across the Territory under NCC Housing Provisions Part 3.4, with NT-specific variations prohibiting polymer termite barrier sheets being used as moisture or damp-proof membranes, and reactive soil profiles around Darwin commonly drive Class M to H1 footings under AS 2870.

Source link

NCC 2022 (all volumes, free read-only): https://ncc.abcb.gov.au/editions/ncc-2022/adopted

NCC 2025 (released 1 May 2026): https://ncc.abcb.gov.au/ncc-2025

Free ABCB account required to access the online edition; PDFs also free to download.

References

Australian Building Codes Board, National Construction Code, NCC overview. https://ncc.abcb.gov.au/ (verified 2026-05-07).
Australian Building Codes Board, NCC Building Classifications (Part A6). https://ncc.abcb.gov.au/ncc-navigator/building-classifications (verified 2026-05-07).
Australian Building Codes Board, Introduction to the NCC, NCC 2022 Volume One Preface. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-one/preface/introduction-national-construction-code-ncc (verified 2026-05-07).
Australian Building Codes Board, NCC 2022 Volume Two, Building Code of Australia Class 1 and 10 buildings. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two (verified 2026-05-07).
Australian Building Codes Board, NCC 2022 Volume Three, Plumbing Code of Australia. https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-three (verified 2026-05-07).
Australian Building Codes Board, NCC 2025 state and territory adoption information. https://ncc.abcb.gov.au/ncc-2025/ncc-2025-state-and-territory-adoption-information (verified 2026-05-07).

NCC 2022 Volume Two overview, Section H in detail: energy, livable housing, fire separation
AS 3740, wet area waterproofing, referenced in NCC Volume Two H4
AS/NZS 3000, the Wiring Rules referenced in Volume Three
Deemed-to-Satisfy (DTS), the default NCC compliance pathway
Performance Solution, the alternative NCC compliance pathway
ABCB Housing Provisions Standard, where the DTS numbers for Class 1 and 10 live
DA process NSW, where NCC classification is assessed at approval
CDC (NSW), the complying development pathway assessed against the NCC