NCC 2022: Key Changes in Residential Construction
Understanding the Impact of NCC 2022 on Residential Building
Stage One of National Construction Code (NCC) 2022 is adopted by most States and Territories and needs to be complied with for building permit applications submitted from 1 May 2023, it is timely to refresh your knowledge of the key things that have changed for residential construction.
Putting it simply, NCC 2022 is a substantial amendment. The changes include new requirements and changes to existing requirements across Volumes One, Two and Three.
The changes will affect the design and construction of most houses and apartments and will require changes to many standard building materials you currently use.
“The changes will affect the design and construction of most houses and apartments and will require changes to many standard building materials you currently use.”
Some of the main changes to be aware of include:
The complete restructuring of the code and re-ordering of Volume Two The NCC requirements for housing look very different this year. This is due to the restructuring and renumbering of the full code. The code now consists of two separate documents, the NCC Volume Two which then refers to the ABCB Housing Provisions Standard which has the Deemed to Satisfy (DtS) provisions. Both documents must be read in conjunction with each other.
While this doesn’t affect compliance, it’s worth pointing out since it will take some time to get familiar with the new layout and clause numbering. It is also worth noting NCC 2022 retains reference to the previous NCC 2019 clause numbering. This is to enable old test reports and other documentation to remain valid if they reference the NCC 2019 numbering unless there has been a technical change to a provision.
“It is also worth noting NCC 2022 retains reference to the previous NCC 2019 clause numbering.”
Internal waterproofing changes
Volume One and Two contain a range of both internal and external waterproofing changes, including a complete restructuring of the provisions into clauses from the tables that were in F1.7 and 3.8.1. Some new requirements have been added which include the walls in a shower area must be waterproofed to a height of 1800mm and provisions for WCs with a hand-held bidet spray installation.
Volume Two includes a re-introduction of the wet area Acceptable Construction Provisions (ACP) that was last included in BCA 2011. This can be adopted as an alternate compliance option to AS 3740.
Other changes include:
Adoption of the revised AS 3740:2021, which includes changes to the classification of different types of showers and updated figures for the treatment of shower niches and strip drains. More extensive waterproofing requirements for shower walls, greater choice for wet area waterproof and water-resistant substrates and surface materials and more contemporary design options.
Fibre-cement sheeting supported on a structural floor as an allowable waterresistant substrate (as opposed to only compressed cement sheet in NCC 2019).
Concrete that has been treated to resist moisture can be used as a surface material, and inclusion of cable floor heating treatment.
“Concrete that has been treated to resist moisture can be used as a surface material, and inclusion of cable floor heating treatment.”
Falls to floor wastes
Regardless of whether you choose the NCC DtS or AS 3740 waterproofing compliances options for internal wet areas, NCC 2022 requires falls to be provide to all floor wastes located in a wet area. This applies regardless of whether the floor waste is a ‘required waste’ under the wet area waterproofing standards, a non- required floor waste in the bathroom area or laundry or is just included to simplify the plumbing design.
“Regardless of whether you choose the NCC DtS or AS 3740 waterproofing compliances options for internal wet areas, NCC 2022 requires falls to be provide to all floor wastes located in a wet area.”
All floor wastes in wet areas will require a gradient to the waste of between 1:50 and 1:80 in the surrounding floor.
Clarification of external waterproofing requirements
NCC 2022 now makes it clear when and where the external waterproofing provisions apply and when the external waterproofing Standard AS 4654.1 & 2 applies.
The use of the Standard will apply to flat roofs and roof terraces, balconies and podiums, and exposed joints in roofs or similar horizontal surface parts of a building located above internal spaces of a building.
“The use of the Standard will apply to flat roofs and roof terraces, balconies and podiums, and exposed joints in roofs or similar horizontal surface parts of a building located above internal spaces of a building.”
The specific application and exemptions for external waterproofing in housing construction can be found in NCC Volume 2 Clause H2D8.
Changes to plumbing and drainage, such as branch drain connections
Plumbers and builders will need to pay close attention to the design and installation of the branch drain connections for sanitary plumbing installations for two-storey houses.
“Plumbers and builders will need to pay close attention to the design and installation of the branch drain connections for sanitary plumbing installations for two-storey houses.”
NCC 2022 adopts the revised plumbing standard AS/NZS 3500.2:2021, which contains changes for typical connection arrangements for graded branch drains entering the main drain. This includes requiring a DN100 branch drain to connect at an elevated incline of 15 degrees. (Victoria has a variation in NCC 2022 Volume Three clause VIC C1D3 )
If you have not designed the sanitary drainage system with this change in mind, there is a potential that the first-floor ceiling joists may not be deep enough to accommodate the added gradient.
What else has changed?
The changes in NCC 2022 are extensive and can’t easily be covered in a single article. Some other changes you should be aware of include:
The ABCB housing provisions Standard contains revised and updated acceptable construction practices for masonry, slabs, glazing, steel framing, gutters (including sheet roofing overhang) and downpipes.
“The ABCB housing provisions Standard contains revised and updated acceptable construction practices for masonry, slabs, glazing, steel framing, gutters (including sheet roofing overhang) and downpipes.”
Changes to encroachment provisions to capture elements extending beyond the vertical projection of an adjoining building on the same allotment.
Want to know more
HIA has a dedicated page to the changes to NCC 2022, along with many information sheets and articles on the changes these can be accessed at:
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