Last updated: October 2026
The National Construction Code (NCC) sets the minimum requirements for the design and construction of buildings across Australia. The latest update, NCC 2025, was published on 1 May 2026, and each state and territory decides when it formally adopts it.
Most jurisdictions have now confirmed their dates, and for the majority of Australia the switch happens on 1 May 2027. That sounds like plenty of time, but approvals take months, and which edition your project is assessed under can depend on where you are and how far along you already are.
So, what does this mean for anyone looking to build in Australia? Let’s break it down.
In this article:
- Why is the NCC being updated?
- What are the two changes that affect Greenspan buildings most?
- Who is affected by the NCC 2025 changes?
- When does NCC 2025 apply in your state?
- Why timing matters
- What this means for a Greenspan build
Why is the NCC being updated?
The NCC is a living document that is updated periodically to reflect advances in building performance, safety and quality. NCC 2025 introduces a number of changes, but for anyone building a habitable Class 1 building, two particular updates stand out. Both relate to moisture and ventilation.
Over the past decade, the building industry has seen a significant rise in condensation-related defects, particularly in cooler and wetter climate zones, as homes have become better sealed and insulated. While these improvements are a great thing for energy efficiency, they have had the adverse effect of contributing to moisture build-up inside wall cavities and roof spaces. Without adequate ventilation, moisture has nowhere to go, and over time this can lead to structural rot, mould growth, and poor indoor air quality that affects the health of the people living inside.
The NCC 2025 changes are a direct and evidence-based response to this problem.
What are the two changes that affect Greenspan buildings most?
NCC 2025 introduces two significant changes that directly affect how habitable buildings are constructed: mandatory ventilated wall cavities, and rewritten roof ventilation requirements. Both apply in Climate Zones 6, 7 and 8.
1. Ventilated wall cavities in Climate Zones 6, 7 and 8
Under the previous code, cladding can be fixed directly to the wall frame or sarking, a method known as direct-fix. Under NCC 2025, this is generally no longer permitted in Climate Zones 6, 7 and 8. Instead, external walls must include a continuous drained and ventilated cavity between the cladding and the layer behind it. In plain speak, this means there must be an air gap behind the cladding, with openings top and bottom. This allows both drainage and cross-ventilation, ensuring any rain or condensation that gets past the cladding drains down and vents out.
In practice, this requires battens to be installed over the wall wrap before the cladding is fitted, creating the necessary channel for air and moisture to move freely, with ventilated cavity closers top and bottom to keep insects and debris out while maintaining airflow and drainage.
Where (and when) your project requires it, we will upgrade the ventilated cavity system into your design, with the battens, extended fixings and cavity closers included in your specification. Your Design Solutioneer will confirm what your project needs for your zone and approval pathway, when it will start to apply, and how this may affect costings.
2. Roof space ventilation in Climate Zones 6, 7 and 8
Roof and ceiling space ventilation continues to apply in Climate Zones 6, 7 and 8, but NCC 2025 rewrites how it works. The provisions are now split according to whether the insulation runs parallel to the roof plane or not, with minimum opening areas that depend on roof pitch or roof area. In most cases the roof space must be at least 18mm high above the insulation and ventilated to outdoor air through openings at low level and high level; your certifier will confirm the exact figures for your design.
For pitched roofs and cathedral ceilings, this means eave vents, ridge vents or an equivalent system. For skillion roofs, a dedicated ventilation path must be built into the roof construction itself, creating an air gap between the structural roof timbers and the roofing above. NCC 2025 also exempts roofs made of structural insulated panels (SIPs).
Our habitable-spec Mod and eSpace designs use SIP roofing as standard, so they satisfy the requirement by exemption. Other habitable designs can be upgraded to incorporate a ventilated batten system as and when required. As with the wall cavity upgrades, your Design Solutioneer will confirm what your project needs for your zone and approval, and when.
Who is affected by the NCC 2025 changes?
This is where many people are surprised, and where two separate things determine whether these changes apply to you: your climate zone, and your state.
First, your climate zone. The mandatory wall cavity and roof ventilation provisions only apply in Climate Zones 6, 7 and 8, Australia’s cooler regions. Here’s a broad guide to the eight zones. Exact zones are set by local government area, and most cities and states take in more than one:
- Zone 1 – high humidity summer, warm winter (northern WA, Darwin, far north QLD including Cairns and Townsville)
- Zone 2 – warm humid summer, mild winter (coastal QLD from Mackay south to around Coffs Harbour NSW, including Brisbane)
- Zone 3 – hot dry summer, warm winter (inland QLD, central NT including Alice Springs, northern and inland WA)
- Zone 4 – hot dry summer, cool winter (inland NSW and QLD, parts of WA and SA)
- Zone 5 – warm temperate (Sydney metro, Adelaide metro, Perth, coastal NSW including Wollongong)
- Zone 6 – mild temperate (Melbourne, western and southwestern Sydney, parts of SA and WA)
- Zone 7 – cool temperate (Canberra and the ACT, most of Tasmania including Hobart and Launceston, southern NSW tablelands, inland and upland Victoria)
- Zone 8 – alpine (alpine areas of NSW, Victoria and Tasmania)
If you’re building in Adelaide, Perth or coastal Sydney, these two provisions don’t apply to your project. Other parts of the condensation rules still do, including requirements for building membranes and, in every climate zone, for exhaust systems in kitchens, bathrooms and laundries. In some states, these requirements come from the NCC 2022 edition rather than NCC 2025, but they still apply. And the detailing behind the cavity and roof requirements improves how any building manages moisture, whatever zone it sits in.
It’s worth noting that while roof ventilation has been rewritten, it has not been extended to new zones. It applied in Climate Zones 6, 7 and 8 under NCC 2022 and it still does. What has widened is the wall membrane side of the provisions, which now reach Zones 1 and 3 for the first time.
Second, your state. Even within Zones 6, 7 and 8, some states have varied the condensation provisions, which means the new wall cavity and roof ventilation mandates may not apply in the way the national code sets them out. Variations differ between jurisdictions and can change, so two projects in the same climate zone but different states can face different requirements. Your certifier will confirm exactly what applies at your address.
Because zones are assigned by local government area, outer suburbs of a city can sit in a neighbouring zone to the city centre. Always check your specific address using the ABCB Climate Zone Map, and confirm your state’s current position with your certifier.
When does NCC 2025 apply in your state?
NCC 2025 was published on 1 May 2026, and each state and territory sets its own adoption date. Here is where things stand as of August 2026.
Victoria
NCC 2025 is already in force. Victoria adopted it on 1 May 2026 with no transition period, so new designs are assessed under the new code now.
Western Australia
Adopted on 1 May 2026 with a 12-month transition. Until 1 May 2027, projects can comply with either NCC 2022 or NCC 2025.
ACT
Adopted on 1 May 2026 with a 12-month transition. Either code applies until NCC 2025 becomes mandatory on 1 May 2027. The ACT has also confirmed that well-advanced projects with planning or works applications lodged before 1 November 2026 may be built under either code, even after the changeover.
New South Wales
Adopted on 1 May 2027, confirmed by the NSW Government in March 2026. NCC 2022 Amendment 2 applies until then. New South Wales has also varied the condensation management provisions, and the requirements that will apply from 2027 may differ from the national NCC 2025 versions, so confirm the position for your project with your certifier.
Queensland
Adopted on 1 May 2027. NCC 2022 remains in force until 30 April 2027.
South Australia
Adopted on 1 May 2027 for the Building Code of Australia, which governs the wall cavity and roof ventilation changes. South Australia adopted the Plumbing Code from NCC 2025 earlier, on 1 May 2026.
Tasmania
Adopted on 1 May 2027. NCC 2025 briefly commenced on 1 May 2026, then the Building Amendment Act 2026 reinstated NCC 2022 from 5 June 2026. Tasmania has also varied the condensation management provisions, so the requirements that apply may differ from the national NCC 2025 versions; your certifier can confirm the current position. A ventilated cavity is still strongly recommended in Tasmania’s cool, wet climate, and we can upgrade your building to include this, whether it is required or not.
Northern Territory
Has not adopted NCC 2025.
Adoption dates and state variations can change. Always confirm the current position with your certifier or your state building authority.
Why timing matters
For most people looking to build a Class 1 building, it makes sense to start moving now, and the reason is your approval timeline more than anything else.
The new condensation requirements can be incorporated into your habitable Greenspan build where they apply, and whenever your state switches over. What you need to think about is your approval.
Transitional arrangements differ between states, and in some cases the edition that applies depends on when your application was lodged rather than when it was approved. Your certifier can confirm the position where you’re building. And there’s a practical point about changeovers: when new code requirements come into effect, consent authorities and private certifiers need time to adjust to the new criteria, and there’s often a period of uncertainty around interpretation and documentation as the industry adapts. Approvals routinely take months from lodgement, and certifiers get busier as any deadline approaches. If your timing matters, getting your application in early is the practical move.
There can also be a cost consideration. The additional materials and labour involved in meeting the new requirements can affect the price of a build, depending on what your site and approval require. Your Design Solutioneer will talk you through the specification that applies to your project and how it affects costings.
What this means for a Greenspan build
These changes are a direct response to a genuine, industry-wide problem. In pursuit of energy efficiency, buildings across Australia have become increasingly sealed and insulated over the past decade, and the unintended consequence has been a rise in condensation and moisture defects, as buildings that can’t breathe trap moisture inside wall cavities and roof spaces. NCC 2025 is the industry’s attempt to fix that.
But we’ve never built like the rest of the industry. Our materials and methods have long favoured breathability alongside energy efficiency. Timber, as a hygroscopic material, naturally helps buffer moisture, so managing condensation is something our buildings have always done well. In many ways, traditional construction is only now catching up on principles that have long been part of how we build.
So for most of our customers, NCC 2025 changes the paperwork more than the building. Because every Greenspan building is made to order, we can supply the condensation measures your project requires and build to the code it is actually assessed under, wherever you build and whenever your state adopts the code.
If you’re planning a build, talk to our team about what applies where you are and how it fits your timeline. And if you have an existing order currently in design or approval, speak to your Design Solutioneer about how these changes may affect your project.
This article provides general information only and does not constitute planning, building or legal advice. NCC adoption and transitional arrangements vary by state and are subject to change. Always confirm requirements with your local certifier or authority.
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FAQs
NCC 2025 was published on 1 May 2026. It is already in force in Victoria, and Western Australia and the ACT are in a transition period until 1 May 2027 where either code can be used. New South Wales, Queensland, South Australia and Tasmania adopt it on 1 May 2027 for building work, and the Northern Territory has not adopted it. Dates and variations can change, so always confirm the current position with your certifier.
No. The new wall cavity and roof ventilation provisions only apply in Climate Zones 6, 7 and 8, Australia’s cooler regions, which take in Melbourne, Canberra, Tasmania, outer western Sydney, the cooler tablelands and alpine areas, and parts of South Australia and Western Australia. Some states have also varied these provisions, so the requirements that apply can differ depending on where you build. Your certifier can confirm the current position for your state.
It depends on your state, and it’s the most important thing to confirm early. Some jurisdictions make concessions for projects already underway. The ACT, for example, has confirmed that projects with planning or works applications lodged before 1 November 2026 may use either code even after the changeover. Others do not. Because approvals routinely take months from lodgement, the earlier you start, the more room you have. Your certifier can tell you the position where you’re building.
These provisions apply to habitable buildings. A non-habitable structure such as a garage or an unlined shed is treated differently. If your project is a studio, granny flat or anything you’ll spend real time in, assume the habitable requirements apply and confirm the detail with your certifier.
Yes. We can upgrade your design to include the ventilated wall cavity and compliant roof ventilation specification on habitable buildings wherever they are required. Your Design Solutioneer will advise what your site and approval need, and every building is assessed against the full code by your certifier for your specific site and design.