NCC 2022 Ventilation & Airtightness for South Australian Homes
The authoritative South Australian guide — the SA commencement dates, the 5 ACH50 trigger, the condensation rules, and how MVHR and blower door testing satisfy the code.
Who this is for: builders, designers, building certifiers and homeowners working on new homes and renovations in South Australia. This guide focuses on what NCC 2022 actually requires for ventilation and airtightness, the SA-specific commencement dates, and the practical compliance pathways. It is general guidance, not a substitute for a project-specific assessment by your certifier.
Ventilation and airtightness are now two sides of one rule
NCC 2022 ties ventilation and airtightness together for the first time. To reach the new 7-star (NatHERS) energy target that applies to SA homes, builders have to reduce uncontrolled air leakage — which makes the home tighter. But a tighter home no longer leaks enough fresh air to dilute the moisture, CO₂ and pollutants that occupants generate. So the same code that pushes the envelope tighter also requires that, below a defined airtightness threshold, the home is mechanically ventilated.
For South Australian projects there is a second thing to get right: the dates. SA adopted most of NCC 2022 on 1 May 2023, but deliberately deferred the “modern homes” package — the 7-star energy provisions, livable housing design and the improved condensation management measures — to 1 October 2024. If you read a generic national summary that says “1 May 2023”, it does not describe when the condensation and energy rules actually started for SA homes.
The South Australian timeline
NCC 2022 general adoption in SA
South Australia adopted the bulk of NCC 2022 — but the energy efficiency, livable housing and improved condensation management measures were held back for a later start date.
Modern homes provisions commence
The 7-star (NatHERS) thermal performance target, whole-of-home energy budget, livable housing design, and the Part 10.8 condensation management measures now apply to new Class 1 and Class 2 homes lodged on or after this date. This is the date that matters for ventilation and airtightness.
Alterations & additions to existing homes
Implementation of the modern homes provisions for alterations and additions to existing dwellings is delayed until this date. NCC 2019 applies to that work in the interim.
Concessions: SA approved transitional concessions for small and irregular allotments, worker and tourist accommodation, the Mount Barker Master Planned Neighbourhood Zone, and off-site manufactured homes of 70 m² or less. Some of these may follow NCC 2019 (6-star) thermal performance while still meeting the NCC 2022 energy-usage and condensation management requirements. Always confirm the pathway that applies to your specific allotment and class of work with your certifier.
The two provisions that drive ventilation & airtightness
Ventilation — the 5 ACH50 trigger
VentilationWhat it requires
Where a dwelling has, or is designed to have, an air permeability of less than 5 air changes per hour at 50 Pa (5 ACH50), a mechanical ventilation system must be installed that delivers at least the minimum calculated airflow rate, in accordance with AS 1668.2.
The formula
Minimum airflow (L/s) = 0.05 × Floor Area (m²) + 3.5 × (Number of Bedrooms + 1).
Worked SA example
A 220 m² four-bedroom home in Adelaide: 0.05 × 220 + 3.5 × (4 + 1) = 11 + 17.5 = 28.5 L/s minimum. A well-specified MVHR system for this home would typically be sized at 30–40 L/s to allow proper balancing and commissioning headroom.
Why it exists
Once a home is tight enough to hit 7 stars, it no longer leaks enough air to passively dilute indoor moisture, CO₂ and pollutants. The code formalises building science: reduce uncontrolled leakage, and you must replace it with controlled, purposeful ventilation.
Condensation management — exhaust & vapour
CondensationExhaust direct to outdoor air
Exhaust from a kitchen, range hood, bathroom, sanitary compartment or laundry must discharge directly — or via a shaft or duct — to outdoor air. Venting into a roof cavity, sub-floor or wall cavity is explicitly non-compliant. This closes one of the most common and damaging installation defects in Australian housing.
Wet-area run-on interlock
A non-continuous exhaust fan serving a bathroom or sanitary compartment that has no natural ventilation (no operable window to outside) must be interlocked with the light switch and run on for a minimum of 10 minutes after the light is switched off, ensuring post-shower moisture is cleared.
Vapour permeance by climate zone
Pliable building membranes are now classified by climate zone. In Climate Zones 4 and 5 — which includes Adelaide — wall membranes must be vapour permeable to at least Class 3, or another compliant pathway used. The Adelaide Hills and South East (Climate Zone 6) carry more stringent requirements, including roof space ventilation.
For a deeper treatment of the ventilation clause and the condensation exhaust rules on their own, see our NCC 2022 ventilation requirements explainer.
Where the 5 ACH50 line sits in real construction
5 ACH50 is the number that decides whether mechanical ventilation is mandatory. It is measured with a blower door test — a calibrated fan pressurises the building to 50 Pascals and reports how many times the building’s air volume leaks per hour. Here is how the threshold compares to what SA homes actually achieve:
A new SA home built to the 7-star target with reasonable site practice will usually land below 5 ACH50 — which means the mechanical ventilation requirement is in scope by default, not by exception. Homes deliberately built for high performance or Passive House sit well below 3 ACH50 and are clearly within scope. For more on how the result is measured and what it means, see Airtightness Explained.
Two ways to comply
Deemed-to-Satisfy (DTS)
- Build above 5 ACH50 and rely on the prescriptive ventilation provisions, OR design below 5 ACH50 and install mechanical ventilation to the formula.
- Provide compliant exhaust (direct to outside) and the wet-area run-on interlock.
- Use a climate-zone-compliant vapour-permeable wall membrane.
Performance Solution
- Demonstrate compliance with the relevant Performance Requirements — useful for high-performance and Passive House builds that go well beyond DTS.
- An MVHR system plus a measured blower door result provides strong, documented evidence for a Performance Solution.
- Typically supported by a NatHERS assessment, a verified airtightness test, and ventilation design to AS 1668.2.
How MVHR and blower door testing satisfy the code
A properly designed MVHR system and a verified blower door result together cover the ventilation, condensation and evidence requirements in one coordinated approach:
Part 10.6 — minimum airflow
MVHR is sized to deliver at least the calculated minimum airflow to the dwelling, with margin for balancing and commissioning.
Part 10.8 — exhaust to outside
MVHR extract terminals in kitchens, bathrooms and laundries duct directly outside through the central unit — never into a roof cavity.
Part 10.8 — continuous wet-area extraction
MVHR runs 24/7, keeping wet areas in slight negative pressure and clearing moisture far more reliably than an intermittent fan.
7-star energy target
Heat recovery returns warmth from the exhaust air to the incoming fresh air, so the required ventilation doesn't undo the thermal performance you designed for.
Evidence of airtightness
A blower door test confirms which side of 5 ACH50 the home is on, and provides the measured result for a NatHERS rating or a Performance Solution.
Defect risk
Testing mid-build locates leaks while they can still be sealed — before plasterboard buries them — reducing condensation and callback risk.
A note on SA climate zones
The condensation management requirements — particularly vapour permeance of wall membranes and roof space ventilation — vary by NCC climate zone. Adelaide and most of the coastal plain sit in Climate Zone 5 (warm temperate). The Adelaide Hills, Mount Lofty Ranges and the South East around Mount Gambier fall into Climate Zone 6 (mild temperate), which carries more stringent condensation requirements. Northern and outback SA sit in the hotter, drier Zones 3 and 4. Confirm the climate zone for your exact site, because it changes the compliant membrane class and roof ventilation detailing.
Should you blower door test in SA?
NCC 2022 does not force every home to be tested. But because the 5 ACH50 trigger, NatHERS airtightness credit, and Passive House certification all depend on a measured number, testing is the only way to know rather than assume. A mid-construction test catches leaks while they’re still accessible; a completion test gives you a documented result for compliance and handover.
Our blower door testing service →Frequently asked questions
When did NCC 2022 ventilation and condensation requirements start in South Australia?
South Australia adopted most of NCC 2022 on 1 May 2023, but deferred the 'modern homes' provisions — the 7-star energy efficiency requirements, livable housing design, and the improved condensation management measures — to 1 October 2024. So for new Class 1 and Class 2 homes, the condensation management rules under Part 10.8 (exhaust direct to outside, wet-area mechanical ventilation, and climate-zone vapour permeance) apply to development applications lodged from 1 October 2024. Alterations and additions to existing homes have a further concession: the modern homes provisions are delayed until 1 May 2030, with NCC 2019 applying in the interim.
What is the 5 ACH50 ventilation trigger in NCC 2022?
Under Part 10.6 of the NCC 2022 Housing Provisions, where a dwelling has — or is designed to have — an air permeability of less than 5 air changes per hour at 50 Pascals (5 ACH50), it must be fitted with a mechanical ventilation system delivering at least a minimum calculated airflow. The code formally recognises that a tight building no longer leaks enough air to dilute indoor moisture, CO₂ and pollutants, so designed ventilation becomes mandatory.
What is the NCC 2022 mechanical ventilation formula?
The minimum continuous mechanical ventilation airflow for a dwelling is calculated as: Airflow (L/s) = 0.05 × Floor Area (m²) + 3.5 × (Number of Bedrooms + 1). For example, a 220 m² four-bedroom home requires 0.05 × 220 + 3.5 × 5 = 11 + 17.5 = 28.5 L/s. Systems must be installed in accordance with AS 1668.2.
Does NCC 2022 require a blower door test in South Australia?
Not for every home. NCC 2022 does not mandate airtightness testing across the board — the Part 10.6 mechanical ventilation requirement applies to homes that are at or below 5 ACH50. A blower door test is the only way to objectively confirm which side of that line a home sits on, and it is required to claim airtightness credit in a NatHERS energy assessment or for Passive House certification. Many SA builders and designers now test proactively to confirm compliance, de-risk defect claims, and verify the energy rating they have designed to.
Does MVHR satisfy NCC 2022 in South Australia?
Yes. A correctly designed and commissioned MVHR (mechanical ventilation with heat recovery) system delivering at least the calculated minimum airflow satisfies the Part 10.6 mechanical ventilation requirement, and its continuous extract from kitchens, bathrooms and laundries — ducted directly outside — satisfies the Part 10.8 exhaust requirements at the same time. MVHR is the most complete single solution for a tight SA home because it recovers heat from the exhaust air, which matters for the 7-star energy target.
What vapour permeance does a wall membrane need in Adelaide?
Adelaide is in NCC Climate Zone 5. In Climate Zones 4 and 5, a pliable building membrane used on the outside of the wall must be vapour permeable — a minimum of Class 3 vapour permeance — or another compliant condensation-management pathway must be used. The cooler Adelaide Hills and South East (Mount Gambier) fall into Climate Zone 6, which has more stringent condensation management requirements, including roof space ventilation.
Working on a South Australian project?
HiPer Haus designs, supplies and commissions MVHR and carries out blower door testing across Adelaide and South Australia — helping builders and designers meet NCC 2022 with confidence, and supporting Passive House certification.