Designers, builders, certifiers and property owners will have to alter their approach to moisture management, water ingress and condensation control in light of the NCC 2025 changes. How these play out in practice is a matter of the building class and the provisions in question, as well as the timing of each state or territory’s adoption of the National Construction Code (NCC) 2025.
In this guide Rhys Parker sets out what one needs to be aware of with internal wet areas, box gutters, low-pitch metal roofs, external cladding and balconies. The technical wording is only part of it; transitional arrangements and the date a state comes on board are of equal import. Without proper documentation of the contract, construction or approval schedule a project can find itself straddling NCC 2022 and NCC 2025. For broader context, see NCC updates for wet areas.
What is different in 2026?
The aim of the NCC 2025 is to put moisture risks in plain sight at the design and construction stage, to better resist water and curb ingress. You will not find all of it in a single waterproofing chapter; the changes are spread through Volume One Section F, and Volumes Two and Three of the code.
For official guidance and the current edition of the NCC and its supporting material, the Australian Building Codes Board (ABCB) is where to go. But by 2026 the question that has practical bearing is not “What is in NCC 2025?” but “On this date and with this approval pathway, which edition does this state apply to my project?” The answer is not the same for an alteration, a commercial build or a new dwelling.
Reality and expectation
One might think a new edition of the code takes hold across the board on the day it is released. In fact it is more complicated. There are separate pieces of legislation, variations and commencement dates to contend with in each jurisdiction. For that reason the implementation dates for NCC 2025 in Australia should be verified for the project location and not just taken from some national checklist.
The context provided points to 1 May 2026 and 1 May 2027 as dates to note. Do not take them as universal start dates for every building without looking at the instrument of the state or territory concerned. Put simply, let the legal pathway dictate the building approval, not the calendar.
State Adoption And Timing
Each jurisdiction makes the call on how and when the ABCB’s national model code is to be followed. It is easy for a project team to be caught out by assuming a national pronouncement has already altered the rules on site.
Have the building surveyor or the relevant authority put on record what edition and transitional treatment applies before any design is finalised. Retain the advice with your project file, particularly if procurement or work is to cross a commencement date.
| Jurisdiction | What To Confirm In 2026 | Who Should Check |
|---|---|---|
| Victoria | Confirm NCC 2025 adoption, any state variations or transitional provisions and the commencement arrangements. | Building surveyor, designer, project certifier |
| South Australia | Check the NCC 2025 adoption date, local variations and the approval route. | Plan examiner, building surveyor and builder |
| New South Wales | Find out about NSW amendments and adoption, and if the project is still NCC 2022. | Principal certifier, consent authority and designer |
| Queensland | Review Queensland variations, transitional rules and NCC 2025 commencement. | Building certifier, hydraulic consultant and builder |
| Other states and territories | Check any exemptions, variations and adoption dates. | Relevant local building authority and certifier |
Take this table as a prompt in planning a project, nothing more. Should there be a conflict between NCC 2022 on paper and the site team’s NCC 2025 notes, put a halt to it and sort it. A discrepancy in instructions is what turns a minor wet-area detail into a variation claim.
A matter of dates
Put three dates to the test: when the application was put in, when you received the approval and when the work is due to start. See if the state offers any transitional protection. That will tell you if NCC 2022 or 2025 is in force.
In the course of a day’s review of a project make a point of going over the approval documents, the classification of the building, the state’s notice of adoption and the waterproofing spec. More often than not it will become apparent whether the team is talking about something recommended by a manufacturer, an improvement or a requirement of the law.
A Closer Look at the Waterproofing Changes
In the NCC 2025, the waterproofing changes are in effect a more rigorous approach to moisture-control systems as a whole. Do not think of a waterproof membrane as some sort of magic raincoat; it is only one part of the equation. The end result is determined by drainage and falls, junctions and penetrations, thresholds, flashings, the substrate and finish.
Designers would do well to appraise the risks inside and out. An external above-ground waterproofing job can be undone if cladding, a roof or balcony lets water behind the main drainage plane. Inside, wet areas are prone to failure from a poorly executed penetration or junction.
Details for Internal Wet Areas
Bathrooms, laundries, kitchens and the like will be built and put on paper differently under the NCC 2025. It is for the team to determine where a membrane is called for, what surfaces require water resistance, how to get the water to waste and in what way the system is in line with Deemed-to-Satisfy provisions and Australian Standards.
One should pay particular heed to tile falls. A wrong position for the drain, screed or substrate and the tile work may be neat but it will hold water. There is an easy way to verify: make certain of the fall prior to tiling and have a look at the surface once done, see that the waste is effective and at hand. One does not want to be left with a puddle that has made itself at home after the grout has set.
There are all too common errors, such as making a shower screen the boundary for waterproofing, or letting plumbing penetrations be dealt with in an ad hoc fashion, or supposing silicone is a substitute for a membrane. Read the NCC 2025 requirements on water ingress in conjunction with the standards, product literature and project drawings.
Balconies and the like
An exposed balcony is subject to ponding, cracking, blocked drains, thermal movement and wind-driven rain. So any above-ground external waterproofing must have a co-ordinated detail at the wall junction, edge, balustrade support, door threshold and outlet.
The mistake is to view each trade in isolation. The tiler will have his tiles, the contractor the membrane, the installer the door frame. But water has a way of testing the entire balcony. A good design will demonstrate how the pieces come together and allow for maintenance without putting a hole in the water-control layer. In multi-residential and apartment buildings a balcony problem is not just a matter of a few new tiles; it can involve access, temporary protection, drying and reinstatement of internal finishes and common property, making of a small defect a building project of some disruption.
Roofs, Gutters and Cladding
Water management under NCC 2025 puts a premium on roof drainage and cladding since the source of the damage is often above the room in which it is seen. A mark on the ceiling could be down to a box gutter, a roof junction or wall system rather than something in the internal plumbing.
Box gutters and low-pitch metal roofs have little tolerance for debris or bad detailing and should be scrutinised. The drawings need to cover overflow, flashings, junctions and so on. A roof is hardly robust if it only functions when spotless; gum leaves are not going to wait for a handover date.
Coordinating Roof and Wall
The strategy for drying and draining the external cladding has to be unambiguous. Be it sarking, cavity trays, vapour-permeable membranes or sealed openings, it depends on the wall system and what the provisions dictate.
It is no use assuming a vapour-permeable membrane will protect every assembly. Moisture is present in construction water, condensation, indoor humidity and rain. The compatibility of products and how the wall dries are to be evaluated as part of the system.
When inspecting, see that the sarking is oriented right, that cladding joints conform to the maker’s instructions and that flashings are discharging outside and penetrations sealed without impeding drainage. Put a camera to any concealed work before it is covered over by linings; it is a habit that has prevented its share of arguments and uncomfortable silences.
Controlling Moisture and Condensation
The NCC 2025 takes a wider view of moisture management than waterproofing alone. Humid air can find a cold surface or be trapped in a layer of the build and you will have mould, decay or corrosion even though the building is technically dry of rain.
Ventilation, insulation and vapour control are now part of the discussion thanks to the condensation requirements of the NCC 2025. What is the right solution is a function of the climate, how the building is used and the interplay of indoor and outdoor conditions.
Where it begins
It is where warm and moist air comes up against something cooler that condensation will show up. A tightly sealed bedroom or a kitchen and laundry can generate enough indoor humidity. With poor ventilation or exhaust air being put into a roof space it will build up in places out of sight.
There is no point in a fan that puts on a show with the noise but does little to move steam; it is theatre, not control. Mechanical ventilation must be put in place where air will in fact circulate and be led to a suitable external point. One should also have regard for the building’s airtightness and climate when sizing up windows, passive vents and mechanical systems.
Design in cold climes might call for judicious positioning of insulation and vapour or air-control layers. The risk profile in a tropical or humid area is another matter, especially if air conditioning is cooling internal surfaces. Do not be in the habit of replicating a detail from the Top End that was done in Melbourne without first putting the wall assembly and climate to the test.
Moisture Review Checklist
- Determine what NCC edition and state variation are in force.
- Identify probable sources of water, be it rain, plumbing, cleaning or humidity within.
- Look at overflows, thresholds, penetrations, drainage outlets and falls.
- See that membranes, sarking, flashings, cladding and ventilation are in order.
- Have inspections put on record before any work is concealed.
- For gutters, sealants, fans and outlets, maintenance instructions should be at hand.
It is an unglamorous checklist, as good water management tends to be. The glamour comes in delivering a building that has seen its first proper storm and is still dry.
Who is most exposed?
The risk is not spread equally across residential and commercial stock or apartments and multi-residential buildings. A complex project has more people to contend with on the same drawings and more interfaces and penetrations.
Then there is the home renovator who can fall foul of scope confusion. A bathroom reno is a mix of waterproofing, structural and electrical work, plumbing and certification, not to mention ventilation. The lowest quote will often leave out the documentation or inspection required to show the job is in compliance.
With commercial buildings one finds larger roof spaces, plant penetrations, wet rooms and kitchens. An apartment development brings with it repeated bathrooms, podiums, balconies, façade junctions and the responsibilities of common property. In all of this it is better to put one person in charge of water management than to expect each consultant to make the connections.
Extra precautions
Extra precautions are warranted on a project with a low-pitch roof, box gutters, a sizeable balcony, intricate cladding or high internal humidity, a construction programme that is tight, or where there has been a switch from NCC 2022 to 2025 in the course of delivery.
If the team is at a loss to say how condensation is being dealt with, which provisions are in play or where the water goes once it has got past the outer layer, then do not put the design to construction. It is no pedantry to insist on it; you will save money by ironing out an omission on paper instead of behind a skirting board that has swelled.
Practical Project Actions
Make a brief compliance record prior to procurement. Set out the evidence required at handover, the inspections called for and the relevant Australian Standards, as well as the NCC edition and any state or territory variations.
On a project already in progress, turn your attention to what is about to be covered. Put photographs of the drainage details, sarking, flashings and so on on file. Have the certifier or building surveyor put any doubts in writing, should the team be making use of NCC 2022 in a transition period.
- Verify the building classification and jurisdiction.
- Put the product instructions, specifications and drawings side by side.
- Examine the roofs, cladding, overflow paths, box gutters and balconies.
- Inspect for falls, membranes and outlets in wet areas.
- Check the paths for moisture to dry and for ventilation and condensation control.
- File away the test records, certificates, photographs and maintenance data.
Such measures are sensible for an apartment development, a new home or a commercial fit-out and give one something to go on when the subject of NCC updates for wet areas is raised with a designer, builder or certifier.
NCC 2025 Water Management FAQ
Will NCC 2025 be in effect everywhere in 2026?
Not of itself. As a national model code the National Construction Code is only as local as the state or territory adoption makes it. You would do well to check the transitional provisions and implementation dates for the project, and in some cases NCC 2022 is still the one.
Is it just a case of bathroom waterproofing?
Far from it. Roofs, box gutters, above-ground external waterproofing, balconies and external cladding may all be in scope, along with ingress and condensation. What is required is a function of the NCC provisions, the construction system and building classification.
Can one rely on tiles for waterproofing?
Tiles and grout are a finish. They do not take the place of a compliant system where a membrane or other means of water control is in order. Allowance must be made for tile falls, joints, drainage and the like.
Will a vapour-permeable membrane see off condensation?
No. While they have a part to play in controlling moisture, they do not eliminate the risk. The full assembly of the wall or roof, the climate, the level of indoor humidity and how the air is controlled are all factors.
What to put to the builder?
Find out in writing who is doing the inspection of the waterproofing, where exhaust air is to be discharged and what the record will be at handover. Also ask which NCC edition and state or territory provisions are being followed and how the drainage for the roof and balcony is detailed. Get it in writing if the project is a complicated one or straddles a commencement date.
2026 Final Takeaway
Water control is a whole-building affair, that is the message from the NCC 2025 water management changes Australia 2026 discussion. Condensation control, sarking, ventilation, roof drainage, tile falls and membranes have to be in concert.
Get the details down on paper before they are put out of sight and make sure you know the position on state adoption and the code edition. The rules can be technical enough but the objective is straightforward: let the building dry, keep the water at bay and do not be left with a compliance issue come the first wet season.