Basement – Waterproofing Integrity

NCC 2025 Changes Adopted in Victoria: A Preview of What’s Coming for Waterproofing Nationally

Waterproofing Integrity — Fri, 02 Oct 2026 06:03:05 +0000

Victoria has moved first.

From 1 May 2026, NCC 2025 came into effect in Victoria, bringing with it significant changes to how water management and waterproofing are addressed under the National Construction Code.

For waterproofing, this is more than a change in clause numbering.

NCC 2025 introduces a broader and more integrated approach to water management, particularly for commercial buildings, Class 2 buildings and below-ground structures. The changes place greater emphasis on understanding where water can come from, how it can affect a building, and how the proposed design demonstrates compliance.

For architects, engineers, builders, certifiers, developers and asset owners working in Victoria, these requirements are now part of the compliance environment.For the rest of Australia, Victoria provides an early indication of the direction the industry is heading.

Why NCC 2025 matters for waterproofing

One of the most important changes in NCC 2025 Volume One is the restructuring of the water management provisions within Section F.

Under NCC 2022, water-related requirements were distributed across several Performance Requirements covering surface water management, rainwater entry, drainage, rising damp and weatherproofing.

NCC 2025 brings these requirements together under a consolidated Performance Requirement F1P1.

At the same time, NCC 2025 introduces a defined meaning of “water” for Section F that encompasses:

• surface water

• sub-surface water

• rainwater

• stormwater

• rising damp

• water services overflow

• surface water seepage

That definition is particularly important when considering basements and other structures below ground.

Previously, the regulatory treatment of below-ground waterproofing could be difficult to interpret. NCC 2025 provides a clearer framework for considering the different forms of water that may affect a building.

For project teams, the question therefore becomes broader than:

“What waterproofing membrane are we specifying?”

The more important questions are:

“What water conditions could affect this structure? How will those risks be managed? And how will the design demonstrate compliance with the relevant Performance Requirement?”

That is a significant change in thinking.

Below-ground waterproofing comes into sharper focus

Basements, retaining walls, lift pits, service pits and other below-ground structures face conditions that are fundamentally different from exposed above-ground areas.

They may need to manage groundwater, perched water tables, hydrostatic pressure, surface water migrating through soil, rising damp and changing groundwater conditions over the life of the building.

Unlock Expert Insights on What Changes for NCC 2025

Read the white paper to understand the new compliance requirements for below-ground structures and the practical implications for certifiers, designers, builders, and material suppliers.

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NCC 2025 brings these risks more clearly within the water-management framework through F1P1 and the expanded definition of water.

This means below-ground waterproofing should not be treated simply as a membrane-selection exercise.

It needs to be considered as part of the broader building design.

ground conditions → water source → structure → waterproofing strategy → drainage → detailing → installation → inspection → testing → verification.

A weakness at any point in that chain can compromise the final outcome.

The critical issue: there is no Deemed-to-Satisfy pathway for below-ground waterproofing

This is one of the most important implications for industry.

The Deemed-to-Satisfy provisions within Part F1 address areas including stormwater drainage, external falls and drainage, substrates, above-ground external waterproofing membranes, damp-proofing, roofs and wall cladding.

However, they do not provide a Deemed-to-Satisfy pathway specifically addressing waterproofing of below-ground walls, slabs and substructures exposed to sub-surface water.

AS 4654.2, for example, relates to waterproofing membranes for external above-ground use.

There is currently no equivalent Australian Standard providing a complete Deemed-to-Satisfy pathway for below-ground waterproofing.

For projects where below-ground waterproofing must demonstrate compliance with NCC 2025, this means the design needs to be addressed through a Performance Solution.

And that changes what project teams need to consider.

A Performance Solution is not simply a waterproofing specification with a different title. It needs to demonstrate how the proposed design satisfies the applicable Performance Requirements and be supported by an appropriate assessment method.

This puts greater importance on design rationale, evidence, documentation and verification.

What does a Performance Solution need to consider?

There is no universal below-ground waterproofing solution that can simply be applied to every basement.

The appropriate strategy depends on the building and the conditions surrounding it.

A robust approach may need to consider:

• expected groundwater conditions

• hydrostatic pressure

• site drainage

• surface water and seepage

• intended internal environment

• structural design and movement

• construction joints and penetrations

• waterproofing system selection

• substrate condition and preparation

• drainage and protection systems

• construction sequencing

• accessibility for future maintenance

• inspection and testing requirements

• evidence of suitability for the proposed materials and systems

The objective is not simply to nominate a product.

It is to demonstrate how the complete system will manage the identified water risks and satisfy the relevant Performance Requirements.

The removal of the Class 7 and 8 limitation matters

NCC 2025 also removes previous limitations associated with certain water-related Performance Requirements for Class 7 and Class 8 buildings.

This has important implications for areas such as:

• basement car parks

• below-ground storage areas

• plant rooms

• mixed-use developments with Class 7a basements beneath Class 2 residential buildings

These areas should not be treated as secondary simply because they are not occupied in the same way as apartments, offices or retail spaces.

Water ingress into a basement can affect far more than the visible finish.

It can affect structural durability, services, indoor environmental conditions, adjoining spaces and the long-term operation of the asset.

Under the NCC 2025 framework, project teams need to demonstrate how these below-ground areas satisfy the relevant water-management Performance Requirements.

Why independent waterproofing advice matters more under NCC 2025

As waterproofing moves further into a performance-based compliance environment, the quality and independence of technical advice become increasingly important.

The question is no longer simply:

“Which waterproofing product should we use?”

It is:

“What does this building need to achieve, what are the actual risks, and what evidence demonstrates that the proposed solution is appropriate?”

Those are different questions.

They require advice that begins with the building and the risk: not with a particular membrane, manufacturer or installation system.

This is where an independent waterproofing advisor can play an important role.

Waterproofing Integrity is independent of waterproofing manufacturers, suppliers, installers and applicators.

We do not install membranes.

We do not sell waterproofing products.

Our role is to independently assess the waterproofing risk, advise on the appropriate design and compliance strategy, inspect construction and verify performance through testing.

That independence allows the advice to focus on one outcome:

“What is appropriate for the building?“

Design. Inspect. Test. Remediate.

At Waterproofing Integrity, we approach waterproofing as a building-performance issue rather than an isolated trade package.

Our advisory process extends across the waterproofing lifecycle:

Design: identify water risks early and develop appropriate waterproofing strategies, details and Performance Solutions.

Inspect: independently inspect substrates, interfaces, installation and critical construction stages before they become concealed.

Test: use appropriate testing and inspection methodologies to verify conditions and waterproofing performance.

Remediate: investigate existing water ingress, establish likely pathways and causes, and provide evidence-based recommendations for remediation.

The objective is not simply to respond when waterproofing fails.It is to create greater certainty from design through construction and throughout the life of the building.

Victoria is first: but this is a national conversation

Victoria adopted NCC 2025 from 1 May 2026.

Nationally, however, the NCC does not automatically take effect everywhere on the same date. Each state and territory determines how and when an edition of the NCC is given legal effect within its jurisdiction.

That distinction matters.

Project teams outside Victoria should confirm the applicable NCC edition and transitional arrangements for the jurisdiction in which they are working.

But the direction of the national framework is clear.

The ABCB has identified improved water management as one of the significant changes within NCC 2025, including amendments intended to address water ingress in commercial and apartment buildings.

For practitioners around Australia, the lesson from Victoria is therefore not to wait until the applicable adoption date to start understanding the changes.

Now is the time to consider what the new framework means for design responsibility, Performance Solutions, waterproofing documentation, evidence of suitability, inspection, testing and verification.

Waterproofing needs to be considered earlier

Perhaps the most important outcome from NCC 2025 is not a particular clause.

It is a change in mindset.

Waterproofing problems are expensive to investigate after construction and can be extraordinarily difficult to remediate once membranes, joints, drainage systems and interfaces have been permanently concealed.

The earlier water-management risks are identified, the greater the opportunity to resolve them through coordinated design rather than reactive remediation.

For below-ground construction in particular, the waterproofing strategy should be developed alongside the structure, drainage, geotechnical conditions and intended use of the space.

Not after those decisions have already been made.

From compliance to confidence

NCC 2025 raises important questions for the construction industry.

But better waterproofing outcomes will not come from compliance documentation alone.

They will come from understanding the building, identifying water risks early, developing appropriate solutions and independently verifying that what was designed is what was constructed.

That is the role Waterproofing Integrity is built to provide.

As Australia’s leading independent waterproofing advisors, Waterproofing Integrity provides independent, evidence-based advice across Design, Inspect, Test and Remediate.

Our independence means our recommendations are driven by the requirements of the building: not by the commercial interests of a product manufacturer, supplier or installer.

For project teams navigating NCC 2025, that independence provides something increasingly important:

Confidence that waterproofing decisions are based on evidence, risk and building performance.

Want to understand the NCC 2025 changes in more detail?

For advice on NCC 2025, below-ground waterproofing, Performance Solutions or independent waterproofing design and verification, speak with Waterproofing Integrity.

📞 1300 025 944

✉️ advice@waterproofingintegrity.com.au

🌐 waterproofingintegrity.com.au

📍 Our offices across Australia: Sydney | Newcastle | Melbourne | Brisbane

How We’re Different From a Waterproofing Contractor

	Waterproofing Integrity	Waterproofing Contractor
Diagnoses the cause	Independent testing before any recommendation	Often assumes, based on the job being priced
Recommends the fix	Specifies what’s correct, regardless of who installs it	Recommends what they install
Financial interest in the outcome	Advisory fee only	Paid to perform the work
Verifies the finished work	Independently tests and reports on the completed work	Self-verifies their own work

Below ground and on notice: what NCC 2025 means for waterproofing compliance

Waterproofing Integrity — Mon, 11 May 2026 00:55:00 +0000

Australia’s construction industry is no stranger to code updates, but NCC 2025 carries a change that will have genuine, practical consequences for anyone involved in below-ground construction — certifiers, designers, builders, and product suppliers alike. For the first time, a single Performance Requirement — F1P1 — will govern all water management for Class 2–9 buildings, both above and below ground. The mechanism that makes this work is deceptively simple: a new defined term, “water”, in Schedule 1.

Why this is a structural shift, not a minor amendment

Under NCC 2022, the regulation of water affecting buildings was fragmented across five separate Performance Requirements spread across Parts F1 and F3. Below-ground structures — basements, retaining walls, lift pits, service pits — occupied an ambiguous position. Hydrostatic pressure from groundwater, for example, was not clearly captured by any single clause.

NCC 2025 resolves this by consolidating everything into F1P1 and anchoring it to a defined term that leaves no ambiguity. The Schedule 1 definition of “water” now includes surface water, sub-surface water, rainwater, stormwater, rising damp, water services overflow, and surface water seepage. Every italicised instance of Water in F1P1 carries the full weight of all seven types.

“For a basement, this means sub-surface water, surface water seepage, hydrostatic pressure, and rising damp will all have to be managed — and compliance must be demonstrated through a Performance Solution.”

No DtS pathway. Performance Solutions only.

This is the critical practical consequence. The Deemed-to-Satisfy provisions in Part F1 (F1D1 through F1D15) cover stormwater drainage, damp-proof courses, vapour barriers, and above-ground membranes referencing AS 4654.2. None of them address below-ground waterproofing. There is no equivalent Australian Standard for basement walls, below-ground slabs, or substructures exposed to sub-surface water.

This was true under NCC 2022, and it remains true under NCC 2025. What changes is that the obligation is now unambiguous. Every below-ground waterproofing project will require a bespoke Performance Solution demonstrating compliance with F1P1, typically developed with reference to BS 8102:2022, the British Standard widely used in Australian practice as a framework for water management grades and protection types.

The Class 7 and 8 exemption is gone

Under NCC 2022, F1P2, F1P4, and F3P1 each contained a clause allowing Class 7 or 8 buildings to avoid compliance “where in the particular case there is no necessity.” This was frequently misread as a blanket exemption — and was used to justify the omission of waterproofing in basement car parks, storage areas, and plant rooms.

NCC 2025 removes this limitation entirely. Basement car parks, below-ground storage, and plant rooms in mixed-use buildings must now all demonstrate compliance with F1P1 for all relevant water types. There are no carve-outs.

What the industry needs to do now

Certifiers must recognise that F1P1 is now the relevant clause for below-ground waterproofing, that there is no DtS pathway, and that Performance Solutions are mandatory — not optional. Designers and waterproofing consultants must document their below-ground systems as Performance Solutions, addressing the full range of water types in the Schedule 1 definition. Builders must treat below-ground waterproofing as a non-discretionary scope item with clear inspection and hold points. And suppliers must provide robust evidence of suitability for below-ground conditions, including hydrostatic pressure resistance and long-term durability under permanent immersion.

The absence of a referenced Australian Standard for below-ground waterproofing is a long-standing gap that NCC 2025 will bring into sharper relief. Building industry awareness and capability before the code takes effect is not a nice-to-have — it is an urgent priority.

Every basement is different. At Waterproofing Integrity, our structural engineers and waterproofing specialists assess each project on its own merits — design, intended use, location, and site-specific conditions — to recommend the right solution for your build with confidence.

Contact Waterproofing Integrity on 1300 025 944 or advice@waterproofingintegrity.com.au

Unlock Expert Insights

Read the white paper to understand the new compliance requirements for below-ground structures and the practical implications for certifiers, designers, builders, and material suppliers.

Download White Paper

TANKED OR DRAINED, TREAT YOUR BASEMENT LIKE A BATHTUB.

admin — Mon, 16 Feb 2026 03:08:28 +0000

Choosing between a tanked or drained basement design is not as easy as taking the cheapest option; it’s a high-stakes decision that dictates the lifespan of your structure. The cost difference during construction is often a healthy six-figure sum for the developer for even mid-size developments, and potentially an ongoing maintenance cost for the eventual owner or owners.

At Waterproofing Integrity, the bathtub analogy is one we use regularly. Treat your basement like a bathtub. Either have a continuous structure that prevents water getting in or allow water to enter and drain it effectively.

The right strategy requires complex coordination between architects, builders, consultants, council mandates, and site-specific considerations— all while considering how that space is designed and will actually be used. Whether you’re designing for a high-end office, media room, laboratory or a car park, the wrong call at the design stage leads to more than just damp walls—it leads to costly disputes, loss of use of the space and can impact the health and amenity of those using the space.

Don’t wait for the mould to tell you that the basement needed more attention during design and construction.

Water is the most patient trespasser on your site; it always finds a way, so we make sure it’s the way out.

Water will find every microscopic flaw in a basement’s construction whether that be through a shoring wall, a poorly sealed joint, and every shortcut taken during construction. Because concrete is naturally porous, it cannot be relied upon solely as your waterproofing strategy. Due consideration needs to be given to a solution that respects the intended use, design and specific site conditions—not just a “standard” fix.

So Waterproofing Integrity recommend not to treat waterproofing as an afterthought, unless you want to end up with a basement that feels more like a swamp than a structural asset.

Stop the leak before it starts, because an ‘Indoor Swimming Pool’ should never be a surprise feature of your basement.

From 2026, the National Construction Code (NCC) will require basement waterproofing considerations to be factored in design from residential properties to large commercial developments. This requirement was previously exempt from the NCC which often meant water management was not always a key discussion point in design.

At Waterproofing Integrity, our team of structural engineers and waterproofing industry professionals look at each basement for how it is designed, how it will be used, where it is located and the site specific considerations. From that we advise on the best approaches for your site to provide confidence and peace of mind!

Please reach out to us using our contact form and we will be happy to assist you further.