NCC 2025 Volume One: Water Management Issues that Class 2–9 Projects Need to Resolve Now

For Class 2–9 buildings in feasibility, DA or design development, NCC 2025 Volume One is not a distant consideration.

Even where adoption is delayed, the design decisions being made now may determine whether a project can transition smoothly, or whether compliance risk is discovered too late.

The key issue is timing.

Across Australia, the applicable NCC edition is generally determined through the relevant state or territory building approval pathway. In NSW, for many Class 2–9 projects, the practical benchmark is the date the Construction Certificate application is made.

A project may have development consent and may have been designed under the current NCC, but if the Construction Certificate application is made after the NCC 2025 applies, the project may need to satisfy NCC 2025 Volume One.

This distinction matters because the relevant NCC edition is not necessarily determined by when the project entered feasibility, when DA documentation was prepared, or when development consent was granted.

For Class 2–9 buildings, the more important question is:

What NCC edition will apply on the date the Construction Certificate application is lodged?

For staged or long-running projects, the risk is even more acute. Each stage or separate Construction Certificate application may need to be considered against the NCC edition and transitional arrangements applying at that time.

In NSW, the NCC 2025 will be adopted from 1 May 2027. Nationally, other jurisdictions have adopted from 1 May 2026, with timing varying across states and territories. The NSW Government has stated that the transition period is intended to help industry plan for the changes and minimise future compliance risk.

That creates a practical question for developers, architects, consultants and builders:

Will the Construction Certificate application for this Class 2–9 building be made before or after NCC 2025 Volume One applies?

Why NCC 2025 Volume One Matters for Class 2–9 Buildings

NCC Volume One applies to Class 2–9 buildings, including apartment buildings, commercial buildings, retail premises, health buildings, schools, public buildings, carparks and mixed-use developments.

These buildings often contain the most complex water management conditions on a project, including:

• podiums

• balconies

• roofs

• terraces

• façades

• basement walls

• suspended slabs

• wet areas

• planter boxes

• thresholds

• carpark decks

• mixed-use interfaces

NCC 2025 Volume One places greater emphasis on water management within Section F — Health and Amenity, including provisions relevant to waterproofing, surface water, sub surface water, wet areas and external water management. Industry commentary on the NCC 2025 has identified water management in Volume One Section F as one of the headline changes.

The practical shift is that waterproofing can no longer be treated as a late-stage membrane selection or specification exercise. It needs to be coordinated across architecture, structure, hydraulic services, façade, landscape, civil, access and buildability requirements.

For Class 2–9 projects, this is especially important because many water management decisions are locked in long before the waterproofing package is fully documented.

Key waterproofing design constraints such as structural levels, slab falls, balcony set-downs, podium and roof drainage build-ups, façade interfaces, planter depths, basement wall and floor assumptions, movement joints and finished floor levels, are largely locked in during pre-DA and early design development.

If those decisions do not support compliant water management under NCC 2025 Volume One, the project may carry hidden risk into Construction Certificate documentation, tender, procurement or site delivery.

The Construction Certificate Date Matters

For NSW projects, the Construction Certificate application date is a key commercial risk point.

Under the Environmental Planning and Assessment Regulation, a certifier must not issue a Complying Development Certificate unless the building will comply with the relevant requirements of the Building Code of Australia as in force at the time the application for the certificate was made.

While the exact pathway depends on the project type, approval structure and transitional rules, the practical message is simple:

Do not assume that DA approval locks in the NCC edition.

For many Class 2–9 projects, the more important question is whether the Construction Certificate application will be made before or after the relevant NCC 2025 commencement date.

For staged mixed-use or apartment projects, this can become more complicated. A project may have one development consent, but multiple Construction Certificate applications. Later stages may need to be considered separately against the NCC edition and transitional provisions applying at that time.

That makes early review commercially important.

The project team needs to understand whether the water management strategy being designed today will still hold up when the relevant Construction Certificate application is made.

Water Management Decisions Often Locked in Too Early

On Class 2–9 buildings, waterproofing risk is often created before waterproofing details are drawn.

Common examples include:

• balcony set downs that do not allow for compliant falls, drainage and threshold detailing

• podium build-ups that leave insufficient depth for falls, membranes, protection, drainage cells, screeds, insulation, finishes and accessibility requirements

• roof drainage layouts that conflict with structural falls, plant zones or façade interfaces

• planter boxes designed without adequate drainage, overflow, membrane termination or inspection access

• façade and balcony interfaces that rely on sealant rather than proper water-shedding and drained detailing

• basement wall assumptions that do not adequately address groundwater, construction joints or movement

• wet area layouts that are not coordinated with substrate falls, hob-less transitions or service penetrations

• movement joints placed without proper consideration of membrane continuity and termination

• carpark decks and trafficable areas that do not properly coordinate membrane selection, falls, toppings, drainage and durability

By the time these issues appear in Construction Certificate documentation, they may already be liable to result in substantial remediation costs and delays.

Is Your Class 2–9 Project Exposed?

A project should be reviewed early if any of the following apply:

• the Construction Certificate application may be lodged after NCC 2025 Volume One applies

• the project is staged, or likely to have multiple Construction Certificate applications

• balconies, podiums, terraces or roofs sit above occupied space

• planter boxes are located above habitable areas, basements or podium slabs

• balcony or terrace set downs are tight

• drainage locations are not yet coordinated with structure and finishes

• façade, threshold and balcony door interfaces are unresolved

• basement waterproofing assumptions have not been tested against site conditions

• movement joints pass through, adjacent to or under waterproofed areas

• architectural, structural, hydraulic services, landscape and façade drawings are not yet fully coordinated

If several of these items apply, the project is not necessarily in trouble.

But it is at the point where a specialist waterproofing design peer review can add the most value, because changes can still be made on paper rather than on site.

What Should Be Reviewed Now

For Class 2–9 projects that may be impacted by NCC 2025 Volume One, early waterproofing and water management peer review should test whether:

• structural falls and set downs are adequate

• balconies, podiums, terraces and roofs have coordinated drainage paths

• waterproofing membranes can be installed, protected and terminated correctly

• surface finishes support water management rather than trapping moisture

• thresholds, façade interfaces and balcony doors are detailed as complete water management systems

• movement joints and construction joints are sensibly located and buildable

• planter boxes include coordinated drainage, overflow, access and membrane protection

• basement waterproofing assumptions align with site conditions and structural design

• wet areas are coordinated with substrate falls, penetrations and transitions

• architecture, structure, hydraulic services, landscape, façade and civil design are aligned

• the expected Construction Certificate application date could expose the project to NCC 2025 Volume One

  
  

The objective is not to redesign the project.

It is to identify where current documentation may struggle under NCC 2025 Volume One, while there is still time to adjust levels, falls, interfaces, build-ups and drainage strategy.

Why This Matters Commercially

Late water management changes are expensive.

A missed set down, unresolved drainage path or unbuildable membrane termination can trigger redesign, RFIs, certifier queries, procurement changes, variation claims, site delays, holding costs or future defect exposure.

For developers, this is not just a technical issue. It can affect program, feasibility, settlement timing, occupation and long-term asset performance.

For architects and design teams, early review provides a specialist check on one of the highest-risk areas of building performance.

For builders, it reduces ambiguity before waterproofing becomes a site problem.

For certifiers and approval teams, it helps reduce late-stage uncertainty around whether the documentation properly supports the applicable NCC edition.

For NSW, the Design and Building Practitioners Act also increases the importance of properly coordinated regulated designs and declarations. NSW Government guidance confirms that registered design practitioners provide compliance declarations for regulated designs, and that projects may require a range of registered practitioners across different specialties.

This matters because late waterproofing changes may not be a simple redline exercise. If a detail forms part of a regulated design or affects declared work, amendments may need to be properly coordinated, documented and declared.

In Class 2–9 buildings, water ingress risk is rarely isolated. One poorly coordinated balcony, podium, roof, façade or basement detail can affect multiple lots, common property, occupied spaces and long-term building performance.

The Practical Takeaway

NCC 2025 Volume One gives project teams a clear reason to bring waterproofing design review forward.

For Class 2–9 developments already in the pipeline, the safest approach is to assess water management risk before key design decisions are locked in and well before the project reaches the Construction Certificate application date that may determine the applicable NCC edition.

Small level, falls, drainage and interface decisions made during DA or design development can have significant consequences later.

Don’t Risk a Late-Stage NCC 2025 Redesign

If you have a Class 2–9 project currently in early design/pre DA, design development or Construction Certificate planning, now is the time to review the water management strategy.

Watershed Projects provides independent waterproofing design peer review for Class 2–9 developments, helping developers, architects, consultants and builders identify critical water management interfaces before compliance risk is built into the project.

A focused early-stage review can assess:

• balcony and terrace set downs

• podium and roof build-ups

• drainage paths

• façade and threshold interfaces

• planter box detailing

• basement waterproofing assumptions

• wet area and service penetration risks

• movement joint and membrane termination issues

Request a Waterproofing Design Peer Review fee from us to identify the key water management issues that should be resolved before the Construction Certificate application is made.