BASIX or Section J? How to Know Which One Your Project Needs

When your project isn’t a standard home

Not every project fits neatly into the “typical residential” category. SDA housing, boarding houses, residential flat buildings, or small office developments all fall into a different space when it comes to compliance. And that often raises the same question:

Do we need a BASIX certificate, or a Section J report?

It’s a common point of confusion — especially for projects that sit somewhere between residential and commercial. The answer depends on one key detail: your building class.

Step one: confirm your building classification

The first thing to do is ask your consent authority (your council or private certifier) what building class they’ve assigned to your project. This classification determines which sustainability pathway applies under the National Construction Code (NCC).

Here’s the general rule of thumb:

• Class 1 buildings (typical single dwellings and dual occupancies) require a BASIX certificate in NSW.

• Class 2 buildings (multi-unit residential) may require BASIX and NatHERS compliance depending on the design.

• Class 3 buildings (boarding houses, SDA, hotels, and similar) are not covered by BASIX and instead require a Section J compliance report under NCC Volume 1.

So, if your project is anything outside a Class 1 home, you’ll want to double-check before assuming BASIX applies.

When the answer isn’t clear

Sometimes, the consent authority may not be entirely certain which classification fits best — particularly for mixed-use or specialist developments. That uncertainty can cause delays later in the process, especially if the wrong reports are prepared upfront.

That’s where expert input can make a big difference. At Studio Terra, we regularly liaise with councils and private certifiers to confirm the right sustainability pathway early. This helps prevent redesigns or resubmissions down the track, saving both time and money.

Why getting it right early matters

Choosing the correct pathway isn’t just about ticking a compliance box — it affects your project’s design, performance outcomes, and approval timeline.A BASIX certificate focuses on water, energy, and thermal performance in residential buildings. Section J, on the other hand, covers the broader energy efficiency requirements for commercial and mixed-use developments, looking at elements like glazing, insulation, lighting, and HVAC systems.

Understanding which applies from the outset means your sustainability strategy can be integrated into design decisions from day one, rather than added as an afterthought.

Need clarity on your project?

If your project doesn’t quite fit the “standard home” model, it’s worth checking before you commit to one pathway or the other. We can help you work out where your development sits and liaise directly with your consent authority to confirm the right approach.

At Studio Terra, our goal is to make compliance simple, practical, and stress-free — so you can keep your project moving with confidence.