What is a BASIX Assessment, and Why Does It Matter?

Before your new home or granny flat can get council approval, you’ll need to show that it meets NSW’s environmental sustainability standards. That’s where the BASIX (Building Sustainability Index) Assessment comes in.


A BASIX Report checks that your design meets minimum targets for:

  • Energy use
  • Water usage
  • Thermal comfort (how well your home stays warm in winter and cool in summer)

What does a BASIX Assessor do?

Your BASIX Assessor will complete works according to your agreed scope of works.


Typically, a BASIX Assessor will:

  • Review your architectural plans including floor plans, elevations, sections, site layout, insulation specs, ventilation, hot water systems, etc.
  • Assess your project using BASIX and NatHERS software tools to measure compliance with NSW government sustainability targets.
  • Evaluate three key performance areas:
  • Water efficiency (e.g. WELS-rated fixtures, rainwater tanks)
  • Thermal comfort (insulation, orientation, shading, ventilation)
  • Energy use (appliances, lighting, solar, heating/cooling systems)
  • Identify any changes required to achieve compliance — like material swaps or system upgrades.
  • Generate the official BASIX Certificate and submits it through the NSW Planning Portal.
  • Coordinate with you and your designer to revise plans if needed and ensures everything is ready for DA or CDC submission​

Barry's Toolbox

A BASIX Certificate is one of the very first approvals you’ll need. Your Building Certifier — the person who checks your plans and inspections during the build — can’t even accept your application without it. If you wait too long to organise your BASIX, it can hold up your CDC or DA approval. Getting it sorted early helps keep your project moving.

What Makes a Good BASIX Assessor?

Look for someone who:

  • Responds quickly and clearly
  • Has experience with residential new builds or granny flats
  • Offers a clear breakdown of costs and what’s included
  • Can turn the report around in a reasonable timeframe (ask for an ETA)


You don’t need to be an expert — that's what you have the Pro for!

You’re just gathering a few quotes so you can choose the best fit for you and your project.

Before You Begin: What You’ll Need Ready

To request accurate quotes from BASIX Assessors, make sure you have:

  • Your building plans (drafts are fine, but they should show floor plan, elevation and site layout)
  • A general idea of any sustainability features you’d like to include (like rainwater tanks, insulation, or solar panels)


If you're not sure what features to include yet, that’s okay — your assessor can advise, and you can refine things later. See the Document Library tab for all required documents before requesting quotes.


Average Timeframe

For this task, Pros typically provide quotes within 3–5 business days.

When Can I Expect Quotes?

Timeframes often vary based on demand and the type of Pro you're engaging (e.g. a plumber). If additional communication or clarification is needed is needed, the quoting process may take longer.

 

Don't be alarmed if you don't receive quotes or communication from any Build Buddy Pros straight away. Some work is more complex and the Pro may need time to comprehend your documents or scope of work. Depending on the job, there may even be some work required by the Pro before they are able to quote (e.g. a site visit might be required).

 

If the average timeframe indicated here has passed, and you have not received any messages or quotes, please feel free to contact the Build Buddy Expert Guidance and Support team for an update on quoting for this task.

Frequently Asked Questions

  • Do I legally need a BASIX Certificate to build?

    Yes — a BASIX Certificate is a legal requirement in NSW for all new residential builds, including granny flats, dual occupancies, and major renovations over a certain value. You must include it with your:


    • Complying Development Certificate (CDC) application
    • or your Development Application (DA) through council

    Your certifier or council will not approve your project without it. The certificate proves your design meets NSW’s environmental performance standards — covering water usage, energy efficiency, and thermal comfort. Skipping it can delay your approvals or make your build non-compliant.

  • What happens if my design doesn’t meet BASIX requirements?

    If your initial design falls short of BASIX targets (for water, energy, or thermal comfort), your assessor will recommend changes. This could mean:

    • Adding insulation
    • Upgrading windows
    • Including a rainwater tank
    • Improving ventilation

    These changes are usually cost-effective and can be made early in the design stage. Your BASIX Report isn’t final until you approve it — so you’ll always know what’s being adjusted.

How to Complete this Task?

STEP 1

Review and Adjust the Scope of Works

Timeframes may vary based on demand and the type of Pro you're engaging (e.g., a plumber). If additional communication or clarification is needed, the quoting process may take longer.

STEP 2

Confirm Required Documents Are Uploaded

Check that the following required document(s) are uploaded for this task. These are essential to proceed:

STEP 3

Update the Quality Assurance Checklist

Go to the Quality Assurance tab in this task and review the checklist. Edit any details to suit your project requirements. Being clear and upfront helps set expectations with the Pro. Updating the checklist before requesting quotes ensures everyone is aligned.

STEP 4

Request Quotes

Click the orange ‘Request Quotes’ button to start the quoting process.

STEP 5

Review the Quotes

Once you receive quotes:

  • Review each one carefully, including the payment schedule and any special terms
  • Download attached quote documents for detailed review
  • Check each Pro’s profile and read past client reviews

STEP 6

Communicate with the Pro

If needed, message or call the Pro to clarify details or negotiate terms.

STEP 7

Accept a Quote

Choose the quote that best suits your needs. Once you accept a quote, any other pending quotes will be automatically declined. An agreement will automatically be generated.

STEP 8

Complete the Tasks In Your App

New tasks will appear to guide you through this job — follow each step carefully. Make sure to use the Quality Assurance Checklist, and refer to your contract and final Scope of Works whenever needed.

NEED HELP?

Reach Out to Your Build Buddy Pro

If you have any questions or need a hand, your Build Buddy Pro is your best first contact. They’re a licensed expert in their field and can understand the ins and outs of your project. You can message them via the platform, or you can call them directly.


If you have already contacted your Build Buddy Pro and still need further assistance, the Build Buddy Expert Guidance and Support team are here to help. They will be able to guide you on your next steps or help you find answers to any questions you may have.