BASIX for Alterations and Additions: When Does It Apply?
Renovations can trigger BASIX once they pass a cost threshold or add conditioned space. Here is when you need a certificate and what it covers.
New homes always need BASIX, but renovations are where owners get caught out. The rules are not as obvious, and the wrong assumption can stall an approval. Here is when a renovation triggers BASIX and what the certificate will ask of you.
The triggers to watch
- Cost threshold. Alterations and additions at or above the BASIX cost threshold require a certificate.
- New conditioned space. Adding heated or cooled floor area generally brings the work into scope.
- Pools and spas. A new pool or spa over 40,000 litres triggers BASIX on its own.
What the certificate covers for renovations
For alterations and additions, BASIX focuses on the new and altered parts of the home rather than forcing the entire existing dwelling to comply. That means the targets are applied proportionately, which keeps sensible renovations achievable.
Common renovation scenarios
| Project | Usually needs BASIX? |
|---|---|
| New rear extension with living space | Yes, once over the threshold |
| Internal cosmetic refit only | Often no |
| New first-floor addition | Yes |
| New pool over 40,000 litres | Yes |
How to keep a renovation BASIX simple
Renovations give you a chance to lift comfort cheaply. Insulating the new roof, choosing efficient glazing for added windows and upgrading the hot water system usually satisfies BASIX while making the home nicer to live in. Address these at design stage and the certificate becomes a formality.
Frequently asked questions
Does a small bathroom reno need BASIX? Usually not, unless combined works push the cost over the threshold.
Will I have to upgrade my existing home? No. The focus is on the new and altered areas.
Renovating and unsure if BASIX applies? Send us your scope and we will confirm in plain English.
BASIX & NatHERS specialists, a division of Contrive Consultants. We help NSW homeowners and builders achieve energy-efficient, compliant homes.