Answer first: In NSW you do not need a BASIX certificate for a garage, storeroom, carport, gazebo, verandah or awning, for alterations under $50,000, for open (not fully enclosable) additions, for alterations to State Heritage Register buildings, for hotels or motels, or for boarding houses and co-living over 12 residents or 300 m². Everything else residential usually needs one.
By: giantA Pty Ltd · Updated 12 November 2026
Why does it matter whether BASIX applies to your project?
BASIX (the Building Sustainability Index) sets water, energy and thermal performance standards for homes in NSW. According to the NSW Planning Portal’s About BASIX page, the standards apply to all new residential dwellings, to alterations and additions to dwellings that cost $50,000 or more, and to swimming pools of 40,000 litres or more. Where BASIX applies, your development application (DA) or complying development certificate (CDC) application must include a BASIX certificate, and the commitments on that certificate must be shown on the plans and built.
Getting the question wrong is costly in both directions. Lodge without a certificate when one is required and the application can be returned or held up while you obtain one. Commission a full assessment for work that is excluded and you spend time and fees on a document nobody needs.
For the overall process once BASIX does apply, see our step-by-step BASIX certificate guide.
Where are the BASIX rules set out?
BASIX sits in two instruments. The State Environmental Planning Policy (Sustainable Buildings) 2022 contains the BASIX standards (the policy commenced on 1 October 2023, and the Department’s Increase to BASIX Standards page explains the higher standards it introduced). The Environmental Planning and Assessment Regulation 2021 defines which development BASIX applies to. Its Schedule 7 Dictionary contains four definitions that decide almost every “do I need BASIX?” question:
- BASIX building — the kind of building BASIX is designed for.
- BASIX development — development that must have a BASIX certificate.
- BASIX excluded development — development that is taken out of BASIX even if it would otherwise fit.
- BASIX optional development — development where a certificate can be lodged but is not compulsory.
The Portal’s BASIX legislation summary still cites the older 2000 Regulation in places, so treat the 2021 Regulation as the current wording.
What counts as a “BASIX building”?
Under Schedule 7 of the EP&A Regulation 2021, a BASIX building is a building that contains at least one dwelling, but it does not include:
- hotel or motel accommodation, or
- a boarding house, hostel or co-living housing that accommodates more than 12 residents or has a gross floor area exceeding 300 square metres.
In relation to a BASIX building, a dwelling means a room or suite of rooms occupied or used, or constructed or adapted to be capable of being occupied or used, as a separate domicile.
In building-code terms, the Planning Portal’s building classes page explains that residential buildings classified by the National Construction Code (NCC) as Class 1, Class 2 and parts of Class 4 are subject to BASIX. Houses, townhouses and apartments are therefore the core of the scheme.
What development must have a BASIX certificate?
Schedule 7 defines BASIX development as the following, if it is not BASIX excluded development:
- the erection, but not the relocation, of a BASIX building;
- a change of building use by which a building becomes a BASIX building;
- the alteration of a BASIX building, if the estimated development cost is $50,000 or more;
- a swimming pool or spa, or combination of pools and spas, that services one dwelling only and has a capacity, or combined capacity, of 40,000 litres or more.
In the Regulation, “alteration” of a building includes its enlargement or extension, so additions are covered by the same $50,000 test. For detail on renovation triggers, read our guides on when renovations trigger BASIX and why you still need a certificate over $50k, and our pools and spas guide for the 40,000-litre trigger.
When is a BASIX certificate not required?
There are three different reasons a project can sit outside compulsory BASIX. It is worth knowing which one applies, because they behave differently if your design changes.
1. The development is “BASIX excluded development”
Schedule 7 lists four kinds of excluded development:
- Development for the purposes of a garage, storeroom, carport, gazebo, verandah or awning.
- Alterations to a building listed on the State Heritage Register under the Heritage Act 1977.
- Alterations resulting in a space that cannot be fully enclosed, other than a space that could be fully enclosed but for a vent needed for the safe operation of a gas appliance. The Regulation’s own example is a verandah that is open or enclosed by a screen, mesh or other material that permits the free and uncontrolled flow of air.
- Alterations to a building declared by the Planning Secretary, by order published in the Gazette, to be BASIX excluded development.
2. The building is not a “BASIX building”
If the building does not contain a dwelling, or it falls within the hotel/motel or large boarding house exclusions above, the BASIX development definitions do not bite. The Planning Portal’s large boarding houses page confirms that a BASIX certificate is not required for the erection of a new large boarding house, or alterations to an existing one, because this is no longer BASIX development. The same page notes that the NCC requirements, as administered by your consent authority, continue to apply.
3. The development is “BASIX optional development”
Schedule 7 defines BASIX optional development (if not excluded) as:
- the alteration of a BASIX building where the estimated development cost is less than $50,000; and
- a swimming pool or spa (or combination) that services one dwelling only and has a capacity, or combined capacity, of less than 40,000 litres.
You do not have to lodge a BASIX certificate for optional development, but you may choose to.
Which common projects need BASIX and which do not?
The table below applies the Schedule 7 definitions to projects we see every week in Sydney. It is a starting point, not a substitute for the consent authority’s or certifier’s view of your specific proposal.
| Project | BASIX status | Why |
|---|---|---|
| New detached house, duplex, townhouses or apartments | Required | Erection of a BASIX building |
| Kitchen, bathroom or rear extension with estimated cost of $50,000 or more | Required | Alteration of a BASIX building, $50,000 or more |
| Internal renovation with estimated cost under $50,000 | Optional | BASIX optional development |
| New in-ground pool and spa, combined 40,000 litres or more, serving one house | Required | Pool/spa trigger |
| Plunge pool or spa under 40,000 litres serving one house | Optional (unless other work triggers BASIX) | BASIX optional development |
| Detached garage, carport or storeroom | Not required | BASIX excluded development |
| Open deck with gazebo, verandah or awning | Not required | BASIX excluded development |
| Screened outdoor room that cannot be fully enclosed | Not required | Space that cannot be fully enclosed |
| Enclosing a verandah with glazed walls and doors | Usually depends on cost (confirm with your certifier) | Creates a space that can be fully enclosed, so the open-space exclusion no longer helps; the $50,000 alteration test applies |
| Converting a garage or shop into a dwelling or granny flat | Required | Change of use so that a building becomes a BASIX building |
| Alterations to a State Heritage Register item | Not required | BASIX excluded development |
| Hotel or motel | Not required | Not a BASIX building |
| Boarding house or co-living over 12 residents or over 300 m² GFA | Not required | Not a BASIX building; NCC still applies |
| Relocating an existing house to a new site | Check with consent authority | Erection “but not the relocation” of a BASIX building is BASIX development; other work may still trigger BASIX |
Does a garage, carport or verandah ever need BASIX?
On its own, no. Development for the purposes of a garage, storeroom, carport, gazebo, verandah or awning is BASIX excluded development. The catch is scope. If the same DA also includes, for example, a new upstairs bedroom wing and the overall alteration has an estimated development cost of $50,000 or more, BASIX will apply to the habitable part of the work.
A similar trap applies to “garages” that are really something else. If a structure is built or fitted out so that it is capable of being occupied as a separate domicile, it can be a dwelling for BASIX purposes. The Planning Portal’s single dwellings page lists a secondary dwelling that involves converting non-habitable space (such as a garage) as a project that uses the single dwelling BASIX tool. Our granny flat energy compliance guide covers that pathway.
What about open versus enclosed outdoor rooms?
The test is whether the new space can be fully enclosed. An alteration that results in a space that cannot be fully enclosed is excluded. The Regulation’s example is a verandah that is open or enclosed by screens, mesh or other materials that permit the free and uncontrolled flow of air. A gap left only for a vent needed for the safe operation of a gas appliance does not count as an opening for this purpose; that space is treated as able to be fully enclosed.
In practice, outdoor rooms with operable glass doors or sliding panels on every side are usually enclosable spaces, so they are not excluded on this ground. If you want an outdoor room to stay outside BASIX, design it as a genuinely open or screened space and make sure the drawings and specification describe it consistently. If the room is part of a larger alteration of $50,000 or more, expect BASIX to apply to the alteration as a whole.
Are heritage homes exempt from BASIX?
Only one group is: alterations to buildings listed on the State Heritage Register. Locally listed heritage items and houses in heritage conservation areas are still BASIX buildings, so BASIX applies when the usual triggers are met. Where a heritage control directly conflicts with a BASIX commitment, the Department can remove or revise only the conflicting commitments through a heritage alternative assessment. We explain that process in BASIX and heritage alternative assessments.
What happens with alterations under $50,000?
An alteration of a BASIX building with an estimated development cost of less than $50,000 is BASIX optional development. You are not required to lodge a certificate. Two points are worth knowing before you decide:
- If you lodge one with the DA, you keep it going. The Planning Portal’s legislation summary explains that where a DA for BASIX optional development was accompanied by a BASIX certificate, the construction certificate application must also be accompanied by a BASIX certificate: either the one applicable when consent was granted or another issued no earlier than 3 months before the CC application.
- The estimate must be genuine. The $50,000 figure is assessed against the estimated development cost of the alteration. The legislation summary notes that the consent authority (for a DA) and the certifying authority (for complying development) determine whether an alteration is BASIX development. Splitting one renovation into artificial “stages” to stay under the threshold is a risk we advise clients against.
The threshold is $50,000 or more. Some older material online quotes other figures; the Planning Portal and the 2021 Regulation both use $50,000.
What about non-residential buildings and mixed-use projects?
A building with no dwelling is not a BASIX building, so BASIX does not apply to a shop, office or warehouse on its own. The Planning Portal’s alterations and additions page adds that if alterations valued at $50,000 and over are not for use as a dwelling (or capable of being used as one), you need to check with your local council whether BASIX applies.
Mixed-use buildings with apartments above shops contain dwellings, so the residential part is a BASIX building. The portal’s guidance on submitting more than one certificate lists mixed-use development among the strata projects where separate certificates may be approved. Non-residential parts are dealt with under other parts of the planning and building framework, and your consent authority will tell you what it needs. Our Class 2 BASIX and NatHERS checklist covers apartment developments.
How do I check whether my project needs BASIX? (Step by step)
- Describe the whole proposal. List every element in the DA or CDC: new rooms, decks, pools, garages, outbuildings and changes of use. BASIX looks at the development, not just the part you are focused on.
- Ask whether the building contains a dwelling. If not, and nothing in the proposal creates a dwelling, BASIX generally does not apply. Note the hotel/motel and large boarding house exclusions.
- Check the excluded list. Garage, storeroom, carport, gazebo, verandah or awning only? A space that cannot be fully enclosed? A State Heritage Register building? A Gazette declaration? If yes, it is excluded.
- Check for a new dwelling or change of use. A new house, dual occupancy, apartment, granny flat or conversion of a non-residential space into a dwelling is BASIX development.
- Apply the $50,000 test to alterations. Use a realistic estimated development cost for the whole alteration. $50,000 or more means BASIX is required; less means optional.
- Apply the 40,000-litre test to pools and spas. Add the capacities of all pools and spas serving the one dwelling.
- Pick the right BASIX tool pathway. The portal’s Starting a BASIX application page explains that your primary and secondary selections decide whether the single dwelling, multi-dwelling or alterations and additions pathway applies, and that the pathway cannot be changed once the application starts.
- Confirm with your certifier or council where it is borderline. Enclosed outdoor rooms, studios with kitchenettes and mixed projects are where most disputes arise. A short pre-lodgement question is cheaper than a returned application.
Which BASIX tool pathway applies when BASIX is required?
| Your selection on the Planning Portal | Pathway applied |
|---|---|
| One dwelling on a single lot of land | Single dwelling |
| One dwelling where the lot includes common property and/or the project includes a secondary dwelling | Multi-dwelling |
| Two or more dwellings (separate lots, or combined on one lot such as dual occupancy or residential flat buildings) | Multi-dwelling |
| Secondary dwelling converting a garage, out-building or other existing non-habitable space | Single dwelling |
| Secondary dwelling as a new structure (separate or attached) | Single dwelling |
| Alteration or addition with estimated development cost of $50,000 or more | Alterations and additions |
| Pool and/or spa with combined size of 40,000 litres or more | Alterations and additions |
Source: NSW Planning Portal, Starting a BASIX application (last updated 29 April 2026). For dual occupancy projects specifically, see our BASIX dual occupancy guide.
What is a BASIX report, and how is it different from a certificate?
When people search for “BASIX reports” they usually mean one of two things: the certificate itself, or the draft assessment you can save before you commit. The Planning Portal’s certificate validity page recommends using the BASIX report function until your design is finalised and ready for lodgement, to avoid additional fees. The reason is timing: a BASIX certificate is valid for 3 months before it is submitted to council or an accredited certifier. Once lodged, it is valid for the life of the development application. If it is not lodged within 3 months, you must generate a new certificate, which incurs additional fees.
If your project is excluded, you need neither. If it is not, generate the certificate close to lodgement. Our guide to the 3-month lodgement window explains how revisions work. The validity page says there is no additional charge to revise an issued certificate if it relates to the same property and project and has been lodged or is still valid to be lodged.
We do not quote BASIX certificate fees here because the fee is paid in the Planning Portal when you generate the certificate. Check the current amount in the portal at the time you generate it.
If my project needs BASIX later, what changes?
Projects evolve. An excluded carport can become an enclosed garage studio; a $40,000 renovation can grow past $50,000 after a scope review. If a modification turns the development into BASIX development, you will need a BASIX certificate for the modified proposal. The portal’s legislation summary notes that modification applications under section 4.55(1A) or 4.55(2) of the EP&A Act, and modifications of CDCs and construction certificates, may need to be accompanied by a replacement BASIX certificate.
Once a certificate is lodged, it follows the project. Councils check it at DA or CDC stage, the certifier checks it before the construction certificate and occupation certificate, and the certifier must issue a BASIX completion receipt before the occupation certificate. See BASIX certificate validation and BASIX completion receipt before the occupation certificate.
How giantA can help
giantA prepares DA and CDC design packages for new homes, dual occupancies, granny flats and alterations across Sydney and NSW. At concept stage we check whether BASIX applies and which pathway fits, then coordinate the BASIX assessment and, where needed, the NatHERS assessor so that commitments are on the plans before lodgement. See BASIX and NatHERS, BASIX assessment in Sydney or our design and approvals services, or contact giantA for a project review. If BASIX does apply and you are choosing a thermal method, read DIY, Simulation and Passive House.
Frequently asked questions
Do I need a BASIX certificate for a carport or garage in NSW?
No. Development for the purposes of a garage, storeroom, carport, gazebo, verandah or awning is BASIX excluded development under Schedule 7 of the EP&A Regulation 2021. If the same application includes other alterations of $50,000 or more, BASIX may apply to that work.
Is BASIX required for renovations under $50,000?
No. An alteration of a BASIX building with an estimated development cost under $50,000 is BASIX optional development. You may lodge a certificate voluntarily, but if you do so with the DA, the construction certificate application must also include one.
Do pools under 40,000 litres need BASIX?
Not on their own. A pool or spa serving one dwelling with a combined capacity under 40,000 litres is BASIX optional development. At 40,000 litres or more it is BASIX development and needs a certificate.
Do boarding houses or co-living developments need BASIX?
Not if they accommodate more than 12 residents or have a gross floor area over 300 m². These are excluded from the definition of a BASIX building. The National Construction Code still applies through the consent authority.
What is the difference between a BASIX report and a BASIX certificate?
The Planning Portal recommends using the BASIX report function while your design is being finalised. The certificate is what you lodge; it is valid for 3 months before lodgement, and generating a replacement after it lapses incurs additional fees.
Preferred sources (verify current versions)
- NSW Planning Portal — About BASIX
- NSW Legislation — Environmental Planning and Assessment Regulation 2021 (Schedule 7, Dictionary)
- NSW Legislation — State Environmental Planning Policy (Sustainable Buildings) 2022
- NSW Planning Portal — BASIX legislation summary
- NSW Planning Portal — Large boarding houses
- NSW Planning Portal — Alterations and additions
- NSW Planning Portal — Single dwellings
- NSW Planning Portal — Starting a BASIX application
- NSW Planning Portal — Certificate validity and changes to the project
- NSW Planning Portal — When should more than one BASIX certificate be submitted?
- NSW Planning Portal — What classes of buildings need a BASIX certificate?
- NSW Planning Portal — Increase to BASIX Standards