We get asked this question a lot, so it is one worth covering
a DA is a Development Approval - Occasionally required.
A local/state/federal authorities approval for a project that breaches one or more requirements of the city/state/federal plans. The project is individually assessed, and approved if no overwhelming objections are determined or received.
a BA is a Building Approval - Required on most building projects.
An approval issued for the construction of a project by a building certifier.
In Queensland, the majority of building projects require a Building Approval (BA) prior to commencing construction. A Building Certifier is the person that issues this approval for construction. All required plans are submitted to him for assessment first, and if the project ticks all the boxes against the building code, local city plan and state authority legislation, he issues this approval, and then the builder can start building.
In some cases, where the proposed project does not immediately comply with one or more requirements (aka 'acceptable solutions') of the city plan, or state/federal authority legislation, the project is then required to be submitted to that authority for further, individual assessment by that authority. This type of approval is called a Development Approval (DA).
A BA is assessed mostly against the NCC - the National Construction Code - which the DA is not assessed against. That's the Building Certifiers job.
Typical example requiring a BA:
Your designer has produced a great design that ticks all the city plan's boxes for property boundary setbacks, building heights, site cover, character codes and more. You submit the building design plans, engineering plans and any other documents to a private Building Certifier (some councils have building certifiers in-house so you can submit directly to council for a BA. Not Brisbane) and he issues a BA so you can start construction immediately!
A DA is required for judgement to be passed on whether a project will be acceptable to the local community and how much of an impact it will have on the local area. This is heavily assessed against compliance with the authorities plan (such as a local council city plan).
Just because your DA is approved, doesn't mean you automatically can start building. No. A project that has successfully had a DA issued for it, will then be required to obtain a Building Approval to actually commence construction also.
A DA is assessed against the city plan and other planning authority requirements.
Typical example requiring a DA:
Your project design is amazing! The only thing is, it needs to be 10m above NGL for the design to work perfectly. In the majority of Brisbane, QLD - Brisbane City Council's City Plan 2014 allows for a maximum building height of 9.5m above natural ground level (NGL). This doesn't necessarily mean that you can't build it, you just have to submit the project plans to council with a development application to have it individually assesssed by council and for public comment. You submit the plans to council through a private town planner (in Brisbane at least. Some councils have their own town planners so you can submit directly to council), and
The application is publicly listed so other home owners can have their say in the project too. So, is there a chance that the project won't be approved? Yes. But in most cases, a good designer would have been working with a town planner early on to produce a design that, even though it goes beyond the acceptable solutions of the city plan, has a high likelihood of the DA being approved by council.
WHEN DO YOU NEED BOTH?
Whenever a DA is required, you will also need a BA in order to construct the project.
Fun topic! Not particularly. But it is an important piece of knowledge to understand before starting your dream project. Happy designing!