What does a building designer actually do — and do you need one?
If you're planning to build a new home, extend your existing one, or develop a dual occupancy, you'll quickly find yourself asking: do I need a building designer, an architect, or a draftsperson? It's one of the most common questions we hear at KBG Planning & Design — and getting the answer right can save you considerable time and money.
What is a building designer?
A building designer is a professional who specialises in designing residential and light commercial buildings — new homes, renovations and extensions, duplexes, townhouses and the like. Unlike architects, building designers are not registered with a single state board, and in NSW there is no general licence required to design a detached house (a Class 1 building).
Where registration does apply is the Design and Building Practitioners Act 2020. That Act introduced a registration scheme for design and building practitioners working on Class 2 buildings — apartment and multi-unit residential buildings, or mixed-use buildings with a Class 2 part. For that work, plans must be prepared as “regulated designs” and declared by a registered design practitioner on the NSW Planning Portal before building work starts. Most houses, and many duplexes and townhouses that are Class 1a, sit outside that scheme — but every project must still comply with the National Construction Code and the relevant council’s planning controls. (KBG holds Class 2 design practitioner registration, so we can take on apartment-class work as well as standard residential.)
Building designers are trained in architectural design, construction documentation, Australian Standards and the Building Code of Australia. Crucially, they understand the planning controls of local councils — which is critical for getting your Development Application (DA) or Complying Development Certificate (CDC) approved the first time.
Building designer vs architect — what's the real difference?
This is where homeowners often get confused. Both professionals can design your home. The main differences come down to scope, cost, and project type:
| Factor | Building Designer | Architect |
|---|---|---|
| Typical project types | Houses, duplexes, renovations, extensions, townhouses | Same, plus multi-storey residential, commercial, public buildings |
| Cost (design fees) | Typically 3–5% of build cost | Typically 10–15% of build cost |
| Licensing in NSW | No general licence for Class 1 homes; registration under the Design & Building Practitioners Act 2020 applies to Class 2 (apartment) work | Registered with NSW Architects Registration Board |
| Best for | Most residential projects — high quality, efficient, cost-effective | Complex or large-scale projects, heritage, landmark designs |
| Council knowledge | Typically very strong for local residential planning | Strong, but varies by practice |
KBG insight: For the vast majority of Sydney homeowners — whether building new, extending, or doing a dual occupancy — a building designer will give you everything you need at a fraction of the cost of a full architectural service. The key is choosing an experienced one with deep knowledge of your council's planning rules.
What does a building designer actually deliver?
At KBG Planning & Design, our building design service includes:
- Site analysis — reviewing your block, slope, orientation, easements and planning constraints before a line is drawn
- Concept design — floor plan layouts, room configurations and design options for your review
- 3D visualisations — rendered views so you can see exactly how your home will look inside and out
- Development Application (DA) or CDC documentation — full planning drawings, specifications, BASIX certificate and all supporting documents for council submission
- Construction drawings — detailed working drawings your builder uses to price and build your project
- Council liaison — we manage communication with the council and respond to any requests for additional information during the assessment process
Do you need a building designer for a home extension?
In NSW, most extensions beyond minor cosmetic work need a properly prepared set of plans for a Development Application or Complying Development Certificate, plus structural engineering where there is structural work. For a typical house (a Class 1 building), this does not trigger the registered-design-practitioner declaration regime under the Design and Building Practitioners Act 2020 — that scheme applies to Class 2 (apartment) buildings. What you do need is an experienced building designer (or architect) to prepare compliant plans and coordinate any structural engineering.
The good news is that the process doesn't have to be complicated. With the right designer who knows your council's rules, a straightforward rear extension or second-storey addition can move through the approvals process smoothly and quickly.
How to choose the right building designer
When selecting a building designer in Sydney, look for:
- Appropriate credentials — for example membership of the Building Designers Association of Australia (BDAA), and registration as a design practitioner under the Design and Building Practitioners Act 2020 for any Class 2 (apartment) work
- Experience with your specific project type (new homes, extensions, dual occupancy, etc.)
- Familiarity with your local council — Hills Shire, Sutherland Shire and Camden Councils all have different planning rules
- A track record of getting approvals — ask about their success rate
- Client testimonials and a visible portfolio
- Clear, upfront pricing with no hidden extras
KBG Planning & Design has a 100% current council approval success rate and over 40 years of combined experience across Hills Shire and Sutherland Shire. Book a free consultation to discuss your project — no obligation, just honest advice.