Home Extension Planning in Queensland: What to Check First
Good home extension planning starts with your site, not your floor plan. In Brisbane and South East Queensland, almost every extension needs building approval from a certifier. Some also need planning approval from council, depending on your zone, overlays and how closely the design follows the local code. This guide sets out what decides which approvals you need, the order to work in, and the points where a town planner saves you time and rework.
TL;DR
An extension in Brisbane needs building approval before work starts, and may need planning approval as well. Brisbane City Council sets this out.
Planning approval is usually triggered when the design misses the acceptable outcomes of the relevant code, or when an overlay or neighbourhood plan applies.
Check your zone, overlays and easements before you pay for detailed drawings.
Rules differ by state and by council, so advice written for Sydney or Melbourne will mislead you in Queensland.
If you plan to turn the extension into a dual occupancy or a separate dwelling, the rules change, so settle that question first.
Table of Contents
Why Queensland extensions are not like Sydney or Melbourne
Most guides ranking for this topic are written for New South Wales or Victoria. They are accurate for those places and wrong for yours. States, territories and local governments control land development through different legislation and planning instruments, with councils regulating most local development.
Two examples show how far apart they are. In Victoria, whether you need a planning permit can turn on lot size: Boroondara, for instance, requires a permit for an extension on a lot under 300 m² in several residential zones. In NSW, nine approval pathways exist, including exempt and complying development. Neither framework applies to a house in Caboolture, Logan or Ipswich.
In Queensland, the Planning Act 2016 sorts development into prohibited, accepted and assessable. Assessable development can be code assessable or impact assessable, and it needs a development permit before it can proceed. Most simple house extensions never reach that stage, because they sit within the code. The ones that do are usually the ones with a problem on the site.
The two approvals you need to understand
Think of your extension as facing two separate questions.
Building approval
In Brisbane you need building approval before starting extensions, raising or renovations. A licensed building certifier assesses it, and your extension must comply with the Queensland Development Code. The certifier checks things like boundary setbacks, site cover and structural matters.
If your design does not meet every acceptable solution, for example a side setback that is tighter than the standard, the certifier can ask council for a referral agency response. Council then advises on the variation.
Planning approval
Planning approval asks a different question: is this use and form of development appropriate on this land? For an extension to an existing house in Brisbane, you assess against the Brisbane City Plan 2014. The relevant code is the Dwelling house code, or the Dwelling house (small lot) code. According to Brisbane City Council, you need planning approval if the project does not meet all the acceptable outcomes of the relevant code. Neighbourhood plan areas and overlays add criteria of their own.
The same council page notes that character overlays can matter. For example, external extensions on a site in the Traditional building character overlay generally need planning approval. If your house was built in or before 1946, check this before you fall in love with a design.
Other councils in South East Queensland, such as Moreton Bay, Logan and Ipswich, run their own planning schemes with their own codes. The logic is the same, but the thresholds and names differ. Always check your own council’s scheme.
A sensible order of work
The expensive mistake in extension planning is drawing first and checking later. This order avoids it.
Define the purpose. Extra bedroom, larger living area, a second storey, or a space that could later become a separate dwelling? The last one changes the approval type entirely.
Check the property. Look up your zone, overlays and any neighbourhood plan in your council’s online planning scheme map. For Brisbane that is City Plan online. Also check for easements, flood or bushfire mapping, and sewer or stormwater infrastructure near where you want to build.
Get early advice. A short conversation with a town planner or building certifier before design can tell you whether you are heading for a code-compliant job or an application.
Brief the designer with the constraints. Give your architect or building designer the setbacks, height limits and overlays up front.
Lodge the right applications in the right order. If planning approval is needed, it generally comes before the building approval can be finished.
Engage a builder once approvals are clear, so quotes match the approved plans.
What usually triggers planning approval
These are the situations we see most often tipping a simple extension into an application.
Trigger | Why it matters |
Design misses an acceptable outcome in the dwelling code | Needs assessment against the performance outcome, which means a planning application |
Character or heritage overlay | External works often need planning approval |
Neighbourhood plan area | Extra height, setback or design criteria apply |
Flood, bushfire, landslide or other hazard overlay | Floor levels, materials and siting may be controlled |
Extension close to infrastructure (sewer, stormwater easements) | Building over or near services may need approval from the service owner |
Use changes, such as adding a second kitchen or separate entry | May be assessed as a dual occupancy or other use |
Not every item on this list means refusal. It usually means the application needs to explain why the design still meets the intent of the code. That argument is what a planner writes.
When your extension is really a dual occupancy or granny flat
Many owners start with an extension and end up with two dwellings on one lot. If you add a self-contained unit, the proposal is no longer a house extension. In Brisbane, dual occupancy developments may be code assessable or impact assessable, and impact-assessable applications need public notification before a decision.
Other councils set their own thresholds. In Bundaberg, for example, a dual occupancy in a Low or Medium Density Residential zone that meets the code’s acceptable outcomes generally needs building approval only, while other proposals need a code-assessable application. That is a Bundaberg rule, not a South East Queensland rule, which is exactly why you check your own scheme.
If you are weighing a bigger project, a feasibility check on the site is worth doing before design. Our guide to site feasibility assessment explains what we look at.
Documents and timing
If you do need a development application, expect a staged process. After lodgement, the assessing authority checks whether the application includes everything mandatory. Under Queensland’s rules, the assessment manager must decide within 10 business days whether an application contains all the mandatory requirements. Incomplete applications stall at this step, so the quality of your first submission matters.
A typical package for an extension application includes:
a site plan showing existing and proposed buildings, setbacks and site cover
floor plans and elevations
a planning report addressing the relevant codes and overlays
specialist input where needed, such as flood, stormwater or tree reports
Councils may also offer faster pathways for simple matters. Ipswich, for example, determines Fast Track applications within five business days of receiving all relevant material. Check whether your council has a similar pathway. For the full sequence, see our step-by-step guide to the development application process in Queensland.
If you receive a show-cause notice or an information request, do not ignore it and do not rush a reply. Read exactly what the council is asking, note the deadline on the notice, and get advice on whether to respond, amend the design or seek more time. A considered reply is worth more than a fast one.
Budgeting an extension properly
Budget for more than construction. Extension costs that owners overlook include:
design and drawings
building certifier fees
council application fees, if planning approval is needed
consultant reports (survey, engineering, stormwater, flood)
service connection or relocation, such as sewer upgrades
a contingency for the unexpected
Fees are set by each council and change, so check your council’s current fee schedule rather than relying on a figure from a guide. We do not publish a fixed fee for our own work, because the scope depends on the site and the approval pathway. The City of Sydney notes that applicants may need to engage an architect, engineer or land surveyor to prepare an application, and the same applies here. Add those costs early.
Do you need a town planner?
Not always. If your extension is a modest, code-compliant addition on a site with no overlays, your designer and building certifier may handle it. A planner earns their fee when:
an overlay or neighbourhood plan applies
the design cannot meet an acceptable outcome and you need to argue for a variation
a neighbour objection or public notification is likely
the extension may change the use of the property
you have received an information request or show-cause notice
Town planners can prepare development applications, advise on development and design, and provide project-management services, according to Brisbane City Council. For a plain overview, read what town planners do.
How to choose one
Brisbane City Council suggests checking that the expert can provide the service you need, is qualified and insured, asking about previous projects and getting several quotes. You can also check whether a planner holds registered status on the Planning Institute of Australia’s public Members Register. Ask for examples in your council area. Local knowledge of how a particular council reads its own code is hard to replace.
Our perspective
The most common thing we see is a design finished before anyone has checked the site. The owner has paid for drawings, then learns an overlay or a sewer line changes what can be built. That is avoidable, and fixing it late costs more than checking early.
We approach extensions the way we approach larger projects: practically and with the commercial outcome in mind. We look at what the land allows, what the owner wants from it and whether a modest redesign avoids an application altogether. Sometimes the best advice is to adjust a setback and stay within the code. Sometimes a well-argued application is the right path. We cannot promise any outcome, because approval is a decision for the assessing authority, but a complete, well-reasoned application gives you the best footing.
We also think about what comes next. If the lot could one day support a second dwelling or a subdivision, an extension placed in the wrong spot can close that door. A short conversation now can protect that option.
— Jwal
Get your site checked before you design
We are Brisbane and South East Queensland town planners, based in Caboolture. We prepare and manage development applications for dual occupancies, townhouses, subdivisions and other residential and commercial projects, and we guide clients from the first site investigation through to lodgement. If your extension might touch an overlay, change the use of the property or lead to a second dwelling, talk to us before you commission drawings. See our services or the areas we service.
FAQ
Do I need council approval to extend my house in Brisbane?
You need building approval from a licensed certifier before starting work. You may also need planning approval from council if the design does not meet all the acceptable outcomes of the dwelling code, or if an overlay or neighbourhood plan applies. Check your property in City Plan online first.
Does a second-storey addition need a development application?
Not automatically. It depends on whether it meets the acceptable outcomes for height, setbacks and site cover, and on any overlays. A character overlay or neighbourhood plan can bring in planning approval, so check your site before design.
What if my extension does not meet the setback rules?
Your certifier can ask council for a referral agency response on the variation. If the issue goes beyond building provisions and misses a planning code outcome, you may need a planning application that explains how the design still meets the intent of the code.
Can I build an extension that becomes a separate dwelling later?
You can plan for it, but a self-contained unit is assessed as a different use, such as dual occupancy. The approval type and public notification requirements differ, so decide this at the start.
Can a town planner guarantee approval?
No one can. The council or assessing authority makes the decision. A planner can make sure the application is complete, addresses the right codes and presents the case clearly.
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