Top 10 DA Refusal Mistakes and How to Fix
August 20, 2026by Alex MachkevitchBlogDual OccupancySubdivision
Most DA refusals and delays come down to the same handful of errors
A Development Application that is refused, or that sits with Council for eight months collecting requests for information, is rarely the victim of an unusual or unlucky site. In most cases the problem was built into the application well before it was lodged, usually during the design and preparation stage.
The mistakes below are the ones we see most often across residential and commercial applications in NSW. None of them are difficult to avoid, but almost all of them are expensive to fix once the plans are finalised and the application is in Council’s hands. If you are unfamiliar with the process itself, our companion article covers how the DA process works from preparation through to determination.
1. Designing first and checking the planning controls and site constraints later
One of the biggest mistakes is getting too far into the design before understanding what the site can actually accommodate. Height, setbacks, floor space ratio, heritage, flooding, bushfire and trees can all fundamentally influence the design. Discovering these constraints after the plans are largely complete means significant redesign, additional consultant costs, and delays or issues with Council during assessment.
Planning controls are only part of the picture. Easements, rights of carriageway, covenants, restrictions, sewer infrastructure and other matters affecting the title can also place significant limitations on what can be built. A title and site constraints review should form part of the early due diligence process.
2. Not understanding who needs to provide owner’s consent prior to submission
Written consent must be provided by the registered legal land owner, or all co-owners, company directors, or the owners corporation for the affected property, before a DA can be lodged and processed. This can involve more than just the person proposing the development. Company ownership, multiple registered land owners, and strata or community title arrangements all affect the signatures required at lodgement. Getting this wrong can delay preparation and lodgement, or require documents to be corrected after submission.
If the property is part of a strata scheme, obtaining consent can be more complicated than simply having the unit owner sign the DA. Depending on the proposed works and the strata arrangements, approval from the Owners Corporation may be required before the application can proceed. This may involve putting the proposal to the strata manager, or having the matter considered at a strata meeting and obtaining a formal resolution. That can add significant time, particularly where meetings are held periodically or the proposal is contested by other owners. Even where an owner supports the development, they may not have authority to provide consent on behalf of the Owners Corporation.
3. Underestimating building compliance requirements
This is a frequent and costly oversight on commercial sites, particularly for alterations and additions or change of use applications for a new business operation. Applicants assume that because the building already exists, only the new works need to meet current standards.
In reality, a change of use or significant alteration can trigger the need to upgrade the entire building, substantial parts of it, or at minimum the area being used for the new use and the pedestrian access to that area from the public street. This may include works to comply with the current National Construction Code, covering fire safety, access and egress, disability access under the Premises Standards, energy efficiency, and other BCA provisions.
This becomes critical where premises are being leased, or where an incoming tenant’s fit-out or business operations depend on council approval. Landlords and tenants can discover late in the process that the DA or CC requires extensive upgrades that were not expected and may not be feasible. Early engagement with an experienced building surveyor to identify whether the site is suitable for the new use, and the full scope of potential upgrade requirements, is essential.
4. Leaving specialist reports until the end
Specialist reports should not be treated as work that can simply be completed once the architectural plans are finalised. An arborist, flood consultant, heritage consultant, bushfire consultant or stormwater engineer may identify site constraints or planning requirements that require changes to the design. Seeking preliminary advice too late means redesigning after substantial work has already been done, rather than allowing that advice to inform the design from the beginning.
5. Submitting incomplete or poorly prepared documentation
Many applications are lodged with a Statement of Environmental Effects that simply restates the proposal rather than properly assessing it against the relevant planning controls, zone objectives and site constraints. Missing or inconsistent plans, outdated surveys, or failure to address key issues such as privacy, overshadowing, traffic, stormwater, bushfire, flooding or heritage almost always trigger RFIs and delay assessment.
An experienced town planner significantly reduces this risk by reviewing the full package before lodgement, ensuring the Statement of Environmental Effects addresses all relevant controls and site constraints, identifying missing or inconsistent plans and reports, and coordinating the necessary inputs.
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6. Assuming that ‘existing’ means ‘approved’
A common mistake is treating everything physically present on a site as lawfully existing. In planning terms, lawfully existing means what has been lawfully approved, constructed under valid exempt or CDC provisions, or otherwise legitimised. Anything outside those categories may be considered unauthorised and cannot safely be treated as a baseline for a new proposal.
Garages, extensions, decks, outbuildings, rooms, swimming pools, carports and even internal alterations may look established and long-standing, yet many were built without any recorded approval. Council planners are required to assess the proposal against the lawfully existing development on site. This commonly triggers RFIs, the need to regularise unauthorised works through a separate or concurrent application, or in more serious cases refusal, because the impacts cannot be properly evaluated and the documentation is considered inconsistent or inaccurate.
For example, an extension proposed over an existing deck seems simple, with no change to site coverage or landscaped area. But if that deck was never approved and the area beneath it is recorded as landscaped area under the original consent, Council will assess the extension against the approved landscaped area, not the existing site conditions, and the proposal may fall short of landscaping or site coverage requirements. Similarly, replacing an existing carport with a new garage looks like a like-for-like swap, but if the carport was never approved it cannot be relied upon to justify the size, height or location of the new garage. Council will assess the proposal as though the carport does not exist.
The same issue arises in a commercial context, where a business lodges a change of use or extension of trading hours application without recognising that works undertaken to support its expanded operations, such as a fitout into an adjoining tenancy or an altered internal layout, were never approved. Council may require those works to be regularised before the current application can proceed.
7. Designing in isolation from the local context and streetscape
Applicants often focus so heavily on maximising yield that the design ends up appearing out of place in its street and neighbourhood context. A proposal that ignores prevailing setbacks, roof forms, materials, landscaping patterns or the established rhythm of the street can struggle even when it meets the written controls. Councils across NSW increasingly expect proposals to demonstrate how they respond to, and positively contribute to, the existing and desired future character of the locality, not just how they fit within the numerical envelope.
8. Assuming a variation will be supported by Council
Designing outside the planning controls on the assumption that Council will simply accept the variation is a common and costly error. While the DA process allows Councils to consider justified variations in some circumstances, this is not a guarantee. A proposal relying on multiple or significant departures from the controls is much harder to justify and may result in major design changes being required, or refusal. It is generally better to start with a design that works within the controls and seek variations only where there is a genuine site-specific planning reason.
Equally costly is relying on unapproved works, or works approved under past planning controls, as a precedent to support a variation to the current controls. Applicants sometimes argue that because a neighbouring property, or their own, has a non-compliant setback, height, floor space ratio or landscaped area, the proposed variation should be accepted on the same basis. This line of reasoning almost never succeeds.
9. Not allowing enough time or budget for Council RFIs or design changes
Applicants frequently budget for the initial set of architectural plans and consultant reports while underestimating how often a DA requires minor or major redesign during assessment. Council RFIs, advice from external referral agencies, neighbour objections and compliance issues regularly mandate changes to DA documentation. Where architectural plans are amended, the accompanying consultant reports and plans usually need updating too, causing further delays and additional consultant fees.
Where no allowance has been made in the project timeline for these amendments, the process quickly becomes stressful. Applicants can find themselves under pressure to accept a compromised design simply to keep the application moving. Building a realistic timeline in from the beginning allows flexibility to respond properly to Council feedback and secure a better outcome.
10. Not understanding the difference between planning approval and construction approval
A DA determines whether a proposal is acceptable from a planning perspective, assessing matters such as zoning, height, setbacks, impacts on neighbours and consistency with planning controls. Once consent is granted, many applicants assume they can proceed straight to building.
In reality, DA consent is only the first step. Before construction can begin a Construction Certificate must be obtained. This stage focuses on technical and building code requirements: structural design, fire safety, accessibility, stormwater, sewer, service provider engagement, and compliance with the National Construction Code and Building Code of Australia. Depending on the works, separate approvals may also be required from Council under other legislation, such as the Roads Act for new services within the road reserve or a new vehicular crossing. The timing of these depends on Council’s own processing timeframes rather than the applicant’s. Overall, the CC process can take 1 to 3 months for a simple project such as an extension to an existing house, or 3 to 6 months for an entirely new building.
How do I avoid these mistakes on my own application?
Almost every item on this list is resolved the same way: front-load the work. Confirm the zoning, planning controls, title constraints and approval history of the site before the design is drawn. Identify which specialist reports are needed and get preliminary advice from those consultants early enough that it can shape the plans. Confirm who is legally required to sign the owner’s consent. Then have the full package reviewed against the Council’s submission requirements before it goes onto the Planning Portal.
Done properly, this adds a few weeks at the front of a project. Skipped, it routinely adds several months at the back of one.
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