How to Legalise an Unapproved Secondary Dwelling - A Central Coast Council NSW Case Study

Context: "Dear StraightLine Planning, I need your help. I live on the Central Coast in NSW and I am about to buy a property that has a secondary dwelling incorporated into the lower level of the house. While it is permissible with consent in the LEP zone, it was never approved by council."

Understanding Building Information Certificates (BIC)

Building Information Certificate (BIC) – in plain English – is a certificate from the council that essentially says “we won’t take action against your building for now.” 

It’s used when building work was done without approval (i.e. unauthorised works) and you need to regularise it after the fact.

Under NSW law (the Environmental Planning & Assessment Act 1979), any structure built or altered without the required permits is considered illegal.

Since you generally cannot get a normal approval (DA or Construction Certificate) once something is already built, a BIC is the main tool to address the issue.

A BIC involves council inspecting the existing structure and checking it against regulations.

If the certificate is granted, it prevents council from issuing demolition or alteration orders for that building for a set time (usually 7 years).

In other words, council agrees not to force you to knock it down or fix anything major for those years.

This gives you peace of mind that your downstairs flat won’t be subject to sudden council enforcement.

However, a BIC does not officially “approve” the works or make them comply with today’s codes – it’s more like an assurance that council won’t take action about the unauthorised construction.

Think of it as a retroactive safety net, not a full-fledged approval.

When do you need a BIC? 

Typically, whenever you discover (or council discovers) that part of your property was built or modified without the necessary approvals.

In our case – an unapproved secondary dwelling on the lower level – a BIC would be needed to cover the physical building works that were done (new walls, kitchen installation, etc.) without prior sign-off.

Councils often request a BIC if they become aware of illegal works (for example, through a complaint or during an inspection)

It’s also common for buyers or sellers of a home to seek a BIC before sale, to ensure the house they’re trading isn’t carrying unapproved structures that council might object to later.

So if you’ve built a downstairs granny flat without permits, a BIC is usually the only way to legitimise the structure’s existence in the eyes of Council.

A BIC is your path to make the building itself acceptable to Council after-the-fact. It says “the Council won’t demand I tear this down”.

But it doesn’t give you permission to use the space as a secondary dwelling – that’s where a Development Application comes in, which we’ll cover next.

The Role of a Development Application (DA) and “Change of Use”

Legalising an unapproved flat isn’t just about the building – it’s also about the use.

In planning terms, creating a separate dwelling unit in your house is considered a change of use for that part of the property.

Originally, your downstairs area was just part of a single house. Now, you want to use it as an independent rental unit (a secondary dwelling or “granny flat”).

Even if the zoning (in the Central Coast LEP) permits secondary dwellings in your area, you still need to obtain development consent (approval) for that use.

A Development Application (DA) is the process to get development consent from Council. It’s essentially a formal request, with plans and documents, asking “Can I have approval to use/build this according to the rules?”.

For a new granny flat, you’d normally lodge a DA before construction. In our scenario, the construction happened already – but you still need a DA to approve the use of that space as a dwelling going forward.

Under NSW planning law, you cannot get a retrospective DA to legitimise works already done (no backdating).

However, you can lodge a DA now to approve the future or ongoing use of the already-built flat.

Essentially, Council can say “we grant consent for this part of the house to be used as a secondary dwelling from here on,” even though it was built earlier without approval.

This is often called a “regularisation DA” or simply a DA for use of an existing structure.

What does “change of use” mean? 

It means you are changing how the building (or part of it) is lawfully used.

In your case, the downstairs was probably just storage or part of the main house; now it’s a self-contained residence for a tenant – that’s a change from one dwelling on the lot to two dwellings on the lot.

Councils require consent for that because it can have implications (more occupants, parking needs, etc.).

The Central Coast Council’s Local Environmental Plan (LEP) defines a “secondary dwelling” as a self-contained dwelling on the same lot as the main house.

The Central Coast LEP 2022 (and the NSW Housing SEPP 2021) explicitly allow secondary dwellings in most residential zones with Council consent.

So the use is permitted in principle, but you must go through the DA process to get that consent.

In short, the DA is about planning permission. It addresses questions like: Does your property’s zoning allow a granny flat? (On the Central Coast, if you’re in a residential zone like R1, R2, etc., the answer is yes – secondary dwellings are permitted with consent.

Does your proposal meet the requirements – e.g. floor size limits (usually max 60m² or so), adequate parking or open space, etc.?

Council will assess those through the DA. This process also considers any “Environmental Planning & Assessment Act 1979” requirements and the Central Coast Council’s planning controls (the LEP and Development Control Plan).

The DA, if approved, gives you legal development consent to use that part of your home as a secondary dwelling.

Remember: BIC and DA serve different purposes. The DA handles the approval of land use and any planning considerations (“Can I have a secondary dwelling here legally?”).

The BIC handles the building’s status (“Is the structure safe and up to standards so Council won’t object to it physically?”). Both are needed to fully legalise an unapproved dwelling.

Which to Apply for First: BIC or DA?

Homeowners are often unsure whether to go for the building certificate first or the development application first.

It’s a bit of a chicken-and-egg scenario: the BIC won’t be issued if the use isn’t allowable, and the DA won’t cover the already-done building work.

In practice, the recommended approach – and what Council will expect – is to obtain your development consent (DA) for the use first, then follow up with the BIC for the existing building.

Central Coast Council (like others) will want to know that the secondary dwelling can be approved under planning rules before they agree not to take action on the structure.

In fact, when assessing a BIC for unauthorised works, one thing Council considers is “whether development consent would have been granted for the building if it had been sought”.

In other words, Council does a notional planning check: is this secondary flat something we’d approve? 

If the answer is no (maybe the zoning or site doesn’t allow it), they are unlikely to issue a BIC at all and may instead require it be removed.

But if you already have an approved DA for a secondary dwelling, it’s clear that the use is lawful – which strongly supports the BIC assessment.

Moreover, a BIC by itself cannot regularise an unlawful use.

It only addresses the physical works.

So even if you got a BIC first, you would still need to lodge a DA to get the use approved for rental.

For this reason, it usually makes sense to tackle the DA first (to secure the planning approval for the secondary dwelling) and then apply for the BIC (to cover the construction aspect).

Some councils may allow you to submit them in parallel, but generally the DA (use approval) should come before the BIC (building sign-off)

Here’s a simplified reasoning:

• Step 1: Get DA consent – This confirms legally you are allowed to have that second dwelling on your property. It deals with zoning, amenity, parking, etc.

• Step 2: Get BIC – This deals with the fact it was built without approval, verifying the structure is acceptable and protecting you from demolition orders.

If you were to do it the other way around (BIC then DA), you might spend time and money getting a building certificate, only to find your DA refused because of a planning issue – leaving you with a “legal building” that you still can’t lawfully rent out.

So, save the BIC for after (or at least make the BIC issuance conditional on the DA).

In many cases, the Council consent (from the DA) itself will include a condition like: “Within X months, obtain a Building Information Certificate for the unauthorised works.” 

This sequence ensures that use approval is in place before finalising the building’s status.

References to Central Coast Council’s process: 

While Central Coast Council doesn’t explicitly spell out “DA vs BIC first” on their website, their approach aligns with general NSW practice.

For instance, Bellingen Shire (another NSW council) notes that a BIC will consider whether Council has granted approval for the use of the structure– implying you should sort out the use approval (DA) prior to or in conjunction with the BIC.

Likewise, planning experts advise that “all applications for the use of a space, retrospective or otherwise, must be made by way of a Development Application”.

So, start with the DA to get your secondary dwelling use approved, then tackle the BIC to cover the building work.

Step-by-Step Guide: Legalising Your Secondary Dwelling

Legalising an unapproved lower-level unit can be complex, but breaking it into steps makes it manageable. Below is a step-by-step outline of the application process to follow on the Central Coast:

1. Do Your Homework (Planning Rules Check):

Find out what rules apply to secondary dwellings on your property. Check your zoning (use the Council’s online mapping tool or a Planning Certificate). On the Central Coast, most residential zones (e.g. R1 General Residential, R2 Low Density) allow a secondary dwelling with consent.

Verify the basic requirements: generally a secondary dwelling must be on the same lot as the main house, there’s a size limit (often 60m² or so), and it cannot be subdivided off.

Also, review the Central Coast Development Control Plan (DCP) for any specific design controls (setbacks, parking, private open space for the granny flat, etc.)

Essentially, ensure that in theory your as-built flat could comply with the planning controls. If something obvious is non-compliant (for example, no separate entry, or it takes up too much of the yard), you might need to make modifications before seeking approval.

2. Consult Professionals:

Engage a building designer or draftsperson to draw up plans of the existing secondary dwelling.

Even though it’s already built, you’ll need plans (site plan, floor plans, perhaps elevations) to submit with your DA and BIC applications.

Consider hiring a town planner like StraightLine Planning or consultant familiar with Central Coast Council – they can prepare the Statement of Environmental Effects (a report explaining how your proposal meets the rules) and navigate the process for you.

It’s often helpful to get a land surveyor to do a site survey, especially if boundary setbacks or site coverage is in question (many councils require a survey plan showing the buildings on the lot)

Since the construction is done, you should also engage a private building certifier or consultant early – they can inspect the secondary dwelling and identify any Building Code of Australia (BCA) compliance issues that need fixing, and later provide the necessary BCA compliance report for the BIC.

Likewise, a structural engineer may need to inspect and certify that the structure (e.g. any new walls or beams installed) is structurally sound.

Essentially, assemble a little team: a designer, a planner, and possibly an engineer and certifier, to prepare the documentation.

3. Prepare the Development Application:

Your DA will likely be titled something like “Change of use of lower ground floor to a secondary dwelling (existing unauthorised works)”.

Work with your draftsperson to get high-quality plans of the layout.

The town planner (or you, if DIY) will write the supporting report explaining how this secondary dwelling meets the LEP and DCP requirements, and addressing any issues (parking, privacy, fire safety, etc.).

Include details like: the secondary dwelling’s floor area, confirmation it has its own kitchen, bathroom, and entry, and how it remains ancillary to the main house (no separate ownership).

You’ll lodge the DA online via the NSW Planning Portal (Central Coast Council requires all DAs through this portal).

Make sure to include the owner’s consent (if you own the home, that’s you; if joint-owned, all owners sign).

Pay the DA fee (more on costs later). Once lodged, Council will allocate a DA number and begin assessment.

4. DA Assessment & Approval:

After lodgement, the Council planning officers will review your proposal. They will check it against the Central Coast LEP 2022 and Housing SEPP to confirm secondary dwellings are permissible on your land (which they are, with consent, in residential zones.

They’ll also use the DCP guidelines for things like whether there’s adequate parking (some councils require one extra parking space for a secondary dwelling, though this can vary), whether the private open space for both dwellings is sufficient, and any amenity impacts (for example, does the flat have reasonable fire separation from the main dwelling, does it maintain the appearance of a single house from the street, etc.).

Since this dwelling is within your existing house footprint, many issues like setbacks or overshadowing may already be fine – it’s more internal.

However, if your lower level was never intended as habitable space, expect questions about ceilings heights, light and ventilation (the space must meet housing standards).

Council may send you Requests for Information if something is missing or unclear.

They will also likely notify your neighbours about the DA (usually by a letter for a 2-week comment period) since you’re formalising an additional dwelling – don’t panic, secondary dwellings are common and as long as it’s been there without causing issues, neighbours rarely object.

After assessment, if all is in order, Council will grant development consent for the secondary dwelling.

You’ll receive a Determination Notice with conditions. One of those conditions (especially because it was unauthorised) will probably be to obtain a Building Information Certificate for the works within a certain time.

5. Meet Any Conditions and Prepare for the BIC:

Now that you have the DA approved , review the conditions.

Common conditions might include: installing interconnected smoke alarms, ensuring compliance with fire separation requirements (for instance, the ceiling between your flat and the upstairs might need fire-rated construction if considered separate dwellings – your certifier can advise on this), or perhaps some minor upgrades for safety.

You’ll need to comply with these as you move forward. At this stage, gather all documents needed for the BIC application.

Councils typically ask for: the architectural plans of the building, the survey report, the engineer’s structural adequacy certificate, and a BCA compliance report from a qualified building surveyor.

Essentially, you are compiling evidence that the as-built secondary dwelling is structurally sound and meets key building standards (or if not, what must be done to make it comply).

If any small works are needed to bring it up to code (say, additional ventilation or an extra light window, etc.), do them now as part of compliance.

6. Lodge the Building Information Certificate Application:

Using the NSW Planning Portal, you will lodge an application for a Building Information Certificate with Central Coast Council.

(On the portal, it’s a specific form for BIC – often listed under Post Consent Certificates.)

Submit all the documentation you gathered as attachments.

There will be a BIC application fee to pay (including a NSW Planning Portal lodgement fee).

Make sure to note on the form that it’s for existing unauthorised works (there may be a checkbox or description field). Once submitted, Council will schedule an inspection of the property.

7. Council Inspection & Assessment (BIC):

A Council building inspector (or team) will come out to physically inspect the secondary dwelling. They’ll look at the construction quality and verify the details in your documents.

Essentially, they want to ensure there are no evident safety issues or major non-compliances.

They might check things like: the ceiling height is at least 2.4m in living areas (per building code), the electrical and plumbing looks properly installed, there are no glaring fire hazards, etc.

They will also review their records to confirm the works were indeed done without approval and that a DA has now been granted for the use.

If everything looks acceptable, they will proceed to issue the BIC.

If they find problems, they might refuse the BIC or put it on hold and ask you to do certain rectifications.

Council can inform you of “work needed before the certificate can be issued” instead of outright refusal.

For example, they could require that an inadequate balustrade be fixed, or a window added to a bedroom that doesn’t meet light requirements, etc., and then you can have the BIC issued. (It’s in everyone’s interest to get to ‘yes’ on the BIC, so they often give you a chance to remedy issues.)

8. BIC Issuance:

If all goes well, Central Coast Council will issue the Building Information Certificate. This certificate will state that for the area covered (the lower level secondary dwelling) the Council will not take any action under the EP&A Act or Local Government Act to order demolition or alterations for a period of 7 years - (barring issues from normal deterioration).

In effect, your secondary dwelling’s structure is now tolerated as is.

Importantly, because you already secured the DA consent for its use, you now have both pieces of the puzzle: planning approval for the use and building approval (of sorts) for the works.

9. Ongoing Compliance:

Keep the BIC and the DA consent documents safe with your house records.

You may need to show them in the future (for instance, when selling the property or if any questions arise).

Note that a BIC prevents council from acting on those unauthorised works, but it doesn’t stop them from issuing fines for having done it illegally in the first place.

Often, councils have discretion – if you came forward proactively and fixed it, they may not fine you.

But be aware it’s a possibility (more on that below).

Also, a BIC is valid indefinitely for the works that existed at time of issue, but after 7 years, council regains power to issue orders relating to any deterioration of the building.

Many owners re-apply for a new certificate every 7 years if they still own the property, to keep that protection going.

Once these steps are done, your previously unapproved granny flat is legal: you have council’s blessing to rent it out and you can rest easy knowing it meets requirements.

(Side note: In some cases, instead of a BIC, an owner might pursue a Building Regularisation process via a private certifier by essentially obtaining a Construction Certificate and Occupation Certificate after the fact. However, NSW law doesn’t really allow issuing an Occupation Certificate for a building built without prior approval.

So the BIC path with council is the established route for illegal works.)

Does the Council Look Unfavourably on Retrospective Approvals?

A common worry is: “Will the Council be mad at me for doing this backwards? Am I less likely to get approved because it’s an illegal build?” It’s understandable to feel that way, but let’s clarify the Council’s perspective.

Firstly, Central Coast Council’s goal (like any council) is compliance, not punishment.

They want properties to be safe, lawful, and meet regulations.

Yes, they would have preferred you got approval beforehand, but if you’re now following the process to legalise it, they will assess your applications on their merits (objectively against the standards).

That said, councils are also charged with enforcing the rules, so they do take unauthorised works seriously.

For example, if Council becomes aware of illegal building works, they might issue fines (on-the-spot penalties up to $3,000) or formal orders to cease use or even demolish if you don’t act.

By applying for a DA/BIC, you are taking the correct remedial action, which generally will halt enforcement actions while your applications are considered.

Is a BIC/retrospective DA harder to get than a normal one? 

Not necessarily harder in criteria – the same planning and building rules apply.

In fact, Council must consider a BIC application on its merits just like any application, and if the building is sound and would have been approved normally, they should issue the BIC.

However, expect extra scrutiny.

You might find the Council officers a bit less “accommodating” with variations – since from their view, the work was done without oversight, they’ll carefully check everything now.

Central Coast Council notes that you must clearly demonstrate the unauthorised development meets relevant planning objectives and controls.

Essentially, there’s no leeway for corners cut: your secondary dwelling must fully comply with requirements (or be made to comply) as if it were being approved fresh. If something doesn’t meet code or standards, Council won’t brush it aside just because it’s already built – they’ll likely make you fix it or they won’t approve it.

There is a perception that councils are “less favourable” to approving things retrospectively.

It’s not so much that they will refuse out of spite; rather, they will be thorough and may impose consequences. For instance:

• Fees and penalties: Many councils charge higher fees for processing a BIC involving unauthorised works (to cover the extra work involved). Central Coast’s fees will include an additional assessment fee if works are illegal, and the overall cost can be higher than if you did it the right way first (more on fees in the next section). Council also can issue a penalty fine for the breach, even if they grant the BIC

• Wollongong City Council explicitly states that if a BIC is issued for unauthorised works, they may still fine whoever did the work without approval, as it’s a breach of the EP&A Act.

• No “fast-track”: Don’t expect any fast-tracking. In fact, you cannot request priority processing for a BIC on illegal works

• Possible skepticism: If something seems sub-par, Council might be a bit skeptical since they didn’t supervise its construction. For example, if your basement flat has plumbing installed, Council might require a plumbing inspection certificate to be sure it’s not leaking or improperly connected. They are essentially making up for the lack of inspections during construction. This can feel like they’re tougher on you, but it’s about ensuring safety.

However, if you present a well-prepared application and the secondary dwelling complies with all the rules, Council is generally supportive of legalising it.

Central Coast (and NSW in general) recognises that secondary dwellings are a valuable part of housing supply and that many exist informally.

They would rather have them approved and safe than underground.

In fact, one council states they may give “favourable consideration to a BIC application which may allow an unauthorised structure to remain” provided it meets the controls.

This means council isn’t out to get you – if your unapproved flat can fit the rules, they want to legalise it just as much as you do.

In summary, Council does not “hate” BIC or retrospective applications – but they will require full compliance and might enforce some penalties to underscore the importance of doing things correctly.

Treat the process professionally, meet all requirements, and you’ll be on the right side of the law.

Plenty of homeowners on the Central Coast have successfully navigated this, even if sheepishly, and now have fully approved granny flats.

Getting Help: Consultants You Might Need

Legalising an unapproved dwelling is not a simple DIY job for most homeowners.

Engaging the right consultants and professionals can make the difference between a smooth approval and a protracted saga. Here are the types of experts you may need and what they do:

• Private Certifier / Building Surveyor: Even though the final certificate (BIC) must come from Council, a private Building Certifier can be hired to inspect your secondary dwelling and provide reports on its building code compliance. They often prepare a BCA Compliance Report which details whether the dwelling meets the Building Code of Australia and what needs fixing if not.

• This report can be submitted with your BIC application to demonstrate compliance. They can also advise on fire safety measures, insulation, ceiling heights, etc., to meet code. Essentially, they act as your building standards expert.

• Structural Engineer: If your unapproved works involved any structural changes (e.g. removing a supporting wall, adding new beams, new concrete slabs, etc.), you’ll need a Structural Engineer’s report or certificate. The engineer will inspect the construction (maybe even open up part of a wall if needed) and then provide a Certificate of Structural Adequacy

• This certifies that the dwelling’s structure is sound and built to Australian Standards. Councils require this because they didn’t inspect the framing or structural work during construction (since it was unauthorised), so they need an engineer’s sign-off now.

• Building Designer / Draftsperson or Architect: You will need detailed plans of the secondary dwelling as it exists. A professional designer or architect will measure the space and draw up floor plans, elevations, sections, and a site plan. These plans are used in both the DA and BIC applications to show what has been built. Even if it’s “already there,” plans are essential documentation. They can also tweak the design if minor changes are needed to comply (for example, adding a window or adjusting a partition wall position).

• Town Planner (Planning Consultant): A qualified town planner can manage the development application process for you. They will prepare the planning report (sometimes called a Statement of Environmental Effects) explaining how your secondary dwelling meets all relevant provisions of the Central Coast LEP, DCP, and any state policies

• They will also be familiar with Council’s processes and can communicate with the assessing officers, respond to requests for information, and ensure nothing is overlooked. This can significantly ease the burden on you and improve your chances of approval, especially if you’re not familiar with planning jargon. On the Central Coast, there are planners who specialise in secondary dwelling or regularisation DAs.

• Land Surveyor: A survey may be needed to verify the building’s position on the site. If your secondary dwelling is wholly within your existing house, a survey is less critical than for a standalone granny flat, but it’s often still required to confirm boundaries, site levels, or lot dimensions. A survey plan can also prove that things like site coverage or floor space ratios are within limits. Central Coast Council may not insist on a new survey if you have an old one and the footprint hasn’t changed, but if any doubt, a surveyor’s plan is a good idea.

• Certifier (Occupation Certificate): Note, since the work was unauthorised, you typically cannot get an Occupation Certificate (OC) in the usual way (OC is issued after a building is constructed with prior approvals). The BIC kind of takes the place of an OC for these purposes. Some private certifiers can handle issuing an OC for an existing building but only if a valid Construction Certificate was in place, which it wasn’t. So for this process, focus on the BIC. Your private certifier’s role is more as an advisor and report-provider, rather than an approver in this case.

• Others (if needed): Sometimes a council might ask for a specific report – for instance, if your property is in bushfire prone land, a Bushfire Risk Assessment might be needed to ensure the dwelling meets bushfire construction standards. Or if there are plumbing additions, a licensed plumber might need to certify the drainage. These are case-by-case. Generally for a straightforward internal flat, you won’t need too many specialty reports.

While it’s an investment to hire these professionals, it pays off by smoothing the process.

They speak the council’s language and help ensure your paperwork is complete. As Central Coast Council itself advises: use the relevant experts to get all required documentation in order.

This will prevent delays and back-and-forth with Council asking for more info.

Costs and Timeframes

How much will this all cost, and how long will it take? 

These are crucial questions for homeowners.

Let’s break down both the typical costs and the expected timelines for legalising your secondary dwelling on the Central Coast, using recent data and trends.

Typical Costs Involved

• Development Application fees: The DA fee is usually based on the estimated cost of the development. Since the physical work is done, one might use the value of that work. If, say, the cost to fit out the lower level was $50,000, the DA fee as per Council’s fee schedule might be in the ballpark of a few hundred dollars (perhaps $500–$800; councils have sliding scales). There is also a flat Planning Portal lodgement fee (currently around $45) for all DAs

• If your property needs notification (which it will), there may be an advertising fee (~$200). In some cases, councils double the DA fee for retrospective applications (as a penalty) – check with Central Coast Council if they impose any surcharge for “already commenced development.” (Many NSW councils did this in the past, but the practice is less common now; instead they rely on BIC fees for penalties.)

• Building Information Certificate fees: The BIC has its own fees. NSW’s EP&A Regulation prescribes BIC fees based on the building type and size. For a dwelling, typically it might be around $250–$500 base fee per dwelling, plus possibly a calculation based on floor area. For unauthorised works, councils also charge an additional fee. For example, Wollongong Council’s schedule shows $500 per dwelling plus, for unauthorised work, an extra amount equal to the normal development + construction certificate fees that would have been paid

• In practice, that means you pay roughly what you “skipped” by not getting approval originally. So if your DA and Construction Certificate would have cost $1,000 total, you pay that on top of a base fee. Central Coast Council’s exact fee schedule will be similar (they follow the state regulations). So budget a four-figure sum for the BIC fees – often in the $500–$1500 range. There is also a $45 portal fee for lodging the BIC online, similar to the DA.

• Professional reports and plans: These will likely be your bigger expense:

  • Hiring a draftsperson/architect for measured drawings might cost around $1,000 – $2,000 depending on complexity.

  • A town planner to handle the DA and paperwork could be another $1,000 – $2,000 (some charge hourly, others a package).

  • Engineering report: a site inspection and structural certificate might be a few hundred dollars (say $500).

  • BCA compliance report by a certifier: This could be around $500–$800. Sometimes certifiers charge more if the project is complex because they must detail all code compliance issues.

  • If you need a new survey, that could be $1,000 or so.

  • Any additional specialist report (bushfire, etc.) could be a few hundred if required.

Overall, it wouldn’t be unusual for the total out-of-pocket cost to legalise an unauthorised granny flat to be on the order of a few to several thousand dollars (perhaps $3,000–$7,000 all told, including fees and consultant costs).

Every case varies – if minimal fixes and paperwork, it could be on the lower end; if lots of upgrades needed, higher.

While it’s not cheap, consider that it significantly protects your property value (an illegal dwelling can drag down resale price or derail a sale, whereas a legal secondary dwelling can add value through rental income).

• Potential fines: If Council decides to issue a penalty for having carried out development without approval, the fine for a home owner can be up to $1,500 (and up to $3,000 for a company) per offense

• And in extreme cases of defiance, the Land & Environment Court can impose much larger fines (even $1.1 million max)but that’s for serious environmental breaches or continued non-compliance, typically. For a one-off unapproved flat, if you’ve been cooperative, a fine might not be issued at all, or just one fine at the time of the initial notice. It’s somewhat discretionary. There will also be a fee for the building certifier to issue an Occupation Certificate if that route were possible, but since we’re doing BIC, that’s not applicable.

Bottom line on costs: Be prepared to invest a few thousand dollars. It’s a significant outlay, but it’s the price to pay for peace of mind and legality. Compared to the potential fine or the cost of tearing out the unapproved works, it’s the sensible route.

Expected Timeframes

Development Application timeframe: 

Central Coast Council, like many councils, has had backlogs in processing DAs. Recent data (early 2024) showed that the average DA processing time on the Central Coast was about 133 days (over 4 months) which is slower than the NSW state average of ~114 days.

That’s an average – some DAs are quicker, some slower.

A secondary dwelling change-of-use DA is relatively small, but since it’s not complying development, it goes through the full assessment. Expect around 2 to 4 months for the DA approval in a typical scenario.

If you’re lucky and everything is straightforward, it might be faster (statutory target is 6-8 weeks for simple DAs).

But given Council’s backlog, prepare for possibly 3+ months.

You can help by ensuring your application is complete and responds to all rules – that reduces “stop the clock” requests for more info.

Also note any neighbor notification period (usually 14 days) and perhaps Council meeting cycles if needed (though unlikely a minor DA would go to a full Council meeting unless there were objections or variations).

BIC timeframe: 

Once you’ve got the DA, the BIC process is usually quicker. Central Coast Council mentions a typical assessment time of about 10 working days (2 weeks) for BIC applications that have all required info and no illegal works.

However, for applications involving unauthorised works, this timeline does not apply.

In reality, the BIC might take a few weeks to a couple of months. There’s an inspection to schedule, and if Council requests further info or corrective work, that adds time.

Anecdotally, some BICs for simple cases are issued within 3-4 weeks, whereas complex ones can drag on for a few months especially if iterative fixes are needed.

A lot will depend on how quickly you can respond to any Council requirements.

For example, if the inspector says “add a handrail, then we’ll sign off,” the faster you do it, the faster you get the certificate. As a conservative estimate, allow 1-2 months for the BIC process from application to outcome.

Overall sequence time: If we add it up, from the day you start preparing to the day you have approvals in hand could be on the order of 4 to 6 months (perhaps up to 9+ months in worst case). Here’s a possible timeline:

• 2-4 weeks to gather documents and lodge DA.

• 2-4 months for DA determination.

• 1-2 weeks to address any DA conditions (like get final reports ready).

• 2-8 weeks for BIC issuance after application.

The key is to stay on top of requirements and maintain communication with Council.

It’s worth starting the process as soon as possible, especially if you’ve been prompted by Council (to avoid further enforcement).

During this period, you might choose to hold off on renting the dwelling to anyone new until it’s legal (to avoid compounding any “unauthorised use” issue). Once legalised, you can officially advertise it for rent without worry.

The Bigger Picture: Housing Trends and Stats on Secondary Dwellings

It’s worth noting why so many people build secondary dwellings (even sometimes without approval) and how this trend is playing out, especially in regions like the Central Coast.

Understanding the broader context can be helpful – and you might even use this info to explain to a curious neighbour or a buyer in future why that downstairs unit exists.

Housing affordability and demand: 

Across NSW, secondary dwellings (granny flats) have become popular as a way to create affordable rental accommodation or space for extended family.

The Central Coast, in particular, with its mix of urban and suburban areas and an aging population, has seen a rise in granny flats as a solution for elderly parents or as income generators.

They are an important piece in the housing puzzle – providing relatively low-cost rentals and helping homeowners with mortgage support through rental income.

The NSW government recognised this and about a decade ago made it easier to get approval for granny flats (even via fast-tracked complying development in many cases).

Statistics: 

Secondary dwellings now make up a significant chunk of new housing approvals.

In fact, in greater Sydney, over 5,000 secondary dwellings were approved in one recent year, constituting more than 10% of all housing supply that year.

For NSW as a whole, surveys show that in 2017 over 5,900 granny flats were built, and even in 2022, around 4,500 were built across NSW.

That’s thousands of new small homes each year.

On the Central Coast, council’s housing strategy notes that secondary dwellings are a key part of meeting housing needs for the community. (Central Coast specific approval numbers aren’t published separately, but out of the 1,600 total dwellings approved on the Coast in the 12 months to March 2024 a portion of those would include secondary dwellings – it’s a growing trend here as well.)

This rise is driven by the housing affordability crisis – with median rents high, a self-contained flat in someone’s downstairs or backyard can offer cheaper rent to a tenant and extra income to the owner.

It’s a win-win when done legally. The government also encourages it as gentle density increase without changing neighbourhood character drastically (one reason such developments are generally allowed in residential zones).

Legalising an unapproved lower-level secondary dwelling on the Central Coast involves obtaining a Building Information Certificate for the works and a Development Application consent for the use.

It may seem daunting, but by understanding each step – what a BIC is, why a DA for change of use is needed, which to do first (DA before BIC), and how to navigate the process – you can approach it with confidence.

Always refer to the Environmental Planning & Assessment Act 1979 and your local planning instruments (the Central Coast LEP and DCP) as the guiding legal framework, and don’t hesitate to use professional help.

Yes, it will require some investment of time and money, and Council will scrutinise the unauthorised works but at the end of the road you’ll have a fully legal, Council-approved secondary dwelling that can provide rental income and peace of mind.

Given the popularity of secondary dwellings and their role in easing housing stress, bringing yours into compliance is not just about avoiding penalties – it’s about making a legitimate contribution to housing in the Central Coast community, one granny flat at a time.