Regulation Decoded
Granny Flat Approval in NSW (2026): The Rules, the CDC Process, Real Costs and How to Get Approved in Sydney
Everything a Sydney homeowner needs before building a granny flat: whether you need council approval, the 450 m² and 60 m² rules, when a private certifier can approve it in weeks and when it has to go to council, what it really costs from drawings to keys, and the mistakes that get granny flat applications refused. Written by the registered certifiers at Built Smart Solutions, who approve, inspect and sign off granny flats across Sydney and regional NSW.
CURRENT AS AT 2 OCTOBER 2026
22 MIN READ
BY BUILT SMART SOLUTIONS
SEO/AI under the hood (amended per review actions 2 & R4): exact-match H1 restored per audit 2.1 – the personality line survives as the subhead · URL /services/certification/ per the audit keyword map · meta description: “Principal Certifier Appointment, Construction & Occupation Certificates and Complying Development (CDC) from one specialist, ISO 9001-certified team – approval to occupation.” (adopted from Option 1’s written set) · the “Quick Answer” block is deliberately extractable – it’s the sentence we want ChatGPT/Gemini/AI Overviews to quote · FAQPage + Service schema · 800+ words at full build · division-coded breadcrumb.
Quick answer
Yes, every granny flat in NSW needs approval. A granny flat (legally a secondary dwelling) is a self-contained second home of up to 60 m² on the same lot as an existing house. If the lot is at least 450 m², has a frontage of at least 12 m at the building line (more on lots over 900 m²), is in Zone R1, R2, R3 or R4 where a dwelling house is permissible, and the design meets every standard in the State Environmental Planning Policy (Housing) 2021, a registered private certifier can approve it with a Complying Development Certificate (CDC), with no DA. The certifier must determine it within 10 days, or 20 days where neighbour notice is required, which covers most of metropolitan Sydney. If any standard is missed (small lot, heritage item or heritage conservation area, over 60 m², setbacks, certain flood or bushfire land) it needs a development application, which in Sydney usually takes several months.
The approval side of a Sydney granny flat is priced against the site and the design, not a list: the certification package (CDC, Principal Certifier, mandatory inspections and Occupation Certificate), the survey, drawings, engineering and BASIX, and any council contribution. Construction is separate. Built Smart Solutions is a Sydney-based team of registered certifiers that checks eligibility, issues the CDC, carries out every inspection in person and issues the Occupation Certificate on a fixed fee.
Key takeaways
- No granny flat is “exempt”. A secondary dwelling is a home with a kitchen and bathroom; it always needs a CDC or a DA, a Principal Certifier and an Occupation Certificate.
- The four numbers to check first: a lot of 450 m² or more, a frontage of at least 12 m at the building line (more on lots over 900 m²), a granny flat of no more than 60 m² measured to the outside of its walls, and one principal dwelling on the lot.
- CDC is the fast lane: on a qualifying lot, a private certifier approves it in weeks instead of months, with neighbours notified but no objection rights.
- Miss one standard and it is a DA. Heritage items, heritage conservation areas, lots under 450 m², excessive height or setbacks, and some flood and bushfire land are the usual knock-outs.
- Approval is a small slice of the budget. The certification fee is small against the build; the expensive mistakes are building without approval, skipping an inspection, or changing the design on site.
- A granny flat cannot be sold separately. If you want two titles, look at a dual occupancy or a Pattern Book design instead.
- Built Smart Solutions in Sydney can confirm eligibility before you pay for drawings, issue the CDC, inspect every stage in person and sign off the Occupation Certificate, all on one fixed fee.
What a granny flat is in NSW (and what it is not)
“Granny flat” is the everyday name. The legal name in NSW is a secondary dwelling: a self-contained dwelling that sits on the same lot as a principal dwelling, is within, attached to or separate from it, and has its own kitchen, bathroom and living area. Despite the name, most Sydney granny flats are rented to tenants or used by adult children, carers or extended family, and they can be rented to anyone.
A granny flat is defined by four features:
- It is secondary. There must be one principal dwelling on the lot; the granny flat is the second home, not the first.
- It is small. Under the complying development standards the floor area is capped at 60 m², measured to the outer face of the walls (or a larger figure if another planning instrument allows it).
- It is self-contained. Kitchen, bathroom and living space, so it is a dwelling under the National Construction Code (a Class 1a building), not a studio or a shed.
- It shares the title. A granny flat cannot be subdivided off and sold separately. It is part of the same property as the main house.
What it is not: a home office or teenage retreat without a kitchen (that is usually a Class 10a outbuilding with different rules), a second full-size house (that is a dual occupancy), or a short-term holiday unit operated separately from the home (that brings in the short-term rental accommodation rules as well). Getting the classification right is the first thing a certifier checks, because it decides which code applies.
Do you need council approval for a granny flat?
You need approval, but not necessarily council approval. That distinction is why the search is so common and the answers online are so confused.
NSW has three approval pathways for building work: exempt development (no approval at all), complying development (a CDC from a private certifier or council) and a development application (a DA to council). A granny flat is a dwelling, so it is never exempt. That leaves two routes:
- Complying Development Certificate (CDC). If the lot and the design meet every prescribed standard, a registered private certifier such as Built Smart Solutions can issue the approval directly. Council is notified but does not assess it.
- Development Application (DA). If the lot or the design cannot meet a standard, the consent authority, usually the council, assesses the granny flat on merit against its LEP and DCP and the Housing SEPP. After DA consent, a Construction Certificate is still needed before work starts.
Either way you also need a Principal Certifier appointed before work begins, mandatory inspections during the build and an Occupation Certificate before anyone moves in.
Building a granny flat without approval is not a paperwork shortcut. Council can order the work to stop, be altered or be demolished; insurers can refuse claims; lenders will not value it; and when you sell, the buyer’s solicitor will find it. There is no simple retrospective fix: an approval cannot authorise work that has already been done, so getting an existing unapproved granny flat into a lawful position usually means investigation, upgrade works and specialist advice, and it routinely costs more than approving it properly in the first place.
Granny flat eligibility checklist: the rules for a CDC
The complying development standards for secondary dwellings sit in the State Environmental Planning Policy (Housing) 2021, with the general complying development requirements and exclusions in the Exempt and Complying Development Codes SEPP 2008. A granny flat qualifies for a CDC only if every line below is met.
| Requirement | Standard | How to check |
|---|---|---|
| Zone | Zone R1, R2, R3 or R4 (or an equivalent zone) where a dwelling house is permissible. Zone R5 Large Lot Residential is not covered by the complying development pathway | Council LEP zoning map; section 10.7 planning certificate |
| Lot area | At least 450 m², unless the granny flat is created entirely within the existing house | Deposited plan or survey |
| Lot width | Frontage to the primary road at the building line of at least 12 m for lots of 450 to 900 m², 15 m for lots over 900 m² up to 1,500 m², and 18 m above that. A battle-axe lot needs an access laneway at least 3 m wide and a 12 m by 12 m area clear of it. Lawful access to a public road is required | Survey |
| Existing house | One principal dwelling on the lot (existing or approved at the same time); only one secondary dwelling | Site inspection; approval history |
| Floor area | No more than 60 m² (or a larger area another planning instrument permits), excluding attached ancillary structures. The principal dwelling, granny flat and enclosed attached structures together are capped at 330 m², 380 m² or 430 m² depending on lot size | Drawings, measured to the outer face of the external walls at 1.4 m above floor level |
| Height | Maximum 8.5 m above existing ground level; no basement and no rooftop terrace | Survey levels and elevations |
| Setbacks | Side: 0.9 m on lots of 450 to 900 m², 1.5 m up to 1,500 m² and 2.5 m above that, plus 25% of any height above 3.8 m. Rear: 3 m, 5 m or 10 m by lot size, plus 3 times any height above 3.8 m, up to 8 m, 12 m or 15 m. Front: the average of the two nearest dwellings on the same side within 40 m, or a set distance by lot size | Site plan against the Housing SEPP standards |
| Landscape and open space | Landscaped area of 20% to 45% of the lot depending on size, at least half of it behind the building line; more than 24 m² of principal private open space, which the two dwellings can share; site coverage no more than 50%, 40% or 30% depending on lot size | Site plan calculations |
| Land exclusions | Not a heritage item or draft heritage item; not in a heritage conservation area (unless the flat is entirely within the existing house); not environmentally sensitive land or other land caught by the Codes SEPP general exclusions. On a flood control lot, not on the parts certified as floodway, flood storage, flow path or a high hazard or high risk area, with flood standards for the rest. On bush fire prone land, the Planning for Bush Fire Protection, access, water supply and gas standards apply | Section 10.7 certificate; LEP hazard and heritage maps; flood and bushfire reports |
| Building code | Complies with NCC Volume Two as a Class 1a building, including fire separation, waterproofing, energy efficiency and BASIX | Construction drawings, engineering, BASIX certificate |
If every line is a yes, the granny flat is very likely CDC-eligible. If any line is a no or a maybe, stop before paying for full drawings and get the pathway confirmed. A short eligibility check by a certifier costs a fraction of a redraw, and it is the first thing Built Smart Solutions does on every granny flat CDC.
Order the section 10.7 planning certificate from council before anything else. It tells you the zone and many of the constraints on the land in one document, usually within a few days. It is not a clearance, though: it says whether land is bush fire prone but not its bushfire attack level, it does not say which parts of a flood control lot are floodway or flood storage, and a council can state that it does not have enough information. Send it to your certifier with a photo of the backyard and a rough idea of where the granny flat will go, and you will know your pathway within a day.
CDC vs DA for a granny flat
| Factor | CDC (complying development) | DA + Construction Certificate |
|---|---|---|
| Who approves | Registered private certifier (or council acting as certifier) | Consent authority (usually the council), then a certifier for the Construction Certificate |
| Assessed against | Fixed numeric standards in the Housing SEPP plus the NCC | Merit: LEP, DCP, Housing SEPP, impacts, submissions |
| Statutory time to approval | 10 or 20 days: 20 where neighbour notice is required, which covers most of metropolitan Sydney | Often several months in Sydney, plus time for the CC |
| Neighbour notification | Yes, where the notification rules apply (most of metropolitan Sydney), but no objection rights | Yes, with submissions that can delay or change the outcome |
| Planning consultant needed | No | Usually: Statement of Environmental Effects and possibly a town planner |
| Approval fees (excluding construction) | The certifier’s fee for one certificate, plus drawings and reports | Council DA fee, Statement of Environmental Effects, a separate Construction Certificate and the certifier’s fee |
| Design flexibility | Low: every standard must be met | High: variations can be argued |
| Best for | Standard Sydney lots of 450 m²+ with a straightforward design | Small, narrow, heritage, sloping or constrained lots, or designs over 60 m² where the LEP permits a larger secondary dwelling |
If your site qualifies, the CDC is faster, cheaper and more certain. If it does not, a DA is not a failure; it is the correct pathway, and it goes much better with a well-prepared application. Built Smart Solutions’ town planning team handles granny flat DAs and Statements of Environmental Effects when the CDC route is closed, and our planning advisory guide explains how a DA moves from feasibility to consent.
When a granny flat cannot use the CDC pathway
These are the situations we see most often in Sydney that push a granny flat out of complying development and into a DA:
- Lot under 450 m² or below the minimum frontage for its size. Common on older inner-west, eastern suburbs and terrace lots.
- Heritage item. If the property itself is a listed heritage item, complying development is not available. A heritage conservation area also rules out an attached or detached granny flat as complying development; only a granny flat created entirely within the existing house remains available.
- Granny flat over 60 m². Even a few square metres over, measured to the outer face of the external walls, closes the CDC pathway unless another planning instrument permits a larger area, and the same cap applies to a DA.
- Bush fire prone land that cannot meet the bushfire standards. The Housing SEPP requires conformity with Planning for Bush Fire Protection, the building within 200 m of a public road, suitable access, a suitable water supply and gas safety measures. Sites rated BAL-40 or Flame Zone need specific advice before anything is designed.
- Flood-affected land. The parts of a flood control lot certified as floodway, flood storage, flow path or a high hazard or high risk area are excluded, and the rest must meet the flood standards.
- Environmentally sensitive land, foreshore areas and some land with easements or restrictions on title that the granny flat would breach.
- Setbacks or height that cannot be met because of the shape, slope or existing structures on the lot, or a design with a basement or rooftop terrace.
- Zone R5 Large Lot Residential, which the complying development pathway does not cover.
- Unapproved existing structures on the lot. A certifier cannot rely on, or build next to, work that has no approval; its status has to be resolved first.
Our article on the fast-track assumption explains why we confirm CDC eligibility before anyone draws a line. It applies to granny flats more than any other project type.
Design rules: size, height, setbacks, fire separation and BASIX
Passing the planning standards gets you to complying development. The building also has to comply with the National Construction Code as a Class 1a dwelling. These are the technical rules that most often shape a Sydney granny flat design.
| Rule | What it means in practice | Where it comes from |
|---|---|---|
| 60 m² floor area | Measured to the outer face of the external walls at 1.4 m above floor level, excluding eaves, stairways and voids. An attached garage, carport or deck is excluded from the 60 m² test, but if it is enclosed by walls higher than 1.4 m it counts towards the total floor area cap for both dwellings | Housing SEPP |
| Fire separation | External walls within 900 mm of a side or rear boundary, or within 1.8 m of the main house, must be fire-resisting construction, with protected openings | NCC Volume Two |
| Ceiling height | Minimum 2.4 m in habitable rooms (lower allowed in some areas such as bathrooms and laundries) | NCC Volume Two |
| Waterproofing | Wet areas to AS 3740, inspected before they are covered | NCC and mandatory inspections |
| Smoke alarms | Hard-wired, interconnected where more than one | NCC Volume Two |
| Energy, water and thermal | A BASIX certificate for the granny flat is mandatory with the CDC or DA, and the commitments the certificate requires the certifier to monitor are checked before the Occupation Certificate | BASIX (NSW) |
| Livable housing | NSW has not adopted the NCC 2022 livable housing design provisions for Class 1a buildings, so they are not a requirement for a granny flat; design for accessibility where the brief calls for it | NCC NSW variation |
| Stormwater | Must connect to the existing system or an approved discharge point; on-site detention may be required by council | Council requirements and conditions |
| Services | In Sydney Water’s area of operations, a Tap in check for building over or near water and sewer assets; elsewhere, the local water utility | Sydney Water |
Fire separation is the rule that catches out the most kit-home and transportable designs. A granny flat squeezed close to a side boundary or to the back of the house needs fire-rated walls and protected windows, and that has to be on the drawings at CDC stage, not discovered at the frame inspection. If a design departs from the standard NCC provisions, a BCA consultant can usually find a compliant solution before lodgement. NSW stays on NCC 2022 Amendment 2 until NCC 2025 is adopted on 1 May 2027, which our BCA guide explains.
Detached, attached, converted garage and above-garage granny flats
| Type | What it is | Approval notes | Watch for |
|---|---|---|---|
| Detached (backyard) | A standalone single-storey building behind the main house | Most common CDC granny flat | Rear and side setbacks; fire separation to the house; access path |
| Attached | Built onto the side or rear of the main house with its own entry | CDC available if all standards are met | Fire and sound separation between the two dwellings |
| Converted garage | An existing garage or outbuilding turned into a self-contained dwelling | Still needs a CDC or DA: it is a change of use from Class 10a to Class 1a | Ceiling height, slab moisture, insulation, waterproofing, fire separation, and whether the original garage was approved |
| Above garage / two-storey | A granny flat over a garage or as a second storey | CDC possible within the 8.5 m height limit and setbacks | Increased setbacks for upper levels, privacy and overlooking |
| Within the house | Part of the existing house converted to a self-contained unit | CDC available with no minimum lot area, provided the only external change is an additional entrance; otherwise a DA | Fire separation, sound insulation, separate entry |
| Prefab / modular | Factory-built and craned or trucked in | Same approval as site-built | Footings design, fire separation, and documentation from the manufacturer for the certifier |
Converted garages deserve a special warning. A garage is not built to be lived in; the slab, walls, ceiling height and insulation rarely meet the code without real work. “We just put a kitchen in the garage” is one of the most common unapproved granny flats in Sydney, and one of the most common things a buyer’s building inspector finds.
What granny flat approval costs, and what actually moves the number
The approval side of a granny flat is a small part of the total spend, but it is the part that decides whether the rest can legally happen. It is priced against the site and the design, not a list, and a figure quoted without the site behind it tells you very little. The table sets out what drives each part of the approval budget, so you can see what a proposal should include. Construction is excluded.
| Item | What drives it |
|---|---|
| Section 10.7 planning certificate | A council fee set by the Regulation. The first document to order. |
| Eligibility and pathway check | Built Smart includes this in its CDC fee proposal. |
| Site survey | Lot size, slope and the detail and levels needed to check setbacks and height. |
| Drawings | A builder’s standard design costs less to document than a custom one. |
| Structural engineering | Footings, slab and framing, driven by the soil, the slope and the design. |
| BASIX certificate | Mandatory for the new dwelling. |
| Bushfire, flood or geotechnical report | Only where the land requires it. |
| Certification package | The CDC, Principal Certifier, inspections and Occupation Certificate. Driven by the design and by whether the flat is detached, attached or within the existing house. |
| Long Service Levy | Statutory: 0.25% of the cost of works where the works cost $250,000 or more, paid before the CDC is released. |
| Section 7.11 or 7.12 council contribution | Set by the council’s contributions plan, and varies widely between councils for secondary dwellings. |
| Government fees | Planning Portal and Sydney Water building plan check fees. Lodgement, certificate and agency fees are set by government and change from time to time, so a proposal should list them as pass-through items rather than build them into the fee. |
What a comparable proposal has to tell you
- Whether the lot qualifies. Lot area, frontage, zone and land exclusions checked before the drawings are finalised.
- What the fee covers. The CDC, the Principal Certifier appointment, each mandatory inspection and the Occupation Certificate, listed separately.
- What it excludes. Survey, drawings, engineering, BASIX, contributions, the Long Service Levy and government fees, stated as excluded rather than simply left out.
- What happens if something changes. The terms for re-inspections and design changes on site.
- The turnaround. When the CDC will be determined once the application is complete.
- A fixed fee against that scope, rather than an hourly rate with no cap.
Built Smart Solutions quotes every engagement as a fixed fee against a written scope, with the exclusions and the turnaround stated on the same page. Get a fee proposal.
The certification fee is a small part of a granny flat budget, which is the strongest argument for choosing a certifier on reliability rather than price.
How long granny flat approval takes
| Stage | CDC pathway | DA pathway |
|---|---|---|
| Eligibility check and 10.7 certificate | A few days | A few days |
| Survey, design, engineering, BASIX | Usually a few weeks | Usually longer (plus the SoEE) |
| Assessment | 10 or 20 days | Often several months, then a separate CC |
| Principal Certifier and Notice of Commencement | At least 2 days’ notice to the council; neighbours get notice too (7 days in most of Sydney) | At least 2 days’ notice to the council |
| Construction (inspected at each critical stage) | Depends on the design and the builder (prefab can be faster) | Depends on the design and the builder |
| Occupation Certificate | Once the final inspection is passed and the compliance certificates are in | Once the final inspection is passed and the compliance certificates are in |
| Idea to approval | Usually a matter of weeks on a straightforward site | Several months longer |
The biggest delay on CDC granny flats is an incomplete application, not the certifier. A missing BASIX certificate, survey without levels, or engineering that does not match the drawings holds up the CDC. Built Smart Solutions runs a pre-lodgement review on every granny flat so the statutory period runs on a complete set.
Planning a granny flat in Sydney?
Send us the address and a rough sketch of where it will go. Built Smart Solutions will confirm whether it qualifies for a CDC and quote the full approval as one fixed fee.
The approval process step by step
Check eligibility before you design
Order the section 10.7 planning certificate and confirm the zone, lot area, lot width and any heritage, flood or bushfire constraints. Ask a certifier to confirm the pathway (CDC or DA) before paying for full drawings. Built Smart Solutions does this as the first step of every granny flat engagement.
Survey the site
A detail and level survey shows boundaries, existing structures, trees, levels and services so the setbacks, height and stormwater can be designed accurately.
Design within the standards
Keep the floor area, measured to the outside of the walls, at or below 60 m², meet the setbacks and height, plan fire separation where the flat is close to a boundary or the house, and keep the landscaped area and shared private open space the Housing SEPP requires.
Prepare the supporting documents
Construction drawings, structural engineering, BASIX certificate, stormwater plan, any bushfire or flood report the land triggers, and a Sydney Water building plan check.
Lodge the CDC through your certifier
The certifier reviews the package, lodges on the NSW Planning Portal, notifies neighbours and the council where required, assesses against the Housing SEPP and the NCC, and issues the Complying Development Certificate once any Long Service Levy is paid (works of $250,000 or more).
Appoint the Principal Certifier and give notice
Appoint the Principal Certifier, give the council at least 2 days’ notice before work starts, and give neighbours the notice of commencement the CDC requires (7 days in most of Sydney).
Build, with every critical stage inspected
The builder books each critical stage inspection before the work is covered: footing excavation, in-situ concrete, framework, wet area waterproofing, stormwater and final. Any change to the approved design is checked with the certifier first.
Get the Occupation Certificate
At completion the certifier reviews the compliance certificates (waterproofing, smoke alarms, glazing, termite protection, BASIX) and issues the Occupation Certificate. Only then can the granny flat be lived in or rented.
Inspections and the Occupation Certificate
A granny flat is a Class 1a dwelling, so the same mandatory critical stage inspections apply as for a new house. They are carried out by the Principal Certifier, or another certifier the Principal Certifier agrees to, and the final inspection must be done by the Principal Certifier. The duty to make sure they happen sits with the owner as the person with the benefit of the CDC. A missed inspection can be excused only where it was missed through unavoidable circumstances and the work is shown to be satisfactory, and a missed final inspection cannot be excused at all.
| Stage | When | What the certifier checks |
|---|---|---|
| 1. Footings | After excavation, before concrete | Footing size, depth, reinforcement against the engineering |
| 2. Slab / in-situ concrete | Before pouring | Reinforcement, membrane, termite protection, set-out |
| 3. Frame | Before covering the frame | Framing, bracing, tie-downs, fire separation construction |
| 4. Wet areas | Before covering waterproofing | Waterproofing to AS 3740 in bathroom and laundry |
| 5. Stormwater | Before covering drainage | Connections to the approved discharge point |
| 6. Final | At completion, before the OC | Whole-building compliance, smoke alarms, BASIX commitments, documentation |
The Occupation Certificate is the document that makes the granny flat legal to live in, rent out and insure. Our article on occupation certificate delays explains why OCs stall at the last step and how a progressive checklist prevents it; Built Smart Solutions uses that approach on every granny flat.
Common reasons granny flats get refused or delayed
Paying for drawings before checking the lot
A design for a 450 m² lot that turns out to be 438 m², or 11.6 m wide, is a design for a DA. Check the numbers on the survey first.
Creeping over 60 m²
An internal laundry, a wider hallway or a built-in store can push the floor area just over the limit. Floor area is measured to the outer face of the external walls, so wall thickness counts.
Missing fire separation
Granny flats placed close to a boundary or the back of the house without fire-rated walls and protected openings fail at assessment or, worse, at the frame inspection.
Incomplete documentation
A missing BASIX, survey without levels, or engineering that does not match the drawings. Each one holds up the CDC.
Starting work before the Principal Certifier is appointed
It is an offence, and it means the first mandatory inspection never happened. It puts the Occupation Certificate at risk from day one.
Changing the design on site
Moving a window, adding a deck, shifting the flat closer to the fence. Small on site, significant against a CDC. Read why a site change that feels minor can stop your project cold.
Reports that do not match
A bushfire report for a different footprint, or a BASIX certificate for an earlier design. See when your reports don’t talk to each other.
Converting a garage without approval
The most common unapproved granny flat in Sydney, and the most expensive to fix later.
Granny flat vs dual occupancy vs Pattern Book home
Since the Low and Mid-Rise Housing reforms, many Sydney lots that could only take a granny flat a few years ago can now take two full homes on separate titles. Before you commit, check which option your lot supports.
| Factor | Granny flat | Dual occupancy | Pattern Book low-rise home |
|---|---|---|---|
| What you get | Main house + one small second dwelling (max 60 m²) | Two full-size dwellings (attached or detached) | Two or more architect-designed dwellings (semi, terrace, manor house, townhouses) |
| Separate titles | No | Yes, with subdivision | Yes, with subdivision |
| Keep the existing house | Yes | Usually no (knock-down rebuild) unless detached at the rear | Usually no |
| Fast-track pathway | CDC under the Housing SEPP | CDC under the Low Rise Housing Diversity Code (lot and zone dependent) | CDC under the Pattern Book Development Code (lot and zone dependent) |
| Statutory CDC timeframe | 10 or 20 days | 10 or 20 days for a CDC, or months via DA | 10 days |
| Best for | Extra income or family space while keeping the home | Developing to sell or hold two homes | Developing with a ready-made, fast-tracked design |
| Read more | This guide | Dual occupancy rules NSW | NSW Housing Pattern Book guide |
Our Sutherland Shire dual occupancy case study shows a CDC approved on a lot that many owners would have assumed could only take a granny flat. If you are unsure which option gives the best return on your land, planning advice before design is the cheapest money you will spend.
How Built Smart Solutions helps with granny flats in Sydney
Built Smart Solutions is a Sydney-based building certification and construction regulation firm with more than 20 years in certification, fire safety and regulatory policy, ISO 9001 certified and registered under the Building and Development Certifiers Act 2018. We approve, inspect and sign off granny flats across Sydney, from the Sutherland Shire and the Inner West to Western Sydney, the Hills and the Northern Beaches, and throughout regional NSW. Every inspection is attended in person.
Here is how each part of a granny flat project maps to our services:
| Project stage | What you need | Built Smart service |
|---|---|---|
| Before design | Is it exempt, CDC or DA? Is the lot eligible? | Exempt Development Advice and pathway confirmation |
| Best use of the land | Granny flat, dual occupancy or Pattern Book home? | Full Service Planning Advice |
| Approval (CDC) | Assessment and issue of the Complying Development Certificate | Complying Development Certificates |
| Approval (DA) | When the lot or design cannot meet the CDC standards | DA Preparation and Statements of Environmental Effects |
| After DA consent | Construction Certificate before work starts | Construction Certificates |
| Non-standard design | Fire separation, ceiling height or other NCC departures | BCA Consulting |
| During construction | Principal Certifier and the six mandatory inspections | Principal Certifier Appointment |
| Completion | Occupation Certificate so you can live in or rent the flat | Occupation Certificates |
| Accessible granny flat | Ageing in place, family member with disability | Access Consulting |
One team from eligibility to Occupation Certificate. The certifier who confirms your pathway is the one who issues the CDC, inspects every stage and signs off the OC, so nothing is lost between hand-offs. Fixed fee and turnaround in writing, tracked through our ISO 9001 system. Inspections in person, never signed off from photos. And when the lot does not qualify for a CDC, our town planning team takes it through a DA without starting again. Meet the team or see how we work.
Final verdict
A granny flat is one of the simplest ways to add a home, an income or family space to a Sydney property, and for most standard lots the approval is genuinely fast: a CDC from a private certifier within 10 or 20 days. The owners who get there quickly do three things: they check the lot before they design, they keep the design inside the 60 m² and setback standards, and they lodge a complete package. The owners who get stuck either skipped the first step, changed the design on site, or built without approval and are now paying to regularise it.
If you are planning a granny flat anywhere in Sydney or NSW, start with the address. Built Smart Solutions will confirm your pathway, quote the whole approval as a fixed fee, and stay with the project from CDC to Occupation Certificate. Get a fee proposal or call (02) 9127 8249.
Frequently asked questions about granny flat approval in NSW
Do I need council approval to build a granny flat in NSW?
You need approval, but not always from council. A granny flat that meets every complying development standard can be approved by a registered private certifier with a Complying Development Certificate, within a statutory period of 10 or 20 days, without a DA. If the lot or design does not meet the standards, a development application to council is required. A granny flat is never exempt development.
What is the minimum lot size for a granny flat in NSW?
For a granny flat approved as complying development, the lot must be at least 450 m², with a frontage at the building line of at least 12 m for lots up to 900 m² (15 m and 18 m on larger lots). A granny flat created entirely within the existing house has no minimum lot area. On a development application, 450 m² is a non-discretionary standard for a detached granny flat rather than a bar, so a smaller lot may still succeed if the council’s LEP and DCP allow it.
How big can a granny flat be in NSW?
Under the complying development standards a granny flat can have up to 60 m² of floor area, measured to the outer face of the external walls at 1.4 m above floor level, or a larger area if another planning instrument permits it. An attached deck, carport or garage is excluded from the 60 m² test, but if it is enclosed by walls higher than 1.4 m it counts towards a separate cap on the total floor area of both dwellings. A DA cannot approve a larger secondary dwelling either, unless another planning instrument (usually the council’s LEP) permits a larger floor area; otherwise the project needs to be redesigned or approached as a different housing type, such as a dual occupancy.
How long does granny flat approval take in Sydney?
The certifier must determine a granny flat CDC within 10 days of lodgement, or 20 days where neighbour notice is required, which covers most of metropolitan Sydney. Including survey, design, engineering and BASIX, most Sydney owners on a straightforward site go from idea to approval in a matter of weeks. A DA usually takes several months in Sydney, plus a Construction Certificate.
How much does granny flat approval cost in Sydney?
There is no list price, and a range quoted without the site behind it is not much use. The certification package (CDC, Principal Certifier, mandatory inspections and Occupation Certificate) is set by the design and the site; the survey, drawings, engineering, BASIX, government fees and any council contribution sit alongside it, and construction is separate. Built Smart Solutions quotes a fixed fee against a written scope.
Can a private certifier approve my granny flat?
Yes. If the granny flat qualifies as complying development, a registered private certifier such as Built Smart Solutions can assess it, issue the Complying Development Certificate, act as Principal Certifier during construction, carry out the mandatory inspections and issue the Occupation Certificate.
Can I build a granny flat on a heritage property?
If the property is a listed heritage item, the complying development pathway is not available and a development application to council is required. In a heritage conservation area an attached or detached granny flat cannot be complying development, so a DA is needed; a granny flat created entirely within the existing house is not caught by that exclusion. A certifier or town planner can confirm the pathway from the section 10.7 planning certificate.
Can I rent out my granny flat in NSW?
Yes. A secondary dwelling can be rented to anyone, not only family members, once it has an Occupation Certificate. Short-term holiday letting is also possible but is subject to the separate short-term rental accommodation rules and registration.
Can I subdivide or sell my granny flat separately?
No. A granny flat must remain on the same title as the principal dwelling and cannot be subdivided off and sold separately. If you want two separately titled homes, consider a dual occupancy or a Pattern Book design, both of which can be subdivided where the lot and zone allow.
Do I need a CDC to convert my garage into a granny flat?
Yes. Converting a garage into a self-contained dwelling is a change of use from a Class 10a outbuilding to a Class 1a dwelling and needs a CDC or DA. The converted space must meet the NCC for a dwelling, including ceiling height, moisture protection, insulation, waterproofing, smoke alarms and fire separation, and the certifier will need to be satisfied that the existing garage was lawfully built.
Do I need a BASIX certificate for a granny flat?
Yes. A BASIX certificate is mandatory for a new granny flat and must be lodged with the CDC or DA. The commitments the certificate requires the certifier to monitor are checked before the Occupation Certificate is issued.
What happens if I built a granny flat without approval?
An unapproved granny flat can attract a council order to stop using, alter or demolish it, can affect insurance and lending, and will usually be identified when the property is sold. There is no simple retrospective approval for work already carried out, so resolving it usually means investigation, upgrades and specialist advice. Getting independent advice early limits the cost.
Do granny flats need fire-rated walls?
Where an external wall of the granny flat is within 900 mm of a side or rear boundary, or within 1.8 m of the main house, it generally needs to be fire-resisting construction with protected openings under NCC Volume Two. This needs to be shown on the drawings at approval stage, not added on site.
Is a granny flat or a dual occupancy better for my Sydney property?
A granny flat suits owners who want to keep the existing house and add a small income or family dwelling. A dual occupancy suits owners who want two full-size, separately titled homes to sell or hold, at a much higher build cost. Since the Low and Mid-Rise Housing reforms many Sydney lots support both, so it is worth getting planning advice on the land before choosing.
Does Built Smart Solutions approve granny flats outside Sydney?
Yes. Built Smart Solutions approves, inspects and signs off granny flats across Sydney and regional NSW, with every inspection attended in person. The Housing SEPP standards are the same statewide, although the CDC determination period is usually 10 days outside metropolitan Sydney; regional sites more often involve bushfire, flood or rural zone requirements, which we assess site by site.
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Eligibility check, CDC, Principal Certifier, every inspection in person and the Occupation Certificate, from one Sydney team on a fixed fee. ISO 9001 certified.
Related reading from Built Smart Insights
Standards and timeframes in this guide reflect the Housing SEPP, Codes SEPP and NCC 2022 as at October 2026 and are a general guide only. Setbacks, landscaping and exclusions vary with lot size, zone and land constraints; council contributions vary by local government area. Nothing in this article is advice about a particular property. For a fixed fee for your granny flat, request a fee proposal.
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