In New South Wales, the formal planning term is secondary dwelling, commonly called a granny flat. It means a self-contained dwelling established with a principal dwelling on the same lot and may be within, attached to or separate from that principal dwelling. This guide explains the verified statistical context for Dundas and the statewide planning, budgeting, design, rental and procurement checks that should precede a project. It is general information, not property-specific planning, legal, financial or building advice.
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Local granny-flat overview
Dundas (NSW), code SAL11315, is an Australian Bureau of Statistics locality. SAL means the ABS Suburbs and Localities geography: a statistical representation of commonly recognised localities whose boundaries are approximations. A SAL boundary is not a cadastral parcel boundary and does not determine the responsible council, zoning, title conditions or development rights.
The canonical locality record gives the SAL an area of 1.3874 square kilometres and identifies 51 mesh blocks within its statistical geography. These values help identify the locality dataset; they do not describe the dimensions, ownership or development capacity of land within it. No verified address-level evidence supplied for this guide establishes a typical Dundas lot, common zoning, shared constraint or standard secondary-dwelling opportunity.
The canonical locality record places this SAL wholly within the statistical LGA named Parramatta. That is an ABS geographic name, not the formal name of a council organisation. The corresponding organisation identified in the verified source pack is City of Parramatta Council, but its authority over a proposed development must still be confirmed from the legal lot and address. Suburb-to-LGA overlap data cannot establish jurisdiction for an individual parcel.
The 2021 Census Dundas QuickStats recorded 4,959 people, 1,318 families and 1,774 private dwellings in the SAL. These figures are historical context from the 2021 Census, not a description of current population, housing supply, property values or rental conditions. They also say nothing about the size, zoning or development capacity of any particular lot.
Under current NSW secondary-dwelling guidance, the principal and secondary dwellings remain on the same lot. The secondary-dwelling pathway does not create a separately subdividable or independently saleable dwelling. Marketing descriptions such as studio, tiny home or modular home do not determine the legal development classification.
State guidance permits secondary dwellings in specified residential zones and explains that a local environmental plan may permit them in other zones. Permissibility is only an initial planning question. The legal parcel’s zone, existing lawful development, applicable instruments, title restrictions, mapped controls and proposed design must all be checked before suitability can be assessed.
For a Dundas address, begin with the NSW Planning Portal Spatial Viewer and current property records. If City of Parramatta Council is confirmed as the responsible authority, its development information and the Parramatta Local Environmental Plan 2023 mapping route are relevant starting points. Their applicability should not be assumed until the parcel and authority have been verified.
Council rules and approval pathway
A secondary dwelling may proceed through development consent or, where every eligibility rule and development standard is satisfied, complying development. A development application is assessed by the responsible council. A complying development certificate may be issued by a council or appropriately registered certifier under a standards-based process. A certifier cannot disregard an exclusion, vary an unmet planning standard or convert an ineligible proposal into complying development.
For the Housing SEPP complying-development pathway, NSW guidance identifies a lot area of at least 450 square metres, except where the secondary dwelling is located entirely within an existing dwelling house. This is one bounded eligibility requirement, not a universal minimum for a council-assessed development application and not sufficient by itself to establish complying-development eligibility.
The proposal must be tested against the current State Environmental Planning Policy (Housing) 2021, including its relevant schedule, and the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008. The Department’s complying-development guidance explains the certifier’s role and the need to meet prescribed standards and approval conditions.
Address-level due diligence should establish:
- the legal lot and deposited plan, current zoning and lawful principal dwelling;
- the applicable local environmental plan, development control plan and site-specific instruments;
- title easements, covenants, restrictions, legal access and existing consent conditions;
- sewer, drainage and other utility assets, connections and authority requirements;
- mapped controls relevant to the property, rather than hazards assumed from the suburb name; and
- council requirements for stormwater, waste, vehicle crossings, documents, contributions and fees.
The Housing SEPP contains site and floor-area controls, while other applicable provisions may address matters such as setbacks, height, landscaping, site coverage and earthworks. Those standards depend on the property, development form and selected pathway, so they should be read from the current instruments rather than copied from another project. State guidance says the Housing SEPP does not itself require extra parking for a secondary dwelling; nevertheless, existing parking, driveway access, manoeuvring and consent conditions may affect the design assessment.
The documentation may include a survey, architectural plans, engineering, specifications, specialist reports and a BASIX certificate. BASIX addresses water, energy use and thermal performance. The Planning Portal provides both general BASIX guidance and a secondary-dwelling project classification guide for conversions and new work. A quotation, concept plan or BASIX certificate is not planning approval.
After approval, the work must follow its conditions, certification arrangements and required inspections. Service NSW explains that an occupation certificate is required to occupy or use a new building, or to use an existing building following an approved change of use. Confirm the required construction certificates, inspections and completion records with the appointed certifier.
Costs and budgeting
No verified Dundas-specific construction price, council charge or service allowance supports a generic project total. Build the budget from a surveyed site, coordinated design and itemised quotations using the same scope. Package prices should be tested for exclusions and assumptions rather than treated as complete feasibility figures.
Separate the budget into:
- title, survey, service-location and approval-record investigations;
- design, engineering, energy assessment and specialist reports;
- council, Planning Portal, authority and certifier charges;
- contributions where the applicable plan and proposal require them;
- demolition, excavation, remediation, retaining and site preparation;
- building work, fixtures, finishes and documented BASIX commitments;
- stormwater, sewer, water, power and communications connections;
- paths, access, fencing, landscaping and other external work;
- inspections, certificates, insurance and handover material; and
- an allowance developed from identified project risks, not a standard percentage.
Slope, ground conditions, restricted access, service distances, drainage, existing structures, trees and the required finish can materially affect quotations. A conversion may require structural work, waterproofing, insulation, ventilation, fire-safety upgrades and new services. Confirm the existing building’s approval history before pricing it as habitable accommodation.
Prepare a cost plan that records the source, date, scope and assumptions for every amount. Update it when the survey, service enquiries, engineering or approval conditions reveal new work. This creates a traceable feasibility record and helps distinguish an actual price change from a difference in scope. Include ongoing ownership, insurance and maintenance items only after obtaining advice relevant to the completed development and intended use.
Require each quote to identify exclusions, provisional sums, prime-cost items, latent-condition treatment and responsibility for approvals, engineering, BASIX, authority applications and occupation-certificate documents. Verify current council and authority charges directly because fee schedules and contribution requirements can change.
Current Building Commission NSW contract guidance says residential building work costing more than $5,000 requires a written contract, work costing more than $20,000 requires the more extensive large-job contract, and the maximum deposit is 10 per cent. Read the Consumer Building Guide before signing and align progress payments with defined completed stages.
Home building compensation cover is required in the circumstances described by the official guidance for residential building work valued at $20,000 or more including GST. Where required, obtain the certificate and verify its details through the official HBC Check before making a payment. Recheck these statutory requirements when contracting.
Design and site considerations
Choose whether the proposal will be within, attached to or separate from the principal dwelling before developing the design. That choice affects planning classification, construction interfaces, services, privacy and BASIX documentation. For an existing garage, shed or studio, retrieve its approval records and confirm its lawful use; physical space or apparent soundness does not make a residential conversion permissible.
An accurate survey should show boundaries, levels, buildings, access, significant trees, easements and available service information. Use it to coordinate the secondary dwelling with the principal residence and to assess:
- safe, practical pedestrian access and building entry;
- privacy, overlooking, daylight, ventilation and noise separation;
- usable outdoor areas, clothes drying, bins and storage;
- effects on existing parking and vehicle movement;
- stormwater discharge and wastewater connections; and
- access for construction, maintenance and emergency purposes.
Check all dimensional and site standards against the exact pathway and current instruments identified in the council-rules section. Do not rely on a builder’s standard plan until it has been tested against the survey, title and planning controls. Prefabricated, modular and relocatable construction remains subject to the applicable planning, building, BASIX and certification requirements.
Planning maps should be used to screen the actual address for relevant controls. If an official search identifies heritage, flooding, bushfire, biodiversity, contamination, acid sulfate soils, mine subsidence, tree controls or another constraint, obtain advice and reports appropriate to that identified issue. The available evidence does not support claiming that Dundas properties share any particular constraint or are free from one.
Resolve service and title issues early. Locate sewer, drainage and utility assets, confirm lawful stormwater disposal and assess whether easements or private restrictions affect the footprint. Planning consent does not necessarily remove rights or restrictions recorded on title.
Integrate BASIX commitments into orientation, glazing, shading, insulation, ventilation, fixtures and services. Ensure the approved certificate, drawings, specifications and building contract are consistent. Changes during construction should be reviewed through the proper approval and certification process rather than informally substituted on site.
Rental and investment considerations
Before offering a secondary dwelling for residential occupation, confirm that its approved use, completed work and occupation certificate support that use. A kitchen, separate entrance or rental advertisement is not evidence of lawful approval. The dwelling also remains tied to the principal dwelling and land under the secondary-dwelling framework rather than becoming a separately titled asset.
If the arrangement is a residential tenancy, use current NSW Fair Trading tenancy guidance for the written agreement, standard terms, landlord obligations and related processes. The Residential Tenancies Act 2010 provides the legislative framework. Family occupation, boarding, licensing, short-term accommodation and a standard residential tenancy should not be treated as interchangeable arrangements.
Plan the practical relationship between the two dwellings. Define access, private and shared areas, waste handling, garden care and maintenance responsibilities. Confirm lawful arrangements for utilities and any proposed metering or recovery of charges with the relevant provider and adviser. Ask the insurer whether the completed development and intended occupancy are covered.
Assess commercial feasibility using current, comparable evidence for the finished dwelling rather than the 2021 Census or online asking prices alone. Separate achieved-rent evidence from advertised asking amounts, and compare properties only where their location, condition, accommodation and lawful use are genuinely relevant. Obtain advice suited to the owner’s circumstances on lending, insurance, tenancy management, taxation, ownership and estate planning. Keep expected income separate from verified construction, operating, vacancy and maintenance costs so the decision is based on documented assumptions.
Choosing a granny-flat builder
Issue the same survey, plans, specifications and pricing schedule to each tenderer. Compare the complete proposed scope rather than the headline amount, paying particular attention to foundations, earthworks, drainage, services, authority work, BASIX items, external works, certification and handover.
Use the official NSW licence-check service to verify the contracting entity, current licence status and licence category. Match the register details to the entity named in the quote and proposed contract. An ABN, association membership, website badge or review profile is not a substitute for this check.
Ask for recent references from comparable secondary-dwelling projects and inspect completed work where the owner permits it. Ask how the builder handled site access, approval conditions, services, variations, defects, BASIX commitments and completion documents. References help test experience but do not replace licence, contract or insurance verification.
Review each tender for:
- inclusions, exclusions, provisional sums and prime-cost items;
- assumptions about ground conditions, access and service capacity;
- responsibility for design coordination, submissions and inspections;
- consistency with the approval documents and BASIX certificate;
- variation, delay and extension-of-time procedures;
- defined progress-payment stages and defect processes; and
- warranties, manuals, certificates and other handover records.
Follow the statutory contract, deposit and home building compensation checks set out in the costs section. Read the Consumer Building Guide, verify required cover before payment and keep the contract, certificate, approvals, variations, invoices and inspection records together. Do not pay for undocumented variations or stages that have not been completed as defined.
Before final payment, arrange an inspection, document defects and collect warranties, manuals and required certificates. Confirm who is responsible for resolving outstanding certification matters and obtaining the occupation certificate. Seek independent legal or technical advice where contract terms, payment triggers or responsibility for approvals remain unclear.
Planning and feasibility checklist
- Confirm the address, lot, deposited plan and legal title.
- Verify the responsible council from current property records.
- Retrieve the principal dwelling’s approval history.
- Check zoning and mapped controls in the Spatial Viewer.
- Review the current state and applicable local planning instruments.
- Obtain a survey, title search and service information.
- Identify easements, restrictions, access and drainage arrangements.
- Define the proposal as internal, attached, separate or a conversion.
- Test both approval pathways with council or a registered certifier.
- Confirm required reports, plans, BASIX documents and certificates.
- Verify current application requirements, fees and contributions.
- Compare coordinated, itemised quotations.
- Check licences, contract terms and required compensation cover.
- Obtain approval before starting work.
- Complete required inspections and approval conditions.
- Obtain the occupation certificate before occupation or use.
- Establish compliant tenancy documents before renting.