Choosing a location is a legal, safety and whole-site decision before it is a landscaping decision. The apparently empty rear corner may contain an easement, overland flow path, protected tree canopy, sewer, bushfire constraint or the only workable construction route. A compliant footprint can also be a poor location if it makes either dwelling dark, overlooked, inaccessible or expensive to service.
The right process moves from legal lot, to mapped constraints, to measured site, to household use, and only then to a preferred footprint. This article does not promise approval, price, programme, lawful occupation, rent, finance or value.
Jurisdiction and currency note — 11 September 2026: This is general Australian information with NSW examples. “Granny flat”, “secondary dwelling” and related terms do not have identical rules across Australia. Zoning, overlays, title restrictions, approval pathways, setbacks, hazard controls, tenancy rules and building requirements must be checked for the property. Monetary references are Australian dollars (AUD). This is not legal, planning, engineering, certification or financial advice.
Start with the legal and official evidence
In NSW, the Secondary dwellings guidance says a secondary dwelling may be approved with consent or as complying development where the applicable criteria are met. It also explains that a detached or attached complying proposal generally requires a lot of at least 450 m², while a proposal outside complying requirements may still be assessed through a development application. That general statement must not be converted into a conclusion about a particular site.
The current Housing SEPP, Codes SEPP, local environmental plan, development control plan and existing consents may all matter. Read current consolidated instruments and property-specific conditions; an old approval next door is not precedent that binds the authority.
Use the NSW Planning Portal Spatial Viewer as an official screening tool, then confirm the legal parcel and source mapping with the council or responsible authority. Mapping can flag matters such as zoning and hazard layers, but a map screen alone is not a survey or approval.
The NSW Rural Fire Service identifies Planning for Bush Fire Protection as its principal statutory planning instrument for development on bushfire-prone land. Its page expressly says the exhibited draft PBP 2026 cannot be relied on until published and legally recognised. This is an important currency lesson: distinguish current requirements from proposed reforms.
NSW Planning’s flooding material supports risk-based land-use planning, while local councils generally hold the detailed local studies and controls. Flood risk is not resolved merely by raising a slab; safe access, evacuation, hydraulic impacts and downstream consequences may matter.
BASIX’s secondary-dwelling guidance confirms that the project type depends on whether work is a conversion, a new secondary dwelling or construction with a new principal dwelling. The National Construction Code then supplies minimum technical requirements relevant to the classified building. Neither source substitutes for planning permission.
A seven-screen location framework
Screen 1: legal ability
Obtain the current title search, deposited plan and any dealings that affect use. Identify easements, covenants, restrictions, rights of carriageway and positive covenants. Ask a conveyancer or solicitor what each instrument does rather than assuming an easement is “unused”. Check whether existing approvals contain parking, landscape or access conditions that the new location would disturb.
Reject or pause any location whose legality depends on ignoring a registered interest or an unverified right to build.
Screen 2: planning envelope
Overlay surveyed boundaries with required setbacks, building height, site coverage, landscaped area, private open space, separation, parking and relevant local controls. Confirm whether the intended pathway is a development application, complying development or another jurisdiction-specific route.
Do not ask only, “Does the building fit?” Ask, “Does the complete development remain compliant after paths, eaves, decks, retaining, drainage, air-conditioning units and required landscape are shown?”
Screen 3: hazard and environmental constraints
Check bushfire, flood, coastal, contamination, biodiversity, acid sulfate soil, heritage and significant-tree information as applicable. Then obtain the specialist assessment required for the site. A low-frequency event can still govern floor level, materials, access or whether development is suitable.
Locate the dwelling so it does not divert water towards neighbours or obstruct an overland flow path. Preserve defendable space, emergency access and vegetation measures where bushfire requirements apply. Never describe a location as “safe” solely because a public map did not display a layer.
Screen 4: survey, ground and structure
A feature and level survey should locate the principal dwelling, boundaries, trees, visible services, pits, retaining walls and level changes. Geotechnical and structural input may be needed for reactive soil, fill, slope, nearby footings or retaining.
Compare locations by finished floor levels, cut and fill, retaining height, drainage route and effect on existing foundations. The shortest distance from the house may not be the least expensive if it sits across a sewer or steep fall.
Screen 5: services and construction access
Investigate water, sewer, stormwater, electricity, communications, gas if retained, and metering. Confirm authority requirements and whether capacity, fall or pumping is an issue. Separate service billing may be desired but is not always technically or commercially straightforward.
Prepare a construction logistics sketch. Show worker access, material storage, excavation equipment, concrete delivery, waste removal, temporary fencing and protection of the occupied house. A rear location that only works with repeated cranage or hand handling may impose significant cost and disruption.
Screen 6: two-household liveability
Map the daily routes of both households: street to entry, parking to door, dwelling to bins, clothes drying, private open space and meters. Provide a legible address and entry for visitors and emergency response. Avoid placing one household’s bedroom beside the other’s entertaining area or directing windows into private rooms.
Test sun and shade across seasons. A granny flat should not unnecessarily remove the principal dwelling’s only useful winter sun or garden, while the new home should not be left with permanent shade and fence views. Consider noise from roads, pumps, air conditioners, gates and waste areas.
Screen 7: intended occupation and future change
Design for the real occupants without making undocumented assumptions. An older relative may value a step-free route, visible entry, bathroom circulation and proximity to support. A rental occupant may require clearer privacy, services, storage and property-management access. Family occupation can change over time.
Approval to construct does not automatically answer every question about occupation, leasing, short-term accommodation, subdivision or separate sale. Confirm the proposed use and any conditions before relying on it.
Compare locations with a decision table
Shortlist two or three footprints and score each from 0 to 3 against:
- verified legal and planning fit;
- hazard exposure and evacuation;
- earthworks, retaining and drainage;
- service connection complexity;
- construction access;
- daylight, ventilation and energy implications;
- privacy, noise and household separation;
- accessibility and emergency access;
- retained landscape and principal-house amenity;
- documented cost uncertainty.
Weight legal, safety and hazard matters as pass/fail. A high liveability score cannot compensate for an unlawful or unmanageable location. Record the source for every score and who must close each uncertainty.
Use three hold points. Before concept selection, require title, survey and preliminary planning/hazard review. Before application, require coordinated design, services, drainage and specialist reports. Before contract, require approved documents, a priced access methodology and explicit inclusions.
Evidence to retain
Keep the title and plan, planning certificate or equivalent, official map extracts, survey, utility enquiries, council correspondence, arborist, bushfire, flood, geotechnical and engineering reports where required, concept-option comparison, approved plans, conditions, BASIX or equivalent material, certificates and occupation documentation.
For every decisive claim, record: claim; source; date checked; property limitation; responsible adviser; next action. This simple register prevents a general webpage or verbal comment being relied upon as property-specific consent.
Risks and questions
Frequent location failures include building over or too near services, leaving no maintenance route, blocking stormwater, increasing overlooking, removing required parking, confusing a fence with a boundary, harming a significant tree, or discovering too late that machinery cannot enter.
Ask the planner or certifier:
- Which instrument and clause support the pathway and proposed position?
- Which mapped or title constraints apply, and what remains unverified?
- Do existing consent conditions restrict this footprint?
Ask the designer and engineers:
- What survey information controls the levels and setbacks?
- Where will roof and surface water lawfully discharge?
- What bushfire, flood, soil, retaining, fire-separation or structural inputs govern the design?
Ask the builder:
- What is the documented access and staging method?
- Which site costs are fixed, provisional or excluded?
- How will the principal dwelling remain safe, weatherproof and usable?
Practical conclusion
Choose the location that clears legal and hazard screens, minimises unresolved ground and service work, preserves practical access, and creates two dignified living environments. The rear boundary is common, not automatically correct. A side, attached or internal solution may perform better when tested against the whole property.
The reliable answer is a coordinated site plan supported by current evidence. Do not commit to a catalogue plan, demolition or major deposit while the preferred location still depends on an assumed boundary, service route, planning pathway or hazard outcome.
AMESCORP disclosure
AMESCORP may provide building, design, feasibility or project-related services and may benefit commercially if engaged. This reviewed draft is general educational information, not a planning certificate, legal opinion, approval, quotation or warranty of site suitability. Obtain independent property-specific legal, planning, surveying, engineering, certification, insurance, tax and financial advice where relevant.
Reviewed official sources
These are the first-party and authoritative references reviewed for this article.
- Secondary dwellings — NSW Department of Planning, Housing and Infrastructure; accessed 2026-09-11.
- State Environmental Planning Policy (Housing) 2021 — NSW legislation; accessed 2026-09-11.
- State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 — NSW legislation; accessed 2026-09-11.
- NSW Planning Portal Spatial Viewer — NSW Planning Portal; accessed 2026-09-11.
- Secondary Dwelling (Granny Flat or Bedsitter) — NSW Planning Portal BASIX; accessed 2026-09-11.
- Planning for Bush Fire Protection — NSW Rural Fire Service; accessed 2026-09-11.
- Flooding — NSW Department of Planning, Housing and Infrastructure; accessed 2026-09-11.
- National Construction Code — Australian Building Codes Board; accessed 2026-09-11.