What the NSW low- and mid-rise housing policy changes
The NSW Low and Mid-Rise Housing Policy aims to support a broader range of housing types, including dual occupancies, terraces, townhouses and residential flat buildings in eligible locations. Its stages and application criteria differ, and whether an individual property qualifies depends on current mapping, planning controls, exclusions and the proposed development.
Planning eligibility is separate from engineering suitability. A site that may support a duplex or townhouse under the relevant planning framework can still need project-specific advice on soil conditions, foundations, retaining structures, excavation or groundwater.
Why greater housing density changes the ground questions
A replacement duplex or townhouse project can introduce more than one building footprint, new driveways, altered surface drainage, boundary retaining walls or differences in founding depth. In established Sydney suburbs, previous demolition, undocumented fill, old foundations and restricted access can further complicate the investigation.
The correct number and location of test positions depends on the proposed arrangement and expected ground variability. A single older report from a neighbouring block or a previous dwelling does not automatically represent the footprint, depths and construction risks of a new development.
- Several proposed footprints or a larger combined building platform.
- Boundary excavations and neighbouring footings.
- Reactive clay, existing fill or variable weathered rock.
- New retaining walls, stormwater paths and cut-and-fill.
- Basement or undercroft parking where proposed.
Site classification compared with a wider development investigation
Where residential footing design is the principal question, an AS 2870 site classification may provide relevant input on the site's classification and associated footing considerations. Sydney Geotechnical's site classification service starts from $750.
Where the proposal includes multiple dwellings, excavation, difficult ground, significant retaining works or broader foundation questions, an investigation scoped with reference to AS 1726 where applicable may be more appropriate. Geotechnical investigations start from $2,200, with the actual fee depending on access, test locations, depth and agreed deliverables.
Western Sydney and established infill areas need individual assessment
Western Sydney, South West Sydney, the Hills District, North Shore and other established areas have different combinations of soil, shale, sandstone, fill and drainage histories. Broad geological mapping is useful background but does not establish the actual ground beneath a particular property.
Reactive clay can be relevant on some sites, while rock, placed fill, alluvial deposits or local slope conditions may dominate on others. No suburb-wide assumption can replace an appropriate project-specific assessment.
Prepare the geotechnical scope before the design advances
Provide the address, concept plans, survey, proposed number of dwellings, expected excavation depths and information about existing structures. Include a planner, council, certifier or structural engineer request if one has already been issued.
Early review helps identify whether the project primarily needs site classification, a broader investigation, slope input, retaining-wall advice or a combination of services. It does not guarantee approval or replace planning and structural advice.
Common questions
Low- and mid-rise housing geotechnical reports: common questions
Does every duplex allowed under the low- and mid-rise policy need a geotechnical report?+
No. Requirements depend on the particular proposal, ground conditions, structural design and any applicable council, certifier or project-team request.
Is an AS 2870 site classification enough for a townhouse project?+
It can help with residential footing design, but a townhouse development may also require information about variable founding conditions, excavation, retaining walls, groundwater or multiple building footprints.
Does the low- and mid-rise policy apply to every Sydney property near a station?+
No. Eligibility depends on the current policy mapping, applicable planning controls, exclusions and the individual site. Confirm the planning position with the appropriate professional.
Need residential development geotechnical investigation in Sydney?
Get a scope matched to the project
Send the site address, proposed works, current plans and any request from your builder, engineer, council or certifier. Sydney Geotechnical will review the information and confirm an appropriate scope and fee.
This guide provides general information only and is not a substitute for investigation, engineering advice, footing design or approval advice for a particular property. Project requirements and ground conditions must be assessed site by site.
