Understand what has been proposed and what currently applies
The NSW Government has discussed changes intended to simplify some development-assessment pathways and expand opportunities for complying development. A proposal, announcement or consultation should not be treated as an enacted rule, and eligibility for a complying development certificate depends on the planning controls in force for the actual property and proposal.
Even where a project can use a complying development pathway, the design still needs appropriate technical information. A faster approval mechanism does not, by itself, determine the site class, founding conditions, excavation requirements or the suitability of a proposed retaining structure.
When AS 2870 site classification may be relevant
For a new dwelling, granny flat, extension or other applicable residential construction, the footing designer may require a project-specific site classification to inform slab or foundation design. AS 2870 is relevant to residential site classification and footing considerations where its application is appropriate.
Site classification is not a one-size-fits-all description of a suburb. The actual assessment must consider the individual property, soil profile, moisture-related ground movement and other conditions such as fill, slope or unusual ground where relevant.
When a CDC project may need more than site classification
A project can have geotechnical questions beyond residential soil reactivity, including excavation near boundaries, fill, slope stability, groundwater, retaining walls or founding variability. Whether extra investigation is needed depends on the design, site conditions and the actual certifier or structural engineer request.
If a certifier has asked for a particular document, provide the exact request rather than assuming a generic report will satisfy it. A broader geotechnical investigation may be required for some sites, while others may only need a properly scoped residential site classification.
- Proposed excavation or a basement close to neighbouring structures.
- A sloping site, retaining wall or significant change in ground levels.
- Potential placed fill, soft soil or variable founding material.
- A structural designer's request for bearing or foundation information.
- A written certifier request identifying a particular geotechnical issue.
Documents that help your certifier and geotechnical consultant
Provide the property address, proposed architectural plans, survey, existing site photographs, intended excavation or retaining works, and the certifier's written requirements. Previous reports can provide background but may not be suitable for a changed development or a different investigation area.
Site classification starts from $750 where that is the appropriate service. Geotechnical investigations start from $2,200, while DA and CDC support is quoted according to the actual scope rather than presented as one fixed approval package.
Do not mistake a streamlined pathway for an engineering exemption
A complying development pathway can change how a proposal is assessed, but it does not automatically remove the structural designer's need for reliable footing, ground or construction information. Equally, a geotechnical report is not universally mandatory for every complying development.
The correct approach is to confirm the current planning position with the appropriate certifier or adviser and scope the geotechnical work to the documented design and site-specific risks.
Common questions
CDC reforms and site classification: common questions
Do the proposed 2026 CDC reforms remove the need for site classification?+
No general exemption should be assumed. Where a residential footing designer or certifier requires site-specific ground information, the relevant technical evidence remains dependent on the project and current rules.
Does every complying development need an AS 2870 site classification?+
Not necessarily. The need depends on the proposed works, footing design, existing information and the requirements identified by the certifier, structural engineer or other relevant adviser.
Is the $750 starting price for every type of soil testing?+
No. The confirmed starting price from $750 specifically applies to Sydney Geotechnical's site classification service. Other testing or broader investigations are quoted according to their actual scope.
Need CDC and residential geotechnical support 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.
