Geotechnical Report in Sydney and NSW
A geotechnical report tells you what is under your site and what that means for your footings, retaining walls and excavation. Councils ask for one when the land is steep, the soil is reactive, the plans include a basement or deep cut, or the site is mapped as landslip or mine subsidence. Structural engineers also need it, so it is rarely optional once the design gets serious.
Free planning consultation
- 1 to 2 weeks
- Quoted per site - typically from $1,200 + GST
- Quoted fixed after a free scope check
What the investigation involves
A geotechnical engineer visits the site, drills boreholes or digs test pits, and runs simple tests such as dynamic cone penetrometer readings to measure how firm the ground is. Samples go to a laboratory when classification or strength testing is needed. The engineer then analyses the results and writes the report, which is signed by a qualified, chartered professional.
What you get in the report
A site classification under AS 2870, which sets the footing type for most houses, with classes from A through to E and P for problem sites. A description of the soil and rock layers, groundwater levels, bearing capacity for footings, advice on excavation and retaining walls, and, on sloping land, a landslide risk assessment in line with the Australian Geomechanics Society guidelines. For basements it covers dewatering and shoring advice.
Sydney sites that usually need one
Sloping blocks in the Northern Beaches, Hills and Hornsby areas, reactive clay across western and south western Sydney, sandstone sites with rock excavation, filled land and old creek lines, and any lot with a basement. Some councils want the report lodged with the DA, others accept it before the Construction Certificate. We check which applies to your council.
What affects the price
Fees start from $1,200 + GST. The main drivers are the number and depth of boreholes, whether a drill rig can physically reach the site, laboratory testing, whether slope stability analysis is needed, and basement depth. We fix the fee after a free scope check.
Why timing matters
The structural design cannot be finalised without it, and a bad result can change the footing system, the floor level or the cost of the whole job. Do it before the engineer's drawings, not after.
How it works
Site investigation
1 to 3 days on site
Boreholes or test pits taken across the site to assess soil, rock and groundwater conditions.
Analysis and classification
3 to 5 days
Site classified (for example, under AS 2870 for residential footings) and foundation recommendations prepared.
Report and structural handover
Within 1 to 2 weeks of the site visit
Report issued to the structural engineer to inform the foundation design.
What we take off your hands
What EHUP handles
- Coordinating a geotechnical engineer for site investigation and reporting
- Timing the report so it actually informs the structural design, not just documents it after
- Flagging reactive soil, slope stability or fill issues before they affect the design
- Cross-checking geotechnical findings against any contamination assessment on the same site
What you don't have to deal with
- Structural design committed before soil conditions are actually known
- A foundation redesign after footings were already priced and drawn
Frequently asked questions
Do I need a geotechnical report for a granny flat?
Not always. A standard slab on flat ground may only need a soil classification. Sloping sites and rock usually need more.
Can I use a report from my neighbour or an old one?
Usually no. Councils and engineers want a site specific report that is recent enough to rely on.
Is a soil test the same as a geotechnical report?
A soil classification is one part. A full report covers groundwater, bearing, slope and excavation.
Who signs the report?
A qualified geotechnical engineer, which we coordinate for you.
Related approvals
Specialist Reports
Most applications of any size need reports from specialists outside town planning.
Contaminated Land Assessment
If your site has any history of industrial, agricultural chemical or waste-related use, council will likely require a staged contamination assessment before development can proceed - starting with a Preliminary Site Investigation (PSI), which escalates to a Detailed Site Investigation and a Remediation Action Plan only if contamination is actually confirmed.
Access Report
An access report shows council and your certifier that people with disability can reach, enter and use your building.
Structural Design & Certification
Structural design and certification is the structural engineer's design and sign-off confirming the building's structural elements - footings, framing, load paths - are engineered to the National Construction Code.
Acoustic Report
An acoustic report, also called a noise impact assessment, shows council that your project will not unreasonably disturb its neighbours, or that your building will be quiet enough inside for the people who will live or work there.
Why clients choose EHUP
- 10+
- 250+
- 17
- 1
Not sure which approval you need?
Tell us the address and what you want to do. We'll help identify the appropriate planning pathway, whether it is exempt development, complying development or a full DA. Your first conversation is free.