Before any construction project begins, understanding what's beneath the surface is essential. Geotechnical site investigations give you reliable data on soil conditions so you can design foundations that are safe, durable and cost-effective. Skipping this step risks structural failures, surprise costs and non-compliance with the National Construction Code (NCC).
Novus Projects runs geotechnical investigations during the early feasibility stage, so every project is grounded in solid site data before works begin.
What is a geotechnical site investigation?
A geotechnical site investigation is a detailed assessment of the soil and ground conditions at your building site. It examines how the soil will support a structure, flags potential risks and guides foundation design. Builders gather precise data on soil type, moisture content and load-bearing capacity, starting every project on solid ground.
Is a site classification report (AS 2870) the same as a geotechnical investigation report?
No, they serve different purposes. A site classification report under AS 2870 identifies the soil's reactivity class (A, S, M, H1, H2, E or P) to meet standard foundation requirements. A geotechnical investigation goes further, analysing soil composition, groundwater, chemical properties and providing site-specific recommendations for foundation design.
What does a geotechnical soil test report include?
A thorough report for a Perth construction project typically covers:
- Soil profile and composition, including clay, sand, silt, rock and fill
- Bearing capacity and load-bearing characteristics
- Groundwater depth and drainage conditions
- Soil reactivity and shrink-swell classification (AS 2870 site classes)
- Chemical properties, such as sulfate content which affects concrete
- Foundation and footing design recommendations
This data helps your builder choose the right foundation type, materials and construction method before breaking ground.
Why soil testing matters for construction projects in Perth
Perth has highly variable soil conditions. Inner suburbs can have reactive clay, while coastal and outer areas often feature sandy or rocky profiles. These differences affect how foundations perform, how structures settle over time and how buildings respond to rainfall and groundwater.
Without soil testing, you risk uneven settlement, concrete cracking, moisture ingress and foundation movement. All of these can lead to expensive repairs and compromised structural integrity.
Soil conditions also affect timelines. High clay content may require deeper excavation, specialised slab designs or extra reinforcement. Sandy soils might need improved drainage and compaction. Testing early lets you identify these challenges upfront, so your foundation design is both cost-effective and built to last.
How outcomes shape foundation & design choices
Geotechnical data drives key decisions at the design stage:
- Foundation type: whether a slab-on-ground, pier or piled foundation suits the site's bearing capacity and moisture behaviour
- Footing design: adjusting depth, reinforcement spacing and slab thickness to match soil characteristics
- Ground treatment: applying stabilisation, drainage improvements or compaction where soils are variable or reactive
- Long-term performance: designing to reduce differential settlement, cracking and structural movement over time
Tailoring foundations to actual site conditions reduces unexpected costs, supports compliance and keeps the build safe for the long term.
When is a geotechnical report required?
A geotechnical report for construction in Perth is essential wherever site conditions could affect structural performance or regulatory compliance. This requirement surfaces under several circumstances:
Building permit applications
Most local councils require a geotechnical report before issuing permits, especially for new builds on greenfield sites, house and land packages, sloping terrain or land with a history of modification. The report confirms that your proposed foundations suit the soil conditions and meet building regulations.
NCC compliance
The NCC requires all structures to be designed for site-specific soil conditions. A geotechnical report provides the evidence needed to show compliance across key areas, including soil reactivity and shrink-swell behaviour, load-bearing capacity, and drainage and groundwater management. A geotechnical report helps to ensure that foundations are safe, effective and meet statutory obligations.
Different building types
While complex or multi-storey developments will always necessitate full geotechnical assessments, even standard single dwellings require soil testing. Testing is particularly important where sites have reactive clay, high sand content, fill material, sloping terrain, elevated groundwater or custom foundation requirements.
Conducting soil testing ensures that design and foundation choices reflect real-world site conditions, avoiding unforeseen issues.
How Novus Projects uses site investigation data
At Novus Projects, geotechnical investigations are central to our planning process, not just a regulatory checkbox. By understanding soil composition, reactivity, load-bearing capacity and chemical characteristics early, our team can anticipate challenges before they cause delays or cost blowouts.
This data shapes foundation design, drainage strategy and material choices, all tailored to the specific conditions of your site. It also feeds into budgeting, procurement and scheduling, helping clients plan more accurately and avoid mid-build surprises.
Integrating geotechnical data at the feasibility stage means our recommendations go beyond compliance. Clients get optimised foundation solutions, targeted risk reduction and a more predictable build from start to finish.