When planning a construction project, understanding what’s beneath your feet is crucial to a successful build. Soil testing for construction and geotechnical site investigations provide the data needed to design safe, durable and cost-effective foundations. Skipping this step can lead to structural failures, unexpected costs and compliance issues with the National Construction Code (NCC). Novus Projects incorporates geotechnical investigations into the early feasibility stage, ensuring each project is informed by reliable site data before any works begin.
What is a geotechnical site investigation?
A geotechnical site investigation is a detailed examination of the soil and ground conditions at a building site. It evaluates how the soil will support structures, identifies potential risks and informs foundation design. Using geotechnical soil testing, builders gather precise data on soil type, moisture content and load-bearing capacity, making sure every project starts on solid ground.
Is a site classification report (AS 2870) the same as a geotechnical investigation report?
While both reports assess soil conditions, they serve different purposes. A site classification report under AS 2870 identifies the soil’s reactivity class (such as A, S, M, H1, H2, E or P) which informs the standard requirements for the foundation of the property. A geotechnical investigation goes even further, offering a detailed analysis of soil composition, groundwater, chemical properties and site-specific recommendations for foundation design and construction.
What does a geotechnical soil test report include?
A comprehensive geotechnical report for construction in Perth generally 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 information allows your builder to make informed decisions about foundation type, materials and construction methods before breaking ground.
Why soil testing matters for construction projects in Perth
Perth’s diverse soil conditions make thorough geotechnical investigations essential for any building project. Soils can range from highly reactive clay in inner suburbs to sandy or rocky profiles in more coastal or outer regions. These variations will affect how foundations perform, how the structures will settle over time and how buildings respond to rainfall and groundwater. Without proper soil testing for construction, developers run the risk of uneven settlement, cracking in concrete slabs, moisture ingress and foundation movement, all of which can necessitate expensive remedial works and compromise structural integrity.
Additionally, soil composition and reactivity directly influence construction timelines. For example, sites with higher clay content may require deeper excavations, specialised slab designs or reinforcements to manage shrink-swell behaviour. On the other hand, sandy soils might need improved drainage and compaction methods. By conducting this testing early, you can identify potential challenges before construction begins, allowing for foundation designs that are both more cost-effective and durable in the long-term.
How outcomes shape foundation & design choices
The data from a geotechnical soil test report for construction informs every major decision in the early design stage. Key considerations include:
- Determining whether a slab-on-ground, pier or piled foundation is most suitable based on soil bearing capacity and moisture behaviour.
- Adjusting footing depth, reinforcement spacing and slab thickness to account for soil characteristics and reactivity class.
- Applying techniques such as soil stabilisation, drainage improvements or compaction adjustments to manage fluctuating soils, groundwater or highly variable terrain.
- Implementing design solutions that reduce the likelihood of differential settlement, cracking or other structural issues over time.
Through these outcomes, your developer ensures that foundation and structural designs are tailored to the unique characteristics of each site. This proactive approach reduces the risk of unexpected costs, encourages compliance with engineering standards and maximises the long-term safety of a build.
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 detailed geotechnical report before issuing building permits, particularly for new builds in greenfield developments, house and land packages as well as sites with sloping terrain, variable soils or historical land modifications.
Submitting a comprehensive report helps councils verify that the proposed foundations and construction methods are suitable for the soil conditions and that the project complies with relevant building regulations.
NCC compliance
The NCC mandates that all structures are designed for site-specific soil conditions. Key NCC requirements addressed by geotechnical investigations include soil reactivity and shrink-swell behaviour, load-bearing capacity for footings and slabs as well as drainage and groundwater management.
A geotechnical report provides the evidence necessary to demonstrate compliance, ensuring 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. Assessments screen sites for known reactive clay, high sand content or fill material, sloping lots or properties with uneven terrain, areas with elevated groundwater levels or drainage concerns. Projects that plan custom foundations, larger slabs or multi-storey designs also bring unique considerations.
Conducting soil testing for building construction ensures that design and foundation choices reflect real-world site conditions, avoiding unforeseen issues during or after construction.
How Novus Projects uses site investigation data
At Novus Projects, geotechnical site investigations are more than just a formality, they’re a cornerstone of our project planning process. By analysing soil composition, reactivity, load-bearing capacity and chemical characteristics, our team can anticipate potential challenges that may otherwise delay construction or inflate costs.
This information guides foundation type selection, drainage strategy and material specifications, allowing the design to be tailored to the unique conditions of each site. It also informs budgeting, procurement and scheduling decisions, helping clients allocate resources efficiently while mitigating the risk of structural issues cropping up mid-build.
Integrating this data at the feasibility stage enables Novus Projects to provide actionable recommendations that go beyond compliance. Clients benefit from optimised foundation solutions, targeted risk reduction and greater control over project outcomes, making the entire build process more predictable.