How much does a geotechnical report cost? 2026 prices

For a house in 2026, a geotechnical report usually costs from about $700 for a basic soil test (a site classification with two boreholes) to $3,000 or more for a full investigation with lab testing. The full spread runs from $119 for an automated desktop report to $10,000 and beyond for difficult sites, because "geotechnical report" covers several quite different jobs.

Here is what each one is, what pushes the price up, and where the money is best spent.

What are you paying for at each price?

Report type	Indicative cost	Turnaround
Automated desktop report (LayeredGeo)	$119	Minutes
Desktop assessment (engineering consultant)	$800 to $1,200	1 to 2 weeks
Residential site classification (2 boreholes)	from $700	1 to 3 weeks
Site classification + footing design	$1,200 to $2,500	2 to 4 weeks
Full investigation (drilling + lab testing)	$3,000+	3 to 6 weeks
Complex or disputed sites	$3,000 to $10,000+	Varies

A desktop study uses records only: geological maps, soil surveys, bore logs from nearby, groundwater data, terrain and planning overlays. Nobody visits. It is for the stage before you own the block. It can show the soil reactivity to expect, but it is not an AS 2870 site classification. What a desktop study covers goes into more detail.

A site classification is the "soil test" your builder and certifier ask for. Someone drills on the lot, logs what comes up and assigns a class (A, S, M, H1, H2, E or P) that the slab is designed to. Most firms drill two holes on a suburban lot. AS 2870-2011 asks for at least one, and three where the ground dries deeper than 3 m each year (as in Adelaide) or the profile is known to vary. The rules are in how many boreholes a block needs.

A full investigation adds more holes or test pits, penetrometer testing, lab tests for shrink-swell and strength, groundwater readings and an engineer's recommendation on where and how deep the footings should go. Basements, retaining walls, multi-storey work and awkward sites need one. Commercial jobs are priced individually, usually from about $5,000.

Prices are similar across the eastern states. Sydney and regional NSW often sit a little above Queensland because of travel and rig availability. Adelaide quotes come in higher more often, not because rates differ but because the ground calls for more holes and more lab work. See soil test costs in Queensland and soil test cost by state for the local detail.

What pushes a quote up?

Getting a rig in. Steep lots, tight inner-city sites and long travel all add cost. If a truck-mounted rig cannot get onto the block, the job falls back to hand augering or a tracked machine.

What is in the ground. Reactive clay that needs lab testing, fill, shallow rock and shallow groundwater all add field and lab time. Fill is the usual one. Hargreaves (2005), writing from 20 years of practice in South East Queensland, worked through examples where the same clay placed as compacted fill gave 50 to 66 percent more predicted movement than it did in its natural state. That is because the calculation gives fresh fill no cracked zone. A simple classification can become a deeper investigation once fill turns up. What the records show about fill covers how to spot it early.

How deep the problem goes. Hargreaves also describes lowland estates on soft coastal clays where the first investigation sometimes had to go below 30 m to understand long-term settlement. That is a different budget from two holes to 1.5 m, and geology and flood mapping usually show beforehand whether a lot sits on that kind of ground.

A Class P result. Class P means the site cannot be classified as A to E. Typical reasons are fill, soft soils, landslip or abnormal moisture conditions such as large trees nearby, and the footing then needs specific design, with more investigation and fees. Class P is more common than the reports suggest. Hargreaves recounts a consultant estimating that strict application of the abnormal-moisture rules would make about half of their sites Class P, and he thought the real figure was higher. Class P sites lists the triggers.

Extra reports for approval. Some certifiers also want wind classification, bushfire assessment or stormwater advice. These are separate jobs, so check what yours needs before you commission anything.

Is it worth paying for more investigation?

In the late 1990s the University of Adelaide began a $41 million campus upgrade on the buried valley of the River Torrens, where the alluvial gravels, silts and clays vary over short distances. The investigation was minimal. During construction the bored piles under the new engineering building ran into problems, the job switched to jacked piles, and the change added about $170,000 and four to six weeks. Jaksa (2000), who sat on the project team, concluded that the quality and timing of the investigation mattered far more than its price.

Kelly et al. (2020) looked at this across larger projects. Recent Australian infrastructure jobs spent roughly 0.5 to 1.5 percent of cost on investigation. In a review of 41 legal cases, 55 percent of claims came from ground conditions that turned out different from expected. Beyond a few percent of project cost, extra investigation buys little.

For a house lot the lesson is not to spend 3 percent of the build on boreholes. It is to do the cheap, early step properly, so the drilling is aimed at the right questions.

Can a desktop report replace the soil test?

No. Your building approval needs a field classification, and no desktop study, including ours, satisfies that. The reason is variability. Li et al. (2016) tested clay at 47 Melbourne sites and found a wide spread of shrink-swell results within the same mapped geological unit. Only a hole on your lot tells you which end of that spread you are on.

What a desktop report does well is the stage before drilling: comparing blocks, pricing ground risk into an offer and briefing the engineer. Desktop first, drilling second, on the block you end up buying.

If you already have lab shrink-swell results, the free AS 2870 calculator works out the surface movement and class.

How do you keep the cost down?

1. Check the ground before you buy. Ground risk is easier to price into an offer, or walk away from, before settlement.
2. Get the classification and footing design quoted together. It is usually cheaper than ordering the design after an unexpected result.
3. Send good information with the request. A site plan, the proposed footprint and anything known about the site's history (old buildings, filling, flooding) reduce the allowance a consultant builds in for unknowns.
4. Book early. Rigs are booked out in busy periods, and a rushed job costs more.

How to get a geotechnical report covers who to call and what to send.

Common questions

How much does a geotechnical report cost for a house? In 2026 a residential site classification with two boreholes typically starts around $700 in QLD and NSW, a classification with footing design runs $1,200 to $2,500, and a full investigation with laboratory testing starts around $3,000. An automated desktop report is $119.

Is a soil test the same as a geotechnical report? A residential soil test is usually a site classification: limited drilling and an AS 2870 class. A full geotechnical report adds laboratory testing, bearing capacity and founding advice.

Can I skip the soil test with a desktop report? No. A desktop report scopes and de-risks the investigation; it does not satisfy the fieldwork requirement for footing design.

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Check the geology, likely soil reactivity, nearby bore logs, groundwater, slope and constraints for a lot before you book the rig. Generate a report for your address or see a sample report.

LayeredGeo compiles geology, soils, groundwater and site data into an automated geotechnical desktop report for any address in Queensland, New South Wales, Victoria or South Australia.

Sources

• Hargreaves, B. (2005). 20 years of AS 2870 in South East Queensland: a personal view. Australian Geomechanics, Vol 40 No 3. geomechanics.org.au
• Jaksa, M. B. (2000). Geotechnical risk and inadequate site investigations: a case study. Australian Geomechanics, Vol 35 No 2. geomechanics.org.au
• Kelly, R. B., Drechsler, M. and Goldsmith, R. (2020). Connecting geotechnical investigations with project risk. Australian Geomechanics, Vol 55 No 1. geomechanics.org.au
• Li, J., Zou, J., Bayetto, P. and Barker, N. (2016). Shrink-swell index database for Melbourne. Australian Geomechanics, Vol 51 No 3. geomechanics.org.au

About this article. Published by LayeredGeo and written from the published research cited in the Sources section above. It is general information about how property and ground conditions are assessed in Australia, not engineering, planning, legal or financial advice, and it is not specific to any property. Check anything that matters against the source dataset or a suitably qualified professional before you rely on it. If you spot something wrong, tell us at hello@layeredgeo.com.au and we will fix it.

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