Ground investigation fees
What does a site investigation cost?
For a single house or self-build plot, a phase 2 intrusive ground investigation typically costs £1,500–£4,000, and a phase 1 desk study £500–£1,200 (typical 2026 quotes; access, depth and lab testing move the fee). The investigation informs your foundation design, so it is money spent before mistakes rather than after them. Tell us about your plot and relevant ground investigation firms will quote their exact fee.
Three steps
- Tell us about the plot: project type, what has been asked for, any known ground concerns. Two minutes, no account.
- We pass your details to relevant ground investigation firms covering your postcode, and to no one else.
- They contact you directly with a scoped fee for your site. Compare, choose, or walk away.
Site Investigation Cost is a free introduction service operated by Ellul Solutions Ltd; we pass your details to relevant ground investigation firms who quote you directly. We may receive a fee from providers; you pay nothing and are under no obligation. We are not a ground investigation firm or engineering practice and nothing here is engineering or structural advice; cost figures are typical 2026 quote ranges that vary by region, ground conditions and scope.
Typical site investigation costs, 2026
Last updated
What each stage of a site investigation typically costs for a single house or self-build plot. These are typical quote ranges observed across the UK market in 2026, not fixed fees; access, investigation depth, lab testing and reporting scope move the figure.
Ranges reflect typical quotes for domestic-scale ground investigation work observed across the UK market in 2026; they vary by region, ground conditions and scope. Larger development sites are scoped per scheme, so no headline figure is quoted for them. We do not publish per-borehole or per-metre drilling rates because they vary too much by rig, depth and access to be honest as a single number. Get exact fees for your plot via the form above.
| Item | Typical cost (2026 quotes) | Notes |
|---|---|---|
| Phase 1 desk study / preliminary risk assessment | £500–£1,200 | Records, historical maps, walkover; also the usual first step for contaminated land planning conditions |
| Phase 2 intrusive investigation, single house or self-build plot | £1,500–£4,000 | Trial pits or window sampling with lab testing and a factual/interpretative report |
| Trial pit based investigation | Lower end of the phase 2 range | Machine-dug pits are cheaper than boreholes where shallow information is enough |
| Borehole investigation with a drilling rig | Upper end of the phase 2 range and above | Needed for deeper information (basements, piles, poor ground); rig mobilisation and depth drive the fee |
| Multi-plot or development site investigation | Priced per scheme | Scoped to the layout and ground model; no honest headline figure exists |
- A phase 2 intrusive ground investigation for a single house or self-build plot typically costs £1,500–£4,000 (typical 2026 quotes; varies by access, depth and lab scope).
- A phase 1 desk study or preliminary contaminated land assessment typically costs £500–£1,200 (typical 2026 quotes).
- Trial pit investigations are cheaper than borehole investigations; boreholes earn their fee where deeper information is needed for basements, piles or poor ground.
Cite this page
“Typical site investigation costs, 2026”, Site Investigation Cost, https://siteinvestigationcost.co.uk/ (updated 2026-08-14). Ranges reflect typical quotes for domestic-scale ground investigation work observed across the UK market in 2026; they vary by region, ground conditions and scope. Larger development sites are scoped per scheme, so no headline figure is quoted for them. We do not publish per-borehole or per-metre drilling rates because they vary too much by rig, depth and access to be honest as a single number. Get exact fees for your plot via the form above.
Read next
The longer answers, with sources.
- Ground investigation cost: what a GI actually costs in 2026
Ground investigation costs: £1,500–£4,000 for a phase 2 intrusive GI on a single plot, £500–£1,200 for a phase 1 desk study (typical 2026 quotes). What moves the fee.
- Site investigation stages: phase 1, phase 2 and what each one buys
Site investigation stages explained: phase 1 desk study (£500–£1,200), phase 2 intrusive investigation (£1,500–£4,000, typical 2026 quotes), and when each is needed.
- Boreholes or trial pits: choosing the cheaper right answer
Trial pits are cheaper than boreholes and often enough for a house; boreholes earn their fee for basements, piles and poor ground. How the methods compare in 2026.
- Site investigation report: what it contains and who relies on it
What a site investigation report includes: logs, lab results, groundwater, and interpretation for foundation design. Factual vs interpretative reports and 2026 fees.
Frequently asked
How much does a site investigation cost?
Typical 2026 quotes: £500–£1,200 for a phase 1 desk study, and £1,500–£4,000 for a phase 2 intrusive ground investigation on a single house or self-build plot. Trial pit work sits at the lower end, borehole work at the top and beyond. Development sites are scoped per scheme.
Do I need a site investigation for a self-build?
On suspect ground, in practice yes: building control bodies and warranty providers such as NHBC commonly require ground investigation evidence where there is shrinkable clay with trees nearby, made ground, or a suspect site history. It is common practice rather than a blanket legal duty, and it directly informs your foundation design.
What is the difference between a site investigation and a ground investigation?
In UK practice "ground investigation" (GI) usually means the intrusive phase 2 work: pits, boreholes, testing. "Site investigation" is the wider phased process, including the phase 1 desk study. Firms and engineers use the terms loosely; the scope in the quote is what matters.
What standards govern site investigations?
BS 5930, the code of practice for ground investigations, and Eurocode 7, the geotechnical design standard. A proposal that references both, with an itemised testing schedule, is the mark of a firm whose report your engineer, building control and warranty provider can rely on.
Is this quote service really free?
Yes, free to you, with no obligation to accept any quote. We pass your details only to relevant ground investigation firms, who quote you directly; we may receive a fee from those providers, which is how the service is funded.