Geotechnical design competence under Eurocode 7
Eurocode 7 names no qualification. It sets three geotechnical categories and makes the experience needed a function of which one your work falls into.
Eurocode 7 does not name a qualification. What it says, in the general rules of BS EN 1997-1, is that geotechnical design has to be carried out by personnel with appropriate qualifications and experience, and it then makes the required level of experience a function of the geotechnical category of the work. So the question "who is competent to design this?" has a structured answer: classify the work, and the classification tells you what sort of person and what sort of evidence the design needs.
For a developer buying ground engineering, that matters at two points. It decides who you appoint, and it decides what the planning submission and the building control submission can safely say.
What the code expects of the designer
Eurocode 7 sits in two parts. BS EN 1997-1 covers design, and BS EN 1997-2 covers ground investigation and testing, both read with the UK National Annex. Between them they require two documents that are often conflated: a ground investigation report, which records and interprets the factual data, and a geotechnical design report, which sets out the design assumptions, the derived values of geotechnical parameters, the calculations and the checks required during construction.
The competence requirement attaches to the design, and it runs through the whole chain. Choosing where the boreholes go is a design decision. Deriving a characteristic value from a scatter of test results is a design decision, and it is the one where inexperience shows most clearly, because the code asks for a cautious estimate of the value affecting the occurrence of the limit state rather than an average of the numbers.
This is separate from planning. A planning authority will rarely ask whether your design complies with Eurocode 7. Building control will, through Approved Document A and the structural submission. The planning stage question is narrower: is the ground condition capable of supporting the development without unacceptable effects on stability, neighbouring land, groundwater or protected trees.
Geotechnical categories and the competence each implies
Eurocode 7 sets three categories, and the boundaries are matters of judgement rather than arithmetic.
| Category | Typical work | What the code expects |
|---|---|---|
| 1 | Small, simple structures with negligible risk in known ground | Qualitative assessment and comparable experience, no quantitative analysis required |
| 2 | Conventional structures and foundations, no exceptional risk, no unusual ground or loading | Quantitative geotechnical data, routine field and laboratory testing, conventional analysis |
| 3 | Very large or unusual structures, abnormal risks, unusual or difficult ground, unusual loading | Specialist provisions and alternative rules beyond the routine, with specialist input |
Category 1 is for a garage on known firm ground. Most housing and small commercial work is Category 2, and Category 2 is where competence disputes happen, because the word "conventional" hides a lot. A three storey block on made ground over alluvium with a shallow water table is conventional in shape and unconventional in ground. Treat the classification as a decision to record and justify, not a box to tick.
Category 3 pulls in named specialisms: deep basements, piled rafts in variable ground, slope stability in over-consolidated clay, mining legacy, dissolution features. On those, appointing a generalist structural engineer with a geotechnical module is not enough, and the honest position is that the design needs someone whose day job is ground.
Designing the investigation against interpreting it
The commonest procurement error is buying a ground investigation as a commodity. A price per metre of borehole, a standard suite of tests, a factual report, and no one who owns the interpretation.
Eurocode 7 Part 2 expects a phased investigation: a desk study and preliminary ground model first, then intrusive work designed to test that model, then further work where the model fails. British Standard 5930 on site investigation sets out the same sequence. The person who writes the specification for the boreholes should be the person who will later derive parameters from them, because only they know what would change their mind.
So split the appointment consciously. The geotechnical designer specifies and interprets. The investigation contractor drills, samples and tests, and the choice of testing laboratory affects whether the results can be relied on at all. Where the same firm does both, ask who checks the specification.
Who signs the geotechnical design report
The report should be authored by the geotechnical designer and signed by someone who can defend the derived values. For Category 2 work, an experienced geotechnical engineer within a firm with an internal check process is the normal arrangement. For Category 3, expect a named specialist, an independent design check, and a clear statement of what was assumed and what was verified.
Two registers help when you are assessing a firm. The Institution of Civil Engineers maintains a register of ground engineering professionals at adviser, specialist and professional levels, which is the closest thing the discipline has to a competence list. Membership of the trade association for geotechnical and geoenvironmental specialists indicates a firm that works to agreed data formats and reporting conventions. Neither is a legal requirement, and neither substitutes for asking to see two design reports on comparable ground.
For planning purposes, a Geotechnical Assessment is a document councils normally expect to see authored by a suitably qualified engineer, and professional review is strongly advised before submission. PlanScope drafts one from the site answers and flags the facts that only investigation can supply, so the specialist starts from a structure rather than a blank page. The same applies to a Basement Impact Assessment, where several London boroughs set out their own audit procedure and expect a chartered engineer to sign it.
Supervision while the ground is open
Section 4 of Eurocode 7 deals with supervision of construction, monitoring and maintenance, and it ties the intensity of supervision to the category. The point is that a geotechnical design is provisional until the ground is exposed. Founding levels, the depth of soft alluvium, the position of a buried obstruction and the piezometric level are all things the trial pits sampled and the excavation reveals.
Three practical requirements follow. The design report should state what is to be inspected and by whom. Someone with the authority to change the design should attend the critical excavations. And a record of the inspections should be kept, because when a neighbour's wall cracks two years later, the inspection record is the evidence.
Where the investigation is old, treat the parameters as questionable rather than simply out of date. Groundwater levels, contamination and adjacent construction all move, and re-reading an old report against today's site is a cheaper exercise than re-drilling.
Where a second opinion pays for itself
Buy a review, not a redesign, in four situations. Where the geotechnical category has been set at 2 and the site has mining legacy, dissolution, slope instability or deep made ground. Where the foundation solution changed late for cost reasons. Where a neighbouring party has raised a ground movement objection. And where the basement or retaining design controls the programme.
A review of this kind is usually a few days of a specialist's time against a foundation package worth a great deal more. The meaning of competent person in planning legislation is a useful reference point here, because the phrase carries a different weight in different regimes, and the geotechnical one relies on professional judgement rather than a statutory register.
Scoping the work before you appoint
Do this before the first invitation to tender:
- Assemble the desk study material. Geological mapping and borehole records from the British Geological Survey, historic maps, coal mining reports where the site is in a referral area, and any previous investigation on the site or its neighbours.
- Write down the ground model you expect, with the uncertainties named.
- Set the geotechnical category and say why.
- Decide what the investigation has to prove, then let the designer specify the holes.
- Say in the brief who will derive the parameters, who will write the design report and who will attend the excavations.
That brief is short, and it is the difference between a factual report you cannot use and a design you can defend. Where you need the planning-stage documents alongside it, the professional directory is where a draft goes for review and sign-off. Enter your postcode on PlanScope to see which ground and stability reports your site is likely to need.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.
Frequently asked questions
Does Eurocode 7 say who is qualified to do geotechnical design?
It does not name a qualification. BS EN 1997-1 requires design to be carried out by personnel with appropriate qualifications and experience, and links the level required to the geotechnical category of the work. Category 1 allows qualitative judgement and comparable experience, while Category 3 expects specialist provisions and specialist input.
What is the difference between a ground investigation report and a geotechnical design report?
The ground investigation report records and interprets the factual data from boreholes, trial pits and testing. The geotechnical design report sets out the design assumptions, the derived values of parameters, the calculations and the checks required during construction. Eurocode 7 expects both, and they are commonly conflated in practice.
Which geotechnical category applies to a small housing scheme?
Usually Category 2, which covers conventional structures and foundations with no exceptional risk and no unusual ground or loading. Made ground, shallow groundwater, mining legacy or slope instability can push the same building into Category 3. Record the classification and the reasons for it rather than assuming Category 2 by default.
Do planning authorities check Eurocode 7 compliance?
Rarely. Compliance is tested through building control and Approved Document A. At planning stage the authority asks whether the ground condition allows the development without unacceptable effects on stability, neighbouring land, groundwater or trees, which is what a geotechnical assessment is for.
Should the same firm design the investigation and interpret it?
The person who specifies the boreholes should be the person who later derives the parameters, because only they know what result would change the design. Using one firm for both is common and acceptable, provided someone independent checks the specification and the interpretation is not left to the drilling contractor.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.