1. Why ground does not appear in a price per square metre
Three reasons. A price per square metre describes the building, not the plot.
Ground conditions differ from plot to plot, so an average figure is not transferable. The cost of foundations emerges only after the survey.
Commercial quotations normally assume ordinary ground conditions, and exceptions are priced separately. The assumption must be checked in the quotation.
The practical consequence: two identical houses on two plots can cost different amounts without anything in the design having changed. On professional sources, geology and ground conditions can vary significantly not only between neighbouring plots but even within the footprint of a single building.
2. What a ground survey provides
A geotechnical, or engineering geological, survey provides the data needed for design. Without it the design rests on assumptions.
| What the survey provides | For what |
|---|---|
| Data on the ground beneath the building and on groundwater | the basis of the foundation solution |
| Ground properties relevant to design and their characteristic values | geotechnical calculations |
Technical requirements derive from the standards EVS-EN 1997-1 and EVS-EN 1997-2, covering geotechnical design and ground investigation and testing. The terms ground survey, geotechnical survey and engineering geological survey are used synonymously in those standards.
3. Why omitting the survey does not save money
This is the most important point in the article, and it is counter-intuitive. Omitting the survey does not save money.
On professional sources, designing without a ground survey usually leads to oversized foundations. If the bearing capacity of the ground is unknown, design proceeds on the safe side, and the safe side means more material and more work than actually required.
Omitting the survey therefore does not remove the cost, it transfers it to the foundations, usually for a larger sum than the survey itself would have cost. Foundations designed with a margin cost more than the survey.
There is also risk. The same sources note that designing without knowing the actual ground conditions can be dangerous, particularly where geotechnical conditions change.
A simple and light structure may be designed without a new survey where reliable earlier data exist, but that presupposes such data are available and relevant. The decision should nonetheless be documented.
4. Where to find earlier data
Estonia offers a practical option here that is often not used. It concerns the use of earlier surveys.
| Source | Content |
|---|---|
| Engineering geology database, established in 1964 | data from around 37,000 engineering geological and geotechnical survey reports, including building settlement observations |
The database was established to preserve and reuse survey results. Before commissioning a new survey it is worth checking whether earlier data exist for the area, which may reduce the scope of the survey.
It does not replace a survey, but it can change its content and therefore its price. Existing data reduce the amount of fieldwork.
5. What a survey entails
Three obligations follow from the applicable rules. The report must be submitted to both the building register and the Geological Survey of Estonia, within 10 days of the date the report is completed.
The report must be signed by the competent person appointed as responsible for the survey. An unsigned report is not a basis for design.
In the report the surveyor makes proposals for further investigation where the existing survey does not provide sufficient information. Those proposals are read before the foundation is chosen.
The third point is an important signal for the client: a proposal for further investigation means the basis for design is not yet complete. It should not be read as a formality.
In summary, and four practical rules
Ground is a cost independent of the price per square metre and can vary even within the footprint of a single building. Omitting a ground survey does not remove the cost but transfers it to the foundations through oversizing, usually for more than the survey itself. The engineering geology database has held around 37,000 reports since 1964 and is worth checking before commissioning a new survey. A completed report must be submitted to the building register and the Geological Survey of Estonia within 10 days.
Four rules: treat ground as a separate cost, not as part of the price per square metre. Explain to the client that omitting the survey transfers the cost to the foundations. Check for earlier data before setting the scope of a survey. Take seriously any proposal for further investigation.
This article serves professional orientation at the date of checking. It is not a quotation.