Geotechnical surveys – when and whether we should perform them

When buying a plot for our own house, we usually immediately have a vision of our future apartment in mind. Although we usually only plan its external appearance (and often the interior, but purely in terms of arrangement), at the back of the head we also have a basement or an underground floor, which is very useful, among others, for storing larger things (including parking cars), but and organizing a cozy workshop, storeroom or utility rooms, which we will not necessarily want to visit very often. 

We should think about it at the stage of buying a plot , because not every land will allow us to do so . How to check whether this particular one will enable us to do so, or whether our plan for the basement of the future house will fail? It is enough to conduct geotechnical research.

Why is it worth choosing geotechnical research?

As we said earlier, we should conduct geotechnical research when we want to try a basement in our future house – and it is best to do it before buying the plo . We should not build a basement if the groundwater is very high – then it will not only be difficult to build, but also simply expensive. Facing such a situation, however, do not give up the plot – this is not a disadvantage, but only a factor that will prevent us from building our own basement.

Therefore, geotechnical surveys are able to provide us with information on whether we will be able to equip the house with an underground level. They can also tell us (especially in the case of huge plots) where we will be dealing with the most optimal soil conditions for putting up a house (its foundations are always underground) and where it will be more expensive.

What must the geotechnical documentation contain?

Geotechnical tests are carried out by a professional geotechnician and consist in drilling (usually with a depth not exceeding 5m). They last about an hour (although this time may be extended if we need more boreholes), and the very process of their implementation should end with the receipt of geotechnical documentation , consisting of a descriptive and graphic part (the latter contains a map with specific drilling locations) , but also geotechnical sections, giving us an insight into what was actually done). Correct geotechnical documentation should include:

  • description of water conditions – it should contain information on the depth of groundwater deposition, crucial in the entire geotechnical survey; let’s also make sure that the documentation also has a forecast with fluctuating depth;
  • graphical representation of drilling locations and geotechnical cross-sections, which we have already mentioned;
  • conclusions and recommendations – a professional geotechnician is able to determine whether it is reasonable to carry out the activities defined by us in advance on the plot of land presented to him; therefore, he should describe all kinds of recommendations (strictly based on his research), including those related to the type and condition of the land on which our house will be built, where its foundations will be installed, but also presenting possible drainage options (if there are), methods of securing slopes or measures to guarantee our safety during construction and after it;
  • detailed plan and visualizations – the graphic part of the entire documentation should present all elements of the study, but also of our plot, simply explaining all conclusions presented in a descriptive form;
  • forms for additional field surveys – if geotechnical surveys are not able to provide us with a certain answer about the plot, the documentation often includes forms and applications for additional surveys.

What else should we do besides testing?

Regardless of the result of geotechnical surveys performed by a professional geotechnician , we should always do everything ourselves. The most tangible here will be walking around the plot and looking at the buildings erected by the neighbors – if they contain cellars, it may be a good sign, although we should not enter it blindly . Let’s also take care to look at the farm wells – if, of course, they are located in the place where we have our plot. If the water in them is at a high level, it can be alarming for us. However, let us treat all these aspects as preliminary research, confronting them with professional research.


Although not everyone has heard about something like geotechnical research , they are something almost necessary when buying a plot – at least if we want to equip our future home with a basement or anything else that would be underground. Remember to obtain appropriate documentation after their completion, which is not only a confirmation of its proper performance,