The construction of each house involves the handling of many permits and other formalities. It is imperative to carry out a soil test to check the quality and assess the bearing capacity
What is a geotechnical opinion?
One of the first steps to be performed before building a house is soil testing. Thanks to this, you can find out what building can be erected and receive guidelines on which foundations will work best. The groundwater level and soil permeability will also be measured.
The opinion is issued on the basis of geological drillings. Such a document should be divided into two parts: graphic and descriptive. The image will show a plot map showing the boreholes, opencast pits, soil layers and groundwater level. The descriptive part consists of:
- recommendations for the selection of foundations,
- information on soil layers,
- information on the depth and fluctuations of groundwater,
- recommendations on how to protect against groundwater,
- recommendations on how to perform drainage.
Specialists should act at this stage of the research. Geotechnical expertise may be carried out by persons with appropriate permissions. Even the testing process is not the simplest one, therefore it requires professional knowledge and the necessary, often very expensive devices, thanks to which the drilling is carried out. Such activities are aimed at assigning the land to one of three categories. The investor will gain knowledge of what type of building can be erected in the studied area.
Why is a geotechnical survey carried out before starting the investment?
In Poland, soils with adequate bearing capacity are predominant. Many people also say that since there are already buildings in the immediate vicinity, they can start construction without any problems. However, a geotechnical opinion is needed to be sure of this state of affairs. It will not only allow the construction, but it will also allow you to properly select the parameters of the house, choosing a good foundation and the necessary insulation. It will allow to design the best possible drainage of the plot by building a well or a sewage treatment plant. This study is very important and savings on it are not advisable. Cracks in walls and ceilings may be the result of mistakes in examination, analysis or design maladjustment. In extreme cases, the stability of the building may be disturbed, which will only translate into an increase in construction costs or subsequent renovations,
Before starting the investment, it is necessary to conduct a geotechnical survey. The result of such examination should be submitted together with the application for a building permit. Most often, a basic test is sufficient, unless there is a change in soil category. In this case, it will be necessary to conduct a precise and more complex expertise. Departing from the law, soil surveys are carried out for the benefit of the residents and other users of the building. Although at first glance the additional activities seem to be of a kind that make life difficult, the results of the research may lead to the abandonment of investments that threaten the life of residents.
The above mentioned geotechnical categories. With their help, the degree of complexity of the ground conditions, which are the basis for the design of the building, is classified. On the land included in the first category, you can build a small building erected in simple ground conditions. The second category includes buildings erected in simple complex ground conditions, which require a quantitative and qualitative assessment of geotechnical data. On the other hand, on the land belonging to the third category, it is possible to erect atypical structures that require difficult conditions, use unusual technical solutions, and may have a significant impact on the environment as well as high-rise buildings. Research shows that investments are most often given the first geotechnical category, which means that a single-family house can be built on such land. However, the degree of research carried out depends on the type of investment. A different test will be carried out before building the cottage and another before building the block.
The performance of an expert opinion depends on the investor’s needs and the type of investment. However, this is not an excessive amount compared to construction expenses. The costs are most often facilitated by the willingness to perform an expertise within the first geotechnical category.
It is assumed that the price of the test depends on the wells, especially on their number and depth. For the results to be credible, it is enough to drill four geological wells, the depth of which will be about three meters. The standard price list shows that one borehole to a depth of one meter costs a minimum of PLN 100, but the amounts depend on many factors, e.g. the specialist’s place of business. The total cost of drilling should be up to PLN 2,000. In return, the investor receives electronic and paper documentation along with the recommendations of specialists.