The content of the soil study
The geotechnical study is said to be "preliminary" when it identifies the geotechnical risks of a site and defines general construction principles to prevent the risk of ground movement due to drought and soil rehydration.
The geotechnical study is called "design" when it considers the location and characteristics of the building. The purpose of the soil study is then to determine, based on an identification of the geotechnical risks of the site of implantation, the constructive prescriptions adapted to the nature of the soil and the construction project.
Geographical areas concerned by the soil study
The geotechnical study is necessary for an estate located in a risk zone, in practice a clay soil zone. A map of exposure to the phenomenon of differential ground motion is available on http://www.georisques.gouv.fr/. It distinguishes the zones more or less exposed.
- high exposure;
- medium exposure;
- low exposure;
A soil study is mandatory in areas where the risk exposure is qualified as medium or high.
In the geographical areas subject to geotechnical study, are concerned:
- sales of construction free estates that can be built on for the construction of individual houses (building estate);
- contracts for the construction of individual houses (CCMI).
The soil study was to be mandatory for estates sales and CCMIs signed on or after January 1, 2020.
The geotechnical study is valid for 30 years if no soil remediation has been carried out.
The geotechnical design study considering the location and characteristics of the building is valid only for the project for which it was carried out.
Apart from any legal obligation, it is always recommended to carry out a soil study before starting a home construction project.
On July 22, 2020, three decrees were issued to specify the exposed areas, define the content of the geotechnical studies as well as the specific construction techniques. All the measures set up by these texts apply to sale and construction contracts concluded as of January 1, 2020.