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Soil study: stage 1 of a sustainable house in the South-West

Table of contents

The soil study is essential when you build your house. Objective: to avoid cracks, settling and to make the house durable. Indispensable in the Southwest, it aims to understand which foundations are suitable for your land.

G1 soil study: mandatory to protect buyers of building land

Since January 1, 2020 and the Moose law, the seller of a undeveloped land has the obligation to inform the buyer about the risks related to the land. It therefore appends to the agreement to sell a geotechnical study. This obligation concerns areas moderately and highly exposed to the phenomenon of shrinkage-swelling of clays. This study, called G1, is a preliminary study. It makes it possible to characterize the major risks and indicates the general principles of possible construction (fripples, earthworks, buried structures, soil improvements, etc.). Good news, because this Elan law thus secures the buyer of land and allows him to evaluate, with the individual house builder, more easily the cost of his project.

Discover here the decree of July 22, 2020 defining the content of geotechnical studies to be carried out in areas exposed to the phenomenon of differential ground movement resulting from drought and soil rehydration.


G2 study by the new home builder

If your project is located in a sector concerned by the Elan law subject to medium to high hazard with respect to the swelling shrinkage phenomenon of clays, you will have to make a soil study G2 at the stage of your building project. This study is more extensive than the first. It allows you to know precisely the nature and behavior of the ground on which you are building your new house. The objective is to accurately adjust the foundations to your project and the hazards encountered on your land, and to protect your construction. " At the house of Sic houses, we were one of the first builder to make compulsory the G2. Our design office precisely analyzes the needs of each project in terms of foundations, and the appropriate scrap is thus made to measure", explains Jose Longo, Chief Commercial Officer at Sic houses.

Watch here the video interview of José Longo which describes his role as Commercial General Manager in the construction of houses at the builder Sic Houses.

What is clay shrinkage/swelling?

Clay swells or contracts depending on its water content. In period of drought, the lack of water leads to shrinkage. Conversely, a new supply of water will produce swelling. Due to their foundations more superficial, detached houses, which are light buildings, are the first affected by these phenomena. Anal Fissure, detachment of contiguous elements, distortion of doors and windows, dislocation of paving or even rupture of buried pipes, the consequences can be dramatic and the solutions costly.

48% of French territory is in a medium or high exposure zone, but the South-West is the zone most affected by the risk. © BRGM

Shrinkage-swelling of clays: the South/West concerned

The phenomenon of shrinkage/swelling of clays is amplified by global warming. Today, 48% of the territory is subject to the shrinkage-swelling risk of clays. An even larger proportion in the South West.
The clay map was thus reviewed in 2021. “ The areas at risk have greatly expanded. In the past, the risk mainly concerned the Toulouse country, and some areas of Gers, Landes, Lot-et-Garonne and Tarn-et-Garonne. Today, almost all of South West is concerned “says José Longo.

Discover here the risks in your municipality.


A risk covered by insurance with a good builder

The soil study is very important. The knowledge of natural hazards existing on his the land allows you to guard against it. THE new home builder can then design a type and a foundation depth adapted to the properties of the soil. A overhead at the level of foundations does not jeopardize your building project. Your builder helps you optimize your project to reduce costs without reducing your comfort.
“We analyze, before the signature of the contract for the construction of an individual house, what are the solutions to implement to have a quality house. The report is then given to the client by integrating into the house price the special foundations and adapted foundations when it's necessary. Thus, in case of natural disaster, the owner is covered by insurance. The damage work also includes this risk. The customer is thus fully insured and fully covered”, analyzes the Commercial General Manager at Sic houses.

In order to better understand the constructive principles of Maisons Sic, in particular the foundations, visit here the Sic Houses Technical Realization Test Center 


Know how to build on all terrains

Find building land is more and more difficult today. This scarcity is likely to make it increasingly difficult to construct buildings on quality land. Under these conditions, the achievement of G2 soil studies takes on its full meaning, even on land where they are not mandatory. As the saying goes, prevention is better than cure.


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