Sale of building land: a new mandatory diagnosis

Clay soils, in case of drought or massive water supply, can gradually weaken buildings, especially the lightest ones such as detached houses. Cracks can then appear and threaten the solidity of the house. The soil survey should enable the buyer to better assess the potential risk and the builder to adapt its construction rules. It must be annexed to the sale agreement with the promise to sell or, in the absence of a promise, to the authentic instrument of sale.

Which operations are involved?

The soil survey concerns:

• sales of non-built land suitable for building individual houses (building land);
• contracts relating to construction work or project management, in particular contracts for the construction of single-family houses (CCMI).

It does not concern contracts for:

• work which does not affect the foundations or structure of the building, the flow of water or the heat exchange between the ground and the basement of the building;
• work on extensions, including verandas and garages if the project area is less than 20 m² and if this new construction is detached from the existing building.

What is in the soil survey?

• In the context of unbuilt land, the study of soil

  prerequisite

  (type G1) must be provided by the seller. This identifies the geotechnical risks of a site and defines general building principles to prevent the risk. It is valid for 30 years. It is intended to help refine risk assessment at the field level.

• In carrying out construction work, the contracting authority may:
  
  • to provide a geotechnical study of

    design

    (type G2) taking into account the location and characteristics of the building. It prescribes construction provisions adapted to the nature of the soil, it is valid only for the project for which it was carried out;
  • or comply with the particular construction techniques defined by regulation.

Which geographical areas are involved?

One terrain movement exposure map identifies four categories of zones:

• high exposure;
• average exposure;
• low exposure;
• the rest of the territory.

To know the area on which a lot depends, choose the pictogram

Choice of layers

with a sheet and a plus in the column to the right of the card. The choice of layers is displayed. Then select

Clays

. The areas appear on the map where you can zoom.

The study is mandatory only for land in areas where the risk exposure is classified as medium or high.