Since January 1, 2025, the State of Risks and Pollution (ERP) provided to buyers includes new categories: coastal retreat, legal obligation for clearing brush, and enhanced shrink-swell of clays. This change, stemming from decree no. 2024-405 of April 29, 2024, concretely modifies what an investor must read and verify before signing. The document you thought you mastered has changed its scope.
Shrink-swell of clays: the risk that mapping underestimated
Most content on natural real estate risks focuses on flooding. The clay risk deserves at least equal attention. According to data relayed by several specialized sources, French buildings exposed to shrink-swell of clays represent an issue worth several hundred billion euros.
The mechanism is simple: clay soils swell with moisture and shrink during dry periods. This movement causes structural cracks in foundations, load-bearing walls, and slabs. Repairs often exceed the scope of simple renovations.
A public aid program to prevent this risk has been tested in recent years, providing financial assistance to strengthen the foundations of individual homes. For an investor, the question goes beyond diagnosis: it touches on the durability of the building and the resale capacity. A property located in an area with a high exposure to shrink-swell of clays may see its value drop if foundation repair work has not been carried out.
Before committing, checking the natural risks to verify before real estate purchase allows for precise identification of the clay exposure level of the desired plot.
ERP 2025: what the new form changes for the investor
The ERP form is not a fixed document. Its latest update, effective since January 2025, adds sections that previous versions ignored. An ERP dated before 2025 may be incomplete regarding risks that are now mandatory.
Three additions modify the reading of the document:
- The coastal retreat, which concerns coastal municipalities where the shoreline is receding due to erosion. Properties located in these areas may be subject to construction or extension restrictions in the future.
- The legal obligation for clearing brush (OLD), which applies to properties near forests or areas exposed to fires. About 6,900 municipalities report being exposed to the risk of forest fires, according to data relayed by TF1 Info.
- The enhancement of the shrink-swell of clays section, with more precise mapping integrated directly into the form.
For an investor buying remotely or in an area they know poorly, the temptation is to skim the ERP. This reflex can be costly. Each section marked “yes” in the form calls for additional verification: consulting the corresponding prevention plan, targeted site visits, compliance estimates.
Obligation to clear brush and purchasing near a forest
The OLD is a topic still little addressed in real estate buying guides, even though it has direct financial consequences. The seller is required to inform the buyer of the existence of this obligation since the new ERP form came into effect.
Buying a house near a forest involves checking if the municipality is on the list of areas exposed to forest fires. If so, the owner must clear brush within a defined perimeter around the building, at their own expense. Non-compliance with this obligation can lead to penalties, but also complicate compensation in the event of a disaster.
For a rental investment, this recurring charge must be integrated into the budget. It is not limited to hedge trimming: depending on the terrain’s configuration, clearing work can represent a significant annual expense.
Géorisques and site verifications: cross-checking sources before the visit
The site Géorisques.gouv.fr remains the reference tool for consulting an address’s exposure to natural, mining, and technological risks. Since 2022, every real estate listing must mention this site. The online tool Errial allows generating a pre-state of risks from a simple address.
The available data do not always allow for conclusions about the actual state of the land. The official mapping reflects a statistical risk, not the precise history of the plot. Two neighboring houses may have very different exposures depending on the nature of the subsoil, the slope, and the proximity of a temporary watercourse.
Three additional verifications deserve to be conducted before signing:
- Consult the municipal risk prevention plan (PPR) to identify the specific prescriptions applicable to the plot.
- Request from the seller the history of declared claims under natural disasters. This information must be included in the ERP if the property has been subject to compensation.
- Have a soil study (geotechnical study G1 or G2) conducted on lands located in clay areas, particularly for individual homes built before current standards.
These steps take time and incur costs. For an investor targeting an area with attractive rental yields, they help avoid discovering after signing that the low price of the property reflected a risk that the market had already integrated.
The 2025 ERP, updated clay mappings, and the obligation to clear brush redefine the scope of real estate due diligence. An investor who limits themselves to a quick reading of the diagnosis without cross-checking sources exposes themselves to additional repair costs, insurance difficulties, or a depreciation at resale. The displayed price of a property does not always include the real cost of the risk.