Buying a house in France often begins with sun-drenched photos of stone farmhouses, lavender-lined driveways and village squares. Few buyers — especially those purchasing from abroad — think to ask the question that may determine whether their new home can be insured, renovated or even safely occupied: is the property located in a natural risk zone? A landmark ruling handed down by the Cour de cassation on 19 February 2026 has tightened the seller’s obligation to disclose natural risks, and it carries direct consequences for anyone buying or selling French real estate between the signing of the preliminary contract and the final deed.

I. The ERNIAL: France’s Mandatory Natural Risk Disclosure System

A. What Is the État des Risques and Why Does It Matter?

French law requires every seller of real estate — whether a house, an apartment or a plot of land — to provide the buyer with an état des risques naturels et technologiques (ERNIAL), a document that lists all the natural and technological risks affecting the property. This obligation is established by Article L. 125-5 of the French Environmental Code, which states that “les acquéreurs ou locataires de biens immobiliers situés dans des zones couvertes par un plan de prévention des risques technologiques, par un plan de prévention des risques miniers ou par un plan de prévention des risques naturels prévisibles, prescrit ou approuvé, dans des zones de sismicité ou dans des zones à potentiel radon […] sont informés par le vendeur ou le bailleur de l’existence de ces risques.” In plain English: any buyer or tenant of property located in an area covered by a risk prevention plan must be informed by the seller or landlord of those risks.

The ERNIAL is one of the documents that make up the dossier de diagnostic technique (DDT), the mandatory bundle of property surveys that the seller must annex to the sale contract. Under Article L. 271-4 of the French Construction and Housing Code (CCH), the DDT must be attached to the promesse de vente (preliminary sale agreement) or, if there is no promesse, to the final notarised deed. The ERNIAL item — listed at paragraph 5° of Article L. 271-4 — covers flood zones, seismic areas, radon-prone ground, areas subject to forest fires, clay soil shrinkage and swelling (retrait-gonflement des argiles), mining risks and coastal erosion zones.

The practical consequence is severe. If the ERNIAL is missing at the time of the final deed, Article L. 271-4, paragraph II expressly gives the buyer the right to “poursuivre la résolution du contrat ou demander au juge une diminution du prix” — seek rescission of the sale or a price reduction. This is not a cosmetic requirement. It is a ground of nullity written directly into statute.

B. The Obligation to Update: What Happens Between the Compromis and the Final Deed?

French property transactions follow a two-stage structure. The parties first sign a promesse de vente or compromis de vente (preliminary agreement), and several weeks or months later, they appear before the notary to sign the acte authentique (final deed). Under Article 1589 of the French Civil Code, “la promesse de vente vaut vente, lorsqu’il y a consentement réciproque des deux parties sur la chose et sur le prix” — the sale promise is equivalent to a sale when the parties agree on the property and the price. This provision has long been invoked by sellers to argue that all their obligations are fixed at the date of the promesse, not the date of the final deed.

The legislator anticipated this difficulty. Article L. 271-5 of the CCH provides, in its final paragraph, that “si, après la promesse de vente, la parcelle sur laquelle est implanté l’immeuble est inscrite dans une des zones mentionnées au I de l’article L. 125-5 du code de l’environnement ou si les documents à prendre en compte pour l’application du même I ont fait l’objet d’une mise à jour, le dossier de diagnostic technique est complété lors de la signature de l’acte authentique de vente par un état des risques ou par la mise à jour de l’état existant.” In substance: if, between the promesse and the final deed, the property enters a risk zone or the relevant public documents are updated, the seller must complete the DDT with an updated ERNIAL before the final deed is signed.

The Cour de cassation had already applied this rule in a leading precedent, Cass. 3e civ., 19 September 2019, no. 18-16.700 (published in the Bulletin). In that case, a promesse de vente signed on 13 August 2008 was followed by the approval of a plan de prévention des risques naturels prévisibles (PPRNP) by prefectoral order on 25 November 2008, before the notarised deed of 24 March 2009. The Cour de cassation upheld the rescission of the sale, ruling that the seller’s obligation to inform the buyer of natural risks is assessed at the date of the final deed, not the date of the promesse. As the Court held: “il résulte des dispositions combinées de l’article L. 125-5 du code de l’environnement et des articles L. 271-4 et L. 271-5 du code de la construction et de l’habitation […] que, si, après la promesse de vente, la parcelle […] est inscrite dans une zone couverte par un PPRNP prescrit ou approuvé, le dossier de diagnostic technique est complété, lors de la signature de l’acte authentique de vente, par un état des risques ou par une mise à jour de l’état des risques existants.”

II. The 19 February 2026 Ruling: A Stricter Obligation

A. The Facts, the Legal Issue and the Court’s Answer

The case decided by the third civil chamber of the Cour de cassation on 19 February 2026, no. 24-10.524 (published in the Bulletin), involved buyers who had purchased a building plot by way of a promesse synallagmatique de vente signed on 3 November 2011, followed by a notarised deed on 21 and 23 March 2012. At the time of the promesse, an ERNIAL was attached indicating that the land was located within the perimeter of a plan de prévention des risques d’inondation (PPRI, or flood risk prevention plan) that had been prescribed — ordered to be drawn up — but not yet approved.

Between the promesse and the final deed, on 28 February 2012, the prefect approved the PPRI by formal order. Under Article L. 562-4 of the French Environmental Code, an approved PPRNP “vaut servitude d’utilité publique” — it acquires the legal status of a public-interest easement and is annexed to the local urban development plan. The approval therefore changed the legal character of the risk from a mere administrative prescription to a binding land-use restriction enforceable against all owners.

The ERNIAL attached to the final deed, however, made no mention of the 28 February 2012 approval order. In 2016, when the buyers sought to build their house, they were issued a negative certificat d’urbanisme (a town-planning certificate confirming that construction was impossible) on the ground that their plot fell within a high-risk flood zone under the approved PPRI. They sued the sellers and the notaries for rescission of the sale.

The Montpellier Court of Appeal dismissed their claim, reasoning that the prefectoral order had merely approved a plan that was already prescribed and that the buyers had been informed of the flood risk from the outset. The Cour de cassation quashed that ruling. Its reasoning is captured in a single, powerful paragraph:

“Il en découle que si, après la promesse de vente faisant état d’un plan de prévention des risques naturels prévisibles prescrit, celui-ci a été approuvé avant la signature de l’acte authentique, le dossier de diagnostic technique doit être complété par une mise à jour de l’état des risques résultant du plan approuvé valant servitude d’utilité publique.”

In translation: where a promesse mentions a PPRNP that has merely been prescribed, and that plan is approved before the final deed, the DDT must be supplemented by an updated ERNIAL reflecting the approved plan — because the approved plan carries the weight of a public-interest easement. The Court added that the buyers had not been made aware, through the final deed, of the change in their plot’s status resulting from the approval of the plan. The case was remanded to the Nîmes Court of Appeal for a fresh decision.

The ruling goes further than the 2019 precedent in one critical respect: it holds that the obligation to update the ERNIAL applies even when the approved plan does not modify the zoning or the risk classification compared to the prescribed plan. The mere fact of approval — transforming a prescribed plan into a binding servitude — triggers the duty to update. Nothing less than a current ERNIAL reflecting the most recent legal status of the risk will do.

B. Practical Consequences for Foreign Buyers and Sellers

This line of authority has direct implications for anyone buying French property from abroad. The period between the promesse and the final deed is usually two to three months, during which various administrative steps take place: mortgage applications, notarial searches, and the buyer’s ten-day cooling-off period under Article L. 271-1 CCH. An overseas buyer who signs a promesse remotely and plans to travel to France only for the final deed may not realise that a prefectoral order approving a risk prevention plan has been published in the interim. The seller and the notary are jointly responsible for ensuring that the ERNIAL annexed to the final deed is current.

Several related rulings illustrate the scope of the seller’s obligations and the consequences of non-compliance.

In Cass. 3e civ., 7 March 2024, no. 20-17.790, a house sold near Paris had been built on clay soil subject to the retrait-gonflement des argiles phenomenon — the swelling and shrinking of clay that causes structural cracking. The sale deed expressly stated: “le vendeur déclare qu’il existe sur la commune de Noisy-le-Grand un plan de prévention des risques naturels prescrit de mouvement de terrain dus au retrait gonflement des argiles.” The Cour de cassation upheld the buyer’s claim under the garantie des vices cachés (hidden defects warranty of Articles 1641 et seq. of the Civil Code), rejecting the sellers’ argument that the disclosure of the PPR prescription discharged their duty. The existence of a prescribed risk plan does not immunise the seller against a claim that the property itself suffers from defects linked to that risk.

In Cass. 3e civ., 13 July 2022, no. 20-21.293, the Court confirmed that a seller may be liable under the general tort provisions of the Civil Code where the buyer is unable to construct on the land owing to non-compliance with the provisions of a flood risk prevention plan. The Court noted that the seller’s failure to inform the buyer of the practical consequences of the PPR — not just its existence — could constitute fault.

In Cass. 3e civ., 8 June 2023, no. 22-13.855 (published in the Bulletin), the Cour de cassation ruled that a court adjudicating on a construction dispute could not rely on a mere porter à connaissance (an administrative notification to the municipality) to override the provisions of an approved flood risk plan. This demonstrates the legal primacy of the approved PPR over informal administrative documents — and reinforces the importance of the distinction between a prescribed and an approved plan.

In Cass. 3e civ., 8 January 2026, no. 24-11.599, the Cour de cassation dealt with a seller who had failed to disclose the existence of a water-pipe easement crossing the land, which had not been mentioned in the deed. The Court held that the buyers — who complained of structural damage to their building — had been deprived of essential information about a servitude. Although this case concerned a private-law easement rather than a natural risk, it confirms the consistent approach of the third civil chamber: any servitude or restriction affecting the use of the land, whether public or private, must be disclosed to the buyer at the time of sale.

In Cass. 3e civ., 16 March 2022, no. 18-21.154, the Court examined a case where the compromis de vente stated that certain easements were “parfaitement connues des époux [B]” — perfectly known to the buyers. The Court upheld the lower court’s finding that the mere mention of easements in the compromis was insufficient where the precise nature and scope of those easements had not been detailed. The buyer is entitled to precise, not generic, information.

In Cass. 3e civ., 16 November 2022, no. 21-24.473 (published in the Bulletin), the Court ruled that a building permit could be annulled where the construction was located in an area covered by a plan de prévention des risques incendie de forêt (PPRIF, a forest-fire risk prevention plan) in which the right to build new structures was limited. This case confirms that an approved PPR has direct consequences on the right to build, and that the approval of a plan between promesse and final deed is not merely a formality — it can render the land unbuildable.

Conclusion

The February 2026 ruling is a clear signal from France’s highest civil court: the obligation to inform a buyer of natural risks is a living obligation that runs from the signing of the promesse to the moment the notary hands over the keys. A seller who provides an ERNIAL at the promesse stage cannot rest on that document if the legal status of the land changes before the final deed. The approval of a risk prevention plan, even one that does not alter the zoning map, triggers a mandatory update because an approved plan carries the weight of a public-interest easement.

For foreign buyers unfamiliar with the French system, several practical steps follow. Before signing a promesse, request a current copy of the ERNIAL and verify it on the official government website Géorisques (georisques.gouv.fr), which provides free public access to risk data for every French commune. Instruct your notary to confirm in writing, before the final deed, that no new prefectoral order approving a natural risk plan has been published since the date of the promesse. If you intend to build on the land, obtain a certificat d’urbanisme before the final deed — the February 2026 case would never have reached the Cour de cassation if the buyers had known, before paying, that their plot was legally unbuildable. Finally, understand that the notary’s duty of advice extends to the verification of the ERNIAL: if the notary fails to check for updates and the buyer suffers loss as a result, the notary may share liability with the seller.

The French état des risques is not a box-ticking exercise. It is a disclosure requirement backed by the power of a court to unwind the entire transaction. The Cour de cassation has now confirmed, for the second time in eight years and more forcefully than before, that the information given to the buyer must reflect the legal reality of the land on the day the deed is signed — not the day the promise was made.

For more information about French real estate law, see our overview of real estate law services for property buyers and owners in France.