A woman buys a plot in Amiens in 2019 and hires a builder to construct her house. A boundary survey is carried out before work starts. The neighbours who buy the adjacent plot in 2020 discover that her house crosses onto their land along a strip 4 centimetres wide and 31.35 metres long. Building work stops for twenty months. The neighbours claim the rent they pay while waiting, and on 25 June 2025 the Amiens judicial court orders the homeowner, jointly with the builders and their insurers, to pay them 13,246.80 euros. The homeowner, who had done nothing wrong herself, is guaranteed in full by the construction professionals, split 20 percent and 80 percent between the two firms and their insurers. That story, reported by the English-language press in France in May 2026, is the perfect entry point to one of the strictest rules in French property law: an empiètement (encroachment), even a tiny one, can force demolition, and good faith changes nothing. This guide explains the rule exactly as the Cour de cassation restated it in July 2025, what the Amiens case teaches about money and liability, and the concrete steps a foreign owner should take on either side of a boundary dispute.

The first reflex is to understand that French law treats the boundary as absolute. Ownership is defined by Article 544 of the Civil Code as the right to enjoy and dispose of things in the most absolute manner, within the limits of statute and regulation: « La propriété est le droit de jouir et disposer des choses de la manière la plus absolue, pourvu qu’on n’en fasse pas un usage prohibé par les lois ou par les règlements. » (Ownership is the right to enjoy and dispose of things in the most absolute way, provided no use is made of them prohibited by statute or regulation.) The companion provision, Article 545 of the Civil Code, adds the sentence on which every demolition order rests: « Nul ne peut être contraint de céder sa propriété, si ce n’est pour cause d’utilité publique, et moyennant une juste et préalable indemnité. » (No one may be compelled to give up ownership except for public necessity and in exchange for fair prior compensation.) A neighbour who builds over the line is asking you, in effect, to give up a slice of your land for free. The courts answer that Article 545 forbids exactly that, and the size of the slice is irrelevant. The second reflex is to act early and in writing. Boundaries are fixed by a formal demarcation with a sworn surveyor, disputes are documented by a court-appointed expert, and settlements are signed before a notary or recorded in a court-approved boundary report. Owners who build that paper trail before the concrete is poured almost never pay; owners who discover the line after the walls are up pay even when they are innocent.

I. The rule: even a few centimetres can force demolition

A. An absolute boundary, a demolition without mercy, and good faith that saves no one

The founding decision is more than forty years old and has never been departed from. On 19 December 1983, the Third Civil Chamber quashed a Poitiers appeal ruling that had refused to order the demolition of a building crossing onto the neighbouring land, on the ground that demolition would ruin the entire building and would be an excessive sanction compared with the harm suffered by a buyer who had known about the encroachment before purchasing (Civ. 3rd, 19 December 1983, No. 82-15.670). The Court held, under Article 545, that Article 555 of the Civil Code does not apply where an owner extends a building beyond the limits of his own land and thereby encroaches on the neighbouring parcel, so that the builder’s good faith could not justify refusing demolition: in the Court’s words, « LA BONNE FOI DE M Z… NE POUVAIT JUSTIFIER LE REJET DE LA DEMANDE DE DEMOLITION » (the good faith of the builder could not justify rejecting the demolition claim). Two teachings already emerge that still govern today. First, a cross-boundary extension is not treated as a building on another person’s land under Article 555 of the Civil Code, the provision that lets the landowner keep the building or have it removed at the builder’s expense and that modulates the outcome according to good or bad faith; encroachment across a boundary line sits outside that scheme and leads to removal, period. Second, neither the ruinous cost of demolition nor the victim’s prior knowledge of the situation defeats the claim. For a foreign buyer, the message is blunt: the bargain price of a house that everyone knows crosses the boundary does not buy you the strip, and the seller’s disclosure does not cure the defect.

The Cour de cassation confirmed and hardened that line on 3 July 2025 in a case foreign owners should read in full (Civ. 3rd, 3 July 2025, No. 23-12.925, ECLI:FR:CCASS:2025:C300338). The facts were sympathetic to the encroacher: a building containing two living rooms of the family’s home crossed 4.653 square metres onto a 1,622 square metre neighbouring parcel, in the alignment of a party wall, under a granted building permit, and before the current neighbours bought their land. The Nîmes court of appeal had refused demolition as disproportionate, reasoning that knocking down part of a home would breach the occupants’ right to respect for their domicile. The Third Civil Chamber quashed that refusal under Article 545. Its holding deserves quotation because it now frames every negotiation: « tout propriétaire est en droit d’obtenir la démolition d’un ouvrage empiétant sur son fonds, sans que son action puisse donner lieu à faute ou abus. » (Every owner is entitled to obtain the demolition of a structure encroaching on his land, and bringing that claim can never constitute fault or abuse.) The Court added that the perpetrator of an encroachment cannot invoke the European protection of property, since his own building violates the victim’s property rights, and that while demolition of a home does interfere with the right to respect for the domicile, that interference is justified because it protects the landowner’s property rights and demolition is the only measure that restores full ownership: once encroachment is established, the judge must order every measure capable of ending it, in the Court’s phrase, « il lui incombait d’ordonner toute mesure de nature à y mettre fin » (it was for the court to order any measure capable of putting an end to it). The appeal ruling was quashed and the case sent back. Neither the building permit, nor the small surface taken, nor the fact that the encroachment predated the victim’s purchase, nor the human argument of the family home, stopped the demolition claim.

A companion ruling of 15 April 2021 clarifies the one situation where good faith genuinely matters, and it is not yours if you build across a boundary (Civ. 3rd, 15 April 2021, No. 20-13.649). A man had built a house at his own expense on land belonging to his in-laws, with their permission but without any title transferring ownership, and claimed the protection of the good-faith builder. The Court rejected the appeal and upheld demolition at his expense, holding that good faith within the meaning of Article 555 is assessed by reference to Article 550 and covers only a person who possesses as owner under a translative title whose defects he is unaware of: « la bonne foi au sens de l’article 555 du code civil s’entend par référence à l’article 550 du même code et concerne celui qui possède comme propriétaire en vertu d’un titre translatif de propriété dont il ignore les vices » (good faith under Article 555 means, by reference to Article 550, the person who possesses as owner under a title transferring ownership whose defects are unknown to him). A simple family permission is not such a title. The practical distinction for a foreign household is therefore sharp. If you build entirely on someone else’s land, Article 555 and the quality of your title decide your fate. If your own building merely crosses the line, even by centimetres, the 1983 and 2025 rulings apply instead: the victim obtains demolition without having to prove any fault or abuse, and your good faith, your permit and your architect’s error are arguments for your claim against the builders, not defences against the neighbour.

One older decision is sometimes quoted to suggest that judges must weigh proportionality before ordering demolition, and it should be read exactly for what it says (Civ. 3rd, 19 December 2019, No. 18-25.113). A house had been built so as to halve the usable width of a right of way at garage level, and the appeal court ordered demolition of the building. The Third Civil Chamber quashed, but only because the judges had failed to examine, as requested, whether demolition was disproportionate in light of the occupants’ right to respect for their domicile. That 2019 ruling faulted a judge for not conducting the examination; the July 2025 ruling faults a judge for refusing demolition of a proven encroachment after conducting it. The two decisions together describe the current state of the law with precision: the court must consider the human-rights argument when it is raised, but once an empiètement (encroachment) on the neighbour’s ownership is established, that argument cannot preserve the encroaching structure. And the contrast with a neighbouring field of litigation is instructive. On 11 September 2025, the same Chamber quashed a demolition ordered for breach of a subdivision’s private covenants, holding that the appeal court should have checked whether demolition was manifestly disproportionate to the harm suffered by the other lot owners (Civ. 3rd, 11 September 2025, No. 23-17.504, ECLI:FR:CCASS:2025:C300386). Proportionality therefore lives in contractual and covenant disputes; it does not save a structure that takes someone else’s land. Do not let an adviser transpose that September ruling onto your boundary: the July ruling on encroachment is the one that governs.

B. The Amiens 4-centimetre case: twenty months frozen, 13,246.80 euros, and an innocent owner

The Amiens file shows how the abstract rule converts into bills, and every figure below comes from the judgment itself, read in full for this guide. A homeowner had a house built on her plot by a construction company after a boundary survey; the neighbours who acquired the adjacent parcel found the 4-centimetre, 31.35-metre encroachment and sued in 2021 seeking demolition; the emergency judge suspended the case while talks proceeded; on 12 May 2022 the parties signed a formal boundary report, the procès-verbal de bornage (signed boundary demarcation record), which fixed the limits and allowed work to resume; in the meantime, in July 2022, the building company went into court-ordered liquidation. The neighbours then claimed their losses, essentially the rent they had paid while unable to build, from September 2020 to May 2022. On 25 June 2025 the Amiens judicial court (TJ Amiens, 25 June 2025, RG No. 23/01407) held the homeowner, the liquidated builder and the earthworks firm jointly responsible for the encroachment, and ordered them jointly to pay the neighbours 13,246.80 euros in damages for the rent paid between 25 September 2020 and 27 May 2022, with statutory interest, while fixing the same sum as an unsecured claim in the builder’s liquidation.

Three features of that judgment matter more than the headline sum. First, the homeowner’s personal innocence changed nothing toward the neighbours. The Amiens court’s reasoning in the 25 June 2025 judgment recalls that liability for abnormal neighbourhood disturbance is strict liability without proven fault: « La responsabilité pour trouble anormal de voisinage est une responsabilité sans faute prouvée. » (Liability for abnormal neighbourhood disturbance is liability without proven fault.) A prior boundary survey, a reputable builder, a granted permit: none of it shields the owner of the encroaching structure from the victim’s claim, because the claim rests on the disturbance itself, pursued here through the general civil-liability provision of Article 1240 of the Civil Code (« Tout fait quelconque de l’homme, qui cause à autrui un dommage, oblige celui par la faute duquel il est arrivé à le réparer. », any act whatever of man which causes damage to another obliges the one by whose fault it occurred to repair it) combined with the law of neighbourhood disturbance. Second, the judgment then redistributes the bill where it belongs. The homeowner’s guarantee claim succeeded in full against the professionals and their insurers: the court split ultimate responsibility 20 percent to the liquidated builder, covered by its insurer, and 80 percent to the earthworks company, covered by its own insurer, with cross-guarantees between the insurers, while rejecting the guarantee claim directed at the development company that had sold the serviced plots. In economic terms, the innocent owner recovered the damages from the chain that made the error, keeping only a share of irrecoverable legal costs. Third, the liquidation of the builder did not derail the case: the claim was fixed in the insolvency, and the solvent co-defendants and insurers paid. For a foreign buyer commissioning a new build from abroad, the lesson is structural rather than moral. You will answer to the neighbour even if you did everything right, so your file must contain solvent professionals, active insurance policies and written allotment of the setting-out risk before the first trench is dug.

The Amiens settlement pattern also deserves attention because it is the realistic ending of most files. Demolition was claimed, a boundary report was signed instead, work resumed, and money compensated the delay. The English-language lawyer commenting on the case put it plainly: in practice the scale of the encroachment plays a strategic role, nudging the parties toward an amicable settlement rather than full demolition. Nothing in the July 2025 Cour de cassation ruling contradicts that observation; the ruling governs what happens when no settlement is reached and the judge must decide. Your negotiating position therefore depends on the credibility of the demolition threat behind it. A victim who can cite the 2025 decision settles for the strip’s buyout or for damages; an encroacher who knows the builder’s insurance will ultimately pay settles for cash rather than concrete. But note the asymmetry the Amiens figures reveal: twenty months of frozen works cost roughly 13,250 euros in neighbouring rent alone, before counting the owner’s own rehousing, the expert fees and five years of proceedings from writ to judgment. Settlement is cheaper than victory, and early settlement is cheapest of all.

II. What to do in practice as a foreign owner

A. If your building crosses the line: fix the boundary, settle fast, turn against the chain

Start with proof, and understand what proves what. The cadastral map is a tax document; it suggests where the line runs but it does not legally fix it. Only a demarcation by a sworn surveyor, the géomètre-expert (state-licensed land surveyor), followed by a signed boundary report, secures the limits against the neighbour, which is exactly why the Amiens parties’ 12 May 2022 report unlocked the file. Any owner may compel the neighbour to join a demarcation, and the cost is shared: Article 646 of the Civil Code provides that « Tout propriétaire peut obliger son voisin au bornage de leurs propriétés contiguës. » (Any owner may require his neighbour to join in demarcating their adjoining properties.) If you are buying land to build, commission that demarcation before signing the construction contract, or at the latest before the setting-out, and make the builder’s price conditional on building within the surveyed polygon. If you already own and suspect a crossing, instruct the surveyor immediately and invite the neighbour to attend the operations in writing; a unilateral survey informs you, but only a contradictory one binds the other side. Keep the surveyor’s report, the title deeds with their boundary descriptions, the planning file and every setting-out note: the guarantee claim against the chain will be won or lost on those papers.

Second, open the settlement track in parallel with the technical track, because the victim’s incentive to settle is strongest before positions harden. The realistic menu has four items. The parties sign a boundary report adjusting the line where the titles allow it; the encroacher buys the strip at a negotiated price through the notary, with the deed published at the land registry; the encroacher pays damages for the delay and the loss of use while keeping the structure under a recorded agreement; or, where nothing else works, the encroaching element is removed. Which option is available depends on the titles, the planning constraints and the scale of the crossing: moving a fence is trivial, cutting back a house wall is surgery. In negotiation, both sides should keep the July 2025 ruling on the table for what it is, a demolition threat that materialises if talks fail, and the Amiens figures for what they are, proof that delay itself is compensable. A foreign owner negotiating from abroad should mandate a local representative with written authority to sign a boundary report, because surveyors and neighbours settle with whoever is physically present, and files stall for months when every signature must cross a border.

Third, aim your recourse at the right defendants from day one. The victim sues you; you call the builder, the subcontractors, the surveyor if the setting-out was theirs, and their insurers into the case as guarantors. French construction insurance is compulsory at the relevant levels, and the Amiens split shows how courts allocate the technical fault between firms while keeping the owner whole. Two traps await the unwary. If your builder goes insolvent, declare the claim in the liquidation within the deadline and identify the insurer directly, because the insurer answers even when the insured has collapsed, as the Amiens court confirmed by condemning the insurers alongside fixing the claim in the builder’s liabilities. And if you bought the house already built from a seller who knew of the crossing, preserve the hidden-defects and disclosure claims against that seller in parallel: they obey short limitation periods of their own and die quietly while you focus on the neighbour. Finally, a brief fiscal flag, not advice: damages you receive or pay, rent reimbursed, and a strip bought or sold can each carry tax consequences in France and in your country of residence, so route every settlement draft past your tax adviser before signature. Our Paris real estate team handles these multi-party files routinely, and the cases that end well are those where the insurer was put on notice in the first month.

B. If the neighbour encroaches on you: prove it, demand removal, price the loss, know the rare defences

The victim’s path mirrors the encroacher’s in reverse, and it begins the same way: a contradictory survey proving the crossing. Encroachment is interpreted broadly. It covers the visible wall at ground level, but also foundations, rendering, roof overhangs, balconies and any projecting element that crosses the vertical plane of the boundary, above or below ground. Photograph everything, keep the surveyor’s plan showing the overlap in square metres, and put the neighbour on formal notice to remove the structure within a stated deadline. If nothing moves, the claim goes to the judicial court for demolition, or removal of the offending element, plus damages for the loss suffered: loss of use of the strip, delay to your own project with rental costs documented by leases and receipts, and the survey and expert fees. The Amiens neighbours’ 13,246.80 euros for twenty months of rent is the template: documented, periodised, and awarded with interest. Ask the court early for a court-appointed expert survey where the technical facts are contested; judges decide boundary geometry on expert evidence, not on parties’ assertions, and the expert’s operations also create the settlement window most files need.

Expect three defences and know why two of them fail. The neighbour will plead good faith, permit and disproportion, and the answer to all three is the July 2025 ruling: once the crossing is proven, the judge orders the measures that end it, and the claim itself can never be characterised as fault or abuse. The neighbour may then invoke the right to respect for the home where the structure is a dwelling; the answer is the same ruling’s balance, which the court already struck in the owner’s favour because demolition is the only measure restoring full ownership. The neighbour may argue that you knew of the encroachment when you bought and therefore accepted it; the answer is the 1983 ruling, where the buyer’s prior knowledge did not save the building. The one argument that can genuinely complicate your claim is time. Ownership of land can be acquired by long possession: Article 2272 of the Civil Code sets the period at thirty years, reduced to ten for a good-faith buyer with a proper title (« Le délai de prescription requis pour acquérir la propriété immobilière est de trente ans. », the period of prescription required to acquire immovable ownership is thirty years), and Article 2261 of the Civil Code requires possession that is continuous, peaceful, public, unequivocal and as owner (« Pour pouvoir prescrire, il faut une possession continue et non interrompue, paisible, publique, non équivoque, et à titre de propriétaire. », to be able to acquire by prescription requires continuous and uninterrupted, peaceful, public, unequivocal possession as owner). A neighbour who has held the disputed strip openly as owner for decades may therefore defeat you, but mere tolerance, disputed occupation or possession squeezed between two contradictory surveys rarely meets that standard. Treat any such defence as a full evidentiary dispute requiring advice, not as a conversation-stopper.

Two final precautions protect the value of your victory. First, never agree informally to let the encroachment stand in exchange for a handshake payment: an unrecorded tolerance can mature into the very possession the neighbour later invokes, while a recorded agreement, a boundary report or a notarial deed fixes the line and the price durably. Second, move promptly once you discover the crossing. French limitation law distributes different clocks to demolition, damages and seller claims, and documents fade while memories harden; the Amiens neighbours sued the year after discovery and held a judgment four years later, which is fast by the standards of boundary litigation. A foreign owner who discovers a crossing during a short visit should instruct a surveyor and a lawyer before flying home, because the formal notice sent within weeks frames the entire file. Where the file touches Paris or the inner suburbs, anyway, procedural pace, expert availability and enforcement practice follow local rhythms our real estate litigators in Paris know well, and an early local mandate is worth more than a thick file assembled late.

Conclusion

French boundary law holds a paradox that the Amiens 4-centimetre file illustrates perfectly: the strictest rule produces the most negotiated outcomes. The rule is strict because Articles 544 and 545 leave no room for a private taking, because the Cour de cassation has ordered demolition of good-faith buildings since 1983 and confirmed it for family homes in July 2025, and because your claim, as the 2025 Court put it, can never be fault or abuse. The outcomes are negotiated because demolition is expensive for everyone, because insurers and builders ultimately carry the technical bill, and because a signed boundary report plus damages closes faster than five years of proceedings. Act on both halves of that paradox. Fix your line with a sworn surveyor before you build, settle from the strength of the demolition rule if you are the victim, turn immediately against the construction chain if you are the encroacher, and never let an informal tolerance rewrite your boundary. Measured in centimetres, decided in thousands of euros: that is the arithmetic of the French boundary, and it rewards the owner who moves first.

Need a quick opinion on your case

If a boundary survey, a neighbour’s wall or a stalled building project raises an encroachment question on your French property, send us the survey plan and the key dates for a telephone consultation within 48 hours with a lawyer of the firm. Call +33 6 46 60 58 22 or write via our contact page with a short description of the crossing and the documents you hold.