Boundary Surveys and Encroachment: What the Court of Cassation Has Ruled

Imagine the scene: you have just bought a house in Nœux-les-Mines, with a lovely garden. Your neighbour, a retired farmer, claims that a strip of land fifty centimetres wide along your fence belongs to him. He demands that you move the fence, or even pay him compensation. The surveyor instructed by the insurer carries out an amicable boundary survey. The record states that the boundary is at the location of the fence, but the neighbour refuses to sign. You end up in court to have an encroachment established… and you lose. Why? Because the boundary survey, in itself, does not prove ownership. This is exactly what the Court of Cassation recalled in its judgment of 10 July 2013 (No. 12-19.416).

Every year, hundreds of property owners, in Béthune and elsewhere, confuse boundary surveys with title deeds. People believe that the document signed by the surveyor definitively seals their rights. However, the case law is firm: a boundary survey is a purely material operation of delimitation, without impact on the right of ownership. A boundary action does not decide the question of who owns the land. For that, a title (sale deed, donation, adverse possession) is required.

In the commented judgment, neighbours had been disputing the party wall status of a wall for years. A first decision in 1999 had ruled that the wall was not a party wall. Then, in 2008, the Court of Appeal, relying on a boundary survey, found an encroachment and ordered one of the owners to demolish. The Court of Cassation censures this reasoning: a boundary survey cannot be used to establish an encroachment, because it does not determine ownership. Moreover, the question of party wall status, decided in 1999, had res judicata effect. The Court of Appeal could not indirectly revisit it.

The facts: a story like many that happen every day

In Nœux-les-Mines, Mrs A. and Mr B. have been neighbours for twenty years. Their houses are separated by a brick wall. In 1998, a dispute arises: Mr B. wants to install a window, Mrs A. objects, claiming the wall is a party wall. The Lens District Court, hearing an interim application, rules in 1999: the wall is not a party wall, it belongs to Mr B. No appeal is filed. The decision becomes final.

But in 2005, a new conflict arises. Mrs A. sells her house to company X, which begins construction work. Mr B. notices that the foundations of the new building encroach a few centimetres onto his land. He sues company X for a boundary survey and for cessation of encroachment. A boundary survey is carried out by a court-appointed expert, who sets the boundary at the location of the base of the wall. Company X contests: this boundary survey, it argues, has no effect on ownership.

The Douai Court of Appeal, in 2010, rules against it. It considers that the boundary survey, combined with the 1999 judgment, establishes the encroachment. Company X is ordered to demolish the foundations and pay damages. An appeal in cassation follows. On 10 July 2013, the Court of Cassation quashes the judgment: the Court of Appeal could not, without violating the law, use the boundary survey to find an encroachment, because a boundary action has no other purpose than to fix boundaries, without attributing ownership. Moreover, the 1999 judgment had res judicata effect on the party wall status; the Court of Appeal could not go back on this point.

The reasoning of the court — analysed

The reasoning of the Court of Cassation has two main strands. First, it recalls a fundamental principle: a boundary action (fixing boundaries between two adjoining plots) aims only to materialise the separating line, not to determine the owner of each parcel. The boundary survey has no effect of transferring or attributing ownership. Consequently, to establish an encroachment (i.e., an occupation without right of part of another's land), the judge must rely on title deeds, thirty-year adverse possession, or a judicial partition.

In this case, the Court of Appeal had used the boundary survey as proof of encroachment. The Court of Cassation criticises it for confusing delimitation and ownership. It cites consistent case law: 'A boundary action having only the effect of fixing the boundaries of adjoining plots without attributing ownership of the land, the Court of Appeal cannot rely on the boundary survey to find an encroachment' (judgment of 10 July 2013).

Next, the Court examines the issue of res judicata. The 1999 judgment had definitively decided the party wall status of the wall. However, company X, as successor of Mrs A., could not challenge that decision within the boundary action. The Court of Appeal, by relying on the boundary survey to find an encroachment, had indirectly contradicted the 1999 judgment, which is prohibited. This is a classic application of Article 1351 of the Civil Code (now Article 1355): res judicata attaches to what has been decided in the operative part of the judgment.

This decision follows a consistent line: trial judges cannot, under the guise of a boundary survey, rewrite the legal history of a property. If a title deed or a prior decision has already fixed the rights, the boundary survey can only implement them, not modify them.

What this changes for you — in practice

Whether you are an owner, buyer, or co-owner, this judgment has direct implications. Here is how to apply it to your situation.

Landlord: You rent out a property with a garden. The tenant erects a fence that the neighbour claims encroaches on his land. The neighbour sues you for a boundary survey and demolition. The court orders a boundary survey. If the boundary survey matches your title, you are safe. But if the boundary survey is contested, the judge cannot rule on the encroachment without examining the titles. You will gain time if you produce your sale deed and a recent cadastral plan. In Lens, a landlord recently avoided a costly demolition by showing that her title covered the disputed strip — the boundary survey was merely a confirmation.

Tenant: You are a tenant of a house with a garden. A boundary dispute arises between your landlord and the neighbour. You are not a party to the dispute. Nevertheless, if a demolition is ordered, it could affect your enjoyment. Your duty is to inform the landlord and not take sides. The boundary survey only binds the owners. You cannot be ordered to demolish if you are not the owner.

Buyer: Before buying a plot or a house, do not rely solely on an amicable boundary survey carried out by the seller. Request the title deeds and compare them with the boundary plan. A discrepancy may reveal a risk of future encroachment. The 2013 judgment reinforces your security: if the seller guarantees a boundary by a survey, but a neighbour contests, the survey alone will not protect you. Have a contradictory boundary survey carried out (with all concerned owners) and, if possible, have the record approved by a judge. Cost: between €1,000 and €2,500, but it is an investment for decades of peace of mind.

Co-owner: In a co-ownership with common parts adjoining neighbouring plots, the managing agent must ensure the boundaries of the building are surveyed. An encroachment could engage the co-ownership's liability. The judgment reminds that the boundary survey is only one element of assessment; the co-ownership rules and title deeds take precedence. If a co-owner is asked to demolish part of a terrace, they must prove that their right of ownership covers that area, beyond the mere boundary survey.

Four tips to avoid this type of dispute

• Keep your title deeds and have them examined by a notary. Before any boundary dispute, take out the sale deed, the cadastral plan, and, if you have them, the survey documents. That is your best defence. A clear title is worth more than ten boundary surveys.
• Do not confuse boundary survey and record of encroachment. If you suspect an encroachment, do not request a simple boundary survey. Have a bailiff's report drawn up and, if necessary, a court-appointed expert's report. A boundary survey alone does not prove unlawful occupation of land.
• If a dispute arises, propose a settlement before going to court. An amicable agreement on boundaries, approved by a notary, can avoid years of proceedings. In Béthune, a mediation allowed two neighbours to settle a 30 cm dispute for €800, whereas a trial would have cost over €5,000.
• If you inherit a property, check existing boundary surveys. Thirty-year adverse possession (continuous occupation for 30 years) may have altered boundaries. A recent boundary survey may reveal that your possession is insufficient to acquire ownership. Hire a chartered surveyor to update the boundaries.

Further reading: related case law and developments

The position of the Court of Cassation is constant: since a judgment of 13 March 1996 (No. 93-21.739), it has stated that a boundary survey has no effect on ownership. The judgment of 10 July 2013 merely confirms this line. However, some Courts of Appeal had tended to rely on boundary surveys to decide ownership issues, particularly in matters of adverse possession. The Court of Cassation calls them to order.

In a more recent judgment of 12 July 2018 (No. 17-20.971), it even specifies that a boundary survey cannot be used to prove the existence of an easement. The trend is therefore towards a strict separation between fact (the physical boundary) and law (ownership). Judges require solid evidence, either title deeds or thirty-year adverse possession supported by witness statements or deeds.

For the future, case law should become more refined on the issue of res judicata in boundary actions. If an earlier judgment has already ruled on ownership, any subsequent boundary survey must comply with it. Surveyors are increasingly trained in this distinction, but owners must remain vigilant.

Summary and next steps

FAQ:

1. Can I use an amicable boundary survey to prove that my neighbour is encroaching? No. An amicable boundary survey only materialises a boundary; it does not constitute proof of ownership. To establish an encroachment, you need a title or adverse possession.
2. What if my neighbour refuses to sign the boundary survey record? The boundary survey can be judicial. The judge orders an expert report. But the judgment approving the boundary survey does not decide ownership. You will then have to, if necessary, bring an action for recovery of possession.
3. Can a boundary survey be challenged after ten years? Yes, if it is vitiated by error. But recourse is limited by the thirty-year limitation period for real actions. It is best to act quickly upon discovering the error.
4. Does a boundary survey have retroactive effect? No, it is declaratory, not attributive. It sets the boundary for the future.
5. How much does a judicial boundary survey cost? Count between €1,500 and €5,000 for the expert's fees, plus lawyer's fees (about €2,000 to €4,000). The 2013 judgment may save you from incurring these costs unnecessarily if you have no title.

Are you in a similar situation? A first 30-minute consultation with Maître Zakine (€45) can save you months of proceedings — and often much more. Book an appointment →