Party wall without agreement: what happens to ownership in case of encroachment?

Imagine the scene: you own a house in Bollène, in the Vaucluse. One morning, you discover that your neighbour has built a boundary wall along the property line. Not only did he not ask for your opinion, but when digging the foundations, he encroached a few centimetres onto your land. You wonder: this wall, who does it belong to? And what can I do?

This situation, more common than one might think, raises a central legal question: can the owner of the wall claim exclusive ownership despite the encroachment? Or does the encroachment cause him to lose his rights? The Court of Cassation, in a judgment of 9 July 1984, ruled clearly: the wall remains the private property of the person who built it, even if its base encroaches on the neighbouring land. This decision, still relevant today, deserves to be analysed.

In this article, we will examine together what this judgment says exactly, how it applies concretely in towns like Sorgues or Bollène, and above all what your options are if you are faced with a similar situation. Whether you are an owner, tenant or property professional, you will leave with the keys to take action.

The facts: a story like many that happen every day

Mr X, owner in Bollène, decides to fence off his land to protect himself from prying eyes. Without asking any questions, he has a concrete block wall built along the boundary line. The problem? He did not obtain the agreement of his neighbour, Mr Y, and above all, the foundations of the wall encroach 20 centimetres onto the latter's plot. Mr Y notices this during excavation work and sues Mr X before the Tribunal de Grande Instance of Avignon.

Before the judges, Mr Y demands the demolition of the wall and damages. He argues that the encroachment constitutes a violation of his right of ownership (Article 544 of the Civil Code) and that, consequently, the wall should become a party wall (i.e., owned half by each neighbour) or be demolished. Mr X retorts that he built the wall at his own expense, on his land, and that the encroachment is minimal and unintentional. He asks to retain exclusive ownership of the wall.

The tribunal rules in favour of Mr Y and orders demolition. Mr X appeals. The Court of Appeal of Nîmes (on which Avignon depends) reverses the judgment: it holds that the wall remains the private property of Mr X, despite the encroachment. Mr Y appeals to the Court of Cassation. The Court of Cassation, by a judgment of 9 July 1984, dismisses his appeal and upholds the reasoning of the Court of Appeal. The judicial saga ends there: the wall indeed belongs to Mr X, but Mr Y is not without recourse.

The reasoning of the court — analysed

To understand the judgment, we must go back to the texts. The Court of Cassation relies on Article 544 of the Civil Code, which defines the right of ownership as "the right to enjoy and dispose of things in the most absolute manner, provided that one does not make a use prohibited by laws or regulations." But above all, it uses the principle that ownership of a building constructed on land belongs to the person who built it, unless otherwise agreed (Article 553 of the Civil Code).

In short, the High Court considers that the encroachment of the foundations does not change the nature of the wall: it remains a private structure belonging to its builder. Why? Because the encroachment is merely a material fact, which does not cause the builder to lose his quality as owner of the structure. In other words, ownership of the wall is distinct from ownership of the soil on which it partially rests.

However, note: the Court specifies that this solution is only valid if the encroachment is unintentional or without intent to harm. If the builder had deliberately encroached to appropriate another's land, the solution might be different. What few people know is that this decision is part of consistent case law: the Court of Cassation has always protected the good faith builder (who is unaware of the encroachment) against the strictness of property rights. Here, the builder acted without authorisation, but in good faith, because he thought he was building on his own land. The Court of Appeal found that the encroachment was "minimal" and "unintentional".

But what exactly does this change for the neighbour? He is not without recourse: he can request the removal of the encroachment (by having the foundations moved, for example) or, if that is impossible, damages for unlawful occupation of his land. He can also demand the purchase of the encroached strip of land (easement of encroachment). The judgment therefore does not close the door to remedies.

What this changes for you — concretely

If you are an owner in Sorgues and you build a boundary wall without your neighbour's agreement, know that the wall will belong to you exclusively, even if your foundations overflow a little. But beware: you are not immune from legal action. The neighbour can demand redress. For example, if the encroachment is 30 cm, he can request payment of an occupation indemnity (about 50 to 100 € per year per linear metre, depending on the value of the land in Bollène), or even the forced transfer of the strip of land.

If you are a tenant, the issue does not directly concern you, but if your landlord builds a wall on the boundary, you must inform him of the risks. In case of a dispute, it is the owner who will be sued.

If you are a purchaser of land in Sorgues, check the condition of the fences. A wall built without agreement may hide an encroachment that will be enforceable against you. Ask the seller for a declaration on oath (or better, a boundary survey) to avoid nasty surprises. In my practice, I have come across cases where the purchaser ended up with a lawsuit because the party wall had no title.

Finally, if you are a co-owner, note that common parts (such as a boundary wall) cannot be modified without the agreement of the general meeting. A co-owner who builds a wall without authorisation incurs liability.

Four tips to avoid this type of dispute

• Always obtain written agreement from your neighbour before building a wall on the boundary. A simple written document signed by both parties, dated, specifying the location and height, can avoid years of proceedings. In Bollène, the cost of a consultation with a lawyer (about 150 €) is negligible compared to a lawsuit that can exceed 5,000 €.
• Have a boundary survey carried out by a chartered surveyor before any excavation. The boundary survey (about 800 to 1,500 €) materialises the exact boundaries of the land. It is the best evidence in case of a dispute. In Sorgues, a boundary survey may be compulsory before any construction (Article 646 of the Civil Code).
• Do not neglect the encroachment, even if minimal. If you discover that your neighbour has encroached, act quickly: send him a registered letter with acknowledgement of receipt to report the problem. The limitation period for taking action is 5 years from discovery (Article 2224 of the Civil Code). After this period, the encroachment may become tolerated.
• In case of a dispute, prefer an amicable solution. Propose a regularisation: sale of the encroached strip of land or an indemnity. Mediation (about 200 to 400 €) is often quicker than a lawsuit. In Avignon, the courts increasingly encourage alternative dispute resolution methods.

Further analysis: related case law and developments

The judgment of 9 July 1984 is not isolated. In an earlier judgment of 20 November 1979 (No. 78-10.124), the Court of Cassation had already ruled that a wall built without authorisation on another's land remains the property of the builder, unless the encroachment is intentional. This case law has been consistent since the 1970s.

More recently, the Court specified that the encroachment may give rise to compensation for unlawful occupation (Civ. 3e, 17 March 2010, No. 09-11.111). The trend is therefore to protect the good faith builder, while compensating the injured neighbour. How to react if you are the neighbour? You can claim damages calculated on the rental value of the encroached land (about 2 to 5% of the market value per year).

For the future, the question arises of the impact of the ALUR law (2014) which requires a prior boundary survey for any land division. This could reduce unintentional encroachments, but boundary walls remain a fertile ground for neighbour disputes.

What you absolutely must remember

FAQ:

1. If my neighbour builds a wall without my agreement, can I have it demolished? Yes, if the encroachment is substantial or intentional. Otherwise, you can claim damages or the purchase of the strip of land. Demolition is not automatic.

2. Can I build a wall on the boundary without my neighbour's agreement? Yes, but at your own risk. If your foundations encroach, you will own the wall, but you will have to compensate the neighbour. It is better to obtain written agreement.

3. What is the time limit to take action in case of encroachment? 5 years from the discovery of the encroachment. After this period, you risk losing your right to act.

4. How much does a lawsuit for encroachment cost? Expect 3,000 to 10,000 € in lawyer and expert fees, not including any damages. Mediation is often cheaper.

5. What should I do if I bought land with an encroaching wall? Check whether the seller informed you. If not, you can take action against him for hidden defects. If yes, you are deemed to have accepted the encroachment.

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 →