Construction Encroachment: When Your Neighbour's Foundations Are on Your Land (Cass. civ. 3e, 16 December 1998)

Imagine: you have just bought a charming house in Fougères, and while digging to install a swimming pool, you discover that the foundations of the neighbouring house extend 50 centimetres onto your land. What can you do? Can you demand the demolition of this underground extension? And if the neighbour is not the original builder, can he be held responsible?

This is precisely the question put to the Court of Cassation in a landmark case from 1998, opposing the famous Cognacq-Jay foundation to neighbouring owners. This decision, still relevant today, provides a clear answer: the current owner of the building is obliged to stop the encroachment, even if he did not build it. In other words, fault is not required: the mere existence of the encroachment is sufficient to justify a claim for demolition.

But beware, this rule is not absolute. In this article, I will explain what the Court of Cassation actually decided, why this decision is important for you as an owner, tenant or property professional, and how you can protect yourself or take action if you face a similar situation. I will also give you practical advice, illustrated with concrete examples in Cesson-Sévigné and elsewhere.

The Facts: A Story Like Many Others

The case begins in Paris, where the Cognacq-Jay foundation, owner of a building, is sued by the owners of a neighbouring plot. They note that the foundations of the foundation's building encroach onto their property. They therefore seek the removal of the encroachment, i.e. the demolition of the parts of the foundations that extend onto their land.

The Cognacq-Jay foundation resists: it argues that the building was constructed by a previous owner, and that it has committed no personal fault. According to it, for an owner to be ordered to demolish, a fault on his part must be proved, for example that he built it himself or allowed it to happen. But the Paris Court of Appeal rules in favour of the neighbours and orders demolition. The foundation appeals to the Court of Cassation.

The Court of Cassation, in its judgment of 16 December 1998 (No. 96-14.760), dismisses the appeal and upholds the reasoning of the appellate judges. It holds that since the foundations belong to the defendant (here, the Cognacq-Jay foundation) and they encroach on the neighbouring land, the claim for demolition is justified, without it being necessary to investigate whether the defendant built or had the building constructed. In short, the owner's liability is engaged solely by reason of the encroachment, regardless of any fault.

The Court's Reasoning — Explained

To fully understand this decision, we must go back to the legal basis invoked: Article 1240 of the Civil Code (formerly 1382), which provides that 'any act of man which causes damage to another obliges the person by whose fault it occurred to make reparation'. In the case of an encroachment, the fault lies in allowing a construction to encroach on neighbouring land, constituting a violation of the right of property.

But the Cognacq-Jay foundation argued that, not having built, it had committed no fault. The Court of Cassation replied that fault is not a necessary element: the encroachment is itself constitutive of an abnormal neighbourhood disturbance, and the current owner, as owner of the construction, is obliged to stop it. In other words, this is liability without fault, based on the theory of abnormal neighbourhood disturbances (Article 1240 of the Civil Code, combined with the principle that no one must cause another a disturbance exceeding the normal inconveniences of neighbourhood).

This solution is not new: the Court of Cassation had already affirmed it in several earlier judgments (e.g., Cass. civ. 3e, 22 January 1992, No. 90-14.413). The contribution of the 1998 judgment is to clarify that the quality of owner of the encroaching construction suffices, without having to demonstrate that the owner built or allowed it to be built. This strengthens the protection of the owner victim of an encroachment.

However, note: this liability is not automatic in all cases. The encroachment must be established (i.e., demonstrated by precise measurements) and constitute an abnormal disturbance (a minor incursion may be tolerated). But once the encroachment is established, the owner of the neighbouring land can demand demolition, without further proof of fault.

What This Means for You — Practically

This decision has major practical implications for all property players.

• For the owner victim of an encroachment: you can take action directly against the current owner of the construction, even if he did not build it. Concrete example: in Cesson-Sévigné, an owner discovers that the foundations of the neighbouring house extend 30 cm onto his land. He can sue the current neighbour, even if the latter bought the house after its construction. The cost of proceedings? Expect between €2,000 and €5,000 for expert evidence and legal fees, but demolition could cost your neighbour much more.
• For the owner whose construction encroaches: you are obliged to stop the encroachment, even if you did not build. You will therefore have to demolish (or negotiate an easement or purchase of land). In my practice, I have seen cases where owners had to pay €20,000 to €50,000 for works to move foundations, without being able to claim against the original builder (often insolvent or untraceable).
• For the buyer: before buying a property, check the boundaries and the absence of encroachment. A land survey (bornage) (official delimitation of the land) is strongly recommended. If an encroachment is discovered after the sale, you may be able to take action against the seller for latent defects or misrepresentation, but this is more complex.
• For the tenant: you are not responsible for existing encroachments, but you must report any encroachment noticed to your landlord. If you cause an encroachment through your works, you will be responsible for it.

Four Tips to Avoid This Type of Dispute

• Have a land survey (bornage) carried out before any purchase or construction. A surveyor (géomètre-expert) precisely delimits the properties. Cost: €1,000 to €2,500. This is an investment that can save you years of litigation.
• When carrying out works, have the boundaries checked by a professional. Before pouring foundations, a surveyor can mark the property line. In Fougères, a developer thus avoided a dispute by shifting his project by 20 cm.
• Keep all documents relating to your property: deed of sale, cadastral plan, land survey report, building permit. In the event of a dispute, these elements are essential.
• Negotiate amicably if the encroachment is minor. Sometimes a right of way or a transfer of a strip of land can solve the problem without demolition. But always have the agreement recorded by a notarial deed.

Further Analysis: Related Case Law and Developments

The solution of the 1998 judgment is part of a consistent line of the Court of Cassation. As early as 1992, in a judgment of 22 January (No. 90-14.413), the Court had held that the owner of a construction encroaching on neighbouring land is obliged to demolish it, without it being necessary to distinguish according to whether he built or not. The 1998 judgment confirms and clarifies this position by applying it to foundations.

More recently, the Court of Cassation extended this liability to the case where the encroachment results from a construction built by a previous owner (Cass. civ. 3e, 12 June 2013, No. 12-16.723). It also held that the current owner cannot avoid demolition by invoking the thirty-year prescription (acquisitive) if the encroachment was not committed by him (Cass. civ. 3e, 15 December 2010, No. 09-70.370).

What this means for the future: the trend is towards reinforced protection of the right of property, and courts are reluctant to tolerate encroachments, even old ones. If you are a victim, do not hesitate to act. If you are the owner of an encroaching construction, it is better to regularise quickly.

Checklist Before Taking Action

• Have I established an encroachment? Have it precisely measured by a surveyor. A minor incursion of a few centimetres may be tolerated if it is not inconvenient.
• What is the age of the encroachment? If you are the owner of the encroaching construction, check whether acquisitive prescription (30 years) could work in your favour. But beware: recent case law limits this possibility.
• Do I have an interest in taking action? Demolition is a radical measure. Sometimes compensation or an easement is more appropriate. Consult a lawyer to evaluate your options.
• What is the time limit to act? The action for demolition for encroachment is subject to a 5-year limitation period from the discovery of the encroachment (Law of 17 June 2008). Do not delay.
• Should I inform my insurance? If you are the owner of the encroaching construction, your public liability insurance may cover defence costs and even compensation. Report the claim promptly.

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