Title: Party Agreement Overrides Civil Code Article 660 on Party Walls (Cass. 1972)

Picture the scene: in Marseille, in the Panier district, two adjoining houses share a single wall. One day, one of the owners decides to raise his property. He needs this wall to support his new construction. But this wall is a party wall, meaning it belongs half to each neighbour. To use it fully, he must acquire the party wall rights, i.e. buy the other's share. But at what price? Article 660 of the Civil Code provides a calculation method. But what if the two neighbours had already agreed a price, for example in a notarial deed? Should the contract prevail over the law? That is precisely the question put to the Cour de cassation in 1972. And the answer is clear: the parties' intention prevails over the default rule.

The facts: an everyday story

Mr X, owner of a building in Marseille, and Company Y, owner of the neighbouring building, share a party wall. They sign an agreement: if Mr X uses this wall for construction, he will pay Company Y a certain price, fixed in advance. Years later, Mr X (or rather his successors in title) begins work and invokes Article 660 of the Civil Code to set the price at a lower amount than agreed. Company Y and the co-owners' association refuse. The case goes to court. The Court of Appeal of Marseille, by a judgment of 10 February 1971, applies Article 660 and sets a price different from the agreement. Company Y and the association appeal to the Cour de cassation. Their argument: the parties were bound by a contract, and that contract must be respected. The Cour de cassation agrees: it quashes the appeal judgment because the lower courts disregarded the principle of freedom of contract. In other words, when the parties have agreed a price, Article 660 does not apply.

The court's reasoning — analysed

The Cour de cassation relies on a simple idea: Article 660 of the Civil Code is a default provision (i.e. it applies only in the absence of contrary intention of the parties). This article provides that 'the owner of a party wall who wishes to build against it must pay the value of the party wall rights'. But this rule is not mandatory: owners are free to set the price in an agreement. In this case, an agreement had been properly produced before the Court of Appeal. That court should have verified its existence and applied it. By failing to do so, it violated Article 1134 of the Civil Code (old, now 1103) which provides that agreements lawfully formed have the force of law for those who made them. In short, the judges recalled that the contract prevails over the default law. This is neither a development nor a reversal: the Cour de cassation confirms a constant principle. Company Y's argument was simple: we signed an agreement, respect it. Mr X's argument: Article 660 sets a price, apply it. But the court decided in favour of the contract.

What this means for you — practically

If you own a party wall, this decision directly concerns you. For an owner who wants to build: if you have already signed an agreement with your neighbour on the price for acquiring party wall rights, you are bound by that price. You cannot later invoke Article 660 to pay less. Example: in La Ciotat, you buy a house with a party wall. The seller tells you: 'If you want to use this wall for your extension, you will pay me €5,000.' You sign. Later, Article 660 would set the price at €3,000. Well, you will have to pay €5,000, because the contract prevails. For a neighbouring owner: you are protected. If your neighbour wants to use the wall, he must respect the signed agreement. You can demand the agreed price, even if it is higher than the legal price. For a buyer: before buying, check whether there is an agreement on the party wall. It will be binding on you. For a co-owner: in co-ownership, the regulations may contain clauses on party walls. They prevail over Article 660. undefined, I encountered a case where an owner in Marseille had signed a preliminary sale agreement including a price for party wall rights. He tried to back out, but the 1972 case law was invoked against him. Result: he had to pay the agreed price, i.e. €8,000 instead of the €4,500 provided for by Article 660.

Four tips to avoid this type of dispute

• Draft a written and precise agreement: if you own a party wall and are considering works, sign a written agreement with your neighbour. State the exact amount, payment terms, and date. This avoids any later challenge.
• Keep all documents: keep the notarial deed, the agreement, email exchanges. In case of a dispute, it is your best evidence. The Cour de cassation sanctioned the Court of Appeal for ignoring a produced agreement.
• Consult a notary or lawyer before signing: a professional will check that the agreement complies with substantive rules and is enforceable. For example, if you buy a property in La Ciotat, ask to see the previous sale deed to know if a party wall agreement exists.
• In case of disagreement, prefer mediation: before going to court, try mediation. The cost is lower and you can reach an agreement. But beware: if you sign a mediation agreement, it becomes a contract and prevails over Article 660.

Further reading: related case law and developments

Several later decisions confirm this position. For example, in a judgment of 14 November 2001 (No. 99-17.456), the Cour de cassation recalls that the rules on party walls are default rules and that the parties' intention prevails. Similarly, a judgment of 11 July 2018 (No. 17-21.543) insists that agreements lawfully formed must be performed in good faith. What few people know is that even in the absence of an express agreement, conduct may amount to consent: for example, if the neighbour accepts without protest that you use the wall for several years, this may be interpreted as tacit agreement. Courts are increasingly attentive to the reality of neighbourly relations. However, beware: this case law only concerns the price. Construction rules (planning permission, local plans, etc.) still apply.

What you absolutely need to remember

FAQ:

• Does Article 660 always apply? No, only if the parties have not agreed another price.
• Can I challenge a price agreed long ago? Yes, if you prove the agreement is void (defect of consent, mistake, fraud). But it is difficult.
• What if my neighbour wants to use the wall without my consent? You can forbid it, or demand the agreed price, or failing that, the price under Article 660.
• What are the time limits for action? You have 5 years from the day you become aware of the dispute (standard limitation period).
• Do I have to pay notary fees for a party wall agreement? No, a simple private writing is sufficient. But for greater security, a notarial deed is recommended.

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In summary: the contract prevails over the default law. If you have signed an agreement, respect it or enforce it.

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