Co-ownership: private works contrary to the regulations – the Court of Cassation’s solution

In a co-ownership in Aix‑en‑Provence, a couple wishes to convert their loft. The general meeting gives its approval. But neighbours object, relying on the co-ownership regulations which they consider set in stone. The court agrees with them and orders the property to be restored to its original state. However, the Court of Cassation quashes this decision, reiterating a fundamental principle: a text alone is not sufficient to condemn works; there must be actual damage. Each year, thousands of co-owners in Paris face this type of dilemma when considering altering their homes. Can the regulations really be circumvented?

The decision of 25 January 1995 (No. 93‑11.537) sheds light on this grey area. It recalls that the co-ownership regulations, while they set the purpose of private parts (residential, commercial, professional, etc.), are not an impregnable fortress. The general meeting of co-owners can, by its vote, authorise departures. So why do some projects succeed while others fail?

The key lies in the absence of harm. The High Court requires trial judges to check, beyond the letter of the regulations, whether the disputed alterations cause concrete prejudice to neighbours or to the building. In other words, relying on a clause does not excuse the need to prove an actual disturbance. This changes many strategies, both for those wishing to carry out works and for their opponents.

The facts: a story that happens every day

Let us return to the protagonists of this case which, under the rooftops of Aix‑en‑Provence, mirrors many situations experienced in Parisian buildings. Mr and Mrs Z… owned several lots in a co-ownership. Their neighbours, Mr and Mrs Y…, owned lots 19 and 20. The latter obtained authorisation from the general meeting to alter their private parts – probably to create an additional room, remove a load‑bearing wall, or modify the internal layout. Nothing extraordinary: every week, similar resolutions are adopted in co‑ownerships in the capital.

But for Mr and Mrs Z…, this authorisation constituted a flagrant breach of the co-ownership regulations. This document, drafted when the co‑ownership was established, defines with surgical precision the use of each lot: one area is for residential use, another for commercial use, a corridor must remain free. In their view, the general meeting had no power to depart from it. They therefore applied to the tribunal de grande instance, then to the Court of Appeal of Aix‑en‑Provence, to have the collective decision annulled and to obtain an order for the restoration of the premises under a penalty.

On 10 November 1992, the Court of Appeal granted their application in full. Relying on the clauses of the regulations, it annulled the authorisation and ordered Mr and Mrs Y… to restore their lots to their original configuration. However, what the Aix judges had failed to do – and this is where the problem lies – was to investigate how these alterations concretely harmed the rights of Mr and Mrs Z… or the general purpose of the building. The Court of Cassation was to sanction this omission.

The court’s reasoning – dissected

To better understand the Supreme Court’s position, one must bear in mind the distinction between the abstract legal plane and the reality of nuisances. The co-ownership regulations may, for example, prohibit carrying on a commercial activity in a residential lot. But if the general meeting votes an exceptional authorisation in favour of a co-owner, such a resolution is not void as a matter of principle. Article 9 of the Law of 10 July 1965 (which recognises each co-owner’s right to free enjoyment of his private parts, provided he does not cause disturbance to other occupants or to the purpose of the building) requires a concrete analysis of the prejudice.

The Court of Appeal had simply applied a straightforward syllogism: the regulations prohibit → the authorisation is unlawful → annulment. In so doing, it deprived its decision of a legal basis, to use the established phrase. The Court of Cassation points out that the lower judges should have verified whether the alterations carried out genuinely harmed the rights of the other co-owners or the purpose of the building. What does this encompass? It may involve noise nuisance, loss of light, weakening of the structure, or excessive use of common parts. But without any such showing, the annulment becomes an abuse.

This solution is not a bolt from the blue. It is part of a consistent line of authority from the Court of Cassation, which prefers an examination of the factual circumstances to the mechanical application of contractual clauses. As early as 12 June 1991, the Third Civil Chamber had held that a change of use authorised by the general meeting could not be challenged without proof of an objective disturbance. The 1995 ruling confirms this approach, emphasising the need for a “proportionality check” between the collective interest and individual rights. To put it in lay terms: just because it is written down does not necessarily mean it must stay that way.

What this means for you – in practical terms

If you are a co-owner and are considering works that affect the purpose of your lot, this decision gives you a real roadmap. Take a Parisian example: an owner of two adjoining studio flats on Rue des Martyrs wishes to combine them into a single three‑room apartment. The regulations stipulate that the lots are for residential use and that any change of consistency must be approved by the general meeting. If the meeting votes in favour, a neighbour cannot have the authorisation annulled solely on the basis of the regulations. He will have to show that the merger, for instance, eliminates a parking space or increases lift charges.

Conversely, if you are contesting a project, do not go into battle empty‑handed. Gathering tangible evidence of the prejudice is essential: bailiff’s reports, witness statements of nuisances, architect’s reports… Failing this, you risk not only losing the case but also being ordered to pay damages for abusive proceedings. The cost? Such an action can easily run to €3,000 to €5,000, between legal and expert fees, not counting reimbursement of the other side’s costs. In Paris, where the square metre reaches €10,000 in some districts, these sums must be weighed against the possible depreciation of the property.

For a tenant, the situation is different: you are not directly affected by meeting votes, but you may suffer the disruption caused by the neighbouring works. In that case, your recourse lies against your landlord, who is obliged to guarantee you peaceful enjoyment of the premises (Article 1719 of the Civil Code). If the nuisance persists, you could seek a rent reduction or termination of the lease. However, the 1995 ruling reminds us that the evidence must be solid: mere discomfort is not enough.

Finally, for a purchaser, this case law should encourage reading the co-ownership regulations with fresh eyes. Do not hesitate to ask, before signing, whether authorisations for alterations were granted at recent general meetings. A lot that has been “altered” without a solid basis could give rise to future disputes, and you would then be required to restore the premises at your own expense. The notary can help you decipher these documents.

Four tips to avoid this type of dispute

• Analyse the regulations and the history of decisions. Before submitting a project, consult the minutes of recent meetings. Some co-ownerships have tolerated non‑conforming uses for years: this practice may amount to “implied authorisation” and strengthen your position. Conversely, regulations that have become dead letter expose you less than a building where every comma is strictly enforced.
• Anticipate objections by reducing the impact. If you are seeking authorisation, accompany it with a technical file proving that the works will cause neither noise nuisance, nor loss of light, nor over‑use of common parts. An acoustic engineer’s report or an architect’s plan can swing the vote.
• Gather evidence before any legal action. Do you wish to challenge the general meeting’s decision? Do not limit yourself to the breach of the regulations. Photograph, record (respecting privacy), have a bailiff note the disturbances suffered. The slightest crack, the slightest vibration can become your best allies.
• Attempt an amicable resolution. Mediation or conciliation, often proposed by the managing agent or the court, costs far less than a lawsuit (a few hundred euros) and can lead to a compromise: limited working hours, installation of insulating materials, financial compensation. In my practice, I see too many cases where a simple discussion would have avoided years of litigation.

Further insight: related case law and developments

The principle established on 25 January 1995 is by no means isolated. The Court of Cassation had already adopted a similar position in a ruling of 12 June 1991 (appeal No. 90‑10.292), stating that the judge must “investigate whether, despite the authorisation given by the general meeting, the works compromise the solidity of the building or harm its purpose”. This continuity shows that judges are reluctant to turn the regulations into a systematic blocking tool.

Since then, other decisions have refined the notion of “harm to the purpose of the building”. Thus, converting a cellar into a shop may be held contrary to the residential purpose if it generates customer flows incompatible with residential peace (Cass. 3e civ., 6 March 2002, No. 00‑18.369). Conversely, joining two apartments by breaking through a separating wall, without altering the external appearance, is rarely sanctioned. The trend is therefore towards pragmatism: courts assess the actual disturbance rather than formal compliance.

This approach is now found in the Courts of Appeal in Paris, Lyon and Marseille, which are slower to quash meeting authorisations. For the future, the digitisation of co-ownership registers and the rise of online voting platforms may make it possible to better document the effects of works, thus reducing litigation based on mere suspicion.

Key points to remember

Are you in a similar situation? A 30‑minute initial consultation with Maître Zakine (€45) can save you months of proceedings – and often much more. Make an appointment →