All works carried out by a

Practical application:

Under this case law, any works on common parts—even if they seem to comply with the co-ownership rules—require prior authorisation from the general meeting. Sophie must immediately present her project to the next general meeting for retroactive approval; otherwise, she risks being ordered to restore the balcony to its original state at her own expense. If challenged, she should gather all invoices and correspondence, and note that the 10-year legal challenge period for unauthorised works starts from the date the work becomes visible.

Practical application:

This ruling makes clear that even if the conversion aligns with the building’s description of division (e.g., the attic was listed as 'private' in the deeds), the use of common structural elements still requires a general meeting vote. As the new owner, Marc is liable for regularisation; he should immediately request a retrospective resolution from the general meeting. Without it, he faces a possible court order to demolish the conversion, and the cost (around €15,000–€30,000) would be his responsibility. He should check the purchase deed and previous meeting records, and consult a notary to see if he has recourse against the seller.

Practical application:

The Cour de cassation decision means that any modification to common parts—like fixing an air-con unit to the façade—must be approved by the general meeting, regardless of the tenant’s actions. Florence, as the co-owner, is ultimately responsible. She must immediately notify the tenant to remove the unauthorised installation and, if refused, apply to the general meeting for retrospective consent. If the meeting denies approval, she may have to take legal action against the tenant for damages, but she must first prevent further harm by restoring the façade, keeping all evidence of correspondence and quotes (approx. €800–€1,200 for removal and rendering repairs).