Subject to respecting the local rules of urban planning on the height of the walls or fences, the co-owner of a common wall can elevate it, without needing the agreement of his neighbor.
But it is better naturally to prevent it … Especially since he can bring an action before the tribunal de Grande instance if he considers that the elevation constitutes an abnormal disturbance of the neighborhood, and obtain damages for the repair the injury suffered. It can also ask the courts to stop work if they threaten the strength of the work.
The cost of any consolidation work required by the elevation is naturally the responsibility of the person who initiated the work.
The elevation can be done on all or part of the width of the wall. But in all cases, the elevated part belongs wholly to the one who built it.
Subject to complying with the regulations in force (building permit deposit, prior declaration, etc.), the co-owner of a common wall can lean against any type of construction. But before starting the work, he must obtain the agreement of his neighbor. This will verify if the project does not harm or compromise the strength of the wall.
If work of this type is undertaken without the agreement of the neighbor, the latter may appeal to the district court which may order the work stoppage or the demolition of the elements already built. The neighbor may, in addition, call into question the civil liability of the other party and claim damages to repair the damage suffered.
If the neighbor refuses party wall mediator, the other party may appeal to the tribunal de grande instance which, before authorizing or prohibiting the work, will appoint an expert to verify the technical aspect of the project.
Beams or joists
Without going as far back as building, the co-owner of a common wall may want to include beams or joists. In this case, too, the agreement of the neighbor is essential, with recourse to the TGI in case of dispute.
Window or opening
The case law (judgment n ° 13-28137 of the Court of Cassation of March 25, 2015) considers that an owner can not practice a window or an opening on a party wall without having obtained the prior authorization of his neighbor. This is indeed an opening prohibited by the Civil Code.
You can grow plantations against a common wall, without having to respect the minimum legal distances or to ask for the agreement of the neighbor. But, of course, these plantations must not damage the structure. They should not, in principle, exceed the height of the wall.
The co-owner of a dividing wall may renounce the joint ownership at any time and thus transfer the entire property to his neighbor, which then releases maintenance and repair obligations.
Just send a registered letter to your neighbor. But it is still better to draw up a notarial deed and publish it in the mortgage file so that it can be enforced against third parties.
It is however impossible to unilaterally renounce the joint ownership of a wall in several cases:
When we build a building,
When one is responsible for its poor state of maintenance
When the wall supports the lands of his land.