French property law distinguishes retaining walls from party walls

In French real estate law, a distinction is made between party walls (murs mitoyens) and retaining walls (murs de soutènement). While party walls serve as a separation between two properties, a retaining wall is specifically designed to hold back sloping soil to prevent landslides and protect building integrity.

Unlike party walls, a retaining wall belongs solely to the owner for whom it serves a retaining function. The neighboring owner, whose land may be bordered by the wall, holds no rights to it and bears no legal obligation for its maintenance. This distinction is critical when walls undergo structural changes over decades, such as when a property owner alters their terrain level, increasing pressure on the structure.

A February 2022 ruling by the Cour de Cassation clarified that a retaining wall cannot encroach upon a neighbor's land unless the owner can prove it was originally constructed as a shared structure.