Art. 100 Introductory Act to the Swiss Civil Code (EGzZGB) - X. Retaining Walls

1. Retaining walls for preserving natural soil belong to the owner of the property on which they have been constructed and must be maintained by them.

2. If a retaining wall has been constructed on the boundary, it is considered part of the property of the owner who erected it, unless a different arrangement has been made. If it cannot be proven or reasonably inferred from the function of the retaining wall which property owner erected it, it is presumed to be co-owned by the neighbors.

3. If a neighbor, who does not have co-ownership in the retaining wall on or at the boundary, makes structural alterations after its construction which would justify the creation of a retaining wall under neighborly law, they can be required to acquire co-ownership of the existing retaining wall by purchase. Article 98 paragraphs 3 and 4 of this law apply mutatis mutandis.

4. For shared retaining walls, the same principles apply regarding maintenance obligations and structural alterations as for firewalls (Art. 99 of this law).