Short answer. If it is a party wall, fence, hedge, ditch, or drain owned in common, Article 662 of the Civil Code splits the cost of repairs and upkeep among the owners in proportion to each one's share. Any owner may avoid the charge by renouncing their part-ownership, unless the structure supports their own building.
What the law says
The cost of repairs and construction of party walls and the maintenance of fences, live hedges, ditches, and drains owned in common, shall be borne by all the owners of the lands or tenements having the party wall in their favor, in proportion to the right of each.
Civil Code, Article 662 — Sharing the Cost of Upkeep. Read the full provision →
Costs are shared, in proportion to each owner's right
Article 662 states: the cost of repairs and construction of party walls and the maintenance of fences, live hedges, ditches, and drains owned in common, shall be borne by all the owners of the lands or tenements having the party wall in their favor, in proportion to the right of each. The obligation applies specifically to structures owned in common — a fence, hedge, ditch, or drain that genuinely belongs to both neighbors, not one that belongs exclusively to just one of them. Where it is jointly owned, the cost follows each owner's proportional right in it.
Renouncing your share is one way out of the cost
The article gives owners an option: any owner may exempt himself from contributing to this charge by renouncing his part-ownership. If you would rather not pay your share of upkeep, giving up your ownership interest in the fence, hedge, ditch, or drain relieves you of that obligation. This mirrors the general logic that runs through the Code's neighboring provisions on shared structures — you can decline the cost, but only by also giving up the ownership interest that generates it.
The exception when the structure supports your own building
That renunciation option has a limit built into the same sentence: it applies except when the party wall supports a building belonging to him. If the structure is actually load-bearing for your own building — holding it up structurally, not simply running along the boundary — you cannot walk away from the maintenance cost by renouncing part-ownership. Because your building depends on that wall, the obligation to contribute to its upkeep stays with you regardless.
What to establish before assuming a cost is shared
Before relying on this article to demand a neighbor share a maintenance cost, it is worth confirming that the fence, hedge, ditch, or drain is genuinely owned in common rather than exclusively by one side — a question the Code addresses through separate presumptions and exterior signs. Once common ownership is established, this article fixes how the burden is divided: proportionally to each owner's right, with renunciation available except where the structure carries the weight of your own building.