What happens if my neighbour builds onto my party wall?

Question

José Manuel Alburquerque · Accepted Answer

It depends on whether the wall belongs to you alone or is a party wall by agreement. If it is yours alone, your neighbour cannot rest their building on it or put any load on it without your permission. You can require them to remove whatever they have built and to repair the damage. If it is a party wall by agreement, your neighbour can put a load on it, but must first pay you the share of the cost of the wall set by the agreement and, from then on, contribute to its upkeep. In both cases, it is advisable to object in writing as soon as you see the work starting. First, who owns the wall The “Código Civil de Cataluña”, the Catalan Civil Code, never presumes that the wall separating two buildings is a load-bearing party wall, which is one that serves to support buildings on both sides. It is only one if this has been agreed. To find out which case applies to you, check the title deeds and the plans and, if necessary, obtain a report from a qualified professional. On that basis: If the wall is yours alone, your neighbour needs your consent to rest a building on it or put any load on it. If they do so without it, they are interfering with your property and you can require them to remove what they have done and to repair the wall. If they have also occupied part of your land, the rules on building on someone else's land apply. If your neighbour does not rest anything on your wall but builds a wall of their own right up against yours, they may do so provided they do not damage your property and the new wall is sufficiently solid. If it is a fence wall between patios, vegetable gardens, gardens or building plots, it is presumed to be a party wall. Your neighbour does not have to pay half of what it cost to build or of its upkeep until they build on their land or enclose their property, but from then on they do. If your neighbour wants to rest a building on it, it is advisable for a qualified professional to check the wall and for the two of you to agree this in writing. If the wall is a party wall by agreement, your neighbour can put a load on it under the conditions explained below. If the wall is a party wall The Catalan code lays down these rules, unless something else has been agreed: Your neighbour cannot put a load on the party wall you built without first paying you the share of the cost set by the agreement. Either of you can ask the court to review that amount in the light of the nature, age, state of repair and condition of the wall. Once they put a load on it, they must contribute to its upkeep in the agreed proportion or, if none was agreed, according to the use they make of the wall. They must take the necessary measures not to cause you any harm and, if they do, compensate you. Nor can they open windows in the party wall without your consent. In most of the rest of Spain, the Spanish Civil Code (“Código civil”) presumes the wall between two buildings to be a party wall. Each neighbour can rest their building work on it, but first needs the other's consent and, if it is not obtained, experts set the conditions so that the new work does not harm the other neighbour. What to do if the work has already started Do not wait for it to be finished. Object straight away in writing, for example by “burofax” (a certified letter with proof of content). Ask them to stop and to show proof of their right and of the payment due to you. If the work encroaches on your land, from the moment you object the law no longer regards your neighbour as building in good faith. Record the condition of the wall with photos, a notarial record (“acta notarial”) or a report from a qualified professional. If the work has no building permit or does not comply with it, you can report it to the town council. If your neighbour carries on, you can ask the court to stop the work through a fast-track procedure. Before suing, the law generally requires an attempt to reach an agreement. You can demand that the disturbance stop for as long as it lasts. The claim for compensation for the damage becomes time-barred three years after you become aware of the disturbance, in this case your neighbour's building work.