House expansion: General concepts

Usually when someone is a property owner he thinks that he has all the freedom to reform and extend his property as he wants. We want to tell you that this idea is completely wrong.

In Spain, as in any European country, there are urban regulations, and they are mandatory to comply with in any municipality, although there may be small changes from one City Council to another. Failure to comply with these standards may lead to an economic penalty or even the demolition of what was built.

The first thing to do if you want to expand the house is to apply for the building permit at the corresponding City Council, and for that a technical project written by a qualified architect is required.

According to current legislation it is mandatory to present the technical project whenever you carry out a reform, expansion or modifications to the property, in the same way if it were a new construction.

House expansion: requirements

  • Photocopy of the D.N.I. (N.I.E.)
  • Property deed
  • Technical project
  • Details of the construction company and proof of being up to date with payments
  • Proof of payment of municipal taxes

Once the license is granted by the City Council, works can be started. It is important not to start without the license, since in the event of an accident the insurance company won´t be responsible for it.

At that time, a technical architect may be hired to carry out the construction management.

According to the current Spanish law, the intervention of two competent technicians in new and expansion works is compulsory, since it is required by the LOE (Ley de Ordenación de la Edificación / Building Management Law).

Hiring the builder

According to current legislation, the construction contract is a legal agreement that binds two parts about the details and the cost of construction, where it will appear:

  • Quality report (Technical project)
  • The final budget
  • Method of payment
  • Work start / end date
  • Penalty clause for non-compliance by both parties

Very important that it be signed by both parties.

Constructor obligations:

The builder is the agent that undertakes to carry out the works or part of them with human resources and the necessary machinery, his own or that of others, subjecto to the contract and the project.


Builder´s obligations:

  • Carry out the work in accordance with the project drawn up by the architect, in order to achieve the end required therein.
  • Possess an academic qualification or professional training that enables him to act as a builder.
  • Choose the construction manager who will assume the technical representation of the builder.
  • Comply with safety and health measures and provide the necessary means for it .
  • Sign both the act of commencement of work (stakeout) and the final act (reception) of the work.
  • Have contracted civil liability insurance (to third parties) during the time of execution of the work.
  • Have contracted material damage insurance with one-year warranty.

Responsibilities of the builder and architects involved in the work

The responsibility of the technicians intervenign in the works begins when signing the act of receipt of work signed by both technicians. Besides, said responsibility automatically extends according to these criteria:

  • One year for execution work involving finishing elements
  • Three years for figurative defects, humidity and problems derived from building installations
  • Ten years of foundation problems, supports, beams, floor slabs, load-bearing walls, that is, all structural elements, that compromise the strength of the building or its stability.

There is a general error that people think that the ten-year responsibility extends to all the elements of the building when it turns out not to be, as we saw in the previous points so it is enough to have a good maintenance of the houses and not to claim a simple crack after seven years when the insurance covers up to three.

The procedure to follow once the work is finished

After finishing the expansion work, it is evident that the square meters of our house has increased, so it will be necessary to update the square meters and the description of the house before at the Notary and then register it in the Land Registry.



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