Spanish Building Guide Essentail Information to Building in Spain.

Building permits (licencias) are necessary before any construction occurs. Even if the foundations are already in place, a portion of the building is already in place, the home is a pre-fab (pre-fabricated) or the building is a primary home, the building permits must be finalised first. Remember that even additions require licencias.
In Spain, there are 2 different forms of permits for building:
Minor Works Permit for walls, terraces, and barbecue areas. These can be obtained at the Town Hall. Ask for a licencia de obra menor. You will need to provide a summary of the construction you plan to have completed and an estimate of the final costs so that the Town Hall can calculate the taxes. Usually the tax costs upwards of 6% of the building costs.
Major Works Permit for new buildings, demolitions, or remodeling. For this form of permit, you must have a written account from an architect who is registered with the Spanish Architecture College. Your architect must have a technical architect who works as the Site Manager during the construction. Finally, a builder must be lined up already. These three workers must each sign the building permit paperwork.

An application for the building permit (Solicitud de Licencia) must be submitted in person to the Town Hall Offices or by registered post. The clerk on duty will hand you a receipt. Make sure you have this receipt before you leave, as it is the only proof you will have for now that proves you have submitted the application. It takes approximately two months for an application to be processed.
Once the application has been received, the Town Hall will post you a notification letter along with an application number. From here the Town Hall makes sure all of the information is on the application, that the information is correct, and then the details of your request are posted on a bulletin board. The application is combed over to ensure you are meeting the area's building codes. If all goes well, approval is posted back within 8 to 10 weeks from the time you submitted the paperwork and a building permit is included with this approval letter.
If you have not received the official notification within ten weeks, you automatically receive your building permits providing your plans meet the area building codes and all information was correctly submitted.