Short answer: three groups of documents
Before it approves a renovation, the ajuntament asks for three groups of documents. First, who and where: the applicant’s details, their right over the property, the cadastral reference. Second, what is being done: a description of the works, existing and proposed drawings, a budget and, for substantial works, a technical project signed by a professional. Third, supporting papers: community of owners’ consent if shared elements are affected, construction-waste documentation, and payment of fees and the construction tax.
The exact, current list for each procedure is published by the council itself, and it varies with the type of work, the address and whether the building is listed. Which permit your project needs is covered in a separate guide; this one is about the paperwork.
Applicant and property documents
The owner’s DNI or NIE. If someone else files, such as the contractor or a gestor, a signed authorisation to act on the owner’s behalf is needed. If the owner is a company, add its incorporation documents and the signatory’s powers.
Ownership is shown with the title deed or a nota simple from the Land Registry. If a tenant is carrying out the works, the owner’s written consent is needed. Double-check the cadastral reference: one wrong digit and the application belongs to the flat next door.
For foreign owners a common snag is an old NIE with a different transliteration of the surname from the one on the deed. Check it in advance so you are not explaining the mismatch after filing.
Description, drawings and budget
The description states what is being done in plain technical language. Drawings show the existing and proposed layout when it changes. Photos record the current state and, for work on a facade or balcony, the view from the street.
The budget is the base for the construction tax and fees. Understating it is pointless: the final cost can be checked after completion and the tax adjusted. Amounts depend on municipal bylaws and are confirmed by the council.
The key requirement for all three is that they match each other and match what will actually be built.
Technical documents for substantial works
If the works affect the structure or shared services, or the procedure calls for a technical project, the file is signed by a competent professional: an architect, arquitecto técnico or engineer, depending on the work. Who may sign is covered in a separate guide.
Such a file includes the technical project or report, structural calculations where needed, site health-and-safety documentation and, in some cases, a professional college stamp (visado). For listed buildings, heritage requirements are added and the list grows.
Supporting documents
Community of owners’ consent, as meeting minutes or written permission, if the works touch shared elements, the facade or the roof. Construction-waste management documents: in Catalonia these are checked carefully, and the format and any deposit are confirmed by the council.
A skip in the street, scaffolding or an external hoist needs a separate public-space occupation permit. It is a separate application and often forgotten: the works are approved, but there is nowhere to put the skip.
Why applications come back for corrections
The existing-state drawings do not match reality: they were copied from an old sales plan and the partitions moved years ago. The authorisation for a representative is missing. The budget does not match the described scope. Community consent is missing where needed. There are no photos. The wrong procedure was chosen.
Every correction request costs weeks. Spending an extra day checking the file before filing is cheaper than waiting for a second review.
How we organise it
We assemble the file with the responsible technician, follow it through to a decision and tell you about every request from the council. The technician answers for the project’s technical content. On commercial premises an activity licence is added to the works paperwork: at the 250 m² child psychology centre in the Eixample, legalising the healthcare activity was part of the same project as the refit.
To get started we need your DNI or NIE, the deed or nota simple, the property manager’s contact and access to the flat for measuring. We reply within an hour, in Spanish and Russian.