Short answer: what legalising means and whether you can do it yourself
Legalising means obtaining now the permit that should have been obtained before work began: a licence or a comunicat, with a project that describes what was built and shows that it meets current rules. If the City Council finds out first, it is obliged to open a procedure to protect planning legality. Under the Catalan regulation, the owner is then given two months to obtain the permit, file the notice or bring the works into line, and any ongoing works are suspended. Whatever cannot be legalised must be restored, and the breach can lead to a fine under the Llei d'urbanisme.
You can apply yourself as the owner, but you need a qualified technician to survey the property, draw what was built and justify compliance. You apply to the local council; in Barcelona, through the Seu electrònica after the consulta prèvia. Rules change, so check the current procedure page before filing.
When you need it: typical cases
An Eixample flat where the previous owner knocked down partitions and merged kitchen and living room without a comunicat. Under the ORPIMO, an interior refurbishment that changes the layout without touching the structure is minor works type II, so it can be filed now as a comunicat describing what was done, provided the layout meets housing standards. If a load-bearing wall was removed, the works affect the structure and a different procedure applies.
A house in Castelldefels with an enclosed porch, a new room on the terrace or a garage turned into living space. Here the key is not paperwork but the plot's planning parameters: if the added floor area exceeds what the plan allows, it cannot be legalised, only restored or assessed against the limitation period. The same goes for enclosed balconies in Barcelona: the landscape bylaw forbids bringing the frame forward to turn a balcony into indoor space.
Why bother: gaps between the actual layout, the permits and the Catastro surface when you sell, mortgage, apply for a cèdula d'habitabilitat or argue with the community. Buyers and banks increasingly ask about every extra wall or square metre.
The six-year limit and what it really means
Under the Text refós de la Llei d'urbanisme (the consolidated Catalan planning act, art. 207), the council's power to order the physical situation to be restored lapses six years after the breach or after the unlawful works end, and restoration orders already issued also lapse after six years. The exceptions matter: there is no time limit on public green spaces, the road network or non-developable land.
Lapse does not make the works legal. The council can no longer force demolition, but the building falls into the fora d'ordenació or disconformitat status (non-conforming use), with limits on future works, and the issue is still there when you sell. Whoever relies on the time limit has to prove it, which means you: photos, invoices, cadastral data, aerial images. Note also that the duty to legalise or restore falls on the current owner, even if a previous owner did the works.
The Land Registry has its own route. Article 28.4 of the national land act (Real Decreto Legislativo 7/2015) allows a building that can no longer be subject to restoration because of lapse to be registered, if the deed declaring the construction comes with a certificate from the City Council or a qualified technician, a notarial description or the descriptive cadastral certificate, stating that the works were completed on a given date and with a matching description. The registrar checks that there is no provisional entry for a planning enforcement case on the property and notifies the City Council.
The community is a separate front. The Codi civil de Catalunya lets the community demand that common elements altered without its consent be restored. Consent is presumed if the works were obvious, did not weaken the building, did not occupy common elements or create new easements, and the community did not object within four years of completion.
What to prepare and who does it
You gather everything that tells the property's history: the nota simple, cadastral reference, old plans and permits from the municipal archive, purchase deed, photos and invoices that date the works. If common elements are affected, the community minutes.
The technician compares the actual state with the last authorised layout and with the Catastro, surveys and draws what was built, checks housing standards, the Código Técnico and local bylaws, values the executed works for ICIO and, if the structure was touched, issues a structural soundness certificate. In Barcelona they also obtain the informe d'idoneïtat tècnica (IIT) for the comunicat or licence.
A notary and the Land Registry come in if an extension or change of floor area must then be registered. The Catastro is updated with its own declaration.
How to file, step by step
Step one: diagnosis. The technician answers two questions: can the works be legalised under current rules, and which procedure do they need. If they cannot, there is one honest way out: restore, partly or fully. Step two, Barcelona: consulta prèvia on the Seu electrònica, describing the works as already done; you get the procedure and the document list. The same person who ran the consultation must then file.
Step three: file the comunicat or licence application on the Seu electrònica with identification (usually idCAT Mòbil, Cl@ve or a digital certificate), the as-built project and the IIT number. If your technician files for you, it must be online. Step four: pay ICIO and the fee with the payment slip; according to the City Council website in 2026, ICIO is 4% of the works budget and the fee is set in the current ordenances fiscals.
If the City Council has already opened a case and sent you a request, answer within the deadline: file for legalisation and, where relevant, submit objections. Staying silent almost always ends in a restoration order.
After legalisation
Keep the comunicat admission or licence together with the as-built project: it is the document your next buyer and bank will ask for. Legalising does not wipe out a fine by itself: the ORPIMO refers to the Llei d'urbanisme, which handles breaches in a separate enforcement procedure.
Then bring the other records up to date. If the number of rooms or the floor area changed, check whether you need a new cèdula d'habitabilitat. File the change with the Catastro. If there is an extension or extra floor area, sign a declaration of new construction or extension before a notary and register it at the Land Registry. For buildings past the limitation period, use the article 28.4 route described above.
Common mistakes
First: waiting six years hoping it will sort itself out. There will be no demolition, but no legality either, and you will have to prove the date. Second: filing as if the works were still to be done. The ORPIMO treats inaccurate or false data as a breach, and the filing can be declared ineffective. Third: legalising with the City Council and forgetting the Catastro and Land Registry, so the mismatch surfaces again when you sell.
Fourth: not checking the planning parameters before commissioning the project and spending money on something that cannot be legalised. Fifth: ignoring the community when the facade, roof or load-bearing walls were touched. Sixth: not answering a City Council request in time.
If you would rather not deal with it yourself, BCN YARD can take over the paperwork together with the renovation.
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