Unauthorised Construction in Portugal: Procedures and Paths to Legalisation
- Ana Carolina Santos
- Nov 10
- 4 min read
Illegal construction remains one of the most complex urban challenges in Portugal. Many property owners face the daily reality of owning buildings that were erected without proper licensing or in breach of legal and planning regulations. This article outlines the legal framework, available procedures, and conditions under which such constructions may be legalised according to current legislation.
‘The legalisation of unauthorised buildings represents an opportunity to regularise existing situations, provided there is technical and economic feasibility for their rehabilitation.’
What are Unauthorised Constructions?
Unauthorised constructions are buildings erected without the required municipal licence or approval, or in breach of the approved design and applicable regulations. This category includes:
Works carried out without any prior control by the Municipal Council
Buildings executed contrary to the terms of an existing licence or prior communication
Unauthorised extensions, alterations, or reconstructions
Constructions that violate legal or regulatory provisions, including the General Urban Buildings Regulation (RGEU) and municipal territorial planning instruments
The widespread existence of unauthorised construction in Portugal led the legislature to create specific legalisation frameworks, recognising the need for pragmatic solutions that prevent mass demolitions and their associated social and economic consequences.
Historical Context and Legal Framework
The issue of unauthorised construction stems from unregulated urban expansion during the 20th century. The repeal of earlier laws by Decree-Law 804/76, of 6 November, left authorities without a sufficient legal foundation for assessing or approving legalisation projects.
Ordinance 243/84, of 17 April, marked a major step by setting minimum habitability standards for unauthorised dwellings, acknowledging that most could not meet the strict technical parameters of the RGEU.
Currently, the Legal Framework for Urbanisation and Building (RJUE), approved by Decree-Law 555/99, of 16 December, as amended, explicitly provides in Article 102-A specific mechanisms for legalising unlawful urban developments.
When Can an Unauthorised Building Be Legalised?
Legalisation depends on the building’s ability to comply with legal and regulatory requirements. The main criteria are:
Technical feasibility
The building must be adaptable, through corrective works or modifications, to meet applicable technical standards or, at a minimum, the minimum habitability conditions established by law.
Economic feasibility
The investment required to bring the construction into compliance must be proportionate and economically viable.
Urban compliance
The construction must not contravene territorial management instruments, administrative easements, public utility restrictions, or other provisions that definitively prevent its legalisation.
Safety and health
Minimum structural safety, hygiene, and habitability standards must be guaranteed.
Legalisation Procedures
Legalisation follows a specific procedure under the RJUE:
1. Notification for legalisation
When the Municipal Council identifies unauthorised, yet potentially legalisable, works, it notifies the parties to initiate the legalisation process within a set timeframe.
2. Submission requirements
The application must include:
Architectural and engineering designs
Statements of responsibility signed by qualified professionals
Certificates of approval from authorised entities, where applicable
Other safety and public health-related documentation
Documentation may be waived when no building extensions or alterations are required.
3. Minimum habitability conditions
For dwellings eligible for rehabilitation, the Ordinance 243/84 applies, allowing tolerances compared to the RGEU:
Minimum room area: 8 m² (except for halls, bathrooms, and storage)
In dwellings with fewer than five rooms, one room must have at least 10.5 m²
In dwellings with five or more rooms, at least two must have 10.5 m² each
Kitchen: minimum of 5 m², reducible to 4 m² in smaller dwellings
Ceiling height: minimum free height reduced to 2.35 m
Corridors: minimum width of 0.9 m; stairs in collective buildings: minimum 1 m
Bathrooms: a single full bathroom may suffice even in larger homes
4. Assessment and decision
The Council evaluates compliance with technical, urban, and safety requirements. Additional project elements may be requested if necessary.
5. Payment of fees
If approved, the applicant must pay the applicable municipal fees.
6. Official legalisation
If the owners fail to act, the Council may initiate the process ex officio, demanding payment of the corresponding fees. This only applies to structures not requiring stability calculations.
Cases Where Legalisation Is Not Possible
Legalisation is impossible when:
The construction irreversibly violates urban planning instruments
It is located in non aedificandi zones
It negatively affects archaeological, historical, or environmental heritage
Structural safety cannot be ensured
It places unsustainable pressure on public infrastructures or services
It poses a risk to public health or safety
In such cases, the Council may order demolition and restoration of the land.
Liabilities and Sanctions
Unauthorised urban works without required approvals are administrative offences punishable by fines. Liability is shared between:
Developers and owners
Contractors and site managers
Designers and coordinators of projects contravening planning instruments
Sanctions may include monetary fines, suspension of professional activity, withdrawal of subsidies, or compulsory demolition.
Special Conditions
Independent access and utilities
Ordinance 243/84 applies only to buildings with independent access and direct connection to general infrastructure networks.
Demolition of interior walls
Where necessary for compliance, interior partitions must be removed to achieve legal habitability conditions.
Technical inspection
A prior technical inspection must ensure compliance with safety and habitability requirements, including the assessment of adjoining buildings.
Practical Advice
Begin voluntary legalisation as soon as possible to avoid fines and secure property regularisation.
Consult a qualified architect or engineer with experience in municipal processes.
Gather all supporting documents such as old photos, partial plans, and invoices to substantiate the request.
Verify urban compatibility and ensure compliance with applicable planning instruments.
Evaluate financial implications, including technical fees and potential corrective works.
Do not initiate new works without a licence.
Respond promptly to municipal notifications—missed deadlines can lead to mandatory demolition.
In Summary
Legalisation of unauthorised construction in Portugal is possible when compliance or feasible adaptation to current standards can be demonstrated. The procedure requires proper documentation, fulfilment of minimum habitability and safety conditions, and payment of municipal fees. The law acknowledges the need for practical solutions that avoid unnecessary demolitions while maintaining public safety, reinforcing the importance of obtaining prior authorisation for all building works.
