In Castro Marim, the Câmara identified around 100 illegal dwellings in April 2026, and roughly 70% cannot be regularised, so they will be demolished (Público, 7 April 2026). Unlicensed construction in the Algarve is not a paperwork footnote. It is a physical reality of extensions, pools, and annexes that never reached a stamped plan (planta carimbada), and a structure inside a protected RAN or REN zone has no legalisation pathway at all. Since Decreto-Lei n.º 10/2024, de 8 de janeiro (DL 10/2024) ended the licence check at the deed, and no public body ever checked the building itself, so comparing what is built with what was authorised falls to the buyer and their lawyer before signing. A Simplex Safe review (more than 150 technical verification points, report 3 to 5 business days after the visit; not a legal clearance) compares the building with its approved plans before you sign, for a fraction of the €5,500 to €7,000 typical legalisation cost it screens for.
Table of Contents
- How common is unlicensed construction in the Algarve?
- What is the planta vs realidade problem?
- Which structures can never be legalised?
- What does an inspector physically check?
- What does a buyer inherit with unlicensed construction?
- Frequently Asked Questions
- Conclusion
How common is unlicensed construction in the Algarve?
Unlicensed construction runs across the Algarve in the thousands, from enclosed terraces to entire dwellings, and a municipality can order demolition under the RJUE at any time.
The scale is documented and openly acknowledged. Alexander Rathenau, honorary German consul in Lagos, told the newspaper Barlavento in March 2025 that in Lagos, Vila do Bispo, and Aljezur alone there are "thousands of illegal constructions, and new ones appear every day," and that the figure may reach "thousands, or even hundreds of thousands, of illegal constructions in the Algarve alone." Estate agencies say the same. A1 Algarve reports that "more and more houses for sale have illegal extensions, unauthorised swimming pools or missing documents."
The enforcement record shows this is not theoretical. In April 2026 the Câmara of Castro Marim identified around 100 illegal dwellings, including prefabricated homes, wooden houses, modular structures, and containers, and stated that about 70% cannot be regularised and will be notified for demolition (Público, 7 April 2026). In the Parque Natural da Ria Formosa and other protected areas, more than 3,000 illegal constructions have been recorded, with 297 demolitions carried out under the POLIS programme by 2018 (RTP; Observador, November 2018).
Enforcement is uneven. Municipal services often act only on a neighbour's complaint, and demolition orders are not always executed. The Castro Marim case shows what changes when a structure cannot be regularised under the current municipal plan: notification, then demolition at the owner's cost. This is the Algarve defect profile that a generic inspection misses, and it sits alongside salt-air corrosion and flat-roof failure as a primary regional risk.
What is the planta vs realidade problem?
The Algarve's core legal-physical risk is the gap between the stamped plan and the building as built, where the house has quietly grown beyond what was ever approved.
Azul Properties describes the verification step plainly. The first document an inspector reads is the stamped plan (planta carimbada), which carries a Câmara Municipal seal confirming it is the registered version. Compared against the physical building, the properties are often "similar to the plans, but larger." The house has "engordado," it has got fat. A terrace becomes a bedroom, a garage becomes a studio, a pool appears where the plan shows none.
This matters for two reasons that a buyer feels directly. A bank appraiser may leave any unlicensed part out of the valuation, which can reduce mortgage capacity and open a financing gap before the deed. An unlicensed pool built larger than its declared dimensions is one instance of this, and the same logic applies to extensions and annexes. Dimensional discrepancies between the plan and the structure are invisible to anyone who does not measure.
Which structures can never be legalised?
A pool, annex, or wall inside a pure RAN or REN zone has no legalisation pathway, and the coastal programmes restrict new construction near the shore.
Some unlicensed structures can be regularised, and some never can. The dividing line is the land classification, and it is the single fact that decides whether a defect is a cost or a demolition. Land inside the Reserva Agrícola Nacional (RAN) or the Reserva Ecológica Nacional (REN) prohibits construction with extremely narrow, ministerial-level exceptions, so a structure standing in a pure RAN or REN zone stays exposed until the Câmara acts on it. The coastal programmes (the POOC, being replaced by the Programas da Orla Costeira, POC) cover a land strip of about 500 metres from the shoreline and restrict new construction and volume increases within it. Heritage protection zones in Lagos, Tavira, Faro, and Silves need prior heritage approval for any works, from Património Cultural, I.P. (which replaced the Direção-Geral do Património Cultural, DGPC, in 2024) or the CCDR Algarve, depending on the monument.
Timing matters, but it never works automatically. Work that predates the rule it now breaches may have an argument; work carried out after it has no right to legalisation, and only the Câmara's own certidão settles which case applies. Decreto-Lei n.º 10/2024, de 8 de janeiro ended the notary's licence check at the deed, but it did not remove the obligation to have authorised works, and the RJUE fines still apply. The full mechanics of that law change sit in our Simplex guide. Under the RJUE as amended by Decreto-Lei n.º 108/2026, de 29 de maio, which applies from 1 October 2026, municipal site supervision (fiscalização) can still act at any time. Approval on file does not close the question. A building that was never authorised stays exposed, and only a measured comparison on site tells you which side of the line a structure falls on.
What does an inspector physically check?
An inspector measures the exterior footprint of the building and every ancillary structure, then compares each one against the stamped plan and the property's registered description.
The method is direct. The inspector measures the outside dimensions of the main building and all separate structures, then checks each against the planta carimbada and the registered description (descrição predial). Anything physically present that is absent from the plans gets flagged for legal verification. The inspector identifies the risk on site. A lawyer or the Câmara assesses the remedy, and InspectOS does not give legal advice on whether a given structure can be legalised.
Several additions recur across Algarve villas, and each has its own physical tell. Enclosed terraces (varandas fechadas) show a different material or construction quality at the junction with the main wall. Extended bedrooms and living areas push the footprint past the plan, with a visible construction joint. Pool bars and barbecue structures (churrasqueiras) sit on lightweight foundations with outdoor electrical circuits that need their own safety check. Annexes (anexos), converted agricultural outbuildings, and prefabricated modular units often appear on no registered plan at all, and Rathenau flags the modular units as a fast-growing problem on rural land. For a converted barn or ruin, the inspector also assesses structural adequacy, damp proofing, and fire safety, which is where a full structural survey earns its place.
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What does a buyer inherit with unlicensed construction?
Since DL 10/2024 no one checks the licence at the deed, so the buyer has to find unauthorised works before signing; legalisation typically costs €5,500 to €7,000.
Since Decreto-Lei n.º 10/2024 the notary no longer checks the licence at the deed (escritura), so an extension or pool that does not match the plan is for the buyer to find before signing. Inspect before signing a binding reservation or CPCV where possible: findings can inform repair requests, pricing and contract terms, and your lawyer should advise on your rights and any inspection condition. Unauthorised construction typically triggers legalisation costs of €5,500 to €7,000, with municipal taxas varying by regulamento, and the absence of a required permit carries fines from €498.80 to €99,759.58 for individuals and up to €249,398.95 for companies (RJUE). The RJUE also makes the owner or promoter jointly responsible with the project authors and the works director for work done without, or against, its título urbanístico, so the owner of record cannot simply point at the builder.
From 1 October 2026, under Decreto-Lei n.º 108/2026, de 29 de maio, as deferred by Decreto-Lei n.º 155-B/2026, de 31 de julho, the professional who draws up the deed (notário, conservador, advogado or solicitador) must record the property's urban-planning title (título urbanístico) situation: that it exists and was shown, that the seller declares having it, or that the seller declares not having it. The declaration covers the paperwork, not the physical building, and our DL 108/2026 título gap guide covers that distinction. The point for the Algarve buyer is concrete. A title says construction was authorised; it says nothing about whether the annex on the plot was ever part of that authorisation. Castro Marim shows the worst case: a structure that cannot be regularised is notified for demolition, and the owner pays. A Simplex Safe review puts a measured comparison in your hands before the CPCV, while you can still renegotiate or walk away.
Frequently Asked Questions
Can I buy a property in the Algarve that has unlicensed construction?
You can, but find out first. Since DL 10/2024 no one checks the licence at the deed, and the Câmara can still order legalisation or demolition after the sale. Signing a contract can affect your options; it does not mean that every defect automatically becomes your sole legal responsibility. Your lawyer should advise on your rights. A measured inspection before the CPCV tells you which structures are missing from the stamped plan, so you can renegotiate the price, require the seller to regularise, or withdraw. The risk is manageable only if you know about it before you sign.
Does DL 10/2024 mean unlicensed construction no longer matters?
No. Decreto-Lei n.º 10/2024 ended the notary's licence check at the deed, but the obligation to have authorised works remains, the RJUE fines still apply, and the Câmara can still order legalisation or demolition. Under DL 108/2026, from 1 October 2026, municipal site supervision can still act at any time. The licence check at the deed went; the underlying risk did not.
What is a RAN or REN zone and why does it matter?
The Reserva Agrícola Nacional (RAN) and Reserva Ecológica Nacional (REN) are protected land classifications that prohibit construction with very narrow ministerial exceptions. A pool, annex, or wall built inside a pure RAN or REN zone usually has no legalisation pathway, which is why the land classification, not just the structure, decides whether a defect can be fixed or must be removed.
Can an inspector tell me whether a structure is legal?
An inspector establishes the physical facts: the measured footprint, which structures exist, and which ones are absent from the stamped plan and registered description. That evidence is what a lawyer or the Câmara needs to assess the legal status. InspectOS reports the physical observation and flags the risk; the legal remedy is assessed by a qualified professional.
Conclusion
Unlicensed construction is the strongest single reason to inspect an Algarve property on site rather than trust the file. The stamped plan and the building often do not match, the land classification decides whether a structure can be saved, and no one checks either at the deed. A Simplex Safe review compares the property with its approved plans before the CPCV and flags the structures that do not match them, as discrepancies for your lawyer to assess, for a fraction of the €5,500 to €7,000 typical legalisation cost it screens for. Book it before you sign.
→ Book a Simplex Safe inspection · get a quote at inspectos.pt/en/home-inspections
Updated October 2026 | Reviewed by the InspectOS engineering team | InspectOS Portugal
Sources
- Decreto-Lei n.º 10/2024, de 8 de janeiro
- Decreto-Lei n.º 108/2026, de 29 de maio
- Decreto-Lei n.º 155-B/2026, de 31 de julho
- RJUE (Decreto-Lei n.º 555/99, de 16 de dezembro)
- Público (7 April 2026, Castro Marim)
- RTP and Observador (November 2018, Ria Formosa / POLIS)
- Barlavento (March 2025, A. Rathenau interview)
- A1 Algarve
- Azul Properties
- CCDR Algarve (RAN/REN cartography)
- APA, Programas da Orla Costeira (POC), successors to the POOC
- Património Cultural, I.P. (Decreto-Lei n.º 78/2023, successor to the DGPC)