Unauthorised Building Work and Buying a Polish Property: What Buyers Risk

You've found the dream house, the price looks right, and then — after the akt notarialny (notarial deed, the document that transfers ownership before a civil-law notary, ≠ a UK notary public) is signed — it turns out the extended terrace, the garage or an entire extra floor was built without the required permits. Unauthorised building work (samowola budowlana) is one of the most damaging risks when buying a resale property in Poland, because the consequences can land on the new owner even though they never laid a single brick. This guide explains what unauthorised building work is, when it can be legalised, what demolition risk means for a buyer, and how to check a building's formal status with the local building control authority (Powiatowy Inspektorat Nadzoru Budowlanego, PINB — the district building supervision inspectorate) before you buy.

This guide is general legal information, not legal advice. Whether a given property is affected by unauthorised building work, what the consequences are, and whether legalisation is possible in a specific case depends on the individual facts, the building documentation and local regulations. We do not guarantee any outcome or the course of any proceedings — every case should be assessed by a qualified Polish lawyer or a person authorised in construction law. Twoja Sprawa helps you organise the documents for that assessment.

Key points

• Unauthorised building work means constructing a building (or part of one) without the required pozwolenie na budowę (building permit) or zgłoszenie (building notification), or significantly departing from an approved design — this is governed by the Polish Construction Law Act (Prawo budowlane; full text: ISAP, isap.sejm.gov.pl).
• The problem can affect the buyer, not just the person who built the work — construction irregularities attach to the property, not solely to the original developer, so a new owner may be drawn into remedial or legalisation proceedings.
• Legalisation of unauthorised work is possible in many cases, but usually requires meeting conditions of compliance with regulations (including the local zoning plan or a warunki zabudowy development conditions decision) and paying a legalisation fee.
• If legalisation is not possible, the building supervision authority can order demolition of the structure or part of it — the most severe consequence for a buyer who has already paid for a property that includes an unlawful part.
• Before buying, it is worth checking the building documentation and asking PINB whether any proceedings relating to unauthorised building work are, or have been, under way regarding the property.
• If the seller concealed the unauthorised work, the buyer may be able to consider a claim under rękojmia (the statutory warranty for defects) for a legal defect in title — but this requires proving that the seller actually knew about the problem and stayed silent about it.

What unauthorised building work is and how it can affect a buyer

Unauthorised building work is a situation where a structure (a house, an extension, a garage, a terrace, or a fence exceeding certain parameters) was built without the required building permit or notification, or in a way that significantly departs from the approved design. This can involve an entire building put up "off the books", but just as often it is a single element — an extra storey added on top, an extension, a roofed-over terrace, or a change of use of rooms without the required consent.

From a buyer's perspective, the key point is that the formal problem attaches to the property itself, not exclusively to the person who built it. Buying a house with an unlawful, unlegalised part can, in practice, mean "inheriting" administrative proceedings that were opened against the building — even though the buyer had no say in the decision to build without permission.

When legalisation of unauthorised building work is possible

Polish Construction Law provides a procedure for legalising unauthorised building work — that is, bringing the actual state of affairs into line with the law without demolition. Broadly speaking, legalisation typically requires showing that the structure:

• complies with spatial planning regulations (the local zoning plan, or a warunki zabudowy development conditions decision),
• meets technical requirements and safety regulations (structural standards, fire safety rules, the technical conditions buildings must satisfy),
• does not significantly infringe the interests of third parties.

The legalisation procedure usually involves submitting documentation (including a technical expert opinion and an as-built survey) and paying a legalisation fee, the amount of which depends on the category of the structure. If any of these conditions is not met, legalisation may not be possible, and a demolition order can follow instead. Legalisation is generally a process, not an automatic entitlement — the authority assesses each case individually, so it is unwise to assume in advance that every instance of unauthorised work can be legalised.

Demolition order after buying a house — the risk for a new owner

If legalisation is not possible, or if the owner (previous or current) fails to complete the required formalities within the deadline set, the district building supervision inspector (PINB) can issue a decision ordering demolition of the structure, or of the unlawful part of it.

For a buyer, this means serious financial and practical risk: having to demolish, at your own expense, part of a house, garage or other part of the property that you paid full price for; losing usable floor space compared with what the listing described; and a lengthy administrative process that can drag on before a final decision is reached.

That is why checking a building's formal and legal status before signing the contract matters so much — after the purchase, your options are limited and usually depend on proving that the seller deliberately concealed the information.

How to check for unauthorised building work before you buy — the role of PINB

Before buying a property, it is worth verifying its formal status in a few steps:

1. Ask the seller for the building documentation — the building permit or confirmation of notification, the approved design, the site log (dziennik budowy), the notice of completion of construction, or the occupancy permit (pozwolenie na użytkowanie), if one was required.
2. Compare the documentation with the building's actual condition — does the floor area, the number of storeys and the layout match the approved design? An added storey, an enlarged terrace or an extra outbuilding are all warning signs.
3. Ask the district building supervision inspectorate (PINB) covering the property's location whether any proceedings relating to unauthorised work are, or have been, under way for that plot (general information on the role of building supervision: the Chief Office of Building Supervision, Główny Urząd Nadzoru Budowlanego, gunb.gov.pl).
4. Check compliance with the local zoning plan or the development conditions decision at the municipal (gmina) office, particularly if you're planning further building work after the purchase.
5. Consider getting an opinion from a qualified professional (a building inspector or a chartered surveyor) when buying a house with a visible extension.

✅ Rule of thumb: if the seller's paperwork is missing an occupancy permit or a notice of completion of construction, treat that as a signal to ask directly about the building's legal status — before you sign the preliminary contract, not after completion.

What if the seller concealed unauthorised building work

If it later emerges that the seller knew about the unauthorised building work and deliberately failed to disclose it, the buyer may be able to consider a claim under rękojmia for a legal defect in the property — a problem with a building's legal status is sometimes treated as a legal defect where it restricts the buyer's ability to use the property freely. Every case requires an individual assessment of the documentation, and the outcome depends on evidence that the seller genuinely knew about the problem.

Regardless of any claim against the seller, the proceedings before PINB itself run on an administrative basis and involve the current owner — so once the problem comes to light, you should act quickly: gather documentation, contact the inspectorate, and weigh up your legal options as early as possible.

Frequently asked questions

If I buy a house, do I inherit liability for the previous owner's unauthorised building work?

In practice, the formal problem attaches to the property, so a new owner can be drawn into legalisation proceedings or a demolition case, even if they never built anything unlawfully themselves.

Does the notary check whether a house has unauthorised building work?

A Polish notary primarily examines the legal status disclosed in the księga wieczysta (the land and mortgage register) and does not generally verify whether the building's actual condition matches its construction documentation — checking that is the buyer's own responsibility.

Can every instance of unauthorised building work be legalised?

Not always. Legalisation depends on the structure's compliance with spatial planning rules and technical requirements, and on completing the administrative procedure — the authority may also decide legalisation is not possible and issue a demolition order instead.

What should I do if I receive a letter from PINB about the building after I've already bought it?

Gather whatever building documentation is available (including anything from the previous owner) without delay, and consult a qualified construction-law professional or a lawyer — time limits in administrative proceedings can be short.

Need help with a situation like this?

If you're planning to buy a house with an unclear building history, or you've received a letter from building supervision after completing a purchase, we can help you organise the documentation and prepare the right questions for PINB and for the seller before you take further steps. Tell us about your situation — we'll take a free look — let us know what building documents you have, whether you've seen the land and mortgage register, and whether any proceedings are already under way. Submitting the form does not create any contract.

See also related guides from this section:

• Buying property in Poland step by step
• Checking the land and mortgage register before you buy
• Legal defects in property — what they mean
• Property in Poland — all guides

Guide last checked: 11 July 2026.