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KMU-Magazin No. 06, June 2022 Building without a building permit is not worth it

Even if a building or plant does not require a building permit according to your own assessment, it is advisable to inform the relevant building authority about the planned building project in advance and to clarify the obligation to obtain a building permit. This article provides information about the building permit requirement and the exceptions to it.

Anyone who wants to build a structure or plant facility requires a building permit - as stipulated by the federal Spatial Planning Act (RPG), which is binding on the cantons. In principle, "buildings or facilities" are any artificially created installations that are firmly connected to the ground and have an impact on the environment.

However, there are also exceptions to the principle of the building permit requirement. For example, for solar installations up to a certain size.

Both federal law and cantonal legislation provide for such exceptions. As a rule, however, they only apply to the smallest building projects. Whereas in the past the authorities often took the view that the demolition of a building that had been erected without a building permit and could not be subsequently approved was disproportionate and that it could therefore remain in place, the wind has changed in recent years: buildings that had been erected without a building permit and could not be subsequently approved usually have to be demolished. This can cost a lot of money and frustration.

Subsequent approval

Before the dismantling of an unauthorized building or installation can be ordered, the competent authority must always check whether the building or installation can be authorized within the framework of a subsequent building permit procedure. The authority initiates the subsequent building permit procedure either ex officio or upon private notification. If the building or structure can be subsequently approved, it may remain in existence. Otherwise, the owner must dismantle it at his own expense.

Whether a building or plant can be approved retrospectively depends in particular on its location: In general, the prospects of obtaining retrospective approval for a building within the building zone are better than outside the building zone. The mere fact that a building or structure has existed for a long time does not justify a claim that it may also remain in existence.

Within the construction zone

Within the building zone, building is permitted within the framework of the cantonal and communal building regulations. Consequently, a structure or installation built without a building permit but which complies with the cantonal and communal building regulations can often be approved retrospectively. If it does not comply with the legal requirements, it must be dismantled. Exceptions are buildings and facilities whose construction dates back more than 30 years. Within the building zone, there is a 30-year forfeiture period for the restoration of the legal condition. Consequently, an unlawfully erected building or structure does not have to be dismantled after the expiry of this period. A counter-exception is made for important public interests, which nevertheless justify the deconstruction.

The forfeiture period of 30 years for the deconstruction claim is justified by considerations of legal certainty. The Swiss Federal Supreme Court is of the opinion (BGE 107 Ia 121, E. 1a) that it would be objectionable if the authorities could oblige a landowner to remove an unlawful structure or installation after a long period of toleration. In addition, the Federal Supreme Court also sees practical difficulties. Thus, after more than 30 years, it is likely to be difficult to clarify and reconstruct the factual and legal circumstances as well as the practice of the cantonal and communal authorities for buildings within the construction zone.

However, buildings that are unlawful and cannot be subsequently approved do not become lawful even after 30 years. After the expiry of the 30-year period, they must merely be tolerated. This means, in particular, that there is no claim to the existing building and that such a building or structure, which has not been approved but only tolerated, may not simply be converted or rebuilt or extended. The owner only has the right to maintain it with measures that do not require a permit. This can restrict the use of the building!

Outside the construction zone

Outside the building zone, it is generally not permitted to build or only to build what serves the zone. For example, it is permitted to build a stable in the agricultural zone, but a workshop for a construction company may not be built. In the past, the authorities also tolerated buildings and facilities outside the building zone that were erected without a building permit and subsequently did not require a permit after the aforementioned 30-year period had expired.

This is now no longer permitted by a recent Federal Court ruling (1C_469/2019 and 1C_483/2019 of April 28, 2021). The Federal Supreme Court has come to the conclusion that outside the building zone it is not necessary to apply the 30-year time limit in view of legal certainty and practicability. Outside the building zone, federal law essentially applies. The cantonal and communal scope for assessment is very limited and the applicable law is therefore easy to determine. As a rule, a glance at the zoning plan is sufficient to determine whether a building or structure is in accordance with the zoning purpose.

This current case law is of drastic importance for practice: If a structure or plant is built outside the building zone without a permit and subsequently not eligible for a permit while it does not serve the corresponding zone, it must as a rule be demolished. Examples of this situation would be apartments built within a former stable or alpine huts converted into vacation chalets. Such deconstructions not only destroy substantial investments, but also incur considerable additional costs for the deconstruction.

For these reasons, building outside the building zone without a building permit cannot be recommended under any circumstances. When purchasing land located outside the building zones, special care must be taken to ensure that all buildings and facilities have been legally approved. This is because the new owner must also dismantle buildings and facilities that were not legally constructed at his own expense.

The new case law has of course also startled politicians. Efforts are therefore currently underway to institute the 30-year forfeiture period within the agricultural zone as well (, visited on 25.4.2022). Whether these efforts will be crowned with success remains to be seen. Until a decision is made, however, caution is advised in any case.

Note: The clarification is more difficult for buildings and facilities located outside the building zone that were already constructed before July 1, 1972. Here, the legality of their construction is a prerequisite for claiming the extended vested rights guarantee under Art. 24c RPG and must therefore be clarified as a rule anyway, which can be very time-consuming. In addition, the forfeiture is also subject to the reservation of important public interests here; in addition to the protection of police assets in the narrower sense (safety and health of persons), this also includes other compelling public interests of the environment, water, townscape and landscape protection, which must also be clarified (judgment 1C_726/2013 of November 24, 2014, E. 4). For the above reasons, according to the Federal Supreme Court, legal certainty and equality of rights outside the building zone are best served if it is clear that an illegal use will not be tolerated - even if it has not been discovered or objected to for a long time.

Falsely approved building

The provisions of building law and their application are complex. They also allow room for interpretation. It is therefore not uncommon for structures to be approved that should not have been. If, after they have been built, a violation of the building code is discovered and they have to be dismantled because subsequent approval is not possible, the question arises as to whether the municipality (or the canton) is liable for the consequences of the originally incorrect building permit. Such a state or trust liability of the municipality or the canton is conceivable - but subject to strict requirements.

For state liability to apply, there must be unlawful conduct on the part of the authorities. Such conduct often does not exist, or the resulting claims can only be proven with difficulty or have become time-barred in the meantime. In addition, the person concerned or his legal successor may have participated in the building permit procedure and thus contributed to the erroneously issued building permit.

In contrast to state liability, liability in reliance is based on the principle that the authorities must also act in good faith and thus in accordance with the law. The person seeking justice may rely on such conduct to the extent that he may trust in it. This is not the case, in particular, if he or she does not act in good faith, for example, if he or she provides false information in the building permit procedure or knows that the information provided by the authorities or the basis for trust created by the authorities - for example, the building permit - is incorrect.

If, however, the person seeking justice acts lawfully himself and makes adverse dispositions on the basis of an erroneous official basis of trust, the person concerned is to be placed in the same position as if he had not made the disposition. If a building or installation is erected on the basis of an unlawful building permit, this does not generally mean that the building may remain in existence; rather, the owner must be placed in the same position as if his building permit had never been granted. As a rule, the owner has to be compensated financially, but is not allowed to keep the building or structure and has to dismantle it.


Building without a building permit is not worthwhile. Even if a building or plant does not require a building permit according to your own assessment, it is advisable to inform the relevant building authority about the planned building project in advance. This will not only save you unnecessary trouble and the associated (financial) effort, but may also result in considerable dismantling costs. Trouble and costs can still arise even decades later!

When purchasing a plot of land, it is not only important to ensure that the structures erected on it are in good condition, but also to check whether they have been legally approved. The purchase does not protect against a possible obligation to deconstruct, because the conduct of the previous owner is generally imputed to the purchaser. A warranty clause in the purchase contract covering the legality of the buildings is recommended.

If a municipality erroneously approves a construction project and this error is subsequently corrected, there is a possibility that the municipality will be liable for damages on the basis of state or reliance liability if the given conditions are met. However, the requirements for such liability are high. Anyone who builds outside the building zone without a building permit must, as a general rule and irrespective of their age, dismantle unauthorized buildings and facilities.

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