What do you need a building permit for? (Author: Krisztina Adamy) Why do you need a building permit? The question can be interpreted in two ways. On the one hand, it includes the question: "Why do you need a building permit?" First and foremost, the idea of protection is at the forefront of planning permission. For example, building permission is required for structures that require a considerable amount of specialist knowledge to build, that could pose a hazard or that could have a negative impact on neighbours. On the other hand, it also implies the question: For which structures do you need a building permit? This is slightly different in each state building code. By and large, new buildings, extensions and conversions in Vienna, Lower Austria and Burgenland are subject to authorisation, but there are minor differences. In Vienna, changes to the terrain can be carried out without a permit to a lesser extent, whereas this project requires a permit in Lower Austria. In Vienna, a permit must be obtained for the installation of photovoltaic or air conditioning systems on larger buildings; in Lower Austria, depending on the capacity, it is only subject to notification or even subject to authorisation, notification or registration. In the Viennese allotment garden areas there are significant simplifications, here only new buildings, extensions and conversions require authorisation, all other structural changes do not need to be reported at all. The different rules of the federal provinces in the field of building authorisations always cause a lack of understanding.