If changes are made to buildings or their use is changed, a building permit is required, with the exception of smaller construction projects for which certain conditions apply.

The Thuringian Building Code thus distinguishes between four different situations when altering or changing the use of buildings:

1. projects for which a building permit procedure must be carried out and a building permit issued. The building permit procedure is carried out by the lower building supervisory authority. The building permit is granted if the project does not conflict with any public law regulations.

2. projects for which a building permit is required, which can probably be granted in a simplified building permit procedure.
Smaller projects (such as detached and semi-detached houses and other comparable buildings) can be examined in a simplified building permit procedure. The Thuringian Building Code regulates which projects this applies to. The simplified building permit procedure is less complex. A decision on the building application is made within three months of submission of the complete application documents.

3.projects for which no building permit is expected to be required, but which must be notified. The construction of selected smaller projects within the scope of a development plan does not require a building permit if the provisions of the development plan are complied with and the development is secured. Projects of this type must be submitted to the municipality for review. The examination is carried out in an approval exemption procedure.

4.projects that do not require a building permit and do not have to be notified. The Thuringian Building Code specifies which projects on structural installations are exempt from procedures. Such projects do not have to be reported to the municipality or the lower building supervisory authority.