Every superfluous construction project, whether it requires a building permit or not, should have a conceptualization or design.

In design practice, there are differences between the preliminary design and the main project. The preliminary design defines the size of the future object, the position of the object and the orientation on the building plot, the main project in which the preliminary design is developed and ultimately the object with all installations. The main project includes all professions and it meets all the necessary standards and requirements for construction.

Complex buildings sometimes require a construction project, which should help the contractors and prevent contractors' improvisations and possible "creative" interventions.