As energetic, health and environmental requirements for buildings are changing, deconstruction of buildings in the course of retrofits or replacing construction is increasingly important. To plan change measures in existing buildings, buildings have to be audited manually which is associated with great effort. In our contribution, we propose and describe a combined system of a hardware sensor with software modules for building information acquisition, reconstruction and project planning. Furthermore, technical requirements, the acquired data, user interaction and system architecture are discussed. Our tool enables planner, experts or decision makers to inspect a building and at the same time digitally audit the building room by room. For this purpose, point clouds are acquired, analysed and a 3D building model is automatically derived to record it. Furthermore, the acquired data is automatically analysed in realtime to detect construction elements that are saved in a database. Then, based on the generated building element database building reconstruction and planning algorithms use the information for building inventorying and proje ... mehrct planning. This allows integrated planning of decontamination, site clearance, and deconstruction activities, as well as to coordinate secondary raw material recovery, resources, logistics, material storage and recycling options time and cost efficiently onsite. Results from first field tests on acquisition, reconstruction and deconstruction planning are presented and discussed. Finally, a summary and a conclusion are given. This is followed by an outlook on potential future research and application areas.