In order to ensure a reliable building life cycle management, it is es-sential to generate an accurate and up-to-date referential mock-up that will be used for renovation, extension and maintenance. Based on this statement, we carried out, in a previous work, a research study in the sake of reconstructing a 3D CAD model from a point cloud acquired using a Lidar. This point cloud is pro-cessed automatically to detect planes and contours and to generate the 3D CAD model. However, during the life cycle of the project, different actors from differ-ent fields intervene on the building, which creates several communication con-flicts, and this means a loss of time, energy and money. In order to ensure a con-structive collaboration and a simplified data exchange between the different con-tributors in the building, we continued our work to propose, in this paper, an au-tomatic conversion of a point cloud to a 3D BIM file. This conversion induces the passage to the standard IFC format and the integration of a valuable knowledge in it. To do so, an automatic classification of contours into architec-tural elements is proposed. It consists in defining a hierarchical classification rule reproducing the human reasoning for classifying the architectural elements. Then, based on the classified set of polygons, an automatic generation of 3D IFC model is proposed.