This paper presents in detail the legislation and regulation related to the use and ownership of building complexes with multiple units (apartments, condominiums) in Saudi Arabia for the 3D registration of the legal spaces. The 3D Land Administration Domain Model (LADM)country profile for Saudi Arabia must be able to represent the identified concepts for multi-owner buildings. Today, there is a trend to directly design these buildings in 3D. Within the spatial development lifecycle thinking, this design will be reused via Building Information Modelling (BIM)/ Industry Foundation Class (IFC) encodings in the subsequent phases, such as, obtaining permits, financing, constructing, etc. However, in order to support the next step, the cadastral registration, we present, at this paper, a mapping from the BIM/IFC to the LADM, both at conceptual modelling and at the level of the individual units with their geometry and topology. This mapping requires that the BIM/IFC file contains sufficient information to identify the different spaces being part of a property. Three different main type of spaces are identified: private part, common part, and exclusive common part. A single property may contain multiple disconnected components, such as the main apartment, the storage in the basement, and a car park. In turn, a component, such as the main apartment, may contain multiple connected spaces, i.e. the various rooms of the main apartment. In addition to mapping the concepts at class level from IFC to LADM, we also extract rules for treating the spaces of various types of walls, slabs, roofs, and constructive elements, such as foundation and pillars. The presented approach is tested with a real-world example IFC file, identifying the issues to be improved, i.e. guidelines for the Architecture, Engineering and Construction (AEC) sector to produce IFC file which can be more easy used as input for 3D Land Administration with minimal manual interventions. This research bridges the gap between the project-oriented world of the AEC sector (with BIM/IFC files) and the legal registration as described through the ISO 19152. Though many of the presented findings are based on the legislation and case study in Saudi Arabia, we have the rather strong impression, that these findings will not be very different in other countries.