This thesis constitutes a study in the field of BIM-GIS interoperability, with a concentration on code compliance checking. Code checking requires appropriate computer-based models of building codes in digital format, zoning plans in GIS and building designs in BIM environment. However, in existing design environments, it is not possible to access neighborhood data. Interoperability and geographical data transfer from GIS to BIM environments are problematic. This study proposes a methodology for the creation of a third-party platform that draws IFC and GML data from both BIM and GIS environments separately and then combines them in a unified domain model appropriate to the field to be used in code checking processes. The proposed methodology includes the identification of the required data in the area of study; identification of how much of the data can be modelled with BIM model or GIS model; construction of the BIM and GIS domain models using the identified data; and development of an application that integrates the two domain models and manages them as a whole. For validation of the methodology and testing the developed platform, a proof of concept prototype is developed. The system retrieves building codes, reads the BIM file sent by the architect, and retrieves the information on the neighborhood the building is located in from GIS and conducts the checking process. The system demonstrates that BIM and GIS information can be compiled together during a code checking process creating a third-party platform. The applicability of the model has been evaluated through use-case scenarios. The use-cases demonstrate that the zoning domain model developed in this thesis can be used as a database to manage geographical information. Coupling the zoning domain model with BIM data supports digital code checking, eliminating the need for hard copies and simplifying approval processes as well as enabling architects to self-check designs for compliance before submitting them to municipalities.