Building Information Modelling (BIM) is seen as a key technology and methodology to improve productivity and integration across various disciplines throughout the Architecture, Engineering and Construction (AEC) value chain. Although many valuable information has been added to such databases in the last years, detailed information about the radio wave propagation characteristics of buildings and building materials have been absent. With the deployment of an ever increasing number of radio based services, such as 5G, this information is expected to be extremely important in the future, both for appropriate indoor radio planning and assessment of human exposure to electromagnetic radiation. This paper presents a multilayer Electromagnetic (EM) simulation tool to assess the radiofrequency transparency of building wall structures, developed in Matlab environment, which allows to explore different layer arrangements and determine the overall frequency response. In particular, the assessment of EM properties of different types of building walls commonly used in building construction, combined into one complete EM tool, is proposed. This is sought to be a valuable feature to be considered towards the integration with BIM-based simulation methods to provide unprecedented visualisation of the radio coverage within the building, allowing for the optimisation to meet specific facility radio requirements.