Though, largely ignored, the building penetration loss (BPL), is a critical consideration during network planning and design of wireless broadband communication systems, especially, disaster communication networks. Different experimental works have established that BPL varies with different building materials. In this work, we aimed at determining the relationship (if any) between the BPL and the electromagnetic (EM) properties (permittivity/permeability) of such materials. We derived the correlation model between the BPL and the two EM properties of permeability and permittivity. An experimental measurement campaign was conducted in seven different sites to determine the BPL of different building materials. Using the measurement data and the derived BPL-permittivity and permeability correlation model, the correlation values for the different building materials were obtained. The results showed multiple correlation values ranging from 0.85 to 0.9. These highly positive correlation values imply that BPL correlates positively with the EM properties. With the result of this work, design engineers of wireless networks, especially, disaster communication systems, can estimate BPL in situations where measurement values are not available.