Electromagnetic Interference (EMI) shielding materials commonly refers to how effective the material in limiting the passage of electromagnetic radiation into the devices. This undesired interference may cause disturbances to the performance of the any electrical systems. Thus, with effective EMI shielding materials, electromagnetic radiations are blocked with barriers made of conductive materials. In military field, the operation of certain communication equipments such as radar system can be interfered by disturbances due to the electromagnetic radiation emitted by external sources. This paper presents the investigations on non-metal materials which are Polyvinyl Chloride (PVC) and carbon fiber composite as EMI shielding materials in building construction. These shielding materials are placed in the concrete block which casted based on the standard wall building of grade 30. These customized structures are proven to reduce signal penetration significantly in the high frequency range up to 2.4 GHz.