Results of an empirical investigation of the shielding properties of a small pre-fabricated reinforced concrete building are presented. The electric field attenuation was measured in the frequency range of approximately 20kHz to 500MHz. The experiments were performed in collaboration with the Italian National Board of Post an Telecommunications (ISPT). An equivalent stick model has been analyzed in frequency domain by numerically solving a set of electric field integral equations. The influence of the real reinforcement mesh (dimensions, spatial disposition, electrical parameters) on the attenuation of the electric field has been investigated. A comparison between computed and measured results is presented.