Over last decades, ancient architectural materials, such as bricks, stones and surface finishing materials, have undergone a deep deterioration, mainly due to the combined action of pollution, rising moisture and weathering agents. This deterioration often leads to a serious loss of mechanical strength and cohesion, to such an extent that consolidation treatments must be carried out, by different kind of impregnation procedures. In this work the consolidating action of some polymeric materials is investigated by both a theoretical approach and laboratory tests on porous building materials. As a matter of fact, the consolidating action might be partially ascribed to the 'Poisson effect' exerted by the high-modulus phase on the how-modulus adhesive phases. Thus a highly porous material can be regarded, after impregnation, as a polymer-ceramic composite where pores in the high-modulus material are filled with the so-called impregnating-consolidating restoration materials. Comparison of the performance of impregnated building materials with those of not impregnated ones was carried out.