Most of the physico-chemical deterioration processes of building materials are related to their open porosity. On this account, there is necessary to investigate the open porosity and other related basic properties of building materials. In this paper we have focused on experimental investigation of basic parameters of load bearing structure materials commonly used in the Czech territory for the construction of historical buildings and monuments. Among the basic material properties, bulk density, matrix density, total open porosity and saturation moisture content of limestone, sandstone, cretaceous marly limestone and brick were experimentally determined. The experimental results show that the tested materials have different porous structure which necessitate to their distinct behaviour.