The main objective of this chapter is to present the important link between a material’s physical properties and its durability. First, the influence of pore structure and the material composition is considered. The diffusion coefficient evolution of cementitious material is also studied taking into consideration the influence of the W/C ratio. The permeability and the effective thermal conductivity of such material are also evaluated in conjunction with the function of porosity, where different correlations are presented. Finally, the liquid vapor interaction inside porous building material is evaluated through the moisture buffer value parameter.