The water-permeability, moisture-diffusivity, and sorptivity concepts of modeling liquid water transport in porous building materials are analyzed. An overall assessment of the particular models is performed using the moisture profiles measured for two types of autoclaved aerated concrete. The water-permeability and moisture-diffusivity modeling approaches are found suitable from a point of view of accuracy of moisture-transport simulation but they have certain limitations. While the water-permeability concept is advisable for compact materials, the moisture-diffusivity concept should be preferred for materials with a high water penetration rate. Therefore, a combination of both these approaches in a single laboratory is beneficial. The sorptivity concept, on the other hand, can be recommended for a basic assessment of water transport capabilities of building materials only.