The ways in which liquid and vapor move through our building envelopes are complex, and even today not completely understood; but the fact that lots of water can (and does) move through porous building materials is a phenomenon that rules over so much of the way we build.
Design teams would be wise to provide natural ventilation strategies that can function with a variety of wind directions in order to provide effective passive cooling for the greatest amount of time.
The building envelope must face a number of damage functions: bulk and capillary water, air-born water, vapor, radiation (ultraviolet degradation), pests, and people.
