How Water Moves: Airflow and Diffusion

Building science and building enclosure consulting is often all about understanding, and controlling, how water moves through a building. Water is the cause of most of the problems we are trying to solve (or, ideally, prevent in the first place). In order to solve those problems, we need to understand how the water is getting to where it is not supposed to be.

Liquid water intrusion into buildings is the main thing to worry about, and there are a number of ways that liquid water can penetrate a building’s defenses. Those pathways, though, will be the subject of a future post. Today, we’re going to focus on the oft-misunderstood water transport mechanisms of airflow and water vapor diffusion.

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