In the last post, I discussed parts one and two of John Edgar’s building envelope video series, covering the air barrier and detailing respectively.
In part three, Mr. Edgar addresses the issue of water vapor within the enclosure. Here he explains how forces such as gas pressure and energy or heat affect water vapor transport. As a point of reference, the concept of relative humidity is discussed and we recall the key difference between dew point and the condensation plane. To best understand the effect of water vapor, we must learn how it moves through a wall section and how to calculate and model the transport of water.
How is relative humidity calculated?
The final part of the series provides an answer to all the above mentioned challenges within the building enclosure. Controlling moisture and preventing mold in wall construction are two bumps in the road many face along the building process journey. A solution provided by Sto is its fluid applied air/moisture barrier. This portion of the series helps us recognize the components and advantages of fluid applied air/moisture barriers vs. building wraps and other moisture barriers. Mr. Edgar ties it all together by outlining the different design considerations one must take when incorporating fluid applied air/moisture barriers into wall assemblies.
Overall, the “Little John Series” should not be utilized as a systematic guide to air/moisture barriers but serve as a set of guiding principles. Shifting gears, Sto recently announced a new set of guiding principles including innovations within the company and sustainability, which we will cover in the next post.
