I get a lot of consulting inquiries about moisture aspects of EIFS. They fall into two basic categories: bulk liquid water leaks and the presence of water somehow related to moisture entrapment due to permeability issues. The former almost always has to do with precipitation and involves leaks in some part of the wall, usually adjacent to the EIFS. The latter is more insidious, as it operates invisibly. It's also a lot harder to understand in terms of how water, in the form of vapor, operates in walls.
Over the years, I have come to feel that most people in the construction community do not understand permeability. It is not taught to want-to-be architects and even with experience, few people come close to understanding what permeability means. This month's column is about how this important topic relates to EIFS walls. Hopefully, it'll help answer questions that come up in conjunction with the all-to-common subject of leaks and mold/mildew.