Vapor Drive
Vapor Drive
(OP)
Can someone give me a definition of "vapor drive" as it relates to moisture migration through building walls. I need a reasonably technical definition that is still understandable to a non-technical person such as an insurance company claims rep or attorney. Thanks





RE: Vapor Drive
RE: Vapor Drive
The mechanics are a bit more complex than that for a building. For example, moisture generally first moves into the exterior finish materials by capillarity, or directly through a leak. It moves laterally and downward.
When a void or cavity is encountered, the relative humidity in the void or cavity is increased by the moisture intrusion. Now we get condensation. There is nothing to drive the moisture backward, so it is cumulative and progressively worsens unless the source is stopped.
The accumulated moisture then "attacks" the next dry area or cooler area. The same mechanics prevail and it will move to some other location, inward and downward. In the process, given reasonable conditions, mold will grow!