Basement vapor barrier –A lot of people heard advice about vapor retarders or vapor barriers. They have walked away confused without getting the ideas. A big part of the problem is that they have been told what to do. Put the ideas on the warm-in-winter side, or never use one of the given ideas. But they have not had the physics about what happens explained to them. On this post, I am not going to get into the vapor barriers’ details or all the scenarios that possible of different moisture loads and wall assemblies. I am going simply to explain about what happens in a wall cavity with and without an installation of plastic vapor barrier.
Understanding the moisture in basement is one of the most important aspects in how to make buildings do properly their jobs and prematurely not fail. I know now that building science in mid-twentieth century is ascribed magical properties incorrectly to vapor barriers. Water vapor from indoor air was not the most moisture problems’ source. Bulk water from deficiencies in flashing, drainage planes and other moisture management details caused mostly of the problems.
The building science has been in progress since then. I know that vapor barriers can cause significant problems. But I still have homes like the one in Orlando with poly in the walls. And I am having $4 million dollar homes with poly on the walls. I saw the one below when my friend came to Orlando last year. That is in the basement but the attic kneewalls also were covered with poly.
18 Best Basement Vapor Barrier Ideas Photos