Tim Hance of All Islands Home Inspections discovered two (2) or more vapor barriers in a crawl space filled with water at a recent Anacortes, WA home inspection. The reason that two (2) or more vapor barriers is frowned upon is because water, if it enters the crawl space, can become entrapped between vapor barriers, prolonging evaporation time and leading to stagnant water conditions. Here in the Pacific NW, water intrusion into a crawl space or basement should be dealt with promptly as it can lead to structural damage/settling and insect activity (e.g., carpenter ants, anobiid beetles and Pacific Dampwood termites are attracted to moist areas). In this particular case, the installation of a perimeter curtain drain was recommended to the clients by a licensed contractor.
Tag Archives: vapor barrier
WHAT DO CELL PHONES, FOOTBALL DEFENSES & CRAWL SPACES HAVE IN COMMON?
Something is mesmerizing about watching a crawl space go through an encapsulation process. What do I mean by “encapsulation?” Basically, it means sealing a crawl space so that a house can avoid indoor moisture issues.
Typically, a heavy-duty polyethylene barrier is added to completely cover the crawl space—usually the floors, and sometimes the foundation walls and even the ceiling.
The process is especially impressive when you start with a dirty, damp area and end with a bright, clean space (like the one featured in the video below).
While I don’t think every house needs or should be entirely encapsulated, I always recommend that homes in our area layer the crawl space ground with a plastic vapor barrier.
This was especially evident during a recent home inspection on Lopez Island, where I noticed apparent mold growth underneath the home in the crawl space at floor joists and pressboard floor sheathing elements. I recommended the installation of a vapor barrier, covering all exposed ground in the crawl space, to help prevent recurrence.
Oh, and I should probably answer the question posed in the headline. The answer/punchline? They should all have good coverage! My wife is currently shaking her head as I write this. Regardless, feel free to use this material at your next cocktail party. You have my permission.
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