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Vented crawl spaces in western Washington

| Posted in General Questions on

I have been going down the vented or conditioned crawlspace habit hole for weeks now and it seems to be a pretty heated topic. I am in climate 4C and wonder if the vented vs not pertains and much here?

It seems as thought the vented system works fine, but I have seen articles on GBA saying they should be outlawed. I can understand why this might apply to very cold climates and humid ones, but does it apply to this climate?


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  1. GBA Editor
    Martin Holladay | | #1

    Here's what I wrote on the topic in my GBA article, "Building an Unvented Crawl Space":

    "While vented crawl spaces often perform poorly in the humid states of the Southeast, they perform well in most Western states. According to an article in Home Energy magazine, “In the drier regions of the West, and even — surprisingly — in the marine climates of the Northwest, vented crawl spaces work acceptably most of the time. The hot-dry conditions in summer and the cold-moist conditions in winter do not cause the same problems that hot-humid conditions cause in the rest of the country. … The Washington State University Extension Energy Program (WSU-EEP), as part of its work for Building America, monitored four test houses in Vancouver and Moses Lake, Washington, for over a year and found that the vented crawls rarely, if ever, reached dew point and that they remained above 80% RH only for brief periods of time.”"

  2. fourforhome | | #2

    Depending on your county, conditioned crawls might be prohibited due to high radon potential. No conditioned crawls are permitted here in Clark County.
    Here's a map of hot radon areas:!/

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