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Community and Q&A

Should I ventilate my crawl space or seal my crawl space?

CaseyMallory | Posted in General Questions on

I live in the northern part of Utah about 50 miles south of the Idaho Utah border and it’s fairly dry all year long except in the early spring months, and I’m not sure if I should ventilate my crawl space or seal it off. I have read several websites that tell me that ventilated crawl spaces in the dry states in the western US are okay to have, then I’ve had several websites tell me ventilating a crawl space is altogether bad no matter where you are. I would very much appreciate if somebody could help shed some light on this for me.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Casey,
    If I were you, I would seal my crawl space. Here is an article you might want to read: Building an Unvented Crawl Space.

    Most crawl spaces include plumbing pipes, and pipes can freeze if your crawl space is vented.

    In your climate, however, most builders report that vented crawl spaces don't have the nightmarish problems that occur with vented crawl spaces in Georgia and North Carolina. Just because you don't have big problems, however, doesn't mean it's a great idea.

  2. Expert Member
    Dana Dorsett | | #2

    From a moisture & radon control point of view vented crawls are fine at the average outdoor air dew points in your area, but they're a real DOG from stack-effect infiltration & energy use point of view.

    It's nearly impossible to air-seal the floor (even with copious spray foam), and it often takes less material to insulate & air seal crawlspace walls (coupling the house to the thermal mass of the soil, which has an energy use benefit), and air-sealing the walls is generally tighter & more reliable.

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