Crawl Space Vents

3 responses

  1. Lucy
    August 8, 2012

    During the rainy season we have a lake under our home in the crawlspace. My home has musty smells and high humidity year round. We are thinking of encapsulating the entire crawlspace, after first installing french drains and a sump pump. The people proposing to do the job (we consulted 3) all say we can then close off all but two of our 22 vents. This makes me so nervous...what if the pump fails when we are out of town...what kind of a moldy mess will we be creating down there with the vents closed? If we encapsulated but left more vents open...would that be a better safer idea?

    • Errol mcDonald
      July 8, 2013

      we have installed many systems like yours; to be on the safe side have your contractor install a battery back up..

  2. Steve
    November 14, 2016

    I am curious of the logic of the foundation vents. Especially here in the South East. In the Summer the vents are open allowing very high humidity air to enter the crawlspace. If the humidity outside it nearing 80% it would seem that the air in the crawlspace would also become 80% or more. To check this theory I installed a wireless humidity gauge. During the summer with the vents open I would see wild humidity swings in the crawlspace. Anywhere from 80% to 90% humidity. I tried closing them all and the humidity levels were still in the low 80'& range, but stable.

    Can you explain?

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