Crawl Space Vents – Open Vents vs Closed Vents

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Crawl Space Vents – Open Vents vs Closed Vents

Hey, Crawl Space Keefer here. Thanks for watching another episode of Truth and No Bull. You know what we’re going to cover today is the myth that we keep hearing “Well, I know a contractor that knows a contractor and he says that yet open your vents during the summer and you close them during the winter and that will control all your crawlspace moisture issues.”

This couldn’t be further from the truth. That was the thought a long time ago and there have been many studies done by the EPA, Advanced Energy in numerous other places that have completely dispelled this type of myth. It is BS. So the real truth is that the moisture that comes through if you open it up during the summertime, those are your humid months.

When your AC, which is usually your duct lines that are running in your crawl space, are kicking on they’re cooling down. When that warm air gets drawn into your crawl space and it hits that cool surface, it turns around and condensates. You’ve reached the dew point. This is the failure point for the moisture.

So now though, now that you have all this condensation on your wood framing members and on your HVAC, your HVAC starts to deteriorate. The insulation has condensation, it starts to fall down and you have enough moisture content in the wood now to start having mold growth and wood decaying fungi. You never want to do this. And if you close it up during winter months, it all that moisture is trapped inside there and it still has nowhere to go. And if you add power vents or vent fans into this situation, you just make things rapidly speed up in really can lead to a lot of wood decay. So you don’t want to do that.

You don’t want open foundation vents. You need a moisture control system in your crawl space and that starts with an encapsulation. A sealed liner, sealed all the way across the floor, sealed up the walls, sealed around all your columns or pillars and you want to make sure that the crawl space is air sealed and gaps between the living space and the crawl space itself. And then once you do all that, you can put environmental controls such as the Aprilaire and have that ducted properly, and then turn around and make sure that you have a monitoring device in there that alerts you if anything in the system fails before mold can regrow.

So that is the true way that you handle a crawl space that used to be open, vented, and has that turned into an encapsulated crawl space. That’s all I have now. Stay tuned for next time.

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