Crawl space vents typically exist in dirt crawl spaces. These crawl spaces sit directly underneath the house with no barrier between the home and the dirt underneath it.
This can be a serious problem. Dirt crawl spaces introduce all sorts of issues into the mixture. These are just a few of those problems.
The first problem with a dirt crawl space may be the most important one. To put it simply, there’s absolutely no way to avoid moisture coming from a dirt crawl space. You’re always going to have more crawl space moisture coming up, and crawl space vents aren’t going to do anything to avoid it.
Sure, you can dry out the top layer of the dirt in your crawl space. However, that won’t do anything in the long run. Only a few inches below the surface, you’ll find moist dirt, and that moisture will always rise to the surface.
Plus, far from venting that moisture, crawl space vents tend to actually reintroduce moisture into the area. The only way to avoid moisture in a dirt crawl space is to seal the crawl space vents and box off the dirt bottom.
Insects and Mites
Dirt is also impossible to keep clean and free from bugs. Think about it: you’re trying to move bugs out of their natural home. It’s just not plausible. That’s why dirt crawl spaces tend to be plagued by mites, insects and other pests.
Crawl space vents can also add to this problem. After all, if you have open crawl space vents, it’s essentially just another way for pests to enter into your crawl space. Then they can just stay in your crawl space until further notice.
The only way to really avoid insects and other pests in your crawl space is to seal the crawl space entirely. Otherwise, you’re fighting a losing battle against these pests.
The Stack Effect
It may surprise you to learn that over half the air on a home’s first floor comes from the crawl space, but it’s the scientific truth. This is mostly due to a physics concept called the “stack effect,” which refers to the way in which air moves up through your home.
Air is always moving, and in your home, it’s typically always rising from the bottom to the top. When you have replacement air moving in from the vents in your crawl space, it creates an effect similar to a chimney, bringing the air in your crawl space up into the rest of your home.
That stack effect also brings with it moisture, mold spores, dust mites and other airborne features that would otherwise stay down in the crawl space. You don’t want un-conditioned air from the outside becoming part of your home, but the vents in your crawl space do just that.