What Causes Crawl Space Humidity?

Now that you understand the problem, you might want to know more about what causes it. Here are the top causes of crawl space humidity.  

Open Crawl Space Vents  

By far the most common cause of crawl space humidity is open crawl space vents. For a very long time, people believed having open crawl space vents was actually a good thing. The common narrative was that open crawl space vents allowed the crawl space to “breathe,” which it needed to avoid the possibility of becoming musty and stale.

However, recent research has shown that’s not really the case. With an unencapsulated crawl space, you’re likely to get moisture coming in through the vents. When that air meets the different-temperature air in your home, it causes an explosion of humidity. That means your open crawl space vents are probably causing more humidity than they’re preventing.

Dirt Crawl Space  

Do you have a dirt crawl space? A surprising number of homes do. Although a concrete crawl space is much better for your home, most homes have dirt crawl spaces simply because they’re cheaper to install when the home is first built. The problem is that the dirt crawl space can significantly impact your home’s moisture levels.

Even if you think the dirt under your home doesn’t have an undue amount of moisture, that doesn’t necessarily mean there are no concerns. The top layer of the dirt might be dry, but what about the dirt under the surface? Moisture in dirt stretches down extremely far, and it’s important that you avoid all dirt surfaces in your crawl space.

General Moisture  

Another less-common problem that might lead to crawl space humidity is general humidity in the area. If you live in an extremely humid area, it’s possible that the humidity may cause symptoms of a high-humidity crawl space, even if you’ve already gone through crawl space encapsulation. In these situations, you might end up with high crawl space humidity when other people would have a more normal level of humidity.

However, you need to make sure you encapsulate the crawl space first. You shouldn’t automatically assume high crawl space humidity is only because of the general moisture in your home or area. Instead, go through the necessary steps for crawl space encapsulation, and if you’re still seeing high levels of moisture, consider a dehumidifier.

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