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The Issue with Open Crawl Space Vents

The biggest problem is that so-called “experts” have often told people that vents actually benefit their crawl space, so learning that it’s not the case can be devastating. Open crawl space vents, especially those that are open year-round, can cause a huge variety of problems.


By far the largest problem associated with open crawl space vents is moisture. The prevailing wisdom for many years had been that by letting the crawl space “breathe,” it was less likely that there would be a buildup of moisture. In fact, this was such a widely believed concept that for many years, it was a requirement in building codes.

The problem is that with open crawl space vents, warm and cool air meet, changing the condensation point of the air and unintentionally causing water buildup in the home. With open crawl space vents, you’re actually more likely to end up with added moisture. This moisture will just start to condense on the inside of the home.

Moisture leads to all sorts of terrible things in your home. For example, if you’re dealing with crawl space moisture, chances are that you’ll also end up with mold, mildew, and sometimes even wood rot. Plus, standing water in your crawl space can lead to material degradation and sometimes electrical hazards, which aren’t something you want to deal with.

Wood Rot

Another significant problem in homes with open crawl space vents is wood rot. That’s because wood rot grows most commonly in homes with a lot of moisture and a medium temperature, which typically describes most homes with open crawl space vents. Wood rot flourishes in many homes that have open crawl space vents.

Wood rot can be a giant problem. In fact, if you let it grow for too long, wood rot can cause irreparable damages. You may have to replace entire sections of your home structure, even sections that don’t seem to have damage on the surface. Wood rot can grow through wood pieces that don’t seem to have this type of rot, and that can mean huge financial problems.

True wood rot is a scourge rivaled possibly only by termites, and it’s something you want to stay away from as thoroughly as possible. If you can avoid wood rot simply by closing your crawl spaces, why wouldn’t you want to take that one step? It’s a simple step that can help your crawl space stay much healthier.

Mold and Mildew

By far the most common issue that most homeowners associate with water is mold and mildew. Both of these problems require an extremely high level of moisture in the air before they can appear, but resting condensation can also cause a high enough level of moisture. Whether you have high relative humidity or just condensation on the walls, mold and mildew can start to form.

If you have a moderately warm home and a lot of moisture, you’re almost certainly going to end up with mold and mildew to some extent. This can exacerbate allergies, weaken your home structure, and cause a musty smell. All of these are terrible things to have to deal with in your home and closing your crawl space vents can avoid them.

Some homeowners who have never had an encapsulated crawl space just feel like this is how it has to be. In these cases, it’s common for homeowners to feel like there’s no option except to leave the crawl space as-is and deal with the mold and mildew. However, that actually couldn’t be further from the truth. If you encapsulate your crawl space, you can almost always get rid of these concerns.

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