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Open Crawl Space Vents

Mold, pests, and other problems are increasingly being discovered to thrive in open crawl spaces. You can improve the safety of your home by seeing and understanding the damage that your own vents produce.


Crawl space vents may seem like a nice idea, which is why many older homes have them. However, open vents are increasingly being discovered to be a breeding ground for mold, bugs, and other issues. You may restore your home’s safety by observing the damage your own vents cause and knowing why.

How Open Crawl Space Vents Affect Your Space 

If your crawl space vents are open, too much moisture can build up and damage the foundation of your home without you knowing it. Mildew, mold, and bacteria love to grow in dark, damp places like crawl spaces. They also bring in bugs and rodents that start living in your open crawl space. At Mount Valley Foundation Services, we know how to fix or close off your crawl space vents the right way. 

Having vents in your crawl space that are open to the outside can have a lot of different effects on your home. This has a lot to do with the weather outside. Summers in North and South Carolina are very hot and humid, so your crawl space is a great place for too much humidity to build up. 

Along with high humidity, open crawl space vents also directly contribute to the stack effect in a home. The stack effect is a process that quickly changes the climate of an entire property and, over time, does a lot of damage. In order for the stack effect to work, there must be vents at both the top and bottom of a building. 

The Risks of Open Crawl Space Vents 

When crawl space vents aren’t covered, they can cause many different problems. Below, we’ll list a few of the problems signs that are common in your area.

rotting wood in crawl space

Wood Rot

You can tell if your wooden building is infested with wood rot since it alters its appearance as well as its texture and smell. If this starts to impair your crawl space’s joists and beams, wooden flooring, and drywall, for example, your home will take a hit because of it. A white-ish shine may appear on these surfaces if they have been affected by wood rot. They will become softer and brittle as a result. It is possible that this can lead to them collapsing or breaking down completely, causing the collapse of any structures that rely on them. 

Crawl space mold on support beam

Crawl Space Mold

A major problem in crawl spaces is the formation of mold. Mold may wreak havoc on your home’s crawl space if left unchecked, resulting in further problems including wood rot and poor air quality. People with allergies or asthma should avoid it because it is harmful to their health and can exacerbate their symptoms. When organic surfaces are damaged by wood rot or other forms of decay, mold thrives. The stack effect will also distribute mold spores throughout your property because they are airborne. Even if you don’t have black mold in your home, most types of molds can have a significant influence on your health. 

mold in crawl space

Musty Odors

If you live in an older home, you might believe that the musty odor in your home is just something that comes with the territory due to the age of the structure. But that unpleasant odor is more than just an annoyance. One of the earliest indications that mold is growing in your crawl space is the presence of a musty stench. Mold, if allowed to grow unchecked, can cause serious problems for both the structure of your home and your health as a whole. In addition to being caused by mold, the smell may also be the result of other problems, such as high relative humidity.


The stack effect is the pattern of airflow in your home from top to bottom. Air pressure is also a factor. Air moves from high-pressure locations to low-pressure ones. This generates a vacuum that sucks outside air into your crawl space and home. Warm air rises and leaves through windows, ceiling gaps, attics, recessed lights, and ventilation apertures. The rising air reduces the pressure at the bottom of your home, allowing chilly air to enter through windows, doors, and other openings. 

As a homeowner, covering your crawl space vents should be high on your priority list, but there are a few things you must accomplish before. After all, you don’t want to keep bugs and issues inside. However, we don’t recommend taking on this problem on your own. 

No, without professional assistance, you should not waterproof your crawl space or seal open vents. There are a variety of reasons behind this. It is not always easier to go it alone due to the risk of personal harm or additional property damage. 

Call Us for A Free Inspection 

Our experienced team at Mount Valley Foundation Services works in humid areas such as Charleston, Columbia, and Savannah. We know a lot about the varied clay, silty-clay, and loam soils that blanket North and South Carolina, in addition to the weather. Contact us if you believe your home is being affected by open crawl space vents. We provide homeowners with free inspections with no strings attached, ensuring that there is a problem that needs to be addressed. Because we never stop a job, you can rest assured that your issue will be resolved correctly the first time. 

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