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Open Crawl Space Vents

Many homeowners wonder whether they should seal off their crawl space vents. Here is what can happen if you leave them open.

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Around the 1950s, every home with a crawl space was built with vents. It was believed that the vents would help the stale, stagnant air exit the crawl space. The thinking was that the fresh air circulating in the crawl space would therefore prevent mold growth. However, over the years it has been proven that these vents caused more damage than good.  

If your home has vents in the crawl space, you might be wondering what to do with these openings. Should you leave them be or seal them? A lot of homeowners are struggling with this dilemma. Read on as we address crawl space vents, their purpose, the problems they often cause, and ways to avert these issues. 

open crawl space vents

What Are Crawl Space Vents? 

Crawl space vents are fixtures that can be found on foundation walls. They are even required by building codes in many areas.  

While crawl space vents are a great idea in theory and should keep the space beneath your home dry and mold-free, they actually cause a whole range of problems. The issue with these fixtures is that they allow wet air to enter the crawl space, which is rather counterproductive as they were invented to help dry out crawl spaces.  

Vents also encourage the airflow from the bottom to the top of the home. In other words, the air from the crawl space eventually ends up in your living area. If the crawl space is full of mold spores, dust and allergens, all those particles find their way to the rest of your home, contaminate the air you breathe, and even cause health problems. 

Should I Seal the Vents? 

A lot of homeowners are not sure whether they should seal their crawl space vents or keep them open. These vents allow outside air to enter the crawl space, which was believed to prevent moisture build-up. Since moisture underneath your home leads to mold growth and rot, in theory, this was a good idea. However, over time, this has been proven untrue. So, when the vents are already down there, should you leave them alone or seal them off? 

Problems Associated with Open Crawl Space Vents 

Unfortunately, open crawl space vents can cause a lot of problems for the homeowner. Here are just a few of them. 

Broken pipes: During the winter, open vents can cause the temperature to drop in the crawl space, which can lead to bursting pipes. 

Instigates moisture: One of the biggest issues with open crawl space vents is that they let moist air into the crawl space. Since controlling humidity in this area of the house becomes practically impossible with open vents, moisture can lead to mold growth and rot. In addition, outside air will bring in various spores, allergens, and pollutants which will contaminate the air you breathe. 

Encourages pests: Open vents are like a welcome sign for all the pests that are circling your home. Spiders, termites, and other insects can easily crawl through the open vents and inhabit the area beneath your home. What is even worse, mice can also get inside. An ordinary mouse needs only a 1/4-inch opening to squeeze into your home. 

Lowers your home’s energy efficiency: With open crawl space vents, you will have a harder time controlling temperature levels in your home. In summers it will be too hot and too cold in the winter, so your heating and cooling appliances will have to run much longer to ensure the ideal temperature. Naturally, your bills will increase and you will spend much more money on utilities. 

Poor indoor air quality: Outside air comes in unfiltered through the vents, so it brings with it a lot of harmful particles such as dust that can contaminate the indoor air. This can lead to various respiratory problems. 

Sealing off Crawl Space Vents 

Whether you live in Alabama, Tennessee, Mississippi, or Georgia, you should make sure that your crawl space vents are sealed when the winter arrives. This way the area underneath your home will stay dry.  

To seal your vents, you will need to plug them with airtight vent covers. While these fixtures may be available in hardware stores, it’s important to have the right size, material, and tools to install them. This can get expensive for non-professionals, so it’s best to leave this installation to crawl space repair experts. 

According to studies, homes with sealed vents are much drier and healthier than those with open ones. In addition, they have fewer mold problems, are more structurally stable, and have better energy efficiency. With sealed vents, you will be able to lower relative humidity levels to below 60%. 

Protecting Your Crawl Space 

If you wish to get rid of your moisture problem, sealing off your crawl space vents is a good decision. However, this step on its own won’t ensure a dry and clean crawl space. Besides sealing off the vents, you will need to invest in waterproofing measures. Covering your crawl space floor and walls with a 120-mil plastic vapor barrier will lock out outside air and prevent it from increasing humidity levels. After all, humid air is the leading cause of crawl space moisture issues. 

If you do not seal off your crawl space vents, you should expect a wide variety of foundation problems in your near future, moisture build-up being just one of them. If you wish to encapsulate your crawl space, do not do it on your own. Instead, contact your local experts at AFS and schedule a free inspection. A member of our team will come to your home, assess the situation, and recommend the best solution for your crawl space problems. Afterward, we can help you seal off the crawl space and encapsulate it, so it stays dry and clean for years to come. 

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