Crawl Space Humidity: Everything You Need to Know

Do you know what humidity in your crawl space can do to your home? Learn more about what causes high crawl space humidity, the problems associated with it, and the solutions you can use to protect your home from it.

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Many homeowners have issues with humidity in their crawl spaces, but it isn’t usually something that people think a lot about. Unfortunately, most homeowners don’t really think about the impact of humidity on their crawl spaces or on the rest of their homes. If you’ve never considered humidity in your crawl space, you might not know what causes it or why you need to get rid of it.

The problem is that crawl space humidity can be a serious concern. If you have higher-than-normal crawl space humidity, you may need to handle it before it becomes even more of a problem. Consider this simple guide to understanding crawl space humidity so you’ll be able to handle it.

stack effect

Crawl Space Humidity

Problems, Causes, & Solutions

There are a variety of problems that arise when you have crawl space humidity that’s too high. These problems can range from very significant to relatively mild, but they’re all important. These are a few of the issues you might end up encountering if you have very high crawl space humidity.

Mold and Mildew  

Mold and mildew can often thrive in damp crawl spaces with humidity in the 60%-70% range. However, anytime you have high levels of humidity, you can have mold and mildew. This is especially true because when water condenses on surfaces, it raises the humidity of that surface, allowing for mold and mildew growth where it may not otherwise grow.

Most people think of the dangers of mold and mildew only in the context of mold spores, but this isn’t exactly accurate. These mold and mildew problems can lead to allergic reactions and respiratory conditions. No matter what they do, mold and mildew can cause serious problems in your home, so it’s best to take them seriously.

Pest Infestations  

When you have mold and mildew, you might also end up with infestations of pests. Many pests actually feed on mold and mildew, which means you’ll create a great food source for these pests if you leave them unchecked. Infestations of even small pests can soon grow into a huge problem because those small pests represent food sources for larger pests.

Pest infestations can happen with even a very small initial infestation. For example, a mouse can have six babies per litter and up to 10 litters per year, which means one mouse can turn into 61 mice over the course of a single year. Whenever you notice even one pest, it’s important to start treating the problem as soon as possible.

High Upkeep Costs  

Something you might not consider is that if you have a crawl space with high moisture content, you might end up with much higher upkeep costs than one with low moisture content. High-moisture air tends to be more difficult to condition than low-moisture air, which means you might need to lower your thermostat if you have a damp crawl space.

Additionally, crawl spaces with high levels of moisture typically get that way because of an existing problem, which is most commonly open crawl space vents. The combination of the additional conditioning necessary with high-moisture air and the fact that crawl space vents allow air in from the outside can lead to a 15-25% increase in your electric bills.

The Stack Effect  

The stack effect refers to the way air functions in a home. Especially if you have open crawl space vents, air is coming in from the outside. As that air warms up, it rises, traveling throughout your home and eventually exiting through the chimney or attic. This isn’t necessarily a big problem on its own, but when you have a dirty crawl space, it becomes a significant concern.

Many things are small enough to become airborne. For example, mold spores, some pest droppings, and dirt from the crawl space can all become airborne and get carried up with the air that rises through your home due to the stack effect. That means the damp crawl space air, along with anything that’s light enough for the air to carry, goes throughout your whole home.

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.

The best way to fix your humidity problems is to make sure you’re at the right crawl space humidity level. The thing is, many people don’t actually know what the best humidity level is, which can lead to a lot of concerns. What can you do to craft a humidity level that’s right for you? 

Take Care of Standing Water  

The first step to fixing crawl space humidity is to take care of any standing water that might be in your crawl space. Unfortunately, standing water is a problem that some crawl spaces have. If you have standing water in your crawl space, it can evaporate and turn into crawl space moisture.

This is why you need to handle standing water first. Standing water can come from condensation, from plumbing leaks, from open crawl space vents, and a variety of other reasons. Once you isolate the cause of the problem, you can stop the initial problem, then pump out any standing water that’s still left in the crawl space.

Close Crawl Space Vents and Doors  

Next, you need to make sure crawl space vents and doors don’t allow in any air or water. Crawl space vents tend to be the biggest problem here because builders intend for them to allow in air, but if you have an ill-fitting crawl space door that opens to the outside, that can also allow in air, water, pests, and anything else you don’t want.

There are easy ways to close crawl space vents that don’t require you to do anything extremely significant. A JES crawl space repair expert can give you more information on sealing crawl space vents. If you’re having an issue with your crawl space door or you’ve never thought about your crawl space door before, you may also want to put some time and money into fixing it.

Put Down a Vapor Barrier  

Your next step should be to put down a vapor barrier. A vapor barrier does exactly what it sounds like: It separates your crawl space from anything that could cause water vapor to accumulate in the crawl space. An expert can install a vapor barrier in a dirt crawl space to make sure the moisture from the dirt doesn’t go into the air, causing extremely high levels of humidity.

However, this isn’t the only thing a vapor barrier does. It also forms a simple, clean barrier for any experts who need to inspect your crawl space for any reason. Make sure you invest in a high-quality vapor barrier instead of just opting for the cheapest one. JES only uses the 20-mil CrawlSeal™ vapor barrier because it ensures the highest levels of safety and security.

Install a Dehumidifier  

Even after you’ve encapsulated your crawl space, you might still have some humidity problems. For example, you may live in a high-humidity area, which can lead to a crawl space that’s more humid than you might like. An energy-efficient dehumidifier may be the right answer to these problems. When you use a JES dehumidifier, you can keep your crawl space at the right humidity level no matter what the humidity level is right now.

Dehumidifiers should never be your first step because you should always try to tackle the cause of the humidity concerns at their root. However, that doesn’t mean dehumidifiers are useless. The truth is exactly the opposite. It’s much better for you to choose a dehumidifier if you’ve already handled the cause of many of your humidity concerns, but there are certain issues you aren’t able to handle that only a dehumidifier can really help with.

Getting Your Start with a Better Crawl Space

There are many issues that can arise if you have high crawl space humidity. From mold and mildew to pest infestations and even enhanced allergic reactions, you can end up with a lot of problems if you choose not to tackle your crawl space humidity issues. Especially if you’re having problem signs of crawl space humidity, you need to look for help as soon as possible.

However, many people don’t really know what they can do to make their crawl space healthier. In fact, a lot of people just assume their crawl space will either be healthy or unhealthy, and there’s really no way for them to make any difference in the healthfulness of their crawl space. You’ll be happy to know there is something you can do. You just have to put in the time, energy, and money to do so.

A crawl space repair expert will be able to look through your crawl space, find any potential problems, and let you know more about a solution. Schedule a free inspection with a JES crawl space repair expert to learn more. An expert can let you know more about the best way to proceed when you have high crawl space humidity, or they can let you know you’re not struggling with high crawl space humidity in the first place.

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