An illuminated crawl space with a vapor barrier installed on the ground at left and a dehumidifier to the right

Regarding crawl space encapsulation and dehumidification, there’s a lot of debate about when to use each option. Some say you should always encapsulate your crawl space, while others say you should only use dehumidification when necessary. 

So, which is the right choice for you?

This article will explore the issue of dehumidifying an encapsulated crawl space. We’ll also discuss the pros and cons of each approach and help you decide which is the best choice for your home.

So, let’s dive in!

When Should I Dehumidify vs. Encapsulate My Crawl Space?

Encapsulation and dehumidification should always be used in a crawl space. Encapsulation is a great way to keep moisture and pests at bay. However, if you live in an area with high humidity, you may still need to use a dehumidifier in your crawl space, even if it is encapsulated.

What Is Crawl Space Encapsulation and Dehumidification?

Encapsulation refers to the process of sealing off your crawl space from the outside environment. This condition is usually achieved with a vapor barrier, a heavy-duty plastic sheet covering the floor and walls of your crawl space. The idea is to prevent moisture, pests, and mold from entering your home.

Polythene is a common vapor barrier material used for crawl space encapsulation. It is available in various thicknesses, and you can choose the right one for your needs. For example, 6-mil polythene is a good choice for most homes, but you may need a tougher material if you live in an area with rodent issues.

A vapor barrier roll, staple gun, and some staples resting atop a piece of plywood

Most homeowners choose to hire a professional to install their vapor barrier, but it is possible to do it yourself. If you’re handy and have some experience with home improvement projects, you can probably handle the installation yourself. Just make sure you buy high-quality polythene and follow the instructions carefully.

If you’re interested in learning more about the costs that typically follow this type of project, read this guide.

Dehumidification, on the other hand, reduces the moisture in the air. You can achieve this reduction with a dehumidifier, a machine that removes water from the air. Dehumidifiers come in various sizes and can be used to dehumidify an entire home or just a tiny area like a crawl space.

Why You Need To Dehumidify Encapsulated Crawl Spaces

You might be wondering why you need to dehumidify an encapsulated crawl space. After all, if the area is sealed off from the outside world, shouldn’t it be naturally dry?

Even though your crawl space is sealed off, the air inside can still be humid. This condition is especially true if you live in an area with high humidity. The air in your crawl space can also become humid if there is a lot of moisture in the soil.

If the air in your crawl space is too humid, it can lead to mold growth. Mold loves damp, dark, and humid conditions, so it can thrive in an encapsulated crawl space. That’s why using a dehumidifier in your crawl space is essential, even if you have sealed it off from the outside world.

Dehumidifiers come in various sizes and capacities. Some are small and portable, while others are larger and more powerful. The size and power you need will depend on the size of your crawl space and the relative humidity in your area.

Most dehumidifiers have a humidistat, a device that measures the amount of moisture in the air. You can set the humidistat to the desired humidity level, and the dehumidifier will turn on and off as needed to maintain it.

Some dehumidifiers also have a built-in drain, which allows the water they collect to be drained directly into a floor drain or sump pump. This component can be a convenient feature, but it’s not necessary. You can also empty the water reservoir manually when it gets full.

A homeowner emptying the tray of a dehumidifier
Courtesy of AirConDirect

When To Combine Encapsulation With Dehumidification

Of course, you don’t necessarily need to choose between crawl space encapsulation and dehumidification. In many cases, it might make sense to combine the two approaches.

For example, if you live in an area with high humidity levels, you might want to encapsulate your crawl space to prevent moisture from entering. However, you will also need to use a dehumidifier to remove the humidity already in the air.

Similarly, if you don’t have a humidity problem, you might want to encapsulate your crawl space to prevent soil moisture from entering your home. However, you might not always need a dehumidifier as the vapor barrier is enough to keep the area relatively dry.

In general, it’s a good idea to use both crawl space encapsulation and dehumidification if you want to create a drier, more comfortable environment in your home. These two approaches can work together to keep the air in your home dry and free of mold and mildew.

The Pros and Cons of Encapsulation

Before encapsulating your crawl space, it’s important to understand the pros and cons of this approach.

Pro: Reduced Humidity Levels

One of the main benefits of crawl space encapsulation is that it can help reduce humidity levels in your home. By sealing off the crawl space, you can prevent outside air from entering and raising the humidity level. This can create a drier, more comfortable home environment.

Pro: Reduced Risk of Mold and Mildew

A picture of a corner of a room showing black mold growing on white walls and ceiling.

Crawl space encapsulation can reduce the risk of mold and mildew. As mentioned, mold loves damp, dark, and humid conditions. By sealing off the crawl space and reducing humidity levels, you can make it less hospitable for the fungi family. This condition can help keep your home in good shape for years to come.

Con: Might Not Be Enough on Its Own

One downside of crawl space encapsulation is that it might not be enough on its own to keep your home comfortable. In some cases, you might also need to use a dehumidifier to remove the moisture already in the air. As a result, the renovation bill can add up quickly.

Con: It Can Be Expensive

Another downside of crawl space encapsulation is that it can be expensive. Depending on the size of your crawl space and the materials used, encapsulating your crawl space can cost several thousand dollars.

If you’re interested in crawl space encapsulation, it’s crucial to weigh the pros and cons before going all in. 

This approach can be a great way to improve the comfort of your home in some cases. However, in other cases, it might not be necessary, or it might not be the most cost-effective option.

The Pros and Cons of Dehumidification

Like crawl space encapsulation, dehumidification has its own pros and cons.

Pro: Measurable Humidity Levels

One of the main benefits of dehumidification is that it can help you to achieve measurable humidity levels. This means that you can set the humidistat to the desired humidity level, and the dehumidifier will turn on and off as needed to maintain that level.

A dehumidifier model with a built-in humidistat
Courtesy of AirConDirect

Pro: Reduced Risk of Mold and Mildew

Another benefit of dehumidification is reducing the risk of mold and mildew. Removing moisture from the air can make your home less hospitable to these harmful organisms. As a result, you’ll be able to preserve your home’s structural stability (and resell value) for years to come.

Pro: Improved Air Quality

The third benefit of dehumidification is that it can improve air quality. In addition to reducing mold and mildew, removing moisture from the air can also reduce dust mites, pollen, and other allergens. This can create a healthier and more comfortable environment for everyone in your home.

Con: Requires Regular Maintenance

One downside of dehumidifiers is that they require regular maintenance. For example, you’ll need to empty the water reservoir regularly, and you might also need to clean the filter. So while you can do some of the processes, there will be some instances in which you’ll have to enlist a professional’s help, which can get costly.

A homeowner laying on his side inspects his crawl space with a flashlight

Con: Can Be Expensive To Run

Another downside of dehumidifiers is that they can be expensive to run. Depending on the size of your home and the humidity levels, it can cost a lot of money to operate a dehumidifier. As electricity becomes more expensive by the day, this is a consideration you’ll want to keep in mind.

Considerations When Setting Up a Dehumidifier in an Encapsulated Crawl Space

If you’re going to use a dehumidifier in an encapsulated crawl space, there are a few things you need to consider.

First, you must ensure that the unit is the right size for your space. If the dehumidifier is too small, it won’t be able to remove enough moisture from the air to make a difference. And if it’s too big, it will use more energy than necessary.

You also need to decide where to place it. The ideal location for a dehumidifier is near the center of the space so that it can evenly distribute the air.

We have seen people place the dehumidifier near an exterior wall to save space, but this is generally not a good idea. The device will have to work harder to distribute the air evenly, which might not be as effective.

Moreover, you must ensure that the dehumidifier has enough capacity for your space. A good rule of thumb is that you need one pint of accommodation for every 1,000 square feet (92.90 sq m) of space. So, if your crawl space is 1,500 square feet (139.35 sq m), you’ll need a dehumidifier with at least one and a half pints.

The Issue of Condensation

Condensation is one of the issues you must be aware of when using a dehumidifier in an encapsulated crawl space. If the air is too cold, water vapor will condense on your joists and walls instead of being removed by the dehumidifier.

This condition can create a severe problem because the water can cause mold and mildew to grow. It can also damage your insulation, and you might end up with a pest infestation.

To avoid the condensation issue, ensure that the air in the space is warm enough. The ideal temperature for a crawl space is between 55-60°F (12.77-15.55°C).

If the temperature in your crawl space is below 55°F (12.77°C), you can use a space heater to raise it. Just be sure to choose a space heater that’s safe for use in an enclosed space.

An illuminated crawl space with a vapor barrier installed on the ground

Other people use an electric fan to circulate the air and prevent condensation. This method can be effective, but it’s crucial to ensure that the space is adequately ventilated for this technique to work.

Conclusion

Crawl space encapsulation and dehumidification are two effective ways to improve the quality of your home’s air. If you have a crawl space, you should consider using one or both of these methods to improve the air quality in your home.

Just be sure to take the time to choose the right products and maintain them properly. Then, with a little effort, you can significantly improve the air quality in your home.

Sources

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