Crawl Space Humidity Solutions

Installing humidity solutions in your crawl space is a great way to prevent mold and keep moisture from becoming a problem. The problem is everyone has a different opinion on how to control crawl space humidity.

Some say to add more fans or vents while others say to just install a vapor barrier.

We have even seen dehumidifiers installed without sealing the crawl space vents.

The first question you should be asking is, “What is my current crawl space humidity?”

Second, “What is the best humidity for my crawl space and the rest of my home?”

What is the Humidity Level of My Crawl Space

I have seen contractors and homeowners go by how a crawl space feels or looks to determine humidity. I understand some crawl spaces are so wet you can see moisture, but many are not, and high humidity is hard to detect. Visible moisture on the ducts, floor insulation, or ground is a great indicator of a crawl space needing a humidity solution. But what if you don’t see water? What if the dirt is bone dry?

Get a Humidity Reader

The only way to accurately detect humidity is to use a humidity reader. Humidity readers can be handheld or permanently installed devices that will tell you what the relative humidity is in your crawl space. Normally pros and DIYers like the handheld devices, while homeowners not interested in going in the crawl space choose humidity readers that are installed permanently.

Learn more about a great handheld portable humidity reader. A great option for a permanently installed humidity reader is the Govee Wifi Thermometer Hygrometer.

What is the Best Humidity Level?

Check out Crawl Space Ninja’s recommended humidity level for crawl spaces.

Vapor Barrier is Humidity Solution #1

A crawl space will suffer from high humidity without a properly installed vapor barrier. The vapor barrier is not the humidity solution, it is a part of controlling humidity. We see many times home inspectors recommend a vapor barrier-only approach to crawl space humidity. Unfortunately, the crawl space vapor barrier is rarely, if ever, a 100% fix to high humidity.

Dehumidifier is Humidity Solution #2

The vapor barrier and dehumidifier work together to keep the crawl space humidity in check. A crawl space dehumidifier is not a stand-alone solution either.

We have installed dehumidifiers only in crawl spaces. Many times they cannot make a dent in lowering humidity without the assistance of the vapor barrier. The vapor barrier slows the evaporation of ground moisture so the dehumidifier has time to remove the excess humidity before it leaches into building materials.

Be sure to install them together for a better humidity solution in your crawl space.

Sealed Vents and Door is Humidity Solution #3

If the vapor barrier is installed and the dehumidifier is running but vents and doors are open, you are dehumidifying the neighborhood. I have seen crawl space doors with screens and a dehumidifier installed running as hard as it can in the crawl space.

I have also seen vents not air sealed with dehumidifiers installed. Make sure you take time to properly air seal and insulate doors and vents.

This will give you a more efficient humidity control solution.

Contact Crawl Space Ninja for Basement Waterproofing and Encapsulation

Please contact us to schedule your assessment to fix your crawl space, basement issue. 


Do you need help with mold removal, crawl space encapsulation, crawl space insulation, vapor barrier, waterproofing, foundation repair, basement waterproofing, or controlling humidity in your crawl space?

If you live in Georgia, Delaware, North Carolina, South Carolina, Tennessee, or Kentucky, Crawl Space Ninja can help!


Also, let us know in the comments below if you have an idea for a new blog topic.

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“This book is the Cadillac for crawl space information and Michael Church is your experienced driver. What can I say? It’s just an amazing read.” 5.0 out of 5 stars The real deal.

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