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3 Steps to Achieve Ideal Crawl Space Humidity Levels

control crawl space humidity

Outdoor humidity in Kansas City is always in flux. Summers are typically hot and humid, while winters are cold and dry. Such fluctuations in temperature and humidity have a huge impact on the home, especially the crawl space.  

If you are grappling with moisture management issues or wondering what humidity level is right for your crawl space, you are in the right place.

Here, we will look at the ideal humidity levels for the crawl space and finish by examining how best to maintain optimal humidity in this below-ground area of your home. 

What Is The Ideal Crawl Space Humidity Level?

The ideal humidity level for a crawl space typically ranges between 30% and 50%.

Maintaining humidity within this range helps prevent the growth of mold, mildew, and other moisture-related issues. It also discourages pests that are attracted to damp environments and helps preserve the structural integrity of your home.

Keeping crawl space humidity at these levels ensures a healthier, more stable environment under your home, which in turn, contributes to better air quality in the living spaces above.

How to Maintain Ideal Crawl Space Humidity

Here are three effective ways of maintaining the optimal humidity levels in your crawl space. 

1. Fix Cracks & Gaps in Crawl Space Walls 

Start by inspecting the crawl space foundation for cracks, gaps, or openings that could be letting in moisture from the outdoors.

Seal them to stop water from entering your crawl space. Plumbing leaks are also a major source of water in the crawl space, so look out for any plumbing leaks and have them repaired.  

2. Encapsulate the Crawl Space 

As long as the crawl space stays exposed or open, it will remain a hotbed for moisture and other unpleasant things.

You can avoid such a scenario by encapsulating it. Encapsulation involves installing a 20-mil vapor barrier system over the crawl space walls and floor to keep water, moisture, and pests out.  

Once the vapor barrier is installed, the crawl space stays clean, dry, free of mold, and resists pests. 

encapsulated crawl space

3. Install a Dehumidifier 

Get a self-draining dehumidifier and have it installed in the crawl space to rid the air of excess moisture.

When moisture levels spike, it kicks in and starts drying out the air.

The dehumidifier turns off automatically as soon as moisture levels go down. This feature helps you maintain steady humidity levels in the crawl space.

It also makes your AC system energy efficient. 

dehumidifier installed inside a crawl space

Can Crawl Space Humidity Be Too Low?  

While you cannot really over-dry a crawl space, a drastic reduction will impact the health of your crawl space and could cause problems.

All buildings require some level of moisture to operate effectively. Drying out your crawl space could result in a drop in the wood’s moisture content, which causes wooden beams or supports to dry out. This isn’t good.

Your wooden structures may start showing signs of stress due to dehydration. Gaps may form between trim joints and hardwood flooring.  

Wood shrinkage may also occur once the moisture content in the crawl space drops below 25% to 30%.

Anything above this range, your wood remains dimensionally stable. For you to maintain an ideal crawl space environment, you need to maintain a relative humidity between 30% to 50%. This will preserve wood moisture yet remain below the threshold for mold growth and wood rot. 

Need Help? FRS Has Expert Solutions

If you have a crawl space and are struggling with moisture buildup, contact the experts at Foundation Recovery Systems for a free crawl space inspection and quote.

Our team in Kansas City, Missouri, will help you identify the sources of moisture and recommend the best solutions to bring the moisture under control. 

Leah Leitow

Leah Leitow

Content Writer

Leah is a Content Writer for Groundworks with nearly ten years of experience working in the foundation repair industry. Her experience ranges from working with homeowners to find the right solution to training inspectors and staff. In her background as a Michigan journalist, she gained invaluable insight into people's lives throughout our state. Leah lives in metro Detroit with her husband and two sons.

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