According to the United States Environmental Protection Agency (1), you should keep relative humidity (RH) below 60% to stop mold from growing in your crawl space. So it is best to set your crawl space dehumidifier to at least 55% energy efficient, or even 50% if you can afford to run it for longer and have hardwood flooring.
It’s also best to never let humidity levels in your crawl space below 30%. But this probably won’t be a problem unless you live in the desert!
When humidity levels are below 30%, it can cause any structural wood to dry out. If wood gets too dry, it can rot.
The dehumidifier measures humidity at the machine. But what about far from the device? If the dehumidifier is set at 55%. All the rooms will be 55%. I think no. I guess some places might still have problems. Where metal is, Behind things, Underthings, Where some leaks… Or something. So maybe 50% is safe.
How to Detect Dampness in Your Crawl space
To check if your setting is working… Use this tool To check for damp areas. Thermal image camera (link). You can use the Android/iOS app, but I’m not sure how accurate it is.
When somewhere is wet. It is colder. Dampness in the crawl space might not only be from high humidity. It could be leaking.
Wait a little time after you have set your dehumidifier. Then check if it is working by using damp detecting tools. Or just check regularly that no mold is growing.
Dangers of Moisture in the Crawl Space
If you notice any signs of excess moisture or humidity level in your crawl space, be sure to take corrective action right away. Otherwise, you could end up with expensive and extensive damage to your home.
For a crawl space under your home, it’s essential to keep it dry. Moisture in the crawl space can cause several problems, including:
Mold and Mildew Growth
Mold growth, indoor air quality, dust mites, and mildew can cause several health problems, including asthma, allergies, and respiratory problems. They can also damage your home’s structure and furnishings.
Another danger in the crawl space is wood rot. Wood rot can cause the supports in your home’s foundation to weaken and even collapse. This can lead to extensive damage to your home and even injuries or fatalities.
Rodent and Insect Infestations
In the crawl space is the risk of rodent and insect infestations. These pests can cause problems, including damage to your home’s structure, the spread of disease, and even injuries.
Damage to Insulation and Wiring
It can damage insulation and wiring. This can lead to higher energy bills and create a potential fire hazard.
Rust and Corrosion
Finally, moisture in the crawl spaces can also cause rust and corrosion. This can damage your home’s plumbing and electrical systems, as well as its fixtures and appliances.
Be sure to take corrective action if you notice any moisture in your crawl space. Maintaining a safe and healthy home for you and your family is important.
How to Maintain the Ideal Relative Humidity in Your Crawl Space?
Like many homeowners, you probably have no idea what the humidity level in your crawl space should be. And if you’re unsure, that’s okay – because I’ll tell you!
Your crawl space’s relative humidity should be between 50 and 55%. This range is ideal because it helps protect your home against moisture damage while preventing mildew and indoor air quality mold growth.
So, how do you maintain the ideal humidity rises in your crawl space? Here are a few tips:
Install a Dehumidifier
A dehumidifier is a great way to control the humidity rises in your crawl space. If you don’t have one already, consider investing in one.
Seal any Cracks or Openings
Cracks and openings can allow moisture to enter your crawl space, leading to water damage and mold growth. Sealing these openings is a quick and easy way to help keep the high humidity level down.
Ventilate your Crawl Space
Ventilation is another crucial component of maintaining the ideal humidity in your crawl space. Ensure adequate ventilation so outside air can flow freely in and out of the area.
Monitor the Crawl Space Humidity Level
Checking the relative humidity level in your crawl space is an excellent way to ensure that it stays within the ideal range. If it isn’t, take steps to adjust it.
You can buy a thermometer or hygrometer to check indoor relative humidity (RH) and temperature together. Otherwise, you could end up with expensive and extensive damage to your home.
Crawl space encapsulation
Encapsulating crawl spaces involves installing a vapor barrier that prevents moisture from entering.
Following these tips, you can keep the low humidity levels in your crawl space healthy and protect your home.
The Bottom Line
Moisture in the crawl space can lead to several dangers, including structural damage, pest infestations, and health problems.
My name is Theresa Clark. I am an engineer and air quality specialist.