Crawl Space Moisture Control

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Crawl Space Moisture Control is generally one of the primary focuses of any work done in a crawl space. Many other things are important too. This includes insulation, pest management and proper HVAC, plumbing and electrical work. However, most of these things are generally properly addressed during construction and with ongoing maintenance. Unfortunately, crawl spaces are often neglected over the years and often lack sufficient attention during initial construction as well.

If you are reading this page, it is likely that you are searching for a solution to control your crawl space moisture. You’ve come to the right place. Solving moisture in the crawl space is the primary goal of ATMOX products. This is our niche and expertise – ATMOX products have been part of solutions for over 25 years.

Let’s look at what you should evaluate and why a healthy crawl space is so important.

Use drying options to protect the foundation of your home.

Why Crawl Space Moisture Is An Issue

Crawl space moisture is a common concern in many, many homes. And, it should be. Unfortunately, unaddressed moisture can lead to a whole new set of issues that you want to avoid.

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ATMOX Picture of Mold Growth on Wood
ATMOX Picture of Pests in Crawl Space
ATMOX Picture of Wood Rot

What Causes Crawl Space Moisture

There are many contributing factors that lead to crawl space moisture problems. It’s usually a combination of building construction and environmental issues not working well together. Traditionally, vented crawl spaces often suffer from low clearance, trapped air in sections or corners, and wet air getting in from underneath decks and porches. Furthermore, all dirt crawl spaces will typically have moisture coming up from the ground. Outside hot, humid air can also bring moisture into the crawl space in some cases.

One of the biggest issues in a crawl space can be water intrusion. A plumbing leak is easy to find and fix. However, water coming in periodically or only under certain weather storms can be harder to identify and correct.

Moisture vs Water

Water and moisture are not the same problem, although they can be very connected. You cannot begin crawl space moisture control until you address water intrusion though proper drainage or waterproofing. Where there is water, there will be moisture in the air. At the same time, when there is too much moisture in the air, it can lead to condensation and show up as water.

You can read more about “What do about water in the crawl space?” in a recent blog post. It cannot be emphasized enough that water intrusion and drainage issues must be addresses for a healthy crawl space.

What Is The Goal For Crawl Space Moisture Control?

Think about why you care about crawl space moisture control. Ultimately, you are probably trying to protect two things: (1) Your family and their health; and (2) Your home and its structure.


Humidity is a measurement of the moisture in air at a given temperature. Relative humidity can bounce around with temperature changes, but it is a good indicator of overall crawl space moisture conditions. When humidity gets too high, it can affect the overall air quality of the crawl space and also the home. Air quality can in turn affect your overall health.

Humidity levels inside your conditioned home should be lower for a more comfortable living environment. You are probably not living in your crawl space, but you still want to maintain reasonable humidity ranges as a measurement of your overall conditions. As mentioned, humidity can vary by temperature, but most solutions will target a range of 55-65% humidity.

Wood Moisture

Target humidity levels should be around 55-65% for most crawl spaces.

Environmental Protection Agency (EPA)

Keeping humidity in check will ultimately affect the wood moisture content of the foundation structure. For example, keeping the wood moisture content in a healthy range is what you should focus on. The foundation of your home really shouldn’t be too dry or too wet. Just like in nature, wood moisture can go up and down, but you want to avoid the extremes. When wood moisture gets too high, it is prone to mold growth or even worse wood rot.

You can read more about “What is an acceptable crawl space wood moisture content?” in a blog post. Monitoring your wood moisture will give you the best indicator of actual conditions in the crawl space.

Ideal wood moisture content ranges from 10-16%

Forest Products Laboratory

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