How to Get Rid of Mold in Your Crawl Space

If you’ve got mold in your crawl space, you aren’t alone! A mold issue in crawl spaces is one of the most common problems in homes with that foundation type. 

What you may not realize is that mold in your crawl space affects the air quality throughout your home. At the same time, mold is an indication that water is present and has been for some time, so addressing your mold issues early will help you avoid costly repairs due to water damage later on.

What is a Crawl Space?

Crawl spaces are a type of foundation where the ground floor of a home is raised 1-3 feet off of the ground. This foundation type is used in areas where the freeze-thaw cycle poses risks to other foundation types such as slab-on-grade or basements, or where significant moisture may affect your foundation over time. Crawl spaces may also be used in locations with sandy soil, which is common in the coastal areas of the United States.

Why Does Mold Form in Crawl Spaces?

Before we outline how to get rid of mold in crawl space, it’s helpful to understand why mold forms in this area in the first place. 

The most important thing to understand is that mold can’t form without water. If mold is present, that means water is also present. For mold to form on common building materials takes time, which means that any mold in your crawl space is preceded by a time where the wood or insulation in that area is saturated and kept wet. This can occur from a consistently high humidity level where moisture buildup is frequent in the air. 

Mold is specifically a problem in vented crawl spaces. In a vented crawl space, small vents are placed along the perimeter of the crawl space to facilitate passive air circulation with the outside. During cooler months this works adequately, but during warmer months it creates a moisture problem. 

In warmer months, the ground and air in a crawl space are a few degrees cooler than the outside air. As that warmer outside air enters the crawl space it begins to cool. Once that warm air hits the dew point it will form condensation. In most vented crawl spaces this condensation will form on the underside of the subfloor, on the floor joists and insulation placed there. As the moisture along the floor joists and insulation persists, it will begin to form mold. 

Why is Mold in Your Crawl Space Bad?

No one wants mold in their home, but having mold in crawl space can be especially bad. The simple reason for this is because the air quality in your crawl space impacts the air quality throughout your home. As the air in your crawl space rises it passes up into the conditioned portion of your home where it is circulated. So, while you might only have mold in one part of your crawl space, that mold is affecting the air quality throughout your home.

Mold in your crawl space is also bad because it is an indication that there is water present. The water that causes mold to form in your crawl space will seep upward into your subfloor and insulation. Your insulation will begin to perform poorly, impacting the energy efficiency of your home. At the same time, that moisture build up in your subfloor may cause your flooring to buckle or warp, leading to costly repairs when the time comes to replace your crawl space insulation.

How to Address a Moldy Crawl Space

Addressing a mold issue in your crawl space can be difficult, but it isn’t impossible. Here’s a broad breakdown of the process:

  • Identify whether any mold is present, where it is, and the extent of the water damage.
  • Remove any existing insulation.
  • Remediate any mold and water damage.
  • Rebuild the subfloor and replace flooring if necessary.
  • Install new insulation and implement proper moisture mitigation strategies (such as a vapor barrier or converting a vented crawl space to an unvented crawl space).

Unfortunately, there’s no one-size-fits-all crawl space mold remover. DIY solutions to crawl space mold tend to ignore the most important aspect: how that mold formed in the first place. Some DIY solutions may only be able to get rid of some visible mold as well. However, we understand that mold is an issue you don’t want to keep dealing with. That is why we get to the root of your moisture problem to know exactly where the mold is coming from and how to deal with it. 

Addressing mold in your crawl space requires an understanding of how moisture forms in crawl spaces and what techniques can be used to eliminate the impact of that moisture. Simply removing your old insulation and replacing it will only reset the clock and will result in significant repairs down the road if the root cause of moisture in your crawl space isn’t addressed.

Because of this, we strongly recommend using the services of professionals familiar with crawl spaces. Our team at Attic Construction has decades of experience working with crawl spaces, so we understand exactly what it takes to return your crawl space to peak health.

Additionally, before continuing with your insulation process, it may be essential to use a crawl space cleaning service. Especially if you are dealing with a mold problem, it is important to undergo a crawl space mold removal process before moving forward. This can help to prevent air quality issues in your home or repairs down the road. 

Closing Thoughts

Mold in your crawl space is a serious issue that can affect the air quality throughout your home. A moldy crawl space is also a wet crawl space, which means that the energy efficiency and durability of your home will be degraded as well. Not only does it lead to a loss in energy efficiency, but a mildew or musty odor can also form in addition to your decreased air quality and nobody wants that!

If you have mold in your crawl space, leave it to the professionals at Attic Construction! We start every project with a professional inspection, so you’ll know exactly what the current state of your crawl space is and what it will take to address any issues we find. If you have mold in your crawl space, don’t wait to address it, as that can lead to costly repairs down the road and impact your health in the meantime. Let us help you with your crawl space mold removal so you don’t have to!

Curious about our crawl space services or ready to schedule an inspection? Contact Attic Construction today!


  1. “Guide to Closing and Conditioning Ventilated Crawlspaces”
  2. “Crawlspace Insulation”
  3. “Crawlspaces – Either In or Out”


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