Moldy Wood

When mold and rot are allowed to grow in a crawl space, they lead to health and structural problems that affect the entire home.

Rot and mold in crawl spaces is a housing epidemic that, with a small investment, can be easily avoided.

Installing a crawl space vapor barrier system in your home will protect it from most of the common causes of rot, mold, damage, and humidity. Installation of this kind of system usually takes less than a day to complete.

At Foundation Recovery Systems, we have been dedicated to helping homeowners resolve their issues since 1992. We offer free crawl space repair inspections throughout all of central Missouri and Eastern Kansas, including Kansas City, Columbia, Moberly, and Springfield. Contact us today to schedule your appointment and prevent mold from growing in your crawl space.


Crawl space vents allow humidity, rainwater, and pests into your home.

Crawl spaces are generally dark, moist places. Mold loves dark spaces, unseasoned lumber, and high humidity levels. Because your crawl space is warmed by your home above it and the natural warmth of the ground below, it stays at about 50 °to 60 ° Fahrenheit all year long — an ideal temperature for mold to grow.


Even in the case of dry rot, there will need to be a source of water nearby. This water can enter a crawl space through poorly designed downspouts or grading, through groundwater flooding, and/or through plumbing leaks. Moisture can also enter a crawl space as water vapor passing through soil or concrete, creating a humid environment that can also allow mold to grow.

Crawl space vents are one of the most common reasons for mold and rot growth and can be easily avoided. These vents allow air to flow into your crawl space, so in the humid summer months, it brings in that humid air and leaves your crawl space susceptible to mold growth. Over time, this moisture can turn into condensation, will saturate the wood in your crawl space, and mold will grow.


Ask yourself these questions: 

  1. Are my crawl space vents drying my home when it’s rainy, foggy, or damp outside?
  2. If crawl space vents work, why is my vented crawl space damp and rotting?
  3. When cold winter air is blowing through my vents in the winter, what’s happening to my furnace, hot air ducts, water heater, and hot water pipes? What is that costing me?
  4. Will my open crawl space vents keep out termites, ants, mice, and other pests?


Surface mold creates cosmetic discoloration only and can be cleaned off. Decay fungi (above) darkens and shrinks the wood while causing structural damage.

Signs of mold in a crawl space are often evident without having to enter the crawl space at all. The air in your crawl space circulates and can pull up through the crawl space ceiling, impacting the air quality inside your home. This is known as the “stack effect.” If you start to smell musty odors inside your home or experience more allergic symptoms, it may be a sign of mold issues in your crawl space.

Additionally, as crawl spaces begin to rot and decay, the floor above will begin to sag, buckle, or become uneven. Doors may jam, mold may grow on first-floor carpeting, and, in the long run, the floor itself could actually collapse inwards.

In the crawl space itself, some mold warning signs include visible mold growth, musty odors, and discoloration and/or signs of water damage on the wood.

White, powdery substances on concrete walls are not likely to be mold itself, but it’s indicative of moisture passing through the walls and creating a humid environment. If there are moldy, musty odors, then mold will be somewhere.


Mold and rot fungi can be classified in two ways: what grows on the surface and what grows within the wood itself.

Surface mold fungi will cause cosmetic discoloration only, and it will not significantly damage the structural strength of the wood. This mold can simply be cleaned off the surface.

Decay fungi will darken and shrink the wood, leading to severe structural damage of the wood and the eventual crumbling and decomposition of the wood overall. Wood with decay fungi looks soggy and spongy. This cannot simply be cleaned off, and replacement of damaged wood may be necessary.

Dry rot, as displayed in the image above, is another type of wood-damaging fungi that causes the wood to deteriorate and become weak, which leaves you with a structural integrity issue within your crawl space. Dry rot damage often resembles termite damage and is very damaging to the wood.

One other unique feature of dry rot is its ability to pull water from far-away water sources through “rhizomorphs.” Rhizomorphs can extend for as much as thirty feet, stretching across brick, concrete, mortar, and similar materials. In the case of Serpula lacrymans, water has been transported as much as three stories upwards!


There are many other methods of dealing with mold, such as bleach and water, but these are only short-term solutions and do not provide long-term protection. The reason the mold grew in the first place is because of humidity issues, so that is the problem that needs to be addressed.

Mold will begin growing again in as little as 24-48 hours if the mold-growing environment is not changed. Dormant fungi can reactivate when dry, and infected wood becomes wet again.


Some major cases of crawl space humidity stem from where your dryer vents end. If your dryer is sending air into your crawl space, it’s also sending a ton of humidity with it! This humidity is exactly what mold, rot, and mildew need to start thriving in your home. If your dryer is sending air into your crawl space, fix the problem right away!

The solution to crawl space mold and moisture is to seal the crawl space vents, install a plastic liner on the walls and floors, and dry the space with a self-draining dehumidifier. Otherwise, any repairs and mold remediation steps you take are a temporary fix only.

At Foundation Recovery Systems, we not only fix your issue, but we take the time to communicate with each of our customers and educate them every step of the way. We want to arm you with enough knowledge to know how to avoid potential issues in the future and to know when to call in the experts.

We offer free crawl space repair inspections all of central Missouri and Eastern Kansas, including Kansas City, Columbia, Moberly, and Springfield.

Contact us for a Free Inspection!