Avoid a moldy crawl space that could impact the air quality inside your home
How Mold Affects Your Crawl Space & Your Home
Crawl space mold and rot is a housing epidemic across the United States and Canada 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, damage, and humidity. Installation of this kind of system usually takes between one to three days to complete, depending on the size of the crawl space.
What Causes Crawl Space Mold?
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 °-60 ° Fahrenheit all year long. Practically speaking, mold spores are everywhere -- no matter how clean your home is.
To begin growing in your home, mold needs the following:
- A relative humidity level of at least 60%
- Temperatures at 40°F or higher
- Organic material to use as food
For rot and mold to grow on wood, the wood needs to have a moisture content of 20-29% or higher. If your home meets all of these requirements (many do), then you have mold growing in, and damaging, your home.
Mold & Moisture Sources In Your Crawl Space
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.
Mold can also grow when there's adequate moisture in the air, in the form of humidity. This moisture commonly enters a crawl space as water vapor passing through the soil or concrete. In this case, concrete will wick water and through the ground and releases it into the air.
One of the most common and avoidable reasons for crawl space mold and rot, however, is crawl space vents. In the summer, these open vents let in summer air, which is often loaded with humidity. As the air enters the crawl space, it quickly cools in this dark space. As air cools, it loses some of its ability to hold moisture, and the excess moisture is dropped on surfaces in your crawl space as condensation.
Over time, this condensation will saturate the wood in your crawl space--and mold will grow.
Still Believe Crawl Space Vents Work?
Ask yourself these questions:
Are my crawl space vents drying my home when it's rainy, foggy, or damp outside? If crawl space vents work, why is my vented crawl space damp and rotting? What is that costing me? Will my open crawl space vents keep out termites, ants, mice, and other pests?
Signs Of Crawl Space Mold Problems
Signs of crawl space mold are often evident without having to enter the crawl space at all. Because air moves upwards in a home as it's heated, a vacuum is created that will pull air up through the crawl space through a process known as the "stack effect". If your crawl space has mold, you will be able to tell -- your house will smell musty, and you may even begin to feel and/or display symptoms of mold and dust mite allergies.
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 will collapse inwards.
In the crawl space itself, 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.
Types Of Mold In Crawl Spaces
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 to 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.
One other variety of wood-damaging fungi is dry rot, also known as brown rot and cubical rot. As displayed in the photo above, wood damage from this kind of rot is shown as deteriorating the wood into small squares or rectangles. Often mistaken for termite damage because of its appearance, this is an extremely damaging type of fungi.
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!
Preventing & Eliminating Crawl Space Mold
Traditional methods of mold removal, such as bleach and water, will not provide a long-term solution for mold removal. These methods do not address rot damage or humidity issues.
Mold will begin growing again in 24-48 hours if the mold-growing environment is not changed. And dormant fungi can reactivate when dry, infected wood becomes wet again.
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.