Crawl Space Mold

Don’t let crawl space mold take over your home and threaten your families health.

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When mold and rot are allowed to grow in crawl spaces, they lead to health and structural problems that will affect the entire 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 less than a day to complete.

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.

Open crawl space vents allowing in humidity and water in Brainerd

To begin growing in your home, mold needs the following:

  • Oxygen
  • 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.

To Sum It Up: As Glenn Fellman, executive director of the Indoor Air Quality Association states, “If you are reacting to a problem because somebody’s been sick, you’ve waited way too long to address indoor air quality.” The best way to protect yourself is to prevent the mold or dust mite problem before it begins!

Mold & Dust Mite Health Facts

  • Dust Mites & Mold Eat Organic Materials: That means any organic material at all. Dust, fabric, fiberglass resins and dyes, drywall, wallpaper, glue, paint, wood, or anything else is enough to keep it growing. As for dust mites, 1,000 of these critters can live in a single gram of dust, each one creating 20 waste pellets per day.
  • Mold Can Live In The Cold: Ever see mold in a refrigerator? Research shows that as long as the temperature is above 40 °F (4 °C), mold can grow and spread.
  • Mold & Dust Mites Grow Fast: Mold can begin to grow in a home in as little as 24-48 hours, with a billion mold spores growing on a single foot of drywall. A single female dust mite can lay upwards of 250 eggs in its three-month lifespan.
  • Mold Leads To Insurance Woes: Due to tens of thousands of mold-related lawsuits being filed, most general liability and property insurance companies now exclude mold insurance from their policies.
  • Mold Destroys Your Home: Professional Builder Magazine warns that mold will dramatically lower the value of your home. A home worth $250,000 can easily have $100,000 in mold problems. Mold can even lead to structural damage to your home!
  • Mold Spores Can Damage Your Health: Mold spore exposure can occur through inhalation, ingestion, and skin contact. Mold and dust mite waste is connected to allergies, asthma, and other breathing issues. Even dead mold spores can be damaging to your health.
  • Dust Mite Waste Is Highly Allergenic: 90% of patients show dermal reactivity to dust mite waste and 10% of the general population is also sensitive. Dust mite waste makes up 80-90% of the allergic component of house dust, containing 15 potent allergens that sensitize and trigger allergic reactions. In fact, American Family Physician states that “controlling dust mites is the most important thing you can do in your house to make your asthma and allergies better.”
  • Mold & Dust Mites Are Sneaky: Mold can grow in fiberglass insulation, behind drywall panels, and behind wallpaper. Dust mites can live in furniture, cloth, and pillows. Just because you don’t see a problem does not mean that one does not exist.

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?
  • 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?
  • 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 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.

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!

More About Dry Rot Damage

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.

Innovative Basement Authority offers free crawl space repair quotes in Minnesota, North Dakota and Eastern Montana, including Bismarck, Saint Cloud, Eden Prairie, Grand Forks, Minot, Anoka, Andover and many areas nearby. Contact us today to get started!

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