Crawlspace Mold: What You Should Know!

Crawlspace Mold: What You Should Know!

Mold In A Crawlspace and How To Deal With It!

Mold In A Crawlspace and How To Deal With It!
Mold In A Crawlspace and How To Deal With It!

Valor Mold has been serving the DC Metro area since 2006. One of the key reasons we are so busy: Virginia, Maryland, and the DC area are susceptible to high humidity!

Crawlspaces are the ideal environment for mold to thrive.

Most crawlspaces are dark, dirty, and humid. Bugs like to live in there. They’re vented to the outside air in the summer (and in the winter if you neglect to close your vents) which can be very humid.

Mold is a fungus that requires moisture, air, a food source, and moisture (high humidity) to grow and thrive.

Like plants, mold has cells. However, unlike a plant that has chlorophyll and able to makes it’s food through photosynthesis, mold can not feed without moisture.

Mold reproduces by releasing it’s spores, this is mold’s survival mechanism.

In addition to moisture, mold also requires the right temperature of 41 degrees fahrenheit up to 100 degrees fahrenheit.

The final ingredient mold needs to thrive is food: high cellulose materials such as paper and wood, drywall, wallpaper, carpet, ceiling tiles, dust, and dirt.

Now that you understand why mold grows in your crawlspace, the remainder of this article will list and explain why you have moisture in your crawlspace and what you can do to remove the mold and fix the moisture issues.

How To Measure The Relative Humidity Of Your Crawlspace?

How To Measure The Relative Humidity Of Your Crawlspace?
How To Measure The Relative Humidity Of Your Crawlspace?

The easiest way to determine the relative humidity of your crawlspace is to use a hygrometer or you could install a digital thermo-hygrometer with a remote sensor to track it.

If the relative humidity is greater than 50% this could cause moisture issues that leads to mold.

Mold will begin to grow at 50%, and will thrive when the humidity is greater than 70%.

The key to ensuring that your crawlspace does not become a source of mold is to figure out how to control the humidity.

Listed below are the top three reasons your crawlspace has high humidity.

#1 Water Accumulation

If your crawlspace has standing water, you probably have a drainage problem or a plumbing leak. This needs to be fixed immediately.

You do not want water to accumulate in your crawlspace because this will compound your potential mold problems, not to mention as mold grows it will impact the indoor air quality of your home and health.

#2 Moisture Evaporating from the Ground

When homes are built with crawl spaces, most builders neglect to cover the ground, meaning that the crawlspace is covered with dirt.

Dirt has moisture and as the moisture evaporates, it will increase the humidity in your crawlspace.

Unfortunately, this is a common problem. To prevent moisture from evaporating from the ground, the easiest solution is to cover it up with a vapor barrier during crawlspace encapsulation.

#3 Outdoor Air Coming in through Crawlspace Vents

The third reason your crawlspace could have moisture issues is through the vents.

When you bring outdoor air into the crawlspace, the relative humidity can increase.

Cool air cannot hold as much moisture as warm air, so the air that enters is now closer to its saturation point, referred to as the dew point.

It might be 60% relative humidity outside, relative to a temperature of 90 degrees fahrenheit, but when that air enters the crawlspace and cools down to 75 degrees fahrenheit, the relative humidity jumps up to 95%.

In the past, we were told that crawlspaces needed to be ventilated. Now, however, we are learning that crawlspaces need to be treated almost as if they were living spaces. In other words, areas that are in contact with your living space affect your living space.

Fixing Your Crawlspace Humidity and Mold Problems

Fixing Your Crawlspace Humidity and Mold Problems!
Fixing Your Crawlspace Humidity and Mold Problems!

If your crawlspace is vented and the relative humidity is high, you need to fix the problems. It is not as simple as installing a dehumidifier either.

If you have water accumulation, the source of the water must be addressed. If it is a plumbing issue, fix the leak. If the problem is caused by drainage, this must be fixed as well.

If the problem relates to moisture evaporating from the ground or outdoor air coming into your vents, this can be fixed with crawlspace encapsulation.

10 Steps To A Mold and Moisture Free Crawl Space!

10 Steps To A Mold and Moisture Free Crawl Space
10 Steps To A Mold and Moisture Free Crawl Space

Valor Mold are crawl space mold removal and encapsulation professionals.

We can help you dry out the dampest crawl spaces and turn them into drier, healthier foundations for your home that aren’t breeding grounds for mold spores.

Our crawl space solution is different then our competitors because we follow this 10 step procedure:

  1. Step 1: We level the dirt floor.
  2. Step 2: We seal off the crawl space vents with plastic covers specifically made for this purpose.
  3. Step 3: If your crawl space has ground water problems, we’ll make sure the ground slopes where we want the water to go, meaning we may have to physically re-slope the ground using picks and shovels (highly labor intensive, but worth it). Then we’ll dig a hole at the lowest point, put in an air-tight plastic liner and install the best sump pumps made by Zoeller.
  4. Step 4: Using expanding foam, we seal up the hundreds of small gaps that, unsealed, form a huge air leak. This one step differentiates Valor Mold from most of our competitors, who fail to implement this step because it’s dirty, labor intensive, and very uncomfortable work.
  5. Step 5: We install special insulation on the walls that is custom-made for crawl spaces.
  6. Step 6: We install reinforced 12 mil plastic to the walls with special screws, leaving a gap at the top to facilitate yearly termite inspections.
  7. Step 7: To allow water to drain easily towards the sump pump, we laying dimple board on the dirt floor.
  8. Step 8: We install a special reinforced 20 mil plastic over the dimple board. Both the dimple board and plastic are held in place with spikes driven into the ground.
  9. Step 9: We create one continuous moisture barrier in your crawl space using special tape to seal the plastic on the floor to the plastic on the walls.
  10. Step 10: The first nine steps should keep most of the moisture out of your crawl space. To ensure your crawl space remains dry, we also recommend the installation of a custom dehumidifier made for crawl spaces.

The end result is an energy efficient, healthy home.

Got Crawlspace Mold Questions?

If you are concerned about mold and humidity in your crawlspace, call 703-897-7121 or send us an e-mail. We look forward to serving you! 🙂


  • I had no idea that outside air could bring humidity to your crawl space and cause problems with it. It is important to remember that taking the time to do some research and consult with a professional can help you find the best way to care for your crawl space. My brother was talking about how he needed to encapsulate his crawl space, so I wanted to look into it to know if I needed to encapsulate mine.

  • It’s interesting to know that moisture issues in your crawlspace can be caused because of the vents. My mother noticed mold in her crawlspace, and we are looking for advice to fix it. I will let her know about the benefits of choosing a contractor to help her with that problem.

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