White Mold In Crawl Space: Causes & Solutions

The growth of white mold in crawl space is a common residential problem. It is often a result of damp surfaces after rainy seasons, plumbing leaks, or poor dehumidification. But sometimes, people tend to ignore white mold considering it less harmful than black mold. However, white mold is also capable of causing many negative effects and health issues. Find out more about this white fungus in crawl space and how to get rid of it.

white mold in crawl space

What Are White Mold, Efflorescence, and Mildew?

White mold is quite similar to mildew and efflorescence. Mold has a stronger odor which is more noticeable than that of mildew. Mildew usually grows only on plants and in outdoor areas. Both mildew and efflorescence can develop into mold if left untreated. Efflorescence can be either white, brown, or yellow, which is the main difference from white mold. Efflorescence is also odorless and dissolves in water, unlike white mold. Among the three types, white mold and efflorescence are more commonly confused than mold and mildew.

How to Tell the Difference Between White Mold and Efflorescence?

Efflorescence has a crystalline structure than often grows on concrete surfaces. It occurs when water moves through masonry surfaces and brings salts to the surface. As the water evaporates, the salty structure remains on the surface, which is quite similar to mold in appearance. However, this is quite harmless than mold and mildew. The location of occurrence of the two types is the best way to identify them separately. Mold occurs mostly on organic surfaces, sheetrock, or wood. 

What Are the Signs of White Mold Growth?

Identifying the growth of white mold in crawl space at its initial stage can prevent it from spreading across the house. So, you can protect the structural integrity of the house and also the health of your family members. The crawl space may be under mold infestation if there is a high level of humidity and dampness in the area. You will sense a musty odor caused by the presence of mold. Since mold grows so fast, it is important to follow the steps of mold removal as soon as you detect it.

Direct mold sampling is the most straightforward process to detect white mold. It is a test where a small amount of mold is collected and tested to determine whether it is white mold. This is important because different types of fungi require different treatments. The crawl space professionals obtain these samples as swab/ bulk and tape lifts. Then they will send these samples to a laboratory for analysis.

Is White Mold in Crawl Space Dangerous?

White mold in crawl space can be dangerous due to various reasons. It shows higher levels of humidity and a lack of ventilation that can affect the building. Although it may not cause direct structural damage to wood, mold will be followed by wood-decay fungi types that rot the wood. This happens if the moisture levels stay high for long enough to destroy the wood. 

Since the elevated floors are not perfectly sealed, mold spores can move up the air into the house. This is unavoidable unless you remove mold and mildew from the crawl space. The mold spores can cause different types of allergies at various levels. The reactions include sneezing, coughing, sore throat, watery eyes, itchy skin, dizziness, shortness of breath, and even asthma.

Intense Health Problems Due to Mold

There are various types of reactions to mold depending on how it affects the body. The following are some of the most intense allergic conditions.

  • Mold-induced asthma: The spores could trigger asthma conditions in people who are allergic to mold. They may have to use inhalers or anti-inflammatory drugs to control the discomfort. If you have any breathing disorders or asthmatic conditions, always have an emergency plan for a sudden attack, especially if you have mold somewhere in the house. 
  • Allergic fungal sinusitis: This is an inflammatory condition caused as a response to fungus in the sinuses. Anyone with these problems is likely to have nasal polyps or asthma as well.
  • Hypersensitivity pneumonitis: This is a rare condition caused by direct exposure to airborne particles such as mold spores or dust. The lungs inflame as they come into contact with spores.

How to Check the Mold Condition?

Before you remove or treat mold, it is necessary to check whether it is an old issue or a new growth. This helps to determine how you need to address the situation. Since mold doesn’t go away with time, it is hard to detect the time of growth. Even a mold infestation of over 10 years can look the same as that of two months. So, you can determine the age of mold by checking its moisture content.

Test the mold on the floor and beams using a moisture meter. If the moisture level is greater than 20%, it needs further examination. Check whether the moisture affects a specific region in the crawl space or if it is all over the subfloor. If there is only one area, then it is most likely to be a plumbing issue. If the moisture level is less than 20%, it indicates that the mold is an old problem. The mold has grown due to previous water damage in the building. The mold could then keep growing due to the mild humidity in the air and favorable conditions of the wood. If the crawl space subfloor is insulated and still has mold, it might be mold from the original construction. New mold cannot go beyond plastic encapsulation or any insulation. The mold could have been due to moisture during construction. 

How Do I Treat White Mold in My Crawl Space?

Getting rid of serious mold infestation in the crawl space can be a tough task. It is not limited to scrubbing and cleaning the wood in a confined space. Crawl space specialists may carry out HEPA vacuuming and spraying to eliminate mold. These remedies are not cheap and could cost you thousands of dollars. There are various natural and chemical biocides that kill mold. But it can come again if there is too much moisture and dampness in the area. So, here are some tips to limit the growth of mold.

  • Seal up the whole space using polythene barriers and install vent covers.
  • Fix cracks on the walls to prevent moisture from coming in.
  • Remove organic materials, including cardboard, clothing, and newspapers, that could facilitate the growth of mold.
  • Install a crawl space dehumidifier regardless of having encapsulation or not.
  • Replace any decaying wood in the crawl space so that the mold cannot feed on them.
  • Install a suitable drainage system, such as a French drain, to minimize the effect of water.
  • Fix any pipe leaks and other ways in which water can pool around the basement.

Frequently Asked Questions

Can Color Be Used to Identify the Type of Mold?

You cannot determine the exact type of mold based only on the color. But you can use the color to eliminate some possible choices from the list. You need mold testing to identify the specific type. Many types of mold come in various colors ranging from black, brown, and green to white. So even the simple white mold has various types, such as Penicillium, Aspergillus, and Cladosporium. Sometimes, the white powder in the crawl space could be in the development stage, which means that it will change color after some time. So, the best way to identify the type of mold is through lab testing.

Is White Mold Worse Than Black Mold?

Black mold is a highly toxic mold that causes extreme health risks. White mold, however, imposes fewer health risks when compared to black mold. Nonetheless, it may cause allergies in people who are highly sensitive to mold. The powdery, flakey, white mold could even change color or remain white, making it difficult to identify. 

Do Dehumidifiers Help With Mold?

Dehumidifiers reduce the moisture levels in the air, making the area less welcoming to mold growth. This reduces the chances of mold growth but will not kill the mold. Air purifiers remove mold spores from the air, which prevents the spread of mold to new locations.

How Do I Get My House Tested for Mold?

Mold growth is usually easy to identify as it grows as an infestation that ruins the surface. But sometimes, if the area infected is small, it may be difficult to identify whether it is mold or something else. You can do a quick mold test by creating a diluted bleach solution with bleach and water in the ratio of 1:16 parts. Then dip a swab in the bleach solution and dab it on the moldy wall. If the spot lightens quickly or keeps coming back after cleaning, it is probably mold.

Does Homeowners Insurance Cover Mold?

Most insurance policies do not cover mold, and they openly state that they do not cover damages where the primary cause is mold. However, most policies will still pay if the mold damage is secondary to an insured event. You can clarify this further by contacting the respective insurance provider.


The white mold on wood in crawl space has a lot of negative effects on your health. So, get a professional to inspect the site, and they will test the surface. Once they identify the exact type of mold, suitable remedies can eliminate mold formation completely. This is the best way to restore the condition of your crawl space. You can also get advice on crawl space waterproofing and suitable water discharge methods to keep the surroundings dry.