Mold in Crawl Space: What Causes It and What You Can Do About It

Mold Restoration
Mold problems are common in basements and crawl spaces, owing to dampness and lack of light. The problem usually starts at sump pumps or other drainage features that combine bad design with normal wear and tear, resulting in a mold outbreak.
Mold is a dangerous fungus that can cause respiratory problems and other health hazards. Mold can emit harmful spores into the air that could cause itchy eyes, nose, and/or throat. If not treated immediately, mold infestation could lead to neurological problems as well as sinus infections, allergic reactions, and flu-like symptoms.
If you suspect mold in your crawl space, it’s always best to reach out to a professional mold remediation company. PuroClean can safely and effectively deal with mold in crawl space. If the mold affects an area smaller than 10 square feet, there are some steps you can take to treat the mold yourself. This blog will discuss some common causes of crawl space mold and how to handle a mold issue.
mold in crawl space.

What Causes Crawl Space Mold?

Crawl spaces and basements often suffer from mold because of dampness. Mold can develop from a variety of sources, including water damage, flooding, and plumbing leaks. A lack of adequate ventilation, poor drainage, and crawl space foundation cracks are also possible reasons.

The first step in any mold cleanup is to identify the source of the contamination. If you don’t know why the mold is appearing, you won’t be able to correct the actual problem, and the mold will return.

Basement Cracks and Flooding

Crawl spaces are at risk of flooding during periods of intense rain. If your crawl space floods, mold could appear immediately after the water recedes.

If you have cracks in your basement floor or walls, then you should also investigate if they are linked to any moisture penetration that may be exacerbating your mold problem. For example, faulty sump pumps, poor grading around your foundation, and improperly sealed windows could be the source of the problem.

Some crawl space designs call for plastic sheeting on the floor; this barrier traps water against the foundation walls. The trouble is that the plastic breaks down over time. As it deteriorates, holes develop, and water seeps through them into the soil. Water accumulates in the crawl space just as it does in any basement.

Humidity and Condensation

A humid crawl space creates a perfect environment for mold spores to latch onto a surface and grow. Be sure to keep the humidity levels in your crawl space lower than 50% because higher levels can lead to condensation, which will increase humidity levels even more. Try to decrease humidity with fans or dehumidifiers depending on how humid it is.

Tips to Treat Mold in Crawl Space

Once the source has been identified and fixed, it’s time to treat the actual mold. We always recommend that you reach out to a professional for mold removal because of the health risks caused by exposure.

Crawl space mold can be especially difficult to remediate due to the tight spaces and floor joists. If the mold is affecting an area smaller than 10 square feet, there are some things you choose to do to treat it yourself. Keep in mind that these are not the same processes that professionals would use.

Whenever you are near suspected mold, it is important to protect yourself by wearing proper PPE. Proper PPE includes goggles/eye protection, gloves, and N-95 masks.


One of the most popular house cleaning tips for removing mold is to use vinegar since it kills many bacteria, including molds. Just mix vinegar and water in a 1:1 ratio in a spray bottle. Spray all over the affected crawl space walls or floor. Let it sit for a few minutes, and then scrub the area. Rinse with water afterward.

Baking Soda

Baking soda is another popular cleaner because it can be used for removing mold from many different surfaces in your home. You can spread baking soda on your floor or furniture, let it sit there overnight, and then clean everything with water first thing in the morning. This will remove not only dead mold but also any other dirt that was stuck to it. Baking soda is great because after using it, you won’t smell anything bad – just make sure to wipe everything down thoroughly.


Borax is another compound that works great against all kinds of molds without leaving any traces behind. But keep in mind that this substance can be toxic, so use it in places where you won’t breathe it in or are not planning to eat anything. Also, make sure to use extra caution when using borax because it can harm your skin and eyes and can also be harmful to pets.

Another good thing about borax is that after you’re done spraying the affected area, it’s safe to leave. There is no need to rinse.

How to Prevent Mold Growth in a Crawl Space

Preventing mold growth in your crawl space is the best course of action. It is much easier (and less expensive) to take steps for prevention than mold remediation. If your house has a crawl space, make sure to keep it ventilated and dry. Any moisture or water on the ground of your crawl space can contribute to mold growth, so make sure to keep it dry. Insulate your pipes and keep them sealed to prevent water from seeping into the dirt, where it will contribute to humidity levels. Also, make sure that the dirt doesn’t pile up too much there since this can clog all your vents, allowing water inside your crawl space.

Crawl space insulation is one of the best tools to use for prevention. Insulation can easily be purchased at your local hardware store. Be sure to use mechanical fasteners to attach the insulation snugly to the subfloor. Seal all the seams with weatherstripping so that air cannot get inside easily.

If the current ventilation system doesn’t work that well, consider installing a new one. Make sure to check with your HVAC contractor about setting it up because you will want the fresh air to be pulled out and not pushed in.

Call PuroClean 24/7 for Crawl Space Mold Remediation!

If you have water damage or water stains or notice musty smells in your crawl space then call PuroClean immediately. Our compassionate, empathetic, and experienced technicians are ready to take care of your mold issues, so don’t hesitate to give us a call!

PuroClean of Wilton | Ridgefield’s primary goal is to make people in Fairfield and Westchester Counties feel safe in their homes again by using the best cleaners and all the latest technologies that are effective without being harmful. Look us up on linkedin, facebook, instagram, call us on 475.277.2400 or email at [email protected].

Last edited on 21st of May 2022