How to Remove Mold and Mildew from Your Crawl Space

crawlspace under construction
  • 3-6 hours
  • Advanced
  • 80-250
What You'll Need
Plastic sheeting
Mold removal chemicals
Protective clothes
Sand blaster
What You'll Need
Plastic sheeting
Mold removal chemicals
Protective clothes
Sand blaster

If you're a homeowner, there's something you may have to face and probably will have to face: crawl space mold removal.

Mold and mildew are definitely ugly, even when they appear in a part of your home that no one can see. But mold in crawl space areas is actually hazardous to your health and need to be dealt with immediately, even if it's down in the crawl space and seemingly a safe distance away.

Learning how to remove mold and prevent it from happening in the future is something every homeowner must face. But once you've acquired this knowledge, you can hopefully avoid all mold and mildew problems of the future.

What Are Mold and Mildew, Really?

white corner with mold

Mold and mildew are actually the same thing, though the two terms are used together often. Mildew is a specific type of mold.

In other words, all mildew is mold, but only some mold is mildew.

But either way, it doesn't matter. You don't want either of these ugly, hazardous growths to appear in your crawl space or any other part of your home and the treatment and prevention for mold and mildew are exactly the same.

All molds, including mildew, are microscopic fungi that can survive and thrive on any organic matter, from leather and fabrics to wood and dirt. Mold and mildew can grow anywhere with moisture, and crawl spaces are often a prime location for this growth to appear.

Mold spores travel through the air. When the right conditions for breeding occur, they grow fast and often become a problem quickly.

mold on wall

Why Is Mold Bad?

Mold is a fungus, but so are mushrooms. So what makes mold bad?

For one thing, mold in crawl space areas can cause a number of health problems that cause everything from mild discomfort to severe symptoms. Some types of mold can even cause damage to your home.

In addition to being unsightly and unhealthy, the presence of mold indicates greater humidity and/or moisture levels in your crawl space, which should be addressed as soon as possible. You need to address the moisture problem because this is the way to treat mold on a permanent basis, rather than temporarily killing it before it grows again.

Mold and mildew can cause various allergic reactions or respiratory problems among people of all ages. It is extremely hazardous to your health, and you don't want it to grow anywhere in or around your home...not even underneath your home.

Mold can cause a number of health problems, including headaches, memory loss, depression, eye irritation, and several other symptoms you do not want to experience.

person near mold

Signs of Mold or Mildew

If you suspect that you have mold in crawl space areas or you know this is a moist area of the home, you need to check for signs that indicate you have fungi growing here. It’s a good idea to perform a regular mold check of the crawl space and any other areas of the home where it could potentially begin to grow.

You should always wear breathing protection or a particle mask when you suspect and look for mold. If you find mold in moist areas, it is important to note the color of the mold and its general appearance.

However, you should not attempt to touch or disrupt the mold in any way during your inspection. Be careful not to spread the mold, and be especially careful not to inhale it.

First, assess the state of your crawl space. Note how the air feels and how it smells, and of course, look for any moisture and feel for any humidity with your skin.

Notice any musty smell in crawl space areas or any other crawl space smell you might detect. When a crawl space smells musty, this is a strong indication of mold or mildew in crawl space areas.

If moisture is excessive and ventilation is poor, mold has the right conditions to grow and flourish. If the air is stuffy or if there is a bad smell that is somewhat musty, mold growth has already started.

Get out a flashlight and inspect thoroughly if you smell a musty odor or if you have spotted unnecessary moisture in the crawl space. Look for mold in the corners and search for any moist areas in particular.

Mildew has a gray or white color to it and a powdery appearance. It also grows quite flat, right against whatever surface it is on.

Mold grows in shades of blue, red, green, and black and has a more moist or slimy appearance. It may also appear to be fuzzy, and it does not always grow flat.

Do the best you can to identify the mold or mildew growing in your crawl space. Take some pictures of the growth, if necessary, to try to determine which type you have.

Got mold? It's time to think about crawl space mold treatment options.

gloved hand cleaning mold

Types of Crawl Space Mold and Mildew

There are three common types of mold that are most likely to appear in your crawl space. You can determine which type of mold you have based on color and general appearance.

Black mold is by far the most common and deadliest type of mold you could have in your crawl space. If you see black mold, you’re going to want to act as soon as possible.

Black mold is fuzzy or powdery and may be dark gray or greenish, rather than black. It is dark, however, so it can look black. It often appears as little spots that can look a lot like dirt.

White mold in crawl space areas often grows on exposed wooden joists and on dirt. Though it does not cause health problems as serious as black mold, this is still a health risk that you don’t want hanging around your home.

Yellow mold is known as house-eating mold because it literally feeds on wood and organic materials, which causes deterioration. You definitely don’t want this stuff hanging around.

Crawl Space Mold Removal

You don't necessarily have to buy any special products or chemical mixtures in order to kill mold. There are many common household cleaners that effectively treat mold, including hydrogen peroxide, distilled white vinegar, and standard rubbing alcohol.

Any of these common household chemicals can be mixed with water and sprayed directly on mold to kill it, along with any number of chemical mixtures you can purchase from home improvement stores.

However, the best and most effective way to kill mold is to use bleach. You need to wear gloves and eye protection while working with bleach and when you are also working around mold, wear a mask, so you don't breathe in the spores.

Mix about one cup of bleach in one gallon of water to make a mold and mildew killer that can be sprayed right on the fungus. Put this solution in a spray bottle and spray it directly on every bit of mold you can possibly find, so long as you're sure you're spraying it on mold and you will not do any damage to whatever is under the mold.

Remember that bleach can take the color out of clothing, wood, and just about whatever it touches, so be cautious when using bleach and put on clothing that can be ruined before you treat mold.

Also, you don’t want to breathe in bleach fumes for too long. In fact, don’t breathe in any fumes for too long.

While treating mold, take frequent breaks to get some fresh air and, if possible, open up windows or put a fan in the crawl space to provide some kind of ventilation.

ceiling vent

Preventing Mold and Mildew Problems

You don't have to face a mold or mildew problem to know you never want to have to treat one of these problems. Prevention is essential and the best way to avoid facing this issue.

The best prevention is the regular airing of your crawl space. You need ventilation to keep the area dry.

If that's not possible, however, there are other ways to treat mold, even in enclosed spaces like crawl spaces.

To keep the area dry, you can always use a humidity controller, such as a dehumidifier, which keeps the air dry. Remember, moist conditions are a good friend of mold.

Put a barometer in the crawlspace in order to monitor the humidity level and check this regularly. If it starts to increase, take precautions immediately by drying out the space.

Repair any leaking pipes or drains that might be dripping moisture into the crawl space. Seal any cracks where moisture could be seeping into the crawl space with caulk, including cracks around walls and the ceiling of the area.

Use plastic sheets that prevent moisture. A plastic vapor barrier can prevent mold and mildew from growing.

Replace any decaying joists or other damaged areas of the crawl space. Repair any windows and the crawl space entrance if there is damage or rot present, as these cracked and damaged areas can allow moisture and humidity to get into the crawl space.

How to Remove Mold and Mildew from Your Crawl Space

Every homeowner has to learn crawl space mold removal and how to prevent it from growing in the first place. Knowing how to treat and prevent mold could prevent a lot of health problems and keep your home much healthier for everyone.

Crawl Space Mold FAQ

Will vinegar kill mold in a crawl space?

Vinegar can kill a lot of bacteria, and it can kill some molds, which is why it is such a common ingredient in household cleaners. Mix equal parts of water and vinegar and spray it directly on mold to test this solution.

How do I get rid of mold in my crawl space?

The best way to go about removing mold from crawl space areas is to use bleach. However, some homeowners opt for less dangerous cleaning solutions and try these first before they use bleach because even the fumes of bleach can cause headaches and other problems.

Should I worry about mold in my crawl space? Is crawl space mold dangerous?

If you suspect you have mold in your crawl space, take action as soon as possible to inspect for mold and, if needed, kill it. Crawl space mold and any mold growing in your home are potentially very hazardous to your health and the health of anyone exposed to the mold.

How much does it cost to remove fungus from a crawl space?

If you take a DIY approach and get rid of mold on your own, you will spend only as much as it costs to get a bottle of bleach, gloves, and safety glasses to remove the mold. Hiring a professional removal service can cost thousands of dollars, or between $13 and $30 per square foot.

Treating mold yourself can be somewhat dangerous work, however, and you should wear all proper safety protection and take precautions when you’re talking this on as a DIY task.

Can mold in the crawl space be fixed?

Mold in the crawl space can be killed so that it is gone entirely, and prevention methods can be used to keep mold from growing in the area again. In other words, you can and must absolutely fix the problem if there is mold or a threat of mold in your crawl space.

Can I spray bleach in my crawl space?

Bleach is certainly an effective mold killer that's highly affordable and commonly available. However, bleach is dangerous and toxic.

You don't want to breathe a lot of bleach fumes, for starters, because this can make you dizzy and cause headaches and create other issues. You don't want to get a lot of bleach on your skin, either.

But bleach can also cause damage to wood. It soaks into the porous wood and can weaken it, so you don't want to spray bleach on wooden joists that support your foundation.

Because of this, you may opt for an alternative mold killer that is wood-safe. These chemical formulas are sold in home improvement stores.

What is the best killer for crawl space mold removal?

Non-corrosive mold and fungus formulas that have the power of bleach without the negative effects are probably the best options for removing crawl space mold. However, a simple bleach solution can be sprayed anywhere in the crawl space except for wood.

How do you get rid of mold on floor joists in a crawl space?

Acid-based cleaners are effective at removing wood from wooden surfaces. A solution of two parts baking soda, one part white vinegar, and one part water can be used safely on floor joists and other crawl space wood.

Spray the solution directly on the mold and allow it to sit for a minute or two before using a damp cloth to scrub the area and wipe away the solution.

Other cleaning products, such as over-the-counter products or simple Borax, can be used in the same way for removing mold from crawl space joists.

Further Crawl Space Reading

4 Home Remedies for Mold Removal

How to Build and Install a Crawl Space Access Door

How to Dig Out a Crawl Space to Make a Basement

How to Insulate a Crawl Space