How To Remove Mold From Wood

black mold

We’ll provide a step-by-step guide for safely getting rid of mold in a basement and other damp places, outline the dangers of mold, and help you determine when the problem is too severe for you to tackle by yourself.

What Is Mold and Why Is It a Problem?

Mold is one of the forms a fungus can take when it creates spores to reproduce. It tends to form on the surface of organic matter in warm, damp environments. It’s most commonly found around leaks or in enclosed, humid areas such as basements and crawl spaces in your home. No matter where it is, it can cause several problems.

Health Risks of Mold Exposure

Mold exposure can cause headaches, coughing, wheezing, sore throat, stuffy nose, burning eyes, and skin rashes. People with asthma or allergies to mold often have stronger reactions, and people with weakened immune systems or lung disease may develop fungal infections. Additionally, some people may simply be more sensitive to mold exposure than others.
When people think of toxic mold, they often picture black mold or Stachybotrys chartarum, which can cause multiple health problems. However, the Centers for Disease Control and Prevention (CDC) emphasizes that it isn’t the species of mold but the amount of exposure that is likely to cause health problems. According to the CDC, “You do not need to know the type of mold. If mold is growing in your home, you need to clean up the mold and fix the moisture problem.”

Structural Damage From Mold

Mold can damage your home in addition to causing health concerns. When mold forms on wood, it begins to break down the structure of the wood, causing rot and compromising its integrity. The underlying cause of mold—moisture—also damages wood and most other materials over time. The earlier you catch and fix the problem, the better.

Types of Mold

The CDC doesn’t recommend residential mold testing, but you should remove all mold, regardless of species. Here are some common types of mold found in homes:

• Aspergillus: There are over 180 species of aspergillus mold, but A. fumigatus and a few others can cause a lung disease called aspergillosis in people with weakened immune systems. A. fumigatus is gray-green and tends to grow on compost.
• Penicillium: Some types of penicillium mold are beneficial and used to create penicillin or ferment cheese. However, others can grow on building materials even in relatively low humidity. Typically, penicillium only causes mild respiratory symptoms.
• Stachybotrys chartarum (black mold): While S. chartarum, sometimes called black mold, can cause respiratory problems and should be handled carefully, it’s gotten a bad rap. The CDC finds no solid link between black mold and severe health effects such as pulmonary hemorrhage and neurological symptoms. You usually find this black-colored mold in building materials, such as wood, that contain cellulose.
• Alternaria: Alternaria molds, which can be black, green, or gray, are a common cause of food spoilage. They can also cause opportunistic infections, especially in immunocompromised people, and are a common trigger for asthma symptoms.

Identifying Mold on Wood

Different types of mold have distinct appearances, and some can be mistaken for other contaminants. The following sections cover how to tell what you’re looking at.

Common Signs of Mold on Wood

Mold can grow on all types of wood, even wood that has been painted or stained. Look for the following signs, particularly around leaks or areas of water damage:

• Black, green, gray, white, or red patches
• Fuzzy or slimy texture
• Thread-like growth
• Musty or damp smell

Tips for Distinguishing Mold From Other Discoloration

Mold doesn’t always look green and fuzzy—sometimes, it’s difficult to distinguish from dirt, rot, water stains, or even natural variations in the color of wood. Look closely at any suspected mold spots, which are usually uniform in color and texture, unlike wood grain. Water stains are often yellow or light brown and don’t have the musty smell that mold does. You can buy a home test kit at your local hardware store, but the CDC cautions that these may be unreliable and there are no standards for what counts as “safe” mold.

Additional Considerations

If you suspect mold based on odors or humidity, look for hidden areas that may be home to leaks or water damage. Check around plumbing and windows, behind furniture, and inside cabinets. In some cases, mold can grow on the wood that frames walls or lines floors.

Safety Precautions When Removing Mold

You can clean up small mold infestations yourself, but always wear proper protective gear such as the following:

• Long-sleeved shirt and long pants
• N95 mask or respirator
• Rubber gloves
• Safety goggles without ventilation holes

The Environmental Protection Agency (EPA) recommends that you use the size of the mold infestation as the criteria for determining whether to do the cleanup yourself or hire professionals. Contact professional mold remediators if the mold growth covers more than 10 square feet—that is, an area of more than about 3 feet by 3 feet. You should also consider professional removal if you or someone in your home has asthma, allergies, or a compromised immune system.

Supplies Needed for Mold Removal

In addition to safety gear, make sure you have the following supplies ready:

• Bleach (optional—always use with extreme caution)
• Bucket 
• Cleaning-strength vinegar (optional)
• Microfiber cloths
• Mold-killing cleaner or dish detergent
• Sandpaper or power sander (optional)
• Scrub brush or sponge
• Vacuum with a high efficiency particulate air (HEPA) filter (required if you sand)

Steps To Remove Mold From Wood

Note that mold is far more difficult to remove from porous surfaces and materials such as wood than from a hard material such as plastic. In general, you should start with gentler products and detergents before moving on to harsher ones, and you should never mix cleaning solutions.

Step 1: Ventilate the area

Before beginning, open windows and doors to ensure proper airflow. This will help protect you from fumes and mold spores and help clean surfaces dry. 

Step 2: Apply cleaning solution

Start with a solution of mild dish detergent and water. You can also try a commercial fungicide, but always read the instructions before starting, and consider testing the solution on a small, less-visible area of the wooden surface first. Use your sponge or soft-bristled brush to apply the solution to the moldy area, but try not to saturate the wood, which may worsen the mold problem if it can’t dry completely.

Step 3: Scrub the surface

Remove all the mold you can see with your sponge or brush. Keep in mind that using harsh or abrasive cleaners or scrubbing hard can remove the finish or paint on wood. 

Step 4: Wipe away residue

Don’t rinse the cleaned surface. Instead, use a clean, damp cloth to wipe away the mold residue. Don’t allow the spores to contact non-moldy surfaces, especially if wet, as new mold may grow.

Step 5: Let the wood dry completely

Even if you suspect you haven’t gotten all the mold, allow the wood to dry before trying again. Run a fan or dehumidifier nearby to speed up the process, and keep doors and windows open as long as possible to continue to encourage ventilation.

Step 6: Repeat, if necessary, with stronger cleaners

Sometimes, a mild detergent isn’t enough to kill mold. You can also use cleaning-strength white vinegar to treat mold, though you may need to dilute it first. If you want to use bleach, mix no more than 1 cup per gallon of water and double-check that the area is getting the proper ventilation. Never mix bleach and ammonia.

Step 7: Sand if needed

If mold or stains remain, you can attempt to sand them away by hand or with a power sander. However, remember that this process could put more mold spores in the air. Always wait until the wood is dry, wear eye and respiratory protection, and have a vacuum on hand to safely contain the resulting sawdust. Ensure you remove all surface mold before refinishing wood surfaces.

Step 8: Clean up after yourself

You may inadvertently spread the infestation if you don’t properly dispose of moldy garbage or clean your tools. Bag up moldy items before throwing them away, and wash the clothes you wore separately from other laundry. Once the cleaned area is dry, mop or vacuum the floor and wipe down other surfaces to get rid of any remaining mold spores.

Removing Mold on Wood Floors and Ceilings

Hardwood floors are highly prized, but even high-quality hardwood can grow mold if you don’t finish the wood project properly or if there is standing water. Clean mold off the surface of wood floors using the steps above. If you suspect the damage extends below the surface, press the tip of a screwdriver into the mold spot. The wood may be salvageable with heavier cleaning and resurfacing if the wood feels slightly soft. You’ll probably need to replace it if it feels crumbly or spongy.

The same principles apply when you need to get rid of mold or mildew on a wooden ceiling. You’ll need to stand on a ladder, so make sure to work carefully and observe proper ladder safety. For cleaning both ceilings and floors, make sure the space is well-ventilated and allowed to dry completely once you’ve finished cleaning.

How To Prevent Future Mold Growth

Just as important as cleaning mold is getting rid of the conditions that caused it in the first place. Otherwise, you may find the mold growth returning. What follows are some ways to make your home a less welcoming environment for mold.

Check Your Insulation

Cold spots such as water pipes and windows gather condensation, which dampens surfaces and can encourage mold growth. Particularly if you live in a cold climate, make sure your insulation is in good condition and without gaps. Feel around for cold or wet spots and add insulation where necessary.

Control Moisture

The most important changes you can make are to reduce humidity and eliminate sources of standing water. Address these common trouble spots around your home:

• Allow damp items such as laundry and towels to dry completely.
• Ensure your yard has proper drainage to keep water away from basements and foundations. Also, make sure your gutters are in good shape and properly divert rainwater from the house.
• Fix leaks in and around roofs, pipes, windows, and doors.
• Keep air conditioner and refrigerator drip pans clean, and empty them when full.
• Use dehumidifiers, particularly in damp, enclosed spaces such as your basement and crawl spaces. An air conditioner will also dehumidify the air.
• Wipe up liquid spills as soon as they happen. Use a fan and open doors and windows when practical to increase ventilation for very large spills or flooding.

Improve Ventilation

Your home’s HVAC system shouldn’t just heat and cool the air but also ensure proper ventilation to keep humidity from building up. Use exhaust fans in bathrooms and kitchens. Make sure appliances such as clothes dryers and heaters are venting properly.

Keep Susceptible Areas Clean

Some of your home’s surfaces will get damp regularly, so wipe them down with a mold-killing cleaner. If fabric items in your home begin to smell musty, wash them as soon as possible. Keep floors clean and dry, and clean up dirt and dust so you don’t confuse mold with other contaminants.

Monitor Humidity Levels

Ideally, you should keep the humidity level in your home between 30% and 50%. Buy a moisture meter and adjust your dehumidifier or air conditioner as necessary. 

Use Mold-Resistant Products

If mold is a recurring problem, invest in building materials with mold-killing or moisture-resistant properties. You can buy mold-resistant paint or add mold inhibitors to regular paint, and always clean mold before you paint. Remember that sealed and treated wood will be less prone to mold.

When To Call a Professional

Call a professional mold remediator if you’re dealing with more than 10 square feet of mold. Here are some other situations in which it’s a good idea to hire an expert:

• Mold has grown inside your home’s walls, ceilings, or other structural components.
• Mold is growing in your HVAC system and/or ductwork.
• You or someone in your home has asthma, allergies, immune system deficiencies, or other health concerns.
• Your home has been subject to flooding.
• Your home has suffered structural damage from mold or water damage.

This is a specialized job, so make sure to find someone with experience in mold remediation and removal. Ask whether the contractor will clean according to EPA or other professional organization guidelines.

Our Conclusion

The CDC shares that all indoor mold infestations, regardless of the mold species, should be treated as potentially hazardous and carefully removed. If the mold covers a space of 10 square feet or less, you can tackle the problem yourself. However, if the affected area is larger or you don’t feel comfortable cleaning it yourself, you should reach out to professional mold remediators. The cost of removing mold is often worth it for the peace of mind it provides, and we recommend getting multiple quotes to compare your options.

FAQ About Getting Rid of Mold

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