Black mold on wood should be removed as soon as possible, as it can pose a health risk to those in its vicinity. Wet cellulose materials—e.g., wood that has become damp due to a leak—provide the right environment for many types of mold to grow. Safe removal is key, so the mold doesn't spread on surfaces or in the air. Follow these steps to properly remove mold from wood.
How Often to Clean Mold Off Wood
At the first sign of mold, wood surfaces should be cleaned. For outdoor wood furniture, decks, and siding in humid climates, at least a yearly cleaning is recommended.
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Equipment / Tools
- Long pants and long-sleeved shirt
- Protective air mask
- Rubber gloves
- Safety goggles
- Vacuum with HEPA filter
- Soft-bristled scrub brush
- Measuring cups/spoons
- Spray bottle
- Soft cloth
- Dishwashing detergent
- Distilled white vinegar
- Wood cleaner
- Chlorine bleach
- Sandpaper (if necessary)
- Wood stain/sealer/paint (if necessary)
How to Clean Mold Off Wood
Put on Protective Clothing
Prior to interacting with the mold, put on protective clothing, including a long-sleeved shirt and long pants. Wear old clothes because any bleach splatters will cause permanent stains. Also, wear a protective air mask, rubber gloves, and safety goggles. If possible take the mold-infested wood outside when cleaning to prevent spreading spores indoors. If you must remain indoors, close doors or use plastic sheeting to shield other areas.
Vacuum the Mold From the Wood Surface
A vacuum with a HEPA filter is recommended to capture mold spores. When as much mold as possible is vacuumed up, empty and clean the vacuum canister or remove the bag outside and seal the contents in a plastic bag before tossing it in the garbage.
Wash Sealed or Painted Wood
If the mold has grown on painted wood (such as an interior door) or a sealed wood finish (such as flooring), begin by washing the surface with a liquid dishwashing detergent and water solution. Mix 1 tablespoon of detergent to 1 quart of water. Use a soft-bristled brush to scrub the surface. Try not to saturate the wood, and use a sponge to remove excess water as you clean.
Spritz With Distilled White Vinegar
For a small amount of mold growth that has not left severe stains or penetrated the wood, distilled white vinegar can kill the spores. Use a spray bottle to lightly mist the wood with the vinegar. Allow the vinegar to air-dry on the surface for at least one hour. If there are no stains remaining, use a good wood cleaner, such as Scott's Liquid Gold, to nourish the wood. Then, buff the surface with a soft cloth.
Use Chlorine Bleach for Tough Mold Stains
If the mold is extremely heavy and has left stains after using vinegar, it's time for a stronger solution. This solution should also be used on areas of unsealed wood. Mix a solution of 1 tablespoon dishwashing detergent, 1/2 cup chlorine bleach, and 1 cup warm water. Apply the mixture to the stained area with a soft-bristled brush, and allow it to air-dry. Finish by buffing with a soft cloth.
What to Do if Mold Persists
If the mold stains still remain, the wood surface will need to be sanded to remove the spores that have deeply penetrated the wood. If you are not familiar with wood sanding or refinishing, ask questions at a home improvement store about the right sandpaper grit to use for your situation. After sanding and vacuuming away all of the grit, the wood should be refinished or sealed to help prevent future damage.
The Difference Between Mildew and Mold
The most common type of mold found in homes is mildew. Mildew is a surface mold that grows in warm, damp places like basements, laundry rooms, and shady porches. Mildew begins as a gray or white powdery colony and eventually turns black or brown. To test whether the wood is covered with mildew or just dirt, dab the stain with a cotton swab dipped in household chlorine bleach. If the stain lightens or disappears after two or three minutes, it's mildew. If not, it's probably just dirt.
Mildew can discolor and slowly harm wood surfaces. But there are much more dangerous molds that can damage the structure of your home. If a fuzzy or slimy black or green mold is visible and the drywall or wood underneath is soft or crumbles, there is irreversible rot. The damaged surfaces must be removed immediately.
What Is Black Mold?
Several types of mold are black. But when people refer to black mold, they most commonly mean Stachybotrys chartarum. This is a greenish-black mold that grows on wood, paper products, and cotton. Moisture is necessary for it to grow. This black mold can produce toxins that cause adverse health effects, including coughing, wheezing, and eye irritation. Some people are more sensitive to it than others.
How to Prevent Mold Forming on Wood
If a leak occurs in your home, immediate action is key to prevent mold growth. If you can dry the affected materials within a day or two (and the source of the leak is fixed), chances are mold won’t grow. Likewise, it’s important to promptly investigate the source of any condensation on windows, pipes, or walls. Furthermore, work proactively to reduce moisture and humidity around your home. Keep your gutters and roof in working order, and make sure the ground slopes away from your home’s foundation. Verify that appliances are properly venting. And use exhaust fans and dehumidifiers as necessary.
When to Hire a Professional
If the mold is caught early and only covers a small area, you should be able to remove it with household cleaners. For extensive mold problems—especially those in poorly ventilated areas, such as crawlspaces—or for anyone with mold allergies or a compromised respiratory system, consider hiring a professional.
Basic Facts about Mold and Dampness. CDC - Centers for Disease Control and Prevention.
Mold Cleanup in Your Home. US Environmental Protection Agency, OAR.
What Is a HEPA Filter? US Environmental Protection Agency, OAR.
Cleaning And Disinfecting Your Home. CDC - Centers for Disease Control and Prevention.
How to Prevent and Remove Mildew — Home Methods. Extension University of Missouri.
Facts about Stachybotrys Chartarum. CDC - Centers for Disease Control and Prevention.
Stachybotrys Chartarum Defined. American Academy of Allergy Asthma & Immunology.
A Brief Guide to Mold, Moisture and Your Home. US Environmental Protection Agency, OAR.