How to Remove Mold Stains from Wood Floors

Noticing Your Mold Problem

Pay attention to any symptoms of mold exposure. There are a number of ways you learn about mold on wood floors. If you are suffering from mold exposure, you may experience headaches, itchy eyes, breathing problems, or difficulty concentrating.

Notice any musty smells. Mold emits a gas that gives it a musty smell. If you notice this smell, you likely have mold, even if it is not visible in your house. The mold may be somewhere not immediately visible, such as in your walls, under carpets, or in a crawlspace or heating duct. EXPERT TIP Susan Stocker Susan Stocker Green Cleaning Expert Susan Stocker runs and owns Susan’s Green Cleaning, the #1 Green Cleaning Company in Seattle. She is well known in the region for outstanding customer service protocols — winning the 2017 Better Business Torch Award for Ethics & Integrity —and her energetic support of green cleaning practices. Susan Stocker Susan Stocker Green Cleaning Expert If the mold smells like soil or rotting leaves, it may be black mold. In that case, you'll need to consult a professional.

See if your wood floors are warping. If mold is growing beneath your floors, it will eventually cause the floorboards themselves to begin to twist and warp. If there is any sign of warping of the wood, this means your mold problem is pretty far along. If the mold causing the warping isn’t caught and removed promptly, the warped floor may need to be removed. This process is time-consuming and expensive.

Removing Surface Mold

Wear appropriate safety gear when working around mold or with chemicals. Gloves and safety glasses are sufficient for removing surface mold over small areas, no more than a few square feet. For deeper mold removal or over larger surface areas, use an N-95 mask or P-100 respirator in addition to gloves and safety glasses. Also, wear clothing and shoes that can be easily washed or disposed of after.

Select the proper mold and mildew cleaner. For surface mold, you want to use a cleaner designed for urethane finishes. You can also use a chlorine bleach solution, with a water/bleach ratio of 10:1. If you choose to purchase a mold cleaner, look at your local hardware store or a home and garden center. Read through the safety labels on any and all chemicals you use.

Wipe away the mold using a rag. Minor, surface-level mold growths are relatively easy to clean. Spray the moldy area with your cleaner or bleach solution. Let this sit for 10 minutes, and then wipe the mold off with a rag. For stubborn mold stains, use a firm-bristled hand scrubbing brush. Throw the rag away after you’ve cleaned the mold. When you apply cleaning chemicals or a bleach solution, prevent the chemicals from spreading to uninfected areas. Do not leave the bleach solution on the wood for longer than necessary, as it will remove the wood finish.

Removing Ingrained Mold

Test the depth of the mold. If you have mold growing on your walls (especially drywall) or flooring, the mold may have spread beyond what’s visible. Press into the spot with a screwdriver or sharp tool. If the wood feels soft, the mold has spread below the surface and into the wood. This will require more than surface cleaning. If the spot feels slightly soft, the mold can be removed. If the wood feels spongy or crumbles, it may be rotten and not salvageable.

Dry out the floor using room heaters or fans. Before you begin to physically remove the mold, all of the moisture in the wood needs to be eliminated. Set a large fan (or two) in the room with the mold, and direct the blowing air towards the moldy floor or wall. Let the fans blow for several hours. Drying the moldy area will protect the floors and prevent future mold growth. Make sure your floors are totally dry. Ingrained mold needs to be dry before you remove it.

Ventilate the room. Mold particles can be dangerous to inhale, and you should take precautions to avoid this. Wear a mask or handkerchief over your mouth, and open all exterior windows and doors. For an added precaution, set a large box fan in one of the exterior windows to blow the mold-infused air out of the room you’re working in. If you do not have a box fan, you can purchase one at a hardware store or a home-supply store.

Remove the top layers of mold. First use 100 grit sandpaper or a metal hand scraper to remove as much mold as you can. Use finer 220 grit sandpaper to remove more ingrained mold. If the mold has penetrated deeply into the wooden floor, you’ll need to use a more heavy-duty scraping tool. Use a metal utensil, such as a spackle blade, to scrape away the mold. Sand in a circular motion, and only sand the affected area. Once you’ve removed the mold, polish the affected area with 200 or 250 grit sandpaper until smooth.

Spray diluted bleach onto the moldy area. Mix water and bleach at an 8:1 ratio, and put the solution in a spray bottle. Spray the moldy area with the bleach solution, and let it sit for several minutes. Then use an old rag to wipe up the bleach solution. This will kill any live mold before it spreads. Even if it looks as though you’ve physically removed all of the mold, there may still be spores present that are too small to see. Bleach will kill these and prevent further mold outbreaks.

Cut out any mold-riddled drywall, flooring, or insulation. If the mold has fully permeated a section of carpet or drywall, it’s probably not salvageable. You’ll need to remove and dispose of the material to prevent the mold infestation from spreading. Use a screwdriver, utility knife, or other sharp tool to cut through the moldy insulation or carpet. Put the moldy material into a garbage bag immediately. Once you’ve removed and disposed of the moldy wall or floor segment, you’ll need to replace the material. Visit your local hardware store and purchase the necessary items to patch carpet, drywall, or wood flooring.

Apply a wood finish that matches the original finish. Once you have removed the ingrained mold, you’ll need to apply a finish to the wood flooring. Try to find a wood finish that will cover up the mold stain and restore the coloring of your wood floor. For added protection against moisture in the future, apply a polyurethane finish to the wood. If you can't find the exact colored finish to match the original floors, use the next lightest shade.

Bag and dispose of all the debris. Use heavy-duty garbage bags to throw out all of the trash from the mold-removal process, including rags, sandpaper, and any tools that you used. If you tore up flooring or drywall in the process, use a wet/dry vacuum to clean up the mess. Use a chemical cleaner or bleach solution to wipe down the wet/dry vacuum after use, to kill any mold spores it may have collected.

Preventing Future Mold

Keep floors dry to discourage mold growth. Mold needs moisture to grow. Keep an eye on your wood floors to make sure they are clean and dry. If you have wood floors in places that are prone to moisture, such as bathrooms, basements, or kitchens, make sure you clean up any surface moisture as soon as possible. Warm environments also encourage mold growth. Wood floors in any places that get warm, such as bathrooms or kitchens, need to be aired out to avoid mold growth.

Clean your floors regularly. If your wood floors are clean and dry, then the conditions for mold are less likely to arise. Vacuum and mop your wood floors on a regular basis. While you may not have to clean your wood floors daily, make sure to incorporate it as part of your weekly cleaning routine. When ingrained in wood floors, mold feeds on nutrients on the surface of the wood, but not on the wood itself. Keep your wood floors dry and clean to make sure mold does not have a food source.

Control humidity in your house. Mold grows best in humid environments. Consider buying a dehumidifier to keep a consistent level. Indoor humidity should be at about 50% to avoid most molds. Clean spilled water as soon as possible. Don’t let any water sit on your wood floor as that could lead to mold growth.

Air out your house during the colder months. When it’s colder outside, we tend to keep our homes warmer, which creates warm air that does not escape. Additionally, plants are more likely to die in the fall and winter, which creates more opportunity for mold to grow. Airing out your house will allow this warm air to escape and will clear out any mold spores that have begun to grow.

Maintain your air conditioner during warmer months. Make sure your air conditioner is in working order and not creating excess moisture. An overused air condition can create additional condensation, which will create a favorable environment for mold to grow in.