Effective Ways to Kill and Remove Black Mold on Wood

Black mold, also known as Stachybotrys chartarum, can be a serious problem if it grows inside your home. This toxic mold loves dark, damp environments – making wood a favorite surface to colonize. Left unchecked, black mold can cause a variety of health issues through dangerous mycotoxins. Fortunately, there are ways to both kill and safely remove black mold from wood in your home.

What Causes Black Mold on Wood?

Wood provides the ideal conditions for black mold growth. This mold needs cellulose to feed on, constant moisture, and darkness. Areas of your home where wood regularly gets wet are prime real estate for Stachybotrys chartarum.

Common culprits that lead to black mold on wood include:

  • Leaky roofs or plumbing – When water penetrates behind walls or leaks onto wood framing, mold flourishes in the damp environment. Slow leaks allow more time for black mold colonies to establish themselves.
  • Flooding – If wood gets submerged in a flood, mold spores in the water can attach and start growing. With plenty of moisture, mold spreads rapidly across wet wood.
  • High humidity – Humidity levels consistently above 55% provide enough moisture for black mold to grow on wood and other cellulose-based materials. Bathrooms, basements, and other humid areas of homes are at higher risk.
  • Condensation – When warm, moist air meets colder surfaces, water condenses. Damp wooden windows, cold exterior walls, and unfinished basements often get covered in condensation – creating the perfect home for toxic black mold.
  • Poor ventilation – Stagnant, moist air allows mold to thrive. Wood in attics, crawl spaces, and closets is more prone to black mold without proper air circulation.

Once it has established itself in your home, black mold can be difficult to fully remove from porous wood surfaces like framing lumber, plywood, and oriented strand board (OSB). But taking action quickly to kill and remove mold on wood is critical to prevent it from spreading and causing health concerns.

Dangers of Black Mold Exposure

In addition to damaging your home, black mold can seriously impact your health and should not be ignored.

Some potential health effects from black mold exposure include:

  • Allergic reactions – Mold spores and mycotoxins can trigger allergies, asthma attacks, trouble breathing, and skin rashes in sensitive individuals. Repeated exposure can lead to chronic conditions.
  • Respiratory issues – Toxic black mold spores get into your airways and lungs, resulting in coughing, shortness of breath, wheezing, and lung infections.
  • Weakened immune system – Black mold mycotoxins compromise your immune defenses, making you more prone to illnesses.
  • Headaches and fatigue – Inhaling mold spores or absorbing mycotoxins through your skin causes headaches, dizziness, and chronic exhaustion.
  • Cognitive problems – Research shows exposure to mycotoxins can lead to difficulty concentrating, memory issues, and problems with balance and coordination.
  • Bleeding lungs – In severe cases, the toxins from Stachybotrys chartarum can damage lung tissue and cause you to cough up blood.

Children, infants, elderly people, and those with chronic illnesses are most vulnerable to black mold’s effects. But even healthy individuals can get sick from high exposure.

That’s why it’s so important to act quickly to eliminate black mold from your home. The faster you can kill and remove it, the better.

Killing Black Mold on Wood

To effectively eliminate black mold on wood, you first need to kill the active mold. Otherwise, it will continue spreading spores as you try to remove it.

Here are some common ways to kill black mold growing on wood surfaces:


Bleach is a powerful disinfectant and mold killer. The sodium hypochlorite in bleach disrupts mold cell membranes and breaks down mold proteins.

To kill black mold with bleach:

  • Put on protective gear like gloves, long sleeves, eyewear, and an N95 mask. Mold spores can irritate your skin and lungs.
  • Mix 1 cup of bleach into 1 gallon of water. The diluted bleach solution should be at least 10% bleach.
  • Wash the wood using the bleach solution, scrubbing aggressively with a stiff brush to penetrate into the grain.
  • Allow the wood to dry completely before assessing if the mold is dead. Dried out mold will turn white or gray.

Repeat as needed until all visible black mold is killed. Just take care using bleach on any finished wood, as it can lighten stain or discolor surfaces.


The natural mineral Borax (sodium tetraborate) is an effective DIY mold killer for wood. It is safer for the environment than bleach.

To use Borax on wood mold:

  • Create a saturated Borax solution by mixing 1 cup Borax with 1 gallon of hot water. Stir continuously until fully dissolved.
  • Using gloves, apply the Borax solution liberally to all moldy wood surfaces with a sponge or spray bottle. Scrub aggressively.
  • Allow the Borax solution to penetrate the wood grain for at least one hour. Reapply if drying.
  • Once dry, the treated wood surfaces should show no visible mold growth.

The Borax solution alters the mold cell structure, stopping further growth and reproduction. Like bleach, dead mold will appear white or gray.

Hydrogen Peroxide

As an anti-fungal treatment, hydrogen peroxide can help eliminate active black mold on damp wood.

Follow these steps for using hydrogen peroxide on moldy wood:

  • Protect yourself with goggles, gloves, and an N95 mask to avoid irritation.
  • Mix equal parts 3% hydrogen peroxide solution and water.
  • Lightly mist the moldy wood surface with the hydrogen peroxide solution.
  • Allow it to sit for 10-15 minutes so the peroxide can kill the mold.
  • Scrub aggressively with a stiff nylon brush to remove the dead mold.
  • Repeat as necessary to kill all visible black mold on the wood.

Like bleach, hydrogen peroxide destroys mold by oxidizing and breaking down its cell structures. When dead, the mold will turn white or gray as it dries out.

Concrobium Mold Control

Concrobium Mold Control is a proprietary solution designed to kill and prevent mold growth. This EPA-registered disinfectant is non-toxic, odorless, and safe for use on wood.

To apply Concrobium:

  • Use a respirator, gloves, and goggles for protection from mold spores.
  • Lightly mist Concrobium onto all moldy wood surfaces according to label directions.
  • Allow it to fully dry on the surface, which can take 30-60 minutes.
  • Dead mold will turn a light gray or white color when dry.

The active ingredient in Concrobium, trisodium phosphate, alters the pH balance of the wood to make it inhospitable for mold growth.

Once you’ve killed all visible black mold on wood using one of these methods, it’s time to focus on safe removal.

Removing Black Mold from Wood

Killing mold growing on wood is only half the battle. The dead spores, mycelium, and growth remnants also need to be fully removed.

Here are some safe methods for removing black mold from wood:


Vigorously scrubbing moldy wood with a stiff nylon brush helps remove dead mold from the surface. Use hot, soapy water or a diluted bleach solution. Scrub the entire surface, including the backside of wood boards.

Be sure to wear proper safety gear, including gloves, eye protection, and an N-95 respirator mask. Scrubbing releases higher levels of mold spores into the air. Wipe down all surfaces once finished scrubbing to remove any remaining residue.


For mold growth deeper in the wood grain, sanding may be necessary after the mold is killed. Use a HEPA vacuum attachment held directly above the sanding area to contain airborne spores.

Start with coarse 60-80 grit sandpaper to remove mold staining from the wood fibers. Then smooth the sanded surface with 120 and 220 grit paper. Always wearing PPE, sand all moldy surfaces until no visible mold, discoloration, or raised texture remains.

Protective equipment is critical when sanding mold, as huge amounts of mold fragments go airborne. HEPA vacuuming throughout the process also helps capture spores before they spread.


Handheld planers and electric hand planers allow you to slice away thin layers of wood’s surface along with any dead black mold. For framing lumber or boards thicker than 1″, planing may be the best option to remove all mold penetration.

Make sure to always plane in the direction of the wood grain – never across it. And just as with sanding, use a HEPA vacuum right at the wood surface to contain the high volume of spores released while planing off moldy wood.

Heat Treatment

Heating moldy wood via flame, oven, or heat gun can help bake off dead mold that remains stuck in the grain. Use caution not to scorch or ignite the wood when applying direct flame or heat.

For framing lumber, use a propane torch and carefully run the flame over all surfaces, keeping it moving constantly. Wipe off any scorched black residue. For dimensional lumber, you can kill and remove mold by baking in an oven on the lowest setting, around 170°F.

Regardless of the removal method, containing and disposing of all moldy wood chips, sawdust, rags, and other debris is critical. Bag everything in plastic trash bags, sealing tightly before disposing. This helps prevent spores from dispersing and re-colonizing your home.

Preventing Future Black Mold Growth on Wood

Once you’ve succeeded in removing black mold from wood in your home, you’ll want to take proactive steps to prevent mold from recurring:

  • Keep humidity under 55% throughout your home using dehumidifiers and ventilation.
  • Fix any moisture sources like roof leaks, plumbing issues, or condensation problems.
  • Improve air circulation in enclosed attics, basements, and crawl spaces.
  • Clean up any water damage within 24-48 hours.
  • Add mold-resistant coatings to framing lumber and oriented strand board during construction.
  • Use mold-resistant drywall, especially in damp areas like bathrooms.
  • Be sure all wood materials can fully dry after getting wet.
  • Regularly clean and disinfect shower walls and windowsills prone to mold growth.

An ounce of prevention is truly worth a pound of cure when it comes to toxic black mold. Stopping it before it can gain a foothold will save you from having to kill and remove mold from your wood surfaces down the road.

Stay vigilant, act quickly at the first signs of mold, and take proactive moisture control measures. Follow these best practices, and you can effectively manage black mold risks in your home.

Frequently Asked Questions About Black Mold on Wood

Here are answers to some of the most common questions homeowners have about dealing with black mold on wood surfaces:

What are the first signs of black mold on wood?

Look for visible fuzzy or slimy black growth on wood, especially in damp areas. Discoloration that looks like dirt or dark stains can also indicate mold growing below the surface. A musty, earthy smell is another giveaway.

How do you test for mold behind walls or under surfaces?

Use a moisture meter to detect elevated moisture levels behind walls that may harbor hidden mold growth. Borescope cameras can also visually inspect in wall cavities and other tight areas. Consider mold testing kits to positively identify black mold via swab or air sample.

Can black mold go into wood?

Yes, black mold hyphae can penetrate into the grain of porous woods as moisture and spores migrate below the surface. Softwoods like pine are most vulnerable. The fungi can lie dormant and undetected inside wood for long periods when conditions are unfavorable.

What kills mold permanently?

No mold killer completely eliminates mold permanently from wood. The spores are impossible to eradicate from a home environment. You have to remove or encapsulate mold growth and then maintain an inhospitable environment through moisture control. Borax and Concrobium help prevent future mold, but fixing the underlying moisture issue is key.

Does paint or bleach remove mold?

Paint or bleach only kills surface mold temporarily but cannot remove the root system from wood. Mold will continue growing under paint. Using bleach to kill mold is effective, but physical removal via scrubbing, sanding, or other methods is still required afterwards.

When should you replace wood with black mold?

If the mold growth is widespread or you see major discoloration deep in the grain, replacement may be best. For safety, discard and replace any wood from inside wall cavities, as these are difficult to fully clean. If the mold damage is minimal, you can likely salvage lumber through cleaning.

The Bottom Line

Black mold presents serious risks, but arming yourself with information helps you win the battle against this persistent fungi in your home. Learn the underlying causes, utilize effective killing solutions, remove all traces, and take preventative action. With vigilant maintenance and moisture control, your family can breathe easier knowing toxic mold risks are under control. Stay proactive and safeguard the wood in your home from destructive black mold.

Laura Kassovic

Laura Kassovic, a former engineer at Intel SOC, now dedicates her efforts to mentoring startups in the realms of Wearables and AI. As a co-founder of New Tech Brake, she spearheads a wireless sensing solution enterprise catering to diverse applications including product development, research, location tracking, and people monitoring, as well as asset and cargo supervision. The platform empowers developers to craft an array of innovations such as fitness trackers, temperature-monitored cargo systems, medical trial tools, smart running garments, or even straightforward transmission of unprocessed accelerometer data to cloud-based repositories.

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