Got Mold on Wood? Here’s What To Do

Michael Rubino

Wood is often a staple component of any home. This material is useful in structural aspects of a building, such as attic joists and rafters, and it’s also commonly used for finishings and decor around the house. With an array of wood types and colors, consumers can have their pick of hardwood floors, furniture, fireplace mantels, and more. We’re not the only ones that love this material, though. Mold on wood is one of the most common contamination situations in a home.

This fibrous surface can offer that fungus among us the perfect opportunity to begin growing. Once that mold is established, it takes a thorough process and a little bit of elbow grease to get rid of it properly. Otherwise, the indoor environment will continue to fill with unwanted microscopic particles.

Talk about a toxic situation, right?

To avoid this scenario, having the correct remediation process and understanding how to prevent mold on wood from occurring in the first place can help keep your home safe and free from fungal growth. Here’s what you need to know.

Why Does Mold on Wood Occur?

Knowing how to treat mold on wood and prevent it from occurring in the first place means you’ve got to understand why this indoor contaminant thrives on this particular material.

Mold requires two basic elements to begin growing: food and water.¹

When it comes to food, any type of organic matter is on the table for growth. It just so happens that wood itself is organic matter, so it can be physically eaten and decomposed by mold colonies. Any other organic particles hanging out on the surface of this material are just icing on the cake for checking off a food source for microbial growth.

That leaves moisture as the missing element. High humidity, leaks, flooding, and pooled water can all introduce the H2O needed for mold to begin growing. If this is present on the wood for 24–48 hours, a colony can begin to develop on the wooden surface. Once this occurs, the contamination situation begins.

Why is Mold On Wood a Problem?

As mold grows, it reproduces by creating microscopic spores and sending them into the surrounding space.²’³ Some species of mold can also create microscopic toxins called mycotoxins when threatened, further adding to the particle party.⁴

The longer a colony is thriving and surviving, the more particles will be blown all around. This isn’t a problem in nature because there’s a wide world to disperse through. Mold on wood in a home is not the same scenario. Thanks to modern building techniques pushing for net-zero energy efficiency, there’s very little airflow between indoor and outdoor environments. That means that a majority of the microscopic particles produced by the mold, not to mention fragments from the colony itself, are trapped within the walls of the home.

This leads to:

Poor indoor air quality
Contaminated surfaces all throughout the home (these particles can ride the indoor air current anywhere)
Increased likelihood of a colony opportunistically developing elsewhere in the home

To add another layer of contamination problems, bacteria thrive in similar environments as mold.⁵ That means that where there’s mold growth, there are often bacteria as well.

This situation can create a toxic indoor environment and lead to chronic illness due to exposure.

The Health Aspect

All of the particles produced by the microbial growth are microscopic. They’re so tiny that they’re measured in a unit called micron, which is 1/1000th of a millimeter (those tiny lines on a ruler). The EPA further classifies them as particulate matter and breaks them down into categories.⁶

These two categories are:

PM10: particles that have a diameter of around 10 micrometers or less.
PM2.5: fine particles that have a diameter of around 2.5 micrometers or less.

The size is important to consider because they’re small enough to be inhaled, ingested, and absorbed into the body.⁷ Some of the particles are so small that they can blow straight through the lungs and into the bloodstream.

Exposure to these particles isn’t the end of the world, though. In fact, it’s impossible to completely avoid encountering mold spores, mycotoxins, and bacteria throughout the day. You probably inhaled a few while driving to work, grocery shopping, or taking a walk outside. Thanks to our handy dandy immune system, the body is equipped to kick them out in this situation.

Mold on wood is not the same situation.

Instead of a couple of particles throughout the day, your body is flooded with a high volume of particles every time you step into that environment. It will try to keep up, but the immune system can get bogged down and/or malfunction, leading to a long list of possible chronic symptoms and health conditions such as Aspergillosis, Mast Cell Activation Syndrome, and Chronic Fatigue Syndrome.

Common symptoms of exposure include:

Headaches and migraines
Joint and muscle pain
Cold and flu-like symptoms
Mood swings
Anxiety and depression
Chronic fatigue
Digestive problems
Brain fog
Hair loss
Rashes, eczema, and skin issues

The tricky part about exposure is that no two people will respond to mold on wood or exposure, in general, the same way.⁸’⁹’¹¹’¹²’¹³ Much more research is needed to better understand how these indoor toxins affect the body, but it’s a tricky subject to nail down. Factors such as genetics, immune system status, species of mold, presence of mycotoxins, presence of bacteria, and volume of exposure are a few that play a role.

That being said, just because we don’t know how someone will respond to exposure doesn’t mean that we should brush off issues such as mold on wood. In order to establish a healthy home environment, it’s important to know how to handle this situation and how to prevent it from popping up in the first place.

How Do You Get Rid of Mold on Wood?

The process of getting rid of mold on wood depends on whether or not the surface is sealed. When a colony establishes on a surface, it grows roots called hyphae. These roots will reach into the surface it is growing on. Like a weed, in order to get rid of this indoor contaminant, you’ve got to pull it up roots and all.

That’s why bleach is a no-go when it comes to remediating mold.¹⁴ This harsh product does not take care of the roots or help lift particles to the surface so that they can be wiped away. Dead mold and any other microscopic particles left behind (like mycotoxins) lead to continued exposure and chronic symptoms, so they’ve all got to go.

Proper remediation includes eliminating the growing colony, roots, dead particles, and any other contaminants hanging around as well. Porous surfaces, like untreated wood, make this process more difficult because you’ve got to handle the roots and particles that make their way inside the fibers of the material. Mycotoxins and bacteria are particularly difficult to remove, hence the thorough protocol for all surfaces.

That being said, here are the processes for getting rid of mold on wood.

Pro tip: The absolute first step in remediating mold on wood is to ensure the situation that led to the growth is resolved. For example, a leak leading to water damage needs to be fixed so that the conditions for growth are no longer present and a spore can’t opportunistically settle in.

Steps for Unsealed Wood:

Use a HEPA vacuum and thoroughly go over the surface:
Apply 8% hydrogen peroxide and allow this to dry
Use an abrasive method such as sanding or wire brushing to go over the surface
HEPA vacuum the surface thoroughly once again
Spray a botanical cleaner such as Benefect Decon 30 and allow it to sit for 10 seconds
Wipe with a microfiber towel and then allow this to dry (microfiber towels are 100 times better at wiping away small particles than regular rags)
Complete the spray, wipe down, and drying process once more using a new side of the microfiber towel
Dry encapsulate/seal the surface
When dry, wipe again with a microfiber towel

Keep in mind that when you’re sanding and remediating the surface, particles will become airborne during the removal process Setting up proper engineering controls, wearing personal protective equipment, and creating a containment area should be included to help protect you and your home from all of these particles. Make sure to also deep clean to eliminate these particles and to avoid them from spreading to other areas of the home.

Now onto non-porous surfaces. These typically do not require sanding because the roots will be unable to grow within the fibers of the wood. That being said, if the mold grows right back after remediation, the sealing might have been faulty and the process above should be followed.

Steps for Sealed Wood:

Spray a botanical cleaner such as Benefect Decon 30 on the surface
Allow this to sit for 10 minutes, and then wipe with a microfiber towel.
Repeat the process two more times, flipping the towel to a new side each time
Allow the surface to dry completely
Deep clean the surrounding area

If the mold grows right back after the process of remediating unsealed wood, you can attempt to cleanse the surface again, but it’s best to call in a professional for help. They’ll be able to determine if there's an underlying issue going on. If the mold is on furniture or decor, it’s best to toss the items and start with a new one.

When it comes to your health, there’s no such thing as going too far.

What Does Mold on Wood Look Like?

With over 100,000 species existing in the world, mold colonies can come in a variety of colors, shapes, and textures. Some of the most common colors include green, white, grey, blue, red, black, brown, or a combination of them. As for textures, they could be fuzzy, powdery, velvety, or slimy.

If any type of unidentifiable growth pops up on a wooden surface in your home, it's a safe bet to assume there’s a mold problem.

That being said, visible growth isn’t the only thing you should pay attention to.

Is There Water Damage?

Mold can grow in as little as 24 hours if there’s a source of moisture around. Water damage can often indicate microbial growth problems on the surface where moisture is present.

Things to look out for that may indicate mold on wood include:

Water stains and discoloration
Buckling or warped surface
Peeling paint
Lifted nails

Any signs of these can be signs of an opportunity for mold growth.

Does it Smell?

Mold growth isn’t always visible. It could be in a hidden area like underneath the floorboards, or the colony is too small to be visible to the naked eye yet. In this situation, look to your nose to help determine if there’s a problem.

Growing mold often creates an earthy, musty, damp, cigar-like smell due to the release of gases called microbial volatile organic compounds (MVOC).¹⁵ If this odor is coming from the wood, it points to a problem existing inside.

How Do You Feel?

Neither of those boxes is checked off, but do you still suspect a problem? First of all, always listen to your intuition! Instinct is a powerful tool to ensure we’re avoiding unhealthy exposures.

Our bodies are fantastic warning systems that will let us know when something is wrong, but we’ve got to listen to them when they sound off. If you start feeling unwell every time you’re around the wood surface or while in the home, that can point to a moldy issue. Those chronic symptoms are your body’s way of saying, "Hey, something is definitely not right here."

How Do You Prevent Mold on Wood?

The best way to deal with mold on wood is to stop it from occurring in the first place. That way, you don’t have to deal with the comprehensive remediation process or an army of microscopic particles.

The key to preventing mold on wood is to reduce the opportunities for mold to grow. That means moisture is public enemy number one. Getting rid of spores and other particles that are blowing around is second on the task list. The fewer spores there are in the home, the lower the chances they’ll stumble on a habitable surface and start to grow.

Steps to prevent mold on wood include:

Seal all wood surfaces: This prevents moisture intrusion from being able to saturate deep within the fibers of the wood itself. Since mold can grow so quickly, the sooner moisture can be removed, the better.
Decrease indoor humidity: Some species of mold can grow in high humidity. Maintaining indoor humidity levels between 35 and 50% eliminates this opportunity for growth.¹⁶
Properly wipe and dry pooled moisture within 24 hours: A dry environment is a space that is less likely to support microbial growth. Keeping surfaces such as wood dry by wiping up pooled water can eliminate these indoor contaminant opportunities.
Keep windows and doors closed while the AC is on: When the hot outdoor air meets the chilly indoor air, it can create condensation in areas such as windowsills and door frames, which are typically built with wood. If you decide to open doors or windows, make sure to turn the air off so that this moisture opportunity does not pop up.
Deep clean often: This removes unwanted particles from hanging out in your indoor space and on wood surfaces. Use a HEPA vacuum cleaner, botanical products, and a microfiber towel to kick those particles to the curb.

Collectively, these can help prevent mold on wood nightmares from happening to you.

Home Health

Having action plans in place to deal with scenarios such as mold on wood is a huge part of home health. Our indoor environments play an enormous role in our ongoing wellness. When we breathe 20,000 breaths a day and spend 90% of our time indoors (on average), it makes sense!¹⁷

Yet the state of our indoor spaces is rarely considered in wellness conversations. Reducing indoor contamination and keeping them clean should be a crucial part of any wellness plan so that you can breathe easier. The fewer particles there are inside, the fewer will enter our bodies. Make sure to add this piece of awareness to your home maintenance knowledge foundation.