What are the Signs of Molds Under Hardwood Floors?

Your new hardwood flooring is quite an investment, and you would want it to stay that way.  What if the best insurance you could get for them is to be aware of the signs of molds under wooden floors?

You could up their protection a notch more as well by learning what causes molds to form and how to eliminate them.

Finally, seal the deal by equipping yourself with simple but potent DIY natural anti-mold cleaning solutions and preventive measures.  

We would be covering all these four points in depth to help you, possibly, mold-proof your precious space.

How Can You Tell If There Are Molds Under Your Floorboards? 

Musty Smell

You don’t have to see it to believe it’s there. 😉 You could quickly tell toxic molds are wreaking havoc underneath your flooring by their familiar musty smell which is close to that of a damp carpet or rotting organic matter.  

 The pungent earthy smell is due to mycotoxin, a type of gas among many (microbial volatile organic compounds), produced during the growth and reproduction of molds. As its name implies, they are bad not just for your floor but for your health, too.

Fuzzy Growth

Aren’t we all quite familiar with the powdery look and texture of molds? These webby hairlike filaments are made of millions of minuscule spores. If untreated, they spread fast through air currents mostly. They could also be carried away by water, insects, animals, and upon contact with any moving thing.

White fuzzy growth would commonly be the uninvited guest under hardwood floors because they feed on organic materials like wood.

Off-colored Stained Tiles

Prolonged exposure to molds would dull the color and shine of hardwood floors. Highly pigmented spores could cause heavy staining and discoloration.

Water Damage

Fungi love damp subfloors and over time spread fast onto the floorboards. 

Water-damaged moldy wood flooring would feel weirdly cushiony and moist to the feet. Distortion such as cupping, warping, and crowning could also happen as wood swells from excessive moisture.

Some of these signs would entail dismantling affected wood planks for proper treatment to be carried out. That is why prevention is better than cure. In other words, know your enemy. 😉

What Causes Molds to Form Under Wooden Floors?

Simply put, your hardwood floor’s number 1 enemy is the sum of all three conditions: 

❌ moisture

❌ warm temperature

❌ high humidity

This is how a cycle of neglected spills, untended wet bags or umbrellas left on the floor, kids tracking mud and dirt in the house, and just about anything that causes water droplets to seep in between planks lead to mold growth under your hardwood floor.  

Can Molds Be Removed from Hardwood?

The good news is, if caught early enough, it is rather easy to get rid of molds and keep them at bay.

How easy? Just whip up potent homemade anti-mold floor cleaners that tick all the boxes:

☑️  Mold Protection


☑️Floor Shine

How to Make Safe and Effective Homemade Mold Killers for Wooden Floors

Ingredients for a Strong Solution:

1 Cup Distilled Water

½ Cup White Vinegar

½ Cup Rubbing Alcohol

A Few Drops of Dishwashing Liquid

Essential Oils

7 Drops Lemon Oil

10 Drops Tea Tree Oil

5 Drops Peppermint Oil

Ingredients for a Mild Solution: 

¼ Cup Distilled Water

¼ Cup Apple Cider Vinegar

1 Tablespoon Olive Oil

10 Drops Cedarwood Atlas Essential Oil

10 Drops Lemon Essential Oil

You will need a 750 ml spray bottle.


1.       Mix all the above ingredients in a bowl.

2.       Pour the solution into the spray bottle.

3.       Spray a fine mist on your pre-cleaned floors.

Note: Solution 1 works better in killing molds. The milder one could be for regular sanitation. 

An electrostatic microfiber mop would be perfect for the job.  

✔  It acts like a dust and dirt magnet enabling you to cover more area.  

 ✔ With its densely packed absorbent fibers, you would not have to worry about drips seeping into the subfloor.

✔  Its fiber blend of polyester and nylon would not scratch your wooden floors. These two materials were created as alternatives to fine silk.

Once you’re all done, enjoy the perk of an invigorating aroma permeating your home!  😊

What Makes These Ingredients Effective for Fighting Molds on Hardwood Floors?

Distilled Water

Distilled water is 99.99% contaminants-free making it an unlikely grow medium for molds.

Since there are hardly any minerals left in it, no visible residues would be left on your floors, too. Minerals are abrasive. They also leave streaks after a polish.


Vinegar is highly acidic, and molds cannot live in such an environment. Plus, it is antifungal and antibacterial – undoubtedly mold-unfriendly.  

It’s a favorite home remedy for tough spots which is great to have around brown, green, pink, orange, purple, yellow, black, and grey molds.

Apple Cider Vinegar (ACV)

Apple Cider Vinegar has the same microbial-fighting potency as White Vinegar, but some cleaning experts insist that ACV is gentler on hardwood floors.  Hence, safer for frequent use.

Olive Oil

Olive oil “moisturizes” wood and prevents it from drying out, as would the other oils mentioned here, and it’s beneficial.

Consider the facts before you disagree. Most wood-inhabiting fungi need moderate amounts of oxygen to survive.  Since oxygen is depleted in hydrated wood, it becomes mold resistant.

 ACV also serves as a natural varnish giving your floors a polished look.

Rubbing Alcohol

Rubbing alcohol is a go-to disinfectant and could kill a wide variety of germs, fungi included.

Dishwashing Liquid

Dishwashing liquid would help dissolve grime and other hard-to-remove dirt particles.

Lemon, Tea Tree, Peppermint, and Cedarwood Atlas Essential Oils

These aromatic health boosters are staples in most natural cleaning products for the solid microbial defense they provide.    

           Lemon oil is antibacterial and works well in sanitizing your floors and neutralizing noxious odors.  Sticky dirt particles are no match for it as well.

           Tea Tree oil eliminates most types of disease-causing microorganisms, i.e., viruses, fungi, and bacteria.  Moms swear by its soothing aroma.

Peppermint oil is also a strong antimicrobial. The cooling sensation derived from its scent is calming and mood-lifting. Exactly the boost you need for loads of work ahead. 😉

Cedarwood Atlas oil fights germs and repels roaches, ants, and other pesky bugs.  Its woodsy smell reminds you of nature and relaxes your nerves.   

Although these cleaners do not have harsh chemicals in them, it’s better to err on the side of caution. 

Twice weekly should be more than enough deep cleaning for your floors.

As with all health products, ask your GP about the safety of the essential oils listed above.

Diligence and vigilance are keys to staying on top of things. Keep these preventive measures in mind for mold-free hardwood floors and beyond.  😉

·       Stick to a cleaning routine to help you spot problem areas right away and act promptly.

·       Remember to use damp rather than wet cloth or mop on your floors.

·       Use floor cleaning solutions sparingly.

·       Clean up liquid spills right away.

·       Keep your house well-ventilated.

·       Check plumbing, windows, and doors for water leakage.

·       Pick a designated place for wet shoes, bags, and the like.


Knowing the red flags that point to mold presence under hardwood floors, gaining expertise in whipping up natural anti-mold killers, and adhering to every preventive measure in the book for the sake of floorboards may sound like a tall order for most, but not for those who value the good things in life.

Something about the look of hardwood adds “warmth” to a home which is a good thing – and good things are hard to come by these days. Perhaps, this is the reason why some would go to the lengths to protect such an expensive fixture.  

So, go ahead and do what it takes to preserve that priceless ambiance with which life with your loved ones happens. Warmth in a home – so worth it. 😊

Frequently Asked Questions

1.       How long does it take for mold to grow under wood flooring?

It only takes 1 to 2 days for molds to grow when moisture is present.

2.       How to avoid molds from forming on floorboards under a carpet?

Wash it using an anti-mold solution and let it dry under the sun regularly. Follow the above recommendations to mold-proof your floors and home.

3.       How do you tell if there is moisture under hardwood floors?

Wood planks expand when it absorbs moisture and would push at each other creating a wavy look.

4.       How do I treat mold under my floor?

Apply a solution of borax (1cup of borax to a gallon of water) to kill off spores and molds and let it sit for 24 hours. Spray another layer of the borax solution to guard against re-infestation.

5.       Do you have to throw everything away with mold?

No, you can keep non-porous items that could be thoroughly disinfected.

6.       What kills black mold under subfloors?

A solution of (1 part) baking soda, (5 parts) distilled white vinegar, and (1 part) distilled water would effectively get rid of black molds.

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