Mold on Plywood: How to Prevent Mold on Plywood?

December 24, 2025

Mold can have numerous adverse effects, including ruining wood, shortening its lifespan, and contaminating the air quality of a home or business. Mold damages plywood, costs a homeowner to replace or repair much more than if it was treated before it spread deep into the wood.

This guide will detail the causes of mold, how to manage it, how to treat affected areas, and provide preventative steps to maintain clean, long-lasting plywood products. These preventative measures are cost effective and provide an efficient method to eliminate the presence of mold on plywood products.

Mold Grows on Plywood for Many Reasons

Mold has three essential ingredients for growth, which are the following:

Humidity
Organic Material (wood fibres)
Warm, stagnant air

Because plywood is porous, it will absorb humidity from the air. Bathrooms, kitchens, basements and locations outside are major contributors to moisture build-up on plywood products. Other factors for increasing mold include poor ventilation, leaking pipes and damp concrete flooring.

Signs of mold or mold development include:

Green or black patches
Musty smell
The softening or discoloration of the wood
The expansion and warping of wood

Not addressing these signs of mold will permit further penetration into the wood, thus making treatment much more challenging. It is essential to kill mold on plywood products as soon as possible before it spreads. Plywood that is located in an area where there is continually some moisture under sinks, cabinets, etc. should be kept dry and well-ventilated to prevent mold from developing.

Best Ways to Prevent Mold from Developing on Plywood

Many builders and homeowners would like to know how to prevent mold on plywood before it is affected. Preventing the growth of mold on plywood is usually the most economical way of dealing with the problem.

Ways to accomplish this include:

Reducing Moisture Exposure

Plywood should not be kept near a continual source of water. Ensure leaks are sealed, improve drainage, and do not store plywood directly on damp concrete floors.

Improving Air Circulation

Improving the air circulation around your plywood will remove the moisture in the air. Open windows, use vents, or use exhaust fans in the kitchen and bathroom to help improve the circulation of air.

Applying Protective Coatings

Apply to your plywood one of three types of coatings:

Waterproof sealant
Wood preservative
Anti-fungal coating

By using one of these coatings, you will add a barrier to any potential growth of mold on plywood.

Control the Humidity Inside your Home

Using a dehumidifier will help keep the humidity level controlled in your basement or storage area, and need to be set at 40–60% relative humidity. The less moisture in your home, the better it is for your plywood.

Use Dry and Seasoned Plywood

When purchasing and prior to installation, ensure that your plywood is low moisture content and seasoned. Having dry plywood will significantly improve your chances of preventing mold growth.

How to Kill Mold on Plywood

If you already have mold present, do not be alarmed. There are ways to kill mold on plywood with the right process. Here are some guidelines to achieve this:

STEP 1: Wear your safety gear!

It is advisable to wear gloves, a mask, and goggles as well because the mold spores can cause skin and lung irritation.

STEP 2: Dry out the area.

Eliminate the source of moisture. Drying out the area will prevent any additional mold from developing.

STEP 3: Remove the surface growth.

Using a scrub brush, scrub away the mold. This will loosen the mold from the surface and make it easier to clean.

STEP 4: Apply a cleaning solution.

Some suggested cleaning solutions include:

Vinegar
Borax
Hydrogen peroxide
Commercial mold killants.

These solutions will penetrate deeper into the wood to kill the mold that is present. Be sure to allow the cleaning solution to remain on the surface before rinse off.

STEP 5: Drying completely is essential.

Drying the wood using either fans, or sunlight will ensure that all moisture from the cleaning process has evaporated. Mold can return if the wood isn't dried completely. Using a protective coating after removing the mold will not only promote long-term effectiveness of the cleaning process but also help prevent recurrence of mold on the wood surface by stopping any future moisture from entering into the wood.

Where You Can Expect To Find Mold Growth On Plywood

You will likely find the highest levels of moisture in the following areas of your home: Bathrooms, Modular Kitchen Areas, Laundry Areas, Attics, Basements, Balconies, and Storage Areas.

These areas have constant fluctuations in humidity. Additionally, leaky faucets and high levels of condensation created by steam and heat from hot water will create a constantly humid environment.

Selecting High Quality Plywood Products To Minimize Mold Growth

Using quality plywood products provides you with a means to help minimize the growth of the mold on plywood. Quality plywood products are manufactured with quality hardwood veneers, quality adhesives, and moisture resistant construction methods. The installation of these quality products in kitchens, bathrooms, or for any term or outside applications will provide a much better level of overall performance than installing less expensive products.

Properly sealing the edges of each piece of plywood, as well as ensuring the production of all parts, and using a qualified installer, will increase the likelihood of preventing mold growth from future moisture exposure on plywood.

Best Practices for Maintaining Plywood for Longevity

Following a few simple routines will help your plywood to last longer than if you do not.

Check regularly for stains or wet spots
Clean up spills as soon as they happen
Don’t place pressure on the wet side of your wall by putting furniture against it
Always apply an anti-fungal primer prior to painting any plywood surface
Ensure ventilation is maintained through this product

By practicing these suggestions, you are helping to create an environment where mold growth can be prevented on plywood and contribute to a healthy space.

Signs That You Should Replace Your Plywood That Has Moldy Areas

Plywood that has had deep mold infestation, still shows signs of blotching after you’ve cleaned it and/or shows signs of weakened support may require replacement. The only signs of advanced mold on plywood infestation are buckling and the sponge-like feel of the surface. In those instances, replacing sheets may be more cost-effective than long-term repair strategies.

Make sure you check the safety of the area prior to making a decision.

Conclusion

Contact a reliable brand that makes high-quality plywood products designed for moisture-prone areas, such as Royale Touche Plywood.

If you're looking for plywood that can tolerate moisture, rainy conditions and long-term use without the risk of mold on plywood growing on it, check out moisture-resistant plywood from Royale Touche. Their plywood is engineered to provide strength, stability, and longevity. Reach out to their staff for specifications, samples, and expert advice regarding your project, so you can be confident in constructing without worrying about the mold on plywood.

Frequently Asked Questions

How does mold on plywood?

Mold will grow on plywood when it is exposed to excessive moisture, warmth, and/or lack of air circulation. The most likely areas to have mold on plywood are bathrooms, basements, and kitchens.

What's the best way to prevent mold from growing on plywood used indoors?

The best methods to control moisture, provide ventilation, use protective coatings, and conduct regular checks of the condition of any plywood in use indoors.

What products kill mold on plywood and are safe to use?

The most common household items that can be used to kill mold on plywood include vinegar, borax, and hydrogen peroxide. You can also purchase commercial mold-management products that can be used for deep-cleaning mold on plywood.

Is it possible to eradicate mold on plywood permanently?

Yes, as long as you keep the area dry and clean, the plywood can be cleaned, dried, sealed, and ventilated so it is mold-free.

Will mold weaken the structural integrity of plywood?

Yes, long-term mold growth on plywood will result in weakened structural integrity, discolouration, foul odors, and poor indoor air quality; therefore, it's critical to take preventative measures early on.

7 Easy Ways to Clean Plywood Furniture