4 Proven Methods To Prevent Mold In Your Sauna

Whether you have a brand new infrared sauna or a seasoned outdoor traditional sauna, the menace of mold is probably a constant worry, and rightly so. Mold can grow in a sauna due to the presence of excess moisture especially in traditional steam saunas.

Mold in saunas not only threatens your health with bacterial exposure but also jeopardizes the integrity of your sauna's wood, potentially leading to its decay and deterioration. 

Fortunately, safeguarding your sauna against this threat is a simple task that will ensure years of worry-free sessions with your favorite steamy hideaway.

You'll learn proven methods to prevent mold such as:

• Effective ventilation reduces mold by preventing stagnant air from settling in your sauna especially in basement saunas or areas with less air flow.
• Untreated wood prevents the accumulation of moisture that would otherwise foster an environment for mold growth.
• Consistent sauna cleaning hinders mold development, thereby maintaining the sauna's structural integrity.

Method 1: Ensure Proper Air Flow to Prevent Mold

Proper ventilation is by far the most important measure to take in preventing mold growth in your sauna, primarily because it disrupts the fungal reproduction process.

Mold thrives in damp and humid environments, sprouting up year-round. As such, a well-ventilated sauna denies the fungus these conducive conditions by preventing moisture accumulation and stagnant air.

That said, there are a couple of steps to take that promote proper airflow, and the first is to ensure your sauna has an in-built vent or two to get air circulating during operation.

This requirement is especially critical for traditional saunas, which rely on steam to function. It's also an important step for infrared saunas, which experience high humidity levels from a user's sweat and stale air buildup from breathing.

Consequently, many infrared saunas such as feature inbuilt roof vents for air circulation. Roof vents are more effective as hot air rises, drawing more vapor out of your sauna.

As such, the vents effectively expel rising hot and humid air from the roof while drawing in fresh air from the lower sections, such as beneath the door frame.

The second ventilation measure is to leave the sauna door open for a half hour or so after sessions so the sauna can completely dry out.

Luckily, the high heat of saunas (190° F for traditional and 145° F for infrared) really helps dry things out quickly so long as it's not too steamy in the sauna.

Need a sauna with the best airflow?

The below Dynamic Saunas Venice 2 Person has excellent airflow to help avoid mold taking hold. In addition to promoting air circulation, the roof vent also assists in the dissipation of humidity, which prevents mold growth.

Method 2: Don't Paint, Varnish or Apply Sealant to Your Sauna

This one might be obvious to a lot of people, but we get questions about this all the time.

Bottom line - don't paint, varnish, or seal the inside of your sauna. Mold, in sauna conditions, can really get a hold of the wood under the sealant if you do this.

You want the wood untreated so it's able to breathe easily and naturally, releasing moisture as the sauna heats up and cools down.

As such, sealing or staining the wood prevents this function and creates a conducive environment for mold to grow over time.

Remember, fungus thrives in damp and humid conditions. So trapping moisture within your sauna's wood structure drives up relative humidity (RH) to above 60%, where it becomes a potent breeding ground for mold.

Ideally, a low humidity of 30% discourages fungal growth with the added advantage of turning away associated pests. However, you want your sauna to be as consistently dry as possible, even below the 30% threshold. This is only possible with a ventilated wood structure, free of obstruction from layers of paint, varnish, and sealants.

Pro Tip: Incorporate humidity and moisture sensors into your sauna to ensure optimal condition in your steamy getaway at all times. Bio-graphene sensors, for instance, are highly accurate and capable of detecting as little as 10% humidity.

Method 3: Practice Regular Cleaning and Inspection

Another really simple mold prevention strategy is to practice regular cleaning. This is primarily due to how fast the fungus grows.

Mold colonies start to develop on damp surfaces as soon as 28–48 hours of exposure to humid environments, reproducing via spores to eventually digest the adjacent organic material (the wood in your sauna).

For perspective, 48 hours is about the time from which the onset of exposure to allergens begins to impact users' health, especially in terms of respiratory wellness.

That said, make sure to wipe your sauna down with a soft-bristled brush and warm water after each use. This is just to clean the dirt and sweat off the wood so you don't have to get into every nook and cranny each time.

Thoroughly clean your sauna at least once a week, depending on how frequently you choose to relax in it.

Take this opportunity to visually inspect your Almost Heaven Grayson 4 Person Sauna for black spots and discoloration. You are looking for dark patches that are usually a sign of mold.

Every month, deep clean your cedar sauna even further. Check and clean the sauna’s ventilation system. Excess moisture may be trapped in the fans and vents.

If you happen to find condensation on these surfaces, it means that your sauna is not drying up as it should.

Also, a soft-bristled brush preserves the wood in your sauna by averting damaging scratches all over the various surfaces.

Still, you'll need to get at any sweaty spots and target excessively wet areas for the cleaning process to be effective. And if you notice dirtier spots or sweat stains over time we suggest using a mild wood cleaner or detergent, along with the soft-bristled brush.

Among our favorites is Murphy Oil Soap. It's a mild wood cleaner with 98% natural ingredients that preserve the integrity and finish of your sauna, from wood color to texture.

Method 4: Always Drain Your Sauna

It's true that not all saunas are built with drains, and that not all saunas need drains in the first place. A case in point is an infrared sauna, which generally doesn't need drains since its operation avoids active steam and moisture creation.

However, if you have a traditional steam sauna that gets lots of use and, consequently, moisture build-up, then installing a drain at the bottom — in a floor panel — is an excellent way to prevent mold.

This approach ties in with the earlier point on humidity and dampness control to discourage mold. By completely draining your sauna, you deny the fungus a conducive, wet environment to grow and reproduce.

To this point, a recent publication in the Journal of Fungi found the viability of C. cladosporioides (common mold species) spores at 40% relative humidity conditions. This emphasizes the need to keep your environment as dry as possible to prevent mold and reinforces the idea of draining your sauna regularly.

Take Action: Keep the humidity levels in your sauna between 10-20% to prevent mold growth. Use a hygrometer to measure the humidity levels and adjust accordingly by adding more ventilation or using a dehumidifier, if necessary.

Why Is Cedar Best Suited for Mold-Resistant Saunas?

Cedar is naturally antimicrobial and helps to keep mold and bacteria from forming and colonizing your sauna. The wood is rich in natural resin, which is a complex mix of acids, alcohols, and phenols that has an antiseptic effect on bacteria and mold.

Acidity disrupts the metabolism of microorganisms, alcohols cause cellular leakage, while phenols interfere with the cellular function of the said microbes. For your Sauna, these actions translate into a natural defense system that prolongs the lifespan of your steamy palace and your investment.

On top of having a resin-rich structure that resists mold, cedar wood also does an amazing job of keeping pests away. Its natural aromatic scent (which humans find pleasant) is particularly toxic to insects. This aspect makes the material certainly ideal for anyone with an outdoor sauna, which is more exposed to pests.

With these and more advantages to enjoy with cedar, check out our selection of awesome cedar saunas in the table below and say no to mold forever.

With the steps described above you shouldn't have any issues with mold. All you have to worry about is your next sauna session!

One more thing! If you're looking for the easiest, most effective way to keep your sauna mold-free, Glenn over at Sauna Times (an awesome everything-DIY-sauna-related website) has a really great article covering the bake and breathe method.

Frequently Asked Questions

How do you get rid of mold in a sauna?

The first thing you'll want to do is find out whether the maker of your sauna has their own specialized cleaning product. This means that it is specifically designed for both the task and the sauna.

Sauna wood cleaner is a solid option for mold cleaning.

Other than that, white vinegar is a solid option for removing mold from your sauna as is creating your own bleach solution from water and bleach (roughly a cup of water to a gallon of water).

Apply it to the surface of the sauna where the mold is, with a cloth and leave it for 2-minutes before rinsing. The other thing you might like to try is a 50:50 mix of water and ammonia. Do a test patch first. Always.

Is sauna mold killed by hot water?

Boiling will kill mold but it's a tougher job than when you use chemicals like bleach or ammonia or specialized cleaning products to do it.

Boiling water will kill mold spores though so it's worth a try if you are not comfortable with the chemical options.

The trick is getting the hottest possible water to the areas of mold in your sauna before the water starts to cool so this can become a somewhat hazardous job that we don't recommend. Be careful!

Does lemon get rid of mold in saunas?

The acids in lemon juice are known to help with removing mold and, if you are uncomfortable with chemicals, it's definitely something to try. In most cases, it won't work as well as specialized sauna cleaning products.

One solution to try is to mix lemon juice with salt paste to the consistency of a soft paste. Do a test patch first. Apply it to the moldy areas of your sauna and wash it off after 2 minutes. Reapply as necessary.

Does cedar wood prevent mold?

Cedar is known as having antimicrobial qualities that make it more difficult for mold to take hold in saunas. That is why many manufacturers choose to have a line of cedar saunas. They also have a beautiful smell that we love!

Sun Valley Saunas boasts a 100+ 5-star reviews on Trustpilot. Find out why other buyers love our cedar sauna products now.

View Our Best-Selling Cedar Saunas

Wes McMahon, is the founder of Sun Valley Saunas and a seasoned ski town sauna enthusiast. In early 2021, Wes transitioned from being an attorney and sauna aficionado in Sun Valley, Idaho, to founding Sun Valley Saunas. His deep appreciation for the Finnish sauna tradition has helped him understand and select high-quality, hand-built saunas for customers throughout North America. Combined with his understanding of the therapeutic and communal benefits of sauna culture, he advocates for the wellness practices that saunas can bring to your overall health. Got questions? Get in touch by calling 1-855-963-5665 or info@sunvalleysaunas.com

Important: The information provided in our articles about saunas and related topics is intended for general informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare practitioner before using saunas, especially if you have pre-existing health conditions or are pregnant. Individual health needs vary, and what benefits one person may not be suitable for another.