How to Clean a Sauna and Prevent Mold (Infrared & Traditional)

Whether you have a brand-new infrared sauna or a well-used outdoor traditional sauna, a little regular cleaning keeps it smelling fresh, protects the wood and keeps mold from getting a foothold. Here's exactly how to clean each type, how often, and what to do if you ever find mold.

How Often Should You Clean a Sauna?

How to Clean a Traditional Sauna

1. 1. Let it cool. Clean when the sauna is warm, not hot.
2. 2. Sweep or vacuum the floor and under the benches.
3. 3. Scrub the benches, backrests and floor with a soft-bristled brush, warm water and a mild wood soap like Murphy Oil Soap. A soft brush won't scratch or raise the grain.
4. 4. Rinse lightly with a damp cloth. Don't soak the wood.
5. 5. Dry it out. Run the heater for 15–30 minutes with the door or vent open, or leave the door open until everything is dry.
6. 6. Keep water off the heater itself, apart from normal löyly on the stones.

How to Clean an Infrared Sauna

Infrared saunas need less cleaning because there's no steam and no standing water, but sweat still ends up on the benches.

1. 1. Unplug or switch off the sauna and let it cool.
2. 2. Wipe the benches, backrest and floor with a cloth dampened with warm water and a little mild soap. Wring it out well.
3. 3. Clean the glass with a glass cleaner sprayed onto a cloth, not directly onto the door.
4. 4. Dust the heater panels with a dry, soft cloth. Never spray water or cleaner on the heating panels or electrical parts.
5. 5. Leave the door open for a while to air it out.

Check your sauna's owner's manual too. Some makers recommend specific cleaners or advise against certain products.

How to Clean Sauna Wood and Remove Sweat Stains

Over time, light-colored woods like hemlock, basswood and aspen can show darker sweat marks on the benches.

• For everyday marks: warm water, a soft brush and a mild wood soap. Murphy Oil Soap is one of our favorites. It's gentle on wood and made with 98% natural ingredients.
• For set-in stains: once the wood is dry, sand lightly with fine sandpaper (around 120–150 grit), following the grain, then wipe away the dust.
• To prevent stains: sit on a towel every session. It's the easiest way to keep the benches looking new.

Never paint, varnish or seal the inside of a sauna. Sauna wood needs to breathe so it can release moisture as it heats and cools. Sealing it traps moisture in the wood and can release fumes in the heat. Some saunas use a special paraffin or sauna-specific oil on the benches, so follow your manufacturer's guidance. For more on how different woods hold up, see the best sauna wood types.

4 Ways to Prevent Mold in Your Sauna

Mold is a fungus that grows on damp surfaces, and wood is one of its favorite foods. The key to preventing it is simple: don't let the sauna stay wet.

1. Keep the Air Moving

Proper ventilation is the most important step. Most saunas have an intake vent low on the wall and an exhaust vent up high. Hot, humid air rises out the top while fresh air comes in below. Keep the vents clear, and make sure the sauna isn't tucked somewhere with no airflow, like a closed-off basement corner.

2. Dry It Out After Every Session

Leave the door open for 20–30 minutes after you're done, or run the heater briefly with the door cracked. The heat that made you sweat dries the sauna out quickly. This matters most for traditional saunas after a steamy session.

3. Clean Regularly

Mold can start growing on damp surfaces within 24 to 48 hours. A quick wipe after each session and a weekly clean keep sweat, skin oils and moisture from building up. Once a month, look closely at the benches, corners and floor for dark spots or discoloration.

4. Let Water Drain Away

Many traditional saunas, especially outdoor barrels, have drain holes or a sloped floor so water from löyly can escape. Keep them clear. Infrared saunas don't need drains, since there's no water involved.

Why Cedar Resists Mold and Decay

Western red cedar is a popular sauna wood for a reason. The USDA Forest Products Laboratory rates cedar heartwood as resistant or very resistant to decay, thanks to natural compounds in the wood. Hemlock, spruce and basswood are rated less resistant, which is one reason good ventilation and drying matter even more in those saunas. Browse our cedar saunas.

What to Do If You Find Mold in Your Sauna

1. 1. Find and fix the moisture problem first. If the sauna isn't drying out, mold will come back.
2. 2. Scrub small spots with a soft brush and a mild soap and water, or with white vinegar. Test any cleaner on a hidden spot first.
3. 3. Bleach is a last resort. If you use it, the CDC recommends no more than one cup of bleach per gallon of water. Wear gloves, ventilate well, and rinse and dry the wood thoroughly before using the sauna again.
4. 4. Never mix bleach with ammonia or other cleaners. The combination produces toxic fumes.
5. 5. Lightly sand any staining once the wood is dry.
6. 6. Replace badly affected boards. If mold has gone deep into the wood or keeps coming back, replacing that board is safer than scrubbing it again. Call us and we can help you find parts.

If the mold covers a large area or you have asthma or a weakened immune system, consider a professional.

FAQs

How do you clean a sauna?

Wipe it down after every session, then once a week scrub the benches and floor with warm water, mild soap and a soft brush. Rinse lightly and let it dry completely with the door open.

How do you clean an infrared sauna?

Wipe the benches with a damp cloth and mild soap, clean the glass with a cloth, and dust the heating panels with a dry cloth. Never spray liquid on the heaters or electrical parts.

Can you use vinegar to clean a sauna?

Yes. Diluted white vinegar works well on small mold spots and odors. Test it on a hidden area first, then rinse and dry the wood.

Should you seal or varnish the inside of a sauna?

No. Interior sauna wood should stay untreated so it can release moisture. Sealing traps moisture and can release fumes when heated.

Do saunas get moldy?

They can, if they stay damp. Traditional saunas are more at risk because of the steam. Good ventilation, drying the sauna after each session and regular cleaning prevent it in most cases.

Sun Valley Saunas has 100+ 5-star reviews on Trustpilot. Find out why other buyers love our cedar saunas.

View Our Best-Selling Cedar Saunas

References

CDC: How to safely clean up and prevent mold growth
FEMA: Dealing with mold and mildew
EPA: What is mold?
USDA Forest Products Laboratory: Comparative decay resistance of heartwood of native species

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.