A sauna at full temperature is already doing half the cleaning for you. Most bacteria and fungi multiply between 4°C and 60°C. A full Finnish sauna sits between 70°C and 100°C. The athletes foot fungus, staph, and the virus behind plantar warts all struggle in a dry 85°C room. The problem starts when you leave.
The moment you step out, the temperature drops. Steam condenses on the wood. Sweat soaks into the bench surface. For the next several hours, sometimes overnight, the room sits in a comfortable microbial range. That cooling phase is the cleaning target. You do not clean a sauna to disinfect a hot room. You clean it to remove the fuel and water that microbes need during the cool down.
Sweat is mostly water with salt, urea, and small amounts of amino acids. Once that mix dries on wood, it becomes a thin nutrient film. Add moderate temperature and trapped humidity, and you have a growth medium. The cleaning routine is about breaking that chain before it starts.
This advice applies to dry saunas, not steam rooms. A steam room stays wet and warm around the clock, which is exactly where microbes thrive. Steam rooms need frequent cleaning with disinfectants approved for wet surfaces. A dry sauna's advantage is the dry heat, so the cleaning routine should protect that dryness.
What Finnish sauna culture got right
Shared saunas in Finland have existed for centuries without modern disinfectants. The routine was built into the weekly sauna day. After the last person finished, the benches got scrubbed with water and mild soap, traditionally a birch ash lye or later a pine tar soap. The floor was swept and washed. Then the sauna was left with the door open or the vent open to dry completely before the next firing. Drying was the default, not a special step.
Early smoke saunas had no chimney. Smoke filled the room and was released before use. The walls darkened with soot, but the benches still got scrubbed. The point was never to make the room sterile. The point was to remove sweat and leave dry wood.
The towel was standard equipment. Nobody sat bare-skinned on the bench. The towel carried your sweat off with you and got washed elsewhere. That single habit removes most of the cleaning burden before it starts. American gym and spa sauna culture often skips that step, then tries to make up for it with heavy disinfectants afterward. The room does not need a disinfectant attack. It needs less sweat on the wood and more dry air.
Cedar is working with you
Sauna benches are often made from western red cedar, spruce, or aspen. Cedar has a practical advantage beyond its smell. Western red cedar contains natural compounds called thujaplicins that discourage fungal and bacterial growth. This is a property of the wood, not a marketing claim. The effect is mild, and it does not replace cleaning. But a dry cedar bench resists microbial colonization better than plastic or tile.
The wood only does this work when it stays dry. Soak it with water or let it sit damp, and the natural oils leach out and the wood becomes a habitat. That is another reason the Finnish method avoids soaking the wood. You wipe it with a damp cloth, scrub lightly along the grain, and dry it. You do not hose it down.
Skin infections men actually face
Men who use saunas regularly are often doing it for cardiovascular and recovery benefits. The Finnish cohort research led by Laukkanen and published in JAMA Internal Medicine in 2015 followed 2,315 middle-aged men for about two decades. Men who used a sauna four to seven times per week had lower rates of cardiovascular death compared to men who used it once a week. If you are spending that kind of time in a hot wooden box, the condition of that box matters.
The main risks in a shared sauna are skin infections. Athletes foot, a fungal infection called tinea pedis, thrives on damp floors and duckboards. Plantar warts, caused by certain strains of human papillomavirus, can pass from wet surfaces to bare feet. Staph bacteria, including MRSA in some cases, can survive on skin and transfer to benches. These are not abstract fears. Gyms and spas deal with them regularly. If a skin problem persists, talk to a doctor. Cleaning and prevention are not treatment.
The preventive moves are simple. Sit on a towel, always. Wear sandals or sauna shoes on wet floors. Dry the sauna after use if it is yours. These three habits do more than any cleaning product.
What to use
For routine cleaning you need four things: warm water, a mild soap, a soft brush, and a dry cloth. That is the entire kit.
- Mild soap. A traditional Finnish choice is pine tar soap, still sold in Finland and Scandinavia. Any mild liquid castile soap or natural dish soap works. The key is minimal fragrance and no heavy degreasers.
- Soft brush. Scrub lightly along the grain of the wood.
- Clean damp cloth. Use it to rinse the soap off.
- Dry cloth. Wipe the surface down and leave the door open.
Soap does not need to sterilize if you are physically removing the sweat film and drying the surface. Sterilization is not the goal in a dry sauna. Removal and dryness do the real work.
For dark spots or stains, use fine sandpaper instead of more chemistry. Light sanding removes the surface layer where sweat and skin oils have built up. Sand, vacuum the dust, wipe with a damp cloth, and dry. This works better than scrubbing with strong cleaners and does not soak the wood.
If you want a quick sanitizing wipe for high-touch areas like the door handle or bucket ladle, isopropyl alcohol on a cloth works and evaporates fast. Make sure the room is off and cool, and let it fully evaporate before the next heating. For the benches themselves, soap, water, and drying are enough.
What to skip and why
Skip the bleach. Chlorine bleach is corrosive to wood and can off-gas in a hot enclosed room, which can irritate your airways. Ammonia-based cleaners are worse in heat. Strong disinfectants tend to leave residues that get heated during your next session and released into the air you breathe. A hot sauna is a small sealed space. Whatever you put on the wood ends up in the air.
Skip the pressure washer and the hose. Soaking the wood causes swelling and creates exactly the damp environment you are trying to avoid. If the bench gets soaked, dry it thoroughly and let the room air out.
Skip scented sprays. The heat will release those fragrances into a small space, and some people react to them. If the sauna needs a scent, add a few drops of birch or eucalyptus essential oil to the water bucket. Do not pour oil on the stones.
A schedule that works
- After every session. Take your towel out with you. Leave the vent or door open for at least an hour. Wipe any visible sweat pools off the bench with a damp cloth, then a dry one.
- Weekly, or every three to five sessions if you are a daily user. Wash benches and backrests with warm water and mild soap. Scrub lightly with a soft brush along the grain. Rinse with a damp cloth. Dry with a clean towel and leave the door open.
- Monthly. Pull up the duckboards and check for mold or dark stains. Wash them with soap and water, scrub, rinse, and dry. Check the floor for standing water or damp spots. Lightly sand any bench areas that look dark or feel greasy.
- Annually. Wash the walls and ceiling with mild soap and water if they show buildup. Check the ventilation outlet for dust and obstruction.
Why drying beats disinfecting
Heat is a natural antimicrobial. The problem has never been the hot phase. It is the wet phase that follows. Remove the sweat, remove the water, and keep the wood dry, and the room mostly maintains itself. That is the Finnish insight, backed by basic microbiology rather than any special product. The modern urge to disinfect everything comes from environments that do not have a sauna's thermal advantage.
If you take one thing from this, take the towel. Then take the drying habit. The rest is just maintenance.
This content is for educational purposes only and is not medical advice. For any skin infection or persistent health concern, consult a healthcare professional.
Frequently asked questions
how often should i clean my sauna
Wash the benches and backrests with mild soap and water weekly if you use the sauna often. After every session, wipe visible sweat and leave the door or vent open for at least an hour. Pull up the duckboards monthly to check for mold and damp spots.
can i use bleach to clean a sauna
Skip it. Bleach is corrosive to wood and can off-gas in a hot enclosed room, which can irritate your airways. Mild soap, water, and thorough drying handle a dry sauna's cleaning needs without the residue.
do i need to disinfect sauna benches
No. The heat already keeps most bacteria and fungi from multiplying. Removing sweat and drying the wood matters more than spraying disinfectants, which leave residues that heat releases into the air.
why sit on a towel in the sauna
A towel catches your sweat before it soaks into the bench. That single habit removes most of the moisture that feeds microbes during the cooling phase after you leave. Wash the towel in your regular laundry, and the bench stays dry and cleaner.