A typical question I get after customers have their sauna running for a month or two is about cleaning. "Brian, the benches are getting darker. What do I do?"
I've walked thousands of homeowners through similar conversations on sauna care. Sauna cleaning is straightforward once you know what works and, more importantly, what damages the interior wood.
Here's the process I recommend.
Key Takeaways
- Wipe sauna benches and ventilate after every session. Sixty seconds prevents 90% of deep cleaning needs.
- Warm water and a soft brush handle most routine cleaning. Skip harsh chemicals.
- Deep clean the sauna regularly — monthly for home, weekly for commercial.
- Mold means a ventilation problem. Fix airflow first, then scrub the surface.
- Never seal interior sauna wood with varnish or paint. The wood needs to breathe.
Why Regular Sauna Cleaning Matters
Your sauna runs hot and wet. That combination breeds bacteria, mold, and mildew if moisture sits. Sweat oils and salts stain the wood over time. Customers who skip cleaning for six months end up with benches that look ten years old. The ones who spend sixty seconds after each session? Their saunas look new after five years.
The health side matters too. Cardiovascular recovery, stress reduction, better sleep — these benefits land harder when the air in that hot room is clean and free of dirt.
Essential Sauna Cleaning Supplies
You don't need much. Here's what I tell every customer:
Use these:
- Soft brush or damp sponge (no metal bristles, ever)
- Shop vacuum for floor dirt
- Warm water with a few drops of mild detergent (pH-neutral)
- Baking soda paste for sweat stains
- White vinegar diluted 1:4 with warm water for sanitizing sauna surfaces
- Fine-grit sandpaper (220 grit) for stubborn discoloration
- Clean towels
- Paraffin oil for benches once or twice a year (optional)
Never use these inside a sauna:
- Bleach in any form except diluted last-resort use
- Pine Sol or scented cleaners (they off-gas in the hot room)
- Pressure washers
- Varnish or paint on interior surfaces
- Cold water on hot wood
Pine Sol comes up constantly because people see it recommended online. Don't use it. Anything with fragrance or heavy chemicals releases fumes into your next session, and the hot room amplifies everything. Warm water and mild detergent handle everything you need.
How to Clean a Sauna: Step by Step
Step 1: Let the Sauna Cool to Warm
Not cold. Not still hot. Warm wood cleans better because the pores stay slightly open. Around 100°F to 110°F. Remove towels, buckets, ladles, and any sauna accessories before you start.
Step 2: Vacuum or Sweep All Surfaces
Use a shop vac or soft broom. Get under the benches, around the heater base, corners, door threshold. Dust, hair, dead skin, dirt — all of it. Two minutes, and it makes everything after more effective.
Step 3: Scrub Benches and Sauna Walls
Mix warm water with a few drops of mild detergent. Dip your soft brush and lightly scrub with the wood grain. Always with the grain. Start from the top bench and work down so wet, dirty water flows the right direction.
Bench seating surfaces get the most attention — that's where sweat concentrates from sitting and where darkening starts. Sauna walls get a damp sponge and plain warm water. Rinse your brush frequently.
Step 4: Treat Stains
Baking soda paste works on sweat stains. Mix with warm water, apply directly, let it sit ten minutes, scrub lightly with the brush, rinse. For a stain that won't respond, sand with 220-grit along the grain and wipe the dust with a damp cloth.
I've had customers panic over a dark stain on cedar benches that came out in thirty seconds with baking soda. Try it before you sand.
Step 5: Sanitize
Spray diluted white vinegar (one part vinegar, four parts warm water) lightly across all sauna surfaces. Don't soak the wood — just mist it. Leave the door open and let it air dry. Hydrogen peroxide at 3% works as an alternative. Either kills bacteria without degrading wood fibers the way bleach does.
Step 6: Dry and Ventilate
The step that matters most and the one people skip. Leave the sauna door fully open. Open all vents. Want to speed it up? Run the heater on low for 15 to 30 minutes. Wipe any pooled water off bench surfaces.
Excess moisture left wet on wood is how mold starts. Every time.
Cleaning by Sauna Type
Traditional sauna
Follow the full process above. The zone behind the heater collects mineral deposits from löyly water and needs routine checks most people miss.
Infrared sauna
Dust and skin cells on the heater panels are the main issue, not humidity. Wipe carbon or ceramic panels with a dry microfiber cloth when fully cool. Never spray liquid on infrared emitters. Monthly deep cleans cover home users with minimal maintenance.
Barrel sauna and outdoor builds
Curved seams where bench meets wall collect dirt faster than you'd expect. Vacuum carefully. Treat exterior walls with a sauna-safe stain annually. Periodically check the drainage bung. Interior cleaning follows the same six steps.
Wood fired sauna
Remove ash from the stove regularly and clean the chimney annually. Fire risk from ash buildup in the stove is real. Not optional. Inspect the stove door gasket while you're in there.
How to Remove Mold from a Sauna
Mold shows up as black or green spots in corners, under benches, or around the door frame. A musty smell confirms it.
Spray undiluted white vinegar directly on the mold. Let it sit 15 to 30 minutes. Scrub with a stiff brush, rinse with clean warm water, dry completely. If mold has gone below the surface, sand down a millimeter or two and reapply vinegar.
The real fix: mold means your ventilation is inadequate. Full stop. Intake low, exhaust high. If you close the door immediately after every session and never open the vents, you will grow mold no matter how often you scrub. Surface treatment buys time. Fixing airflow solves it for free.
How to Clean Sauna Stones and Heater
Pull stones from the heater when fully cool. Rinse under running water, scrub off mineral deposits with the brush, inspect each stone for cracks. Discard the damaged ones. Arrange loosely for airflow when you replace them — don't pack tight. Rinse and inspect stones once or twice a year depending on usage. If you're in a hard water area, expect more frequent cleaning — hard water leaves limescale on stones and heater surfaces faster than most people realize.
Replace stones every one to two years depending on use. Tip: if a stone crumbles when you squeeze it, it's done. We carry replacements at The Sauna Place.
For the heater, vacuum around the base and wipe the exterior housing with a damp cloth. Never spray water on electrical components.
Sauna Cleaning Schedule
After every session
Wipe benches with your towel. Leave the door open 30 minutes to ventilate. Always sit on a towel during sessions — it prevents sweat from soaking into the wood and stops most stains before they start.
Weekly
Vacuum the floor and under benches. Quick scrub of sauna surfaces with warm water.
Monthly
Full six-step deep clean. Inspect wood for mold or stain. Clean sauna accessories. Apply paraffin oil if benches look dry.
Quarterly
Sand persistent stain spots. Inspect heater and stones. Routine checks on door seals. Treat exterior walls.
Annually
Full inspection of heater elements, wiring, structural integrity. Replace cracked stones. Deep sand and refinish benches with paraffin oil if needed. This is the sauna care that protects your investment long-term.
Common Mistakes
Too much water tops the list. Wood absorbs moisture and warps when it stays wet. Cleaning while the sauna is still hot risks burns and accelerates off-gassing. Sanding against the grain leaves scratches you can't undo without taking the whole surface down.
Sealing interior wood with varnish or paint is the worst mistake I see, and I see it more than I should. Varnish prevents the wood from breathing, the surface overheats, and whatever's in that finish goes into the air you're sitting in. Tile or sealed finishes belong in a shower, not a sauna. Leave interior wood natural. Always.
Frequently Asked Questions
How often should I deep clean my sauna?
Monthly for a home unit running two to four sessions a week. Commercial saunas need it weekly. The real work happens in the after-session wipe-down. Skip that and monthly deep cleans won't keep up. Tips like a 30-second towel wipe make the difference.
Can I use bleach to clean sauna wood?
Last resort only. One capful per gallon of warm water, only for severe mold when vinegar hasn't worked. Bleach degrades wood fibers and leaves residue that off-gasses in the hot room. White vinegar handles the same job without those problems.
Should I oil my sauna benches?
Once or twice a year, paraffin oil applied sparingly reduces sweat absorption. Paraffin oil is the only oil I recommend for interior benches. Avoid cooking oils and furniture polish — both cause problems. Keep paraffin oil well away from the heater.
What's the best way to prevent sauna odor?
Persistent odor means bacteria or trapped sweat oils have worked into the wood. Deep clean with vinegar, lightly sand affected surfaces, follow up with paraffin oil. A bowl of baking soda overnight pulls lingering smells out. But none of that sticks without fixing ventilation first.
Is infrared sauna cleaning different?
Lower moisture means lower frequency and minimal maintenance compared to a traditional sauna. Wipe heater panels dry, clean the glass door with diluted vinegar, monthly deep cleans are enough. Wood care stays identical.
Sauna maintenance doesn't need to be complicated. Sixty seconds after each session and a monthly deep clean keep the wood right and the air clean for years. Ventilation is the single most important habit. Always leave the door open after your session.