A sauna looks after itself better than most rooms. The heat dries it out after every session, and bare wood has no finish to peel. That is also why cleaning it wrong does more harm than not cleaning it.
Sauna makers do publish care instructions, usually on the last page of a manual nobody reads. This article turns one of them into a schedule. For which accessories to buy first, start with the sauna accessories guide.
Short answer: sit on a towel, empty the bucket after every session, scrub the benches with a soft brush and mild soap when they need it, and keep stains, sealers, and harsh chemicals away from the wood.
Where this comes from
Harvia makes the heaters in several saunas we list. The maintenance page of its KIP heater manual has twelve points on looking after the sauna room. They were written for electric heaters in traditional saunas, and the wood care applies to any sauna. Check your own manual as well, since your maker’s instructions come first.
After every session
- Empty the bucket. Harvia says clean water should always be used and “water should be dumped out after every use.” Standing water leaves a film and, in a wooden bucket, encourages leaks.
- Leave the door open for a while. Let the remaining heat dry the room.
- Hang towels outside. The manual warns against putting anything combustible over the heater, and names towels.
Every week or two
Benches. The manual says to “scrub benches with a soft brush, using soap and water or a mild disinfectant, when needed,” about once a week in commercial saunas, “or depending upon Sauna usage.” A home sauna used three times a week needs it less often. Go by look and smell.
Use little water and let the benches dry with the door open before the next heat-up.
Floor. Harvia says to take out any removable flooring, wash the waterproof floor underneath with disinfectant, and hose off the removable sections. Once a week in heavy use, or as needed.
Heater. Wipe water stains off the heater’s outer surface with a damp cloth, with the power off and the heater cold.
Every few months
Bucket and ladle. The manual says to “scour buckets and dippers occasionally when film collects from usage.” It also recommends a plastic liner in the bucket to prevent leaks. The Harvia 4L bucket has one built in.
Glass. Clean the door glass with a soft cloth. Harvia suggests sealing the wood around the glass in the door, inside and out, to prevent warping. That is the one place the manual recommends a sealer.
Benches, again. Look for dark patches where people sit. Harvia says wood stained by perspiration “may be lightly sanded with fine sandpaper.” Sand lightly, with the grain, and vacuum the dust.
Every few years
Stones. The manual says the heater needs no special maintenance when installed properly, and that “after 5 years of usage, the rocks may need replacing if they have crumbled or powdered.” Heavy use shortens that. If the stones look broken down when you check them, replace them.
What not to do
Here’s what the spec sheet won’t tell you. Some well-meant cleaning does more harm than good.
- No stains or sealers on the benches or walls. Harvia: “We do not recommend stains or sealers as toxic vapors may appear when heated.”
- No pool or spa water on the stones. The manual says to use clean tap water only. Chlorinated water can produce chlorine gas and damage the heating elements.
- No carpet. Harvia says carpet becomes a breeding ground for bacteria in a sauna’s moist conditions and advises against it. It says the same of wooden duckboard used as flooring.
- No pressure washer. This is my advice, not the manual’s. High pressure tears the soft surface of bare wood.
- No soaking. Wood that stays wet between sessions stains and smells. Use a damp brush, not a hose, on anything wooden.
The floor matters most
Harvia “strongly recommend[s] a floor that can be easily cleaned (concrete, ceramic tile, or a poured type of flooring).” In new construction it suggests a floor drain. If you are still planning the room, this is the decision that makes cleaning easy for the next twenty years.
The towel does most of the work
One line in the manual does more than the rest: “For sanitation, each bather should sit or lie on a towel (this will prolong bench life).” Sweat that lands on a towel never reaches the wood.
Use a towel long enough to cover the bench from your seat to your feet, and wash it after each session. A full-length sauna towel such as the Harvia Cotton Sauna Towel is 170 cm long for that reason.
Infrared cabins
There are no stones and no water, so there is less to do. Sit on a towel, wipe the bench and floor with a damp cloth, and keep liquids away from the heater panels and the control panel. Follow the cabin maker’s instructions for the panels themselves.
A cleaning kit
You need very little: a soft-bristled brush, a bucket for cleaning that is not your sauna bucket, mild soap, a few cloths, and a sheet of fine sandpaper.
My rule of thumb: if a product has a strong smell at room temperature, don’t use it in a room you’re about to heat to 180°F.
Bottom line: a towel under every bather and a soft brush now and then. Keep finishes and strong chemicals out, and the heat does the rest.
Sources
- Harvia, KIP electric sauna heater owner’s/operator’s manual (North America), maintenance instructions, September 17, 2015: almostheaven.net
- Harvia 4L bucket and Harvia Cotton Sauna Towel listings, checked September and October 2026