Sauna Maintenance — Keeping a Good Sauna Good

Maintenance is the stuff you can do yourself with a towel, a brush, and an hour every few months. Do it and a sauna lasts decades. Skip it and the wood goes gray, the heater struggles, and the room starts to smell.

Cleaning

The single most important habit isn't scrubbing — it's drying. After every session, leave the door open and let the room air out completely. Trapped moisture is what rots sauna wood and grows mildew, not the heat. Wipe the benches down after you use them so sweat doesn't soak into the grain.

Every month or two, do a deeper clean: scrub the benches, backrests, and floor with warm water and a little mild soap or a dedicated sauna cleaner, then rinse and let it dry fully before you close it up. If the benches have gotten dingy or stained, a light sanding brings the fresh wood back — you don't need to replace anything. Don't use bleach or harsh chemicals; the wood holds the smell and you'll breathe it next session.

Caring for the Wood

The big rule: don't seal or varnish the interior wood. A sealed surface traps heat, gets too hot to sit on, and eventually peels. Bare cedar, hemlock, or aspen is supposed to breathe — that's how it handles the moisture. If you want, you can treat the benches with a food-safe paraffin sauna oil, which helps them shed sweat and water, but it's optional, not required.

The exterior is the opposite story. Outdoor siding takes rain, snow, and UV, and a good stain or sealer every couple of years is what keeps it from graying and checking. If your outdoor sauna is looking weathered, that's usually a refinish, not a rebuild.

Restacking and Replacing the Rocks

People forget the rocks are a consumable. They crack from the constant heating and cooling, and as they break down the small pieces pack together and choke the airflow up through the heater. A heater that can't breathe runs hotter than it should and wears out faster.

Once a year, pull all the rocks out, toss anything cracked or crumbling, rinse the dust off the rest, and restack them loosely so air moves through — bigger rocks on the bottom, smaller toward the top, not jammed in tight. Plan on fully replacing the set every couple of years. Use real sauna stones (peridotite or olivine), not rocks from the yard or creek, which can hold water and crack or pop when they heat up.

The Heater — When the Sauna Won't Get Hot

The most common complaint we hear about an older sauna is simple: it doesn't get hot like it used to, or it never gets all the way up to temperature. A good traditional sauna should hit 170–195°F. If yours stalls out at 140 or 150 and takes forever to get there, something's wrong, and it's usually the heater.

On an electric heater, the usual culprit is a burned-out heating element. Most heaters have three or more elements, and they don't all fail at once — when one goes, the heater still turns on and still glows, so it looks fine, but it's only putting out a fraction of its rated power and it can't reach temperature. Elements are a wear item; they thin out and crack over years of heating and cooling, and they go faster if the rocks are packed too tight and choking the airflow. The good news is elements are replaceable — you don't need a whole new heater. You match the wattage and voltage to your unit, swap the bad one (or do the whole set if the heater's old), and you're back to full output.

The other common failure is the thermostat or the temperature sensor. If the sauna shuts off way too early, never kicks back on, or runs wildly hot and cold, the thermostat or the sensor that feeds it is usually the problem — a sensor drifts out of calibration or a contactor wears out, and the heater stops trusting the room temperature. On a standalone controller this is a straightforward part swap; on a built-in unit it's a bit more involved. Either way it's a repair, not a teardown.

Not every "won't get hot" problem is the heater, though. If the elements and thermostat check out, the next things to look at are whether the heater was ever sized right for the room (an undersized heater never wins — figure roughly 1 kW per 45–50 cubic feet of sauna), and whether the room is losing the heat through failed insulation, a missing or torn vapor barrier, or a leaky door and single-pane glass. A sauna that used to heat fine and slowly got weaker is almost always a dying element. A sauna that never heated well from day one is usually undersized or under-insulated. Tell us which one yours is and we can point you at the fix.

Sauna Renovation — Fixing What Was Never Right

Renovation is the next level up: changing something about how the sauna is built, not just keeping it clean. These are the upgrades we get asked about most, roughly in the order of how much difference they make.

Adding Ventilation

This is the big one. Poor ventilation is the most common thing wrong with existing saunas, and it's why a room feels stuffy and stale after a couple rounds, why your head goes foggy, and why all the heat sits at the ceiling while your feet stay cold. Most kits and a lot of custom builds rely on two passive holes and hope the air moves on its own. It usually doesn't — not enough.

The fix is a proper two-vent system: fresh air in low by the stove, used air pulled out at bench height on the opposite wall. You can add it to almost any sauna without rebuilding. That's exactly what our Sauna Ventilation Kit does — it's a pre-assembled intake and powered exhaust you install with a drill in about an hour. If you only do one thing to an older sauna, do this.

The Sauna Ventilation Kit — a complete intake + exhaust system for any sauna.

Bigger or Better Benches

A lot of older saunas — and most kits — have benches that are too narrow and too low. The goal is to sit with your feet at or above the level of the stove, so the heat is even from head to toe, and to have a top bench wide enough to actually lie down. We aim for benches at least 24 inches wide and an upper bench high enough that your feet clear the top of the heater.

Rebuilding benches is one of the higher-impact renovations because it changes how the sauna actually feels to sit in. It's usually straightforward — new framing and fresh clear cedar or aspen for the tops — and it doesn't touch the shell of the building.

Adding a Floor Drain

If your sauna floor is wood or sealed slab with nowhere for water to go, washing it down and managing sweat and löyly water is a chore. Adding a tiled floor with a drain makes the room far easier to keep clean and dry — which, going back to the top of this page, is what makes a sauna last. This is a bigger job since it involves the floor, but it's worth it on a sauna you use hard or a commercial setup.

Other Renovations

Plenty of other things come up: upgrading or resizing a heater that was never right for the room, adding or replacing insulation and a proper vapor barrier on a sauna that loses heat, swapping a leaky door or single-pane glass, adding a window or a backrest, or refinishing a tired interior with fresh paneling. Some of these are an afternoon; some are real projects. The honest answer is usually "it depends" — on what's behind the walls and how the sauna was built in the first place. That's where it helps to have someone look at it.

What We Can Help With

• ✓Diagnosing why a sauna feels stuffy, weak, or uneven
• ✓A ventilation plan — and the kit to do it
• ✓Bench layout and sizing that fixes the heat
• ✓Heater problems — burned-out elements, thermostats, and sizing
• ✓Drainage, flooring, insulation, and vapor barrier fixes
• ✓A full remote renovation plan with a materials list

Common Questions

Keep Reading

More on the upgrades that make the biggest difference: the Sauna Ventilation Kit, how sauna ventilation should be designed, and the most common ventilation mistakes. Planning a bigger renovation? The sauna materials calculator prices out a parts list, and the sauna reviews show what good benches, heaters, and ventilation actually look like.