Sauna maintenance: the four tasks that decide how long it lasts
A sauna is a wooden box that gets hot and wet several times a week. It does not need much, but the few things it does need are the difference between ten years of use and three.
After every session
Leave the door open for twenty minutes to let the moisture out. Wipe the benches with a dry towel if they are wet. Do not close a sauna while it is still steaming: trapped moisture is what turns into mould at the base of the walls.
Monthly
Brush the benches, vacuum the floor, and check the stones. Stones crack and crumble; when they do, they block airflow around the elements and the heater runs hotter than it should. Replace broken stones rather than adding new ones on top.
Twice a year
| Task | What to look for |
|---|---|
| Treat the exterior timber | Fading, water marks, green algae |
| Check the roof or cover | Pooling water, loose felt |
| Inspect the door seal | Gaps that let heat out |
| Clean the floor drain | Blockage that holds water |
| Check the heater connections | Loose terminals, discoloured cable |
What not to do
Do not varnish the interior: it will off-gas when hot. Do not use chlorine cleaners on the benches. Do not pour water on the elements directly; pour it on the stones. And do not ignore a heater that trips the breaker: that is a fault, not a quirk.
The base is the weak point
Most rot starts at the bottom of the walls, where water sits and air does not move. A ventilated base, a slight gap between the timber and the ground, and a drain in the floor will do more for the lifespan than any coating.
Frequently asked questions
How often should I replace the stones?
When they crumble or crack, typically every one to three years depending on use.
Can I use the sauna in winter?
Yes, and the temperature swing is harder on the timber. Check the exterior coating before and after the cold season.
Does a sauna need a drain?
Not always, but a drain makes cleaning and spillage much easier. If there is no drain, use a mat and dry the floor after each session.
How do I stop mould?
Ventilation, not chemicals. Open the door after use, keep the base dry, and let air move under the structure.
Should I cover the sauna?
A cover protects the roof and the timber from rain and sun. It also keeps the exterior cleaner, which extends the interval between treatments.
The short version
Ventilate after every session, check the stones monthly, treat the exterior twice a year, and keep water away from the base. Everything else is cosmetic.