What Is a Finnish Sauna? Löyly, Temperature and How to Choose One
Share
Ask a Finn what a sauna is and you will not get a description of a product. You will get something closer to a description of a room in a house — because that is what it is. Finland has around 3.3 million saunas for 5.5 million people, and the word itself is one of the very few Finnish words in everyday English use.
This guide covers what a Finnish sauna actually is, how it differs from everything else sold under the same word, and what to look for if you want the real thing in a British garden.
What is a Finnish sauna?
A Finnish sauna is a hot, dry timber room heated to 70–90°C by a stove packed with stones. Water is thrown onto those stones to produce a brief, intense wave of steam. That wave is called löyly, and it is the point of the whole exercise.
Everything else follows from those two facts. The room is timber because timber does not scorch skin at 90°C the way tile or metal does. The benches are tiered because heat stratifies — there can easily be 30°C between the floor and the top bench. The stove holds stones rather than just heating elements because stones store heat and release it gradually when water hits them.
Strip any of that out and you have something else. A room at 90°C with no stones cannot give löyly. A room at 50°C is not a sauna, whatever the label says.
Löyly — the word worth knowing
Pronounced roughly LOY-lu, löyly is the steam that rises when water meets hot stones. It is also used more loosely to describe the quality of heat in a given sauna — and Finns are genuinely particular about it.
Good löyly is soft. The steam moves through the room as a wave of warmth that wraps around you and fades over a minute or two.
Bad löyly is sharp — a hiss, a scald on the shoulders, and then nothing. It almost always means one thing: not enough stone. A heater carrying 5 kg of rock cannot store enough heat to vaporise water gently. It flashes it off in a burst.
This is the single most useful thing to know when comparing saunas. Stone capacity is the specification that separates a real sauna from a hot box, and it is the one most retailers do not put on the page. Look for 20 kg or more.
How a Finnish sauna differs from everything else
| Finnish / traditional | Steam room | Infrared | |
| Temperature | 70–90°C | 40–45°C | 45–60°C |
| Humidity | 10–20%, spiking with löyly | 100% | Ambient |
| Heats | The air, which heats you | The air, saturated | Your body directly |
| Steam | Yes — löyly on demand | Constant | None |
| Build | Timber, stove, stones | Tiled, sealed, generator | Cabin with emitter panels |
None of these is better in the abstract. Infrared warms up in fifteen minutes and costs little to run, which suits daily use. Steam rooms are gentler on the airways. But if you want the thing that Finns mean by the word — the heat, the löyly, the shock of cold air afterwards — it is the traditional sauna you want.
What makes a genuinely Finnish-style sauna
1. Stone capacity
Covered above, and worth repeating. 20 kg minimum. Some stoves take 40 kg or more, and the difference in how the room feels is immediate.
2. Wall thickness
Finnish saunas are built from thick timber — 42 mm boards at a minimum, 70 mm solid logs on traditional cabins. Thickness does two jobs: it slows heat loss, and it gives the building thermal mass so the temperature stays even rather than swinging every time the element cycles.
A 20 mm panel sauna will reach 90°C. It will not hold it, and it will feel different — thinner, harsher, quicker to cool when the door opens.
3. Bench timber
Benches must be low-conductivity and low-resin, or they will burn you and weep sap. Aspen, alder and thermo-treated aspen are the traditional choices. Pine is fine for walls and wrong for benches.
4. Ventilation
A sauna needs air moving through it — an inlet low near the stove and an outlet high on the opposite side. Without it the room goes stale and the heat stratifies badly. It is invisible, easy to omit and immediately obvious in use.
5. Tiered benches
Heat rises, so bench height is the temperature control. The upper bench might be 90°C while the lower is 60°C. That is a feature: you start low and move up.
How to use a Finnish sauna properly
- Shower first. Standard courtesy, and you sweat more readily when clean.
- Heat: 8–15 minutes. Start on the lower bench. Move up when you want more.
- Löyly when you want it. A ladleful at a time onto the stones — not a bucket.
- Cold: shower, plunge, or outside air. This is not optional; the contrast is the ritual.
- Rest properly. Ten minutes, fully cooled, before you go back. Most people rush this and get less from the session.
- Repeat two or three times. Drink water throughout.
Finnish practice is unhurried. A sauna evening is a couple of hours, not twenty minutes.
Common questions
What temperature should a Finnish sauna be?
70–90°C measured at the upper bench, at 10–20% humidity. Finns often sit at the top of that range; if you are new to it, 70–75°C on the lower bench is a much better starting point.
Can I have a Finnish sauna in a British garden?
Yes, and the climate suits it. The cold-exposure half of the ritual is easier here than in a Mediterranean summer. What matters is wall thickness — 42 mm or better — so the room holds temperature through a damp February.
Do I need planning permission?
Usually not. Most garden saunas fall under permitted development, with exceptions for size, siting, listed buildings and conservation areas. See our planning permission guide.
Wood-fired or electric?
Wood-fired is the original and needs no electricity — a real fire, a slower build, and someone to tend it. Electric is set-and-forget but needs a garden supply and an electrician. There is also off-grid propane, which needs neither a cable nor a trench and is the practical answer for a sauna at the far end of a garden.
Are Estonian-built saunas as good as Finnish ones?
Yes, and we would rather be straight about where ours are made. Estonia sits across the Gulf of Finland, shares the same timber and the same building tradition, and has one of the largest concentrations of sauna manufacturing in Europe — supplying across the Nordic region, Finland included. What matters is the specification: stone capacity, wall thickness, bench timber, ventilation. Country of assembly is a much weaker signal than any of those.
Where to start
If you want a traditional sauna for a UK garden, these are the places to look:
- Traditional Saunas — the full range of stove-and-stones saunas, electric and wood-fired.
- Nordic Saunas — our Estonian-built range, from barrels to assembled sauna houses.
- Wood-Fired Saunas — the original method, no electrics at all.
- Garden Saunas — everything for outdoors, by size and format.
And if you are weighing traditional against infrared, our infrared vs traditional sauna guide compares them properly.
