Buying
Sauna vs steam room: which should you choose?
One is hot and dry, one is warm and saturated. At home the decision is mostly about waterproofing, and almost nobody should install both.
These get discussed as two flavours of the same thing, and at home they are not remotely comparable. A sauna is a timber box that gets hot. A steam room is a fully tanked, waterproofed enclosure running at 100% humidity, which is a building job rather than a purchase. That difference decides this for most households before anyone considers how the heat feels.
| Sauna | Steam room | |
|---|---|---|
| Temperature | 80-100°C | 40-45°C |
| Humidity | 10-20%, in bursts | 100%, constant |
| Materials | Timber, breathable | Tiled, fully tanked |
| Session | 10-20 min rounds | 15-20 minutes |
| Home install | Cabin, delivered | Wet room build |
| UK entry cost | £1,500-£5,000 | £4,000-£10,000 installed |
Why 45°C feels hotter than 90°C
Sweat cools you by evaporating. In a sauna at 90°C the air is dry, so sweat evaporates fast and you tolerate the temperature. In a steam room the air is already saturated, so nothing evaporates, and 45°C becomes genuinely hard work. That is the whole physiological difference, and it is why people who find saunas unbearable often prefer steam and the other way round.
It also explains the session lengths. Sauna sessions run in short rounds with cool-downs between them, and running a sauna session properly means three of those rather than one long sitting. Steam sessions are usually one continuous 15 to 20 minutes, because there is no escalation to chase.
The installation gap is the real decision
A home sauna is a product. It arrives as a cabin or a flat-pack, stands on an existing floor, and needs a circuit certified under Approved Document P. A home steam room is a construction project: a fully waterproofed and tanked enclosure with a graded floor, a drain, a sealed door, a vapour-tight ceiling and a generator plumbed to a water supply.
Get the tanking wrong and the moisture goes into the structure rather than down the drain, which is the failure mode that makes steam rooms expensive to fix. That is why a home steam installation starts around £4,000 fitted while a very good sauna cabin starts under £3,600 as a shell, and why the sauna route is the one most UK households take.
What each one is good for
Neither has a decisive evidence advantage for general wellbeing. The long-running observational research that people cite, including the Finnish cohort study in JAMA Internal Medicine, studied traditional hot saunas rather than steam rooms, so the honest position is that saunas have the deeper evidence base and steam rooms have very little published on them either way.
- Choose a sauna for intense dry heat, löyly, and a session you can escalate in rounds
- Choose steam if you find dry heat uncomfortable, or if congestion and sinus relief are the main draw
- Choose a sauna if the space is a spare room, garage or garden, none of which suit tanking
- Choose steam only if you are already rebuilding a bathroom, which is when the marginal cost is lowest
The middle option almost nobody mentions
A combi heater sits between the two. It is a traditional sauna heater with a water reservoir, so the same timber cabin runs as a dry sauna at 90°C or as a softer humid room at 60°C to 70°C. It is not a steam room, and it will not reach 100% humidity, but it covers most of the reason people want one.
For a household that disagrees about heat, a combi in a normal cabin solves the argument for a few hundred pounds over a standard heater, against several thousand for a second installed room. The cabins that support one are on our indoor sauna rankings, and the heater output still has to match the room either way. Running cost also stays on the sauna side of the comparison, at about £1.57 a session for a 6kW cabin at Ofgem's current rate.
If the choice is really about how the heat reaches you rather than how wet the air is, that is a different comparison: infrared against traditional heat covers it, and both sit alongside size and budget in choosing a home sauna. Whichever room wins, sizing it comes down to bench length, which is what deciding how many people it seats is for.
Frequently asked questions
What is the difference between a sauna and a steam room?
A sauna is dry heat at 80°C to 100°C in a timber room, with humidity added in bursts by throwing water on stones. A steam room runs at 40°C to 45°C with 100% humidity in a tiled, fully waterproofed enclosure.
Which is hotter, a sauna or a steam room?
A sauna, by a wide margin on the thermometer. A steam room often feels harder to sit in because saturated air prevents sweat evaporating, so your body cannot cool itself the way it does in dry heat.
Which is better for you?
Neither has a decisive advantage for general wellbeing. Saunas have the deeper evidence base, largely because the long-running Finnish research studied traditional saunas and steam rooms have barely been studied at all.
Can I have a steam room at home?
Yes, but it is a building project rather than a purchase. It needs a fully tanked and waterproofed enclosure, a graded floor and drain, a sealed door and a plumbed generator, which typically starts around £4,000 installed.
Which is cheaper to install?
A sauna, comfortably. Cabins start at about £1,500 for infrared and £3,577 for a traditional shell, and stand on an existing floor. Steam requires waterproofing and plumbing work that a sauna does not.
Which is better for congestion?
Steam is the usual choice, because warm saturated air is what people find helpful for sinuses and airways. That is the single clearest reason to prefer a steam room at home.
Can one room do both?
Not fully, but a combi heater gets close. It adds a water reservoir to a traditional sauna heater so the same cabin runs dry at 90°C or humid at 60°C to 70°C, for a few hundred pounds over a standard heater.
How long should you spend in each?
Sauna sessions run 10 to 20 minutes per round with a cool-down between rounds. Steam sessions are usually one continuous 15 to 20 minutes. Leave either whenever you stop feeling comfortable.
Do steam rooms damage the house?
Only when the tanking is done badly, which is the main risk of a cheap installation. Moisture that gets past the waterproofing goes into the structure instead of the drain, and that is expensive to put right.
Which uses more electricity?
A sauna, because it heats a room to 90°C rather than 45°C. A 6kW sauna session costs about £1.57, while a domestic steam generator typically draws less over a shorter session.