"Wet sauna" and "dry sauna" are used in different ways depending on who you ask. Some people mean a traditional sauna with or without water on the rocks. Others use "wet sauna" to mean a steam room. This guide sorts out the terms, compares how each space is built and how it feels, and helps you decide which fits your home or facility.
The quick definitions
- Dry sauna – a wood-lined room heated by an electric, gas or wood-burning heater with a bed of stones. Air temperature is high and humidity is low.
- Wet (or "steam") sauna – the same traditional sauna, but with water ladled onto the hot stones to release bursts of steam and briefly raise humidity. In Finland this steam is called löyly.
- Steam room – a sealed, waterproof enclosure fed by a steam generator. Temperature is much lower than a sauna, but humidity is close to 100 percent.
So a traditional sauna can be both "dry" and "wet" depending on how you use it, while a steam room is a different kind of room entirely.
Temperature and humidity compared
Typical operating ranges look like this:
- Traditional sauna, used dry: roughly 150–195°F with low relative humidity, often around 10–20 percent.
- Traditional sauna with water on the stones: similar air temperature, with humidity rising for a few minutes after each ladle of water. The room feels noticeably hotter during those bursts because moist air transfers heat to the skin more readily.
- Steam room: usually around 110–120°F with humidity near saturation, so the air is visibly foggy.
Because moist air feels hotter than dry air at the same temperature, a steam room at 115°F and a sauna at 180°F can both feel intense, just in very different ways.
How each room is built
Traditional sauna
Saunas are lined with untreated softwoods such as cedar, spruce, hemlock or aspen. Wood stays comfortable to touch at high temperatures and handles the occasional moisture from ladled water. Behind the paneling there is insulation and a foil vapor barrier. Saunas need ventilation, a heater sized for the room, a heater guard, and benches at different heights.
The heater is the heart of the room. Most heaters hold a tray of stones, and the stones are what make the "wet" experience possible. Water poured over hot stones flashes into steam. Heaters designed for this use protect their elements from water. For example, Scandia's Ultra electric heaters use a solid rock tray so water can be poured on the rocks without reaching the elements, and Scandia gas heaters use a solid rock tray design as well. You can compare models in our sauna heaters collection.
Steam room
A steam room is built for constant moisture. Walls and ceilings are tile, stone, glass or acrylic over a fully waterproofed substrate. The ceiling is usually sloped so condensation runs down the walls instead of dripping on bathers. The floor slopes to a drain, and the door is sealed to keep steam in. A steam generator, often located outside the room, boils water and sends steam through a steam head near the floor.
Because of the waterproofing requirements, steam rooms are often built into bathrooms or purchased as prefabricated enclosures. An example is the Scandia Advanced Hybrid Steam Room (60" × 48" × 96"), a ready-made enclosure.
Using water in a traditional sauna
If you like the feel of a humid sauna, you do not need a separate room. Ladling water onto the stones is the traditional way to adjust the atmosphere. A few tips:
- Use a wooden sauna bucket and ladle so you can add small amounts of water at a time.
- Pour slowly over the stones, not onto the heater body or controls.
- Use only plain water unless your heater manufacturer approves specific sauna scents.
- Replace stones when they crumble or crack. Fresh, dense stones such as natural sauna rocks hold heat well and produce a better steam.
- Add a thermometer-hygrometer so you can see how temperature and humidity change as you add water.
Not every heater is designed for water. Some infrared cabins and certain electric heaters should never have water poured on them. Always check the manufacturer's instructions first.
Maintenance differences
Saunas are relatively low-maintenance. Wipe down benches, leave the door open after use to dry out the wood, and occasionally sand benches lightly if they become stained. Rock trays should be restacked or refreshed periodically so air flows freely through the stones.
Steam rooms need regular cleaning because surfaces stay wet. Grout and seals should be inspected, the drain kept clear, and the steam generator descaled according to the manufacturer's schedule, especially in areas with hard water.
Space, installation and running considerations
- Space: saunas can be built indoors in basements, garages or spare rooms, or installed outdoors as cabins or barrels. Steam rooms are usually indoors near plumbing.
- Utilities: saunas need electrical service or a gas supply for the heater. Steam rooms need electrical service for the generator plus a water supply and a drain.
- Warm-up: a sauna typically needs time to heat the room and stones before use. Steam generators can fill a small enclosure with steam relatively quickly.
- Installation: electric heaters and steam generators should be installed by a licensed electrician, gas heaters by a licensed HVAC professional, and steam room plumbing by a qualified plumber, following manufacturer instructions and local codes.
Which is right for you?
Choose a traditional sauna if you want high heat, the scent and feel of wood, and the flexibility to enjoy it dry or add steam by ladling water. It is also the better choice for outdoor installations.
Choose a steam room if you prefer lower temperatures with very high humidity, already have a bathroom or wet area that can be waterproofed, or want a space that pairs with a shower.
Some people end up with both. A common commercial layout places a sauna and a steam room side by side with showers between them.
Next steps
If you are planning a traditional sauna, start by measuring the room and matching it to a heater. Our guide to sizing a sauna heater by room cubic feet covers the process. If you have questions about a specific heater, rock tray or steam enclosure, contact us with your room details and we will help you compare options.