An outdoor home sauna is simply a home sauna sited in the garden rather than inside the house, and the choice between the two is usually settled by what the building can take rather than by preference. Outdoors solves moisture, heat, smell and floor area in one move, and introduces a base, a weather-proof shell and a longer electrical run in exchange. Which set of problems you would rather have is the decision.
What going outdoors solves
Four things at once. Moisture stops being the building's problem, which removes the biggest risk of an indoor traditional sauna. Heat no longer leaks into a room you are trying to keep cool. The smell of hot cedar, which some households like and others do not, stays outside. And you stop spending indoor floor area, which in most homes is the scarcest resource of all. For a traditional sauna in particular, those four are usually decisive, which is why traditional cabins are overwhelmingly an outdoor purchase in the United States.
What it costs instead
You take on a level, drained base, a shell built and sealed for weather, and an electrical supply that has to travel from the panel to the garden in protected conduit, usually as a dedicated higher-voltage circuit. That run is priced by distance, so a cabin near the house is materially cheaper than one at the bottom of the plot. You also take on maintenance: an outdoor cabin is a timber building in the weather and needs the attention one requires. And you take on the winter walk, which sounds trivial in July and is not in January.
When indoors is still right
If the sauna is infrared rather than traditional, most of the outdoor case weakens: an infrared cabin adds no moisture, runs cooler, usually plugs into an ordinary outlet and does not smell strongly, so a basement or spare room is genuinely fine. If you rent, indoors and freestanding is the only option that leaves with you. And if the alternative is a long cable run to a distant corner of the garden, an indoor cabin near the panel can be the cheaper project even accounting for the floor area it occupies.
Questions people ask about outdoor home sauna
Is an outdoor sauna better than an indoor one?
For a traditional sauna, usually, because it keeps moisture, heat and smell out of the house. For an infrared cabin the advantage largely disappears, since it adds no moisture and runs cooler.
Does an outdoor sauna cost more?
The cabin is built for weather and needs a base and usually a longer electrical run, so the project cost is typically higher than dropping an equivalent cabin in a basement.
Can an indoor cabin be moved outside later?
No. Indoor cabins are not sealed or rated for weather, and doing it voids the warranty as well as risking the electrics. The outdoor decision has to be made at purchase.