Three kinds of home sauna
An indoor cabin is the most common choice: a self-contained wooden room for one to four people that fits a spare room, an attic or a large bathroom, lined in spruce, thermowood or hinoki. A bathroom sauna is built with a glass front next to the shower, sharing the bathroom's waterproofing and drainage, so you step straight from the heat into a cold shower. A garden barrel sauna is delivered pre-built or assembled on site and can run on an electric or wood-fired heater. Each has its own conditions. Indoors, the questions are floor, ceiling height, ventilation and power. In the garden, foundations, drainage, the route for the power cable and the planning rules come first.
Heater size and electrical supply: 230 V or 400 V
Heater power is matched to the volume of the sauna room. As an example, Harvia rates its Vega BC60, a 6 kW heater, for rooms of 5 to 8 m³. On a single-phase 230 V connection it needs a 35 A fuse; on a three-phase 400 V connection, three 10 A fuses. Glass fronts and uninsulated stone or tiled walls lose heat faster, and manufacturers count them as extra volume, which pushes the heater size up. Small heaters run on a normal 230 V circuit; larger ones may need three-phase (400 V). So before anything is chosen we check your meter cupboard in the Netherlands or your supply and contracted power (potencia contratada) in Spain. Rooms with sauna heaters have their own section in the electrical installation standards (IEC 60364-7-703), and the connection is made by our licensed electrician partner.
Ventilation and moisture
A sauna needs fresh air to feel good and to dry out after use. Harvia's heater manual asks for the air in the sauna room to change at least six times an hour. The positions of the supply and exhaust vents follow the heater maker's installation drawing, because air flowing past the temperature sensor can disturb the thermostat. Indoors, the exhaust has to leave the house, not end up in an attic or a cupboard, and the room around the cabin needs its own extraction so moisture does not reach walls and ceilings. A bathroom sauna shares the bathroom's extraction, which we size for both the shower and the sauna. After each session, leave the door open and let the benches dry; wood that dries properly stays fresh far longer.
Garden saunas in the Netherlands: when no permit is needed
Under the Omgevingswet, a building in the back garden can often be built without a permit as an outbuilding (bijbehorend bouwwerk). According to the government's information point, it must stand on the ground in the rear yard area (achtererfgebied), more than 1 m from publicly accessible land, and be no higher than 5 m. Within 4 m of the original house, the permitted height is tied to the floor levels of the house itself. Further away, the limit is 3 m, or up to 5 m with at least two sloping roof planes and an eaves height of no more than 3 m. Only a share of the yard may be built on, and existing sheds count. These rules sit in the municipal environmental plan (omgevingsplan), which can differ, and monuments and protected cityscapes have their own rules. We check your address in the Omgevingsloket.
Garden saunas in Spain: ask the ayuntamiento
In Spain there is no single national rule for garden structures. Each municipality's planning rules decide whether a sauna cabin counts as a construction, how far it must stay from boundaries, and how much of the plot may be built on. Depending on the town and the size of the structure, it may need a prior notice or declaración responsable, a minor works licence (licencia de obra menor), or nothing at all, and a house in an urbanización may also have community statutes to respect. On a roof terrace or communal patio of a flat, the comunidad has a say when the structure, facade or shared elements are affected, and we check the load the terrace can carry. Wood-fired heaters need a safe flue and may be restricted locally. We confirm the procedure with your ayuntamiento before ordering.
Heat, cold, rest: the cold shower and the place to rest
The sauna is only half of the experience. The other half is cooling down and resting, which in Japanese is called totonou: the calm, clear feeling after heat, cold water and a few quiet minutes. So we plan a cold shower within a few steps of the sauna door, ideally with a rain shower and a hand shower, and a place to sit or lie down with fresh air. Indoors, that can be the bathroom next to the cabin or a bench by an open window. In the garden, an outdoor shower needs a proper drain and, in the Netherlands, protection against frost in winter. On a Spanish terrace, shade matters as much as the shower. Small details, such as hooks, a towel rail and a non-slip floor, make the routine easy every time.
How long it takes and what it costs
An indoor sauna cabin usually takes one to three days on site once the electrical supply is ready. A bathroom sauna is built as part of the bathroom renovation, and a garden sauna depends on the foundation, the cable route and any permit. Our indicative price for a home sauna starts at €9,800 including VAT for an indoor cabin for one or two people, with heater, lighting and installation. A three-phase connection, a larger cabin, a cold shower or a garden installation add to that, and costs vary with every home. After a free online consultation, a Japanese engineer surveys your home, checks the power, floor, ventilation and access, and you receive a fixed quote.
