Sauna in a Room: Converting a Spare Room at Home

Sauna Dekor Spa Solutions engineering team, Istanbul · project and press enquiries: Alican Aykaç, Managing Partner

Updated: 12 November 2026

5 things decide whether the room converts easily: its size and ceiling height, the walls (internal or external), the window, the floor, and the electrical board. A room around 2 × 2 m with a ceiling over 2.2 m converts without major works for 2 to 4 people. The survey also finds a route for fresh air and a shower within a few steps.

Anything that cannot take sauna heat or would sit inside the new room, usually 5 kinds of item: carpet, wallpaper, ordinary sockets and light fittings, curtains and built-in furniture. Existing walls usually stay; the sauna is a new timber room built inside them, with its own frame, insulation and vapour barrier. That leaves the building's walls untouched and makes the sauna removable later.

Usually 1 of 2 answers: the window is closed in behind the new wall, or it is kept as a fixed, insulated glass panel for light and view. If it stays, its area enters the heater calculation; Harvia, for example, adds about 1.2 m³ of volume for every square metre of glass. Opening windows inside a sauna are avoided. Our guide to sauna heater sizing shows the method.

A hard, washable floor, such as tiles; timber duckboards can sit on top. Carpet and laminate do not suit the heat. The door is a new sauna door, opening outwards, without a lock, with a small air gap of 1–2 cm at the bottom. It replaces or sits inside the room's existing door opening.

A dedicated circuit sized from the heater datasheet, with an isolator outside the sauna; many heaters above about 9 kW need 3 phases (a typical practice value). The supply and protection points are set out in our page on sauna electrical requirements. Fresh air comes in low near the heater and leaves high or under the bench, as shown in our guide to sauna ventilation.

Usually yes, in 1 or 2 steps: the building management approves new electrical loads and works, and some towers ask for a method statement. Ask before ordering. In villas, the main checks are the board capacity and the route for the cable. If the sauna sits in a bathroom rather than a spare room, see our guide to the bathroom sauna.

In 5 steps over about 2 weeks on site for a single sauna: strip-out and electrical first fix, the new frame with insulation and vapour barrier, panelling and benches, heater and controls, then the first heat-up. The wall build-up is described in our guide to sauna insulation.

1. Strip-out; supply cable and isolator position; fresh-air route opened.
2. New timber frame, insulation and vapour barrier inside the room.
3. Wall and ceiling panelling, benches and backrests, new door.
4. Heater, sensor, panel and heat-rated lighting connected.
5. First heat-up to 80–100 °C and handover.

The sauna types we build, from traditional Finnish rooms to infrared cabins, are on our sauna page.

Sauna Dekor Spa Solutions is a sauna, steam room, hammam and pool manufacturer since 1987: 40 years of manufacturing in Istanbul (İkitelli OSB), a team of 19, TS EN ISO 9001:2015, and 5,000+ projects in 41+ countries, including 577+ hotel and resort projects, with 732 documented references in 32 countries and territories. Our warranty is 24 months on workmanship and manufacturing, 24 months manufacturer's warranty on electrical and mechanical equipment, and 5 years on structure and waterproofing. Our full range is on our products page.