Basics of Building a Sauna

Fire Safety

• Saunas can be heated with hot rocks that are heated outside the sauna, a wood-burning stove, heat lamps or infrared technology. Safety is always a concern in a sauna, and in the case of a wood-burning stove, fire safety should be foremost in your mind when building. The stove should be surrounded by non-flammable surfaces. These surfaces can be metal sheeting with an airspace behind, ceramic tile or bare concrete. Learn about the stove you're using and follow all recommendations for clearances for that particular model. Keep a fire extinguisher handy but not inside the sauna.

Insulation

• For a sauna to work properly, it must retain heat efficiently. This is accomplished through extensive insulation. An outdoor sauna can be built with 2-by-6 walls insulated with batts of fiberglass or rockwool, with extra insulation in the form of rigid foam boards on the interior or exterior. An alternative is to build the walls out of cob, which is a mixture of soil, sand, straw and water. This is more labor intensive but also cheaper and more environmentally friendly than commercial alternatives. The thermal mass in a cob wall will take a long time to heat up. But once it's warm it will stay that way much longer than an insulated wooden wall.

Ventilation

• As you can imagine, a very small room with profusely sweating people in it probably needs ventilation. In between uses of the sauna, it's important to air it out thoroughly both to prevent bad smells and to avoid the growth of mold and mildew. Build a small opening window or hatch into the wall of the sauna opposite the door. Install a fan into this opening or use a portable fan when you are airing out the sauna. You can also include a small vent at floor level and one at ceiling level, both of which can be left open while using the sauna to increase air circulation without losing much heat.

Location

• It's important to build your sauna in the right location to gain maximum use and enjoyment. It should be sited in a convenient place but somewhere that's out of traffic flow and a bit secluded. A corner of a back yard is often an ideal place. An indoor sauna is usually situated as an annex to a bathroom or master bedroom. Saunas needn't be large, so it's possible to fashion a sauna out of a large closet.