Hot air and steam in a small space has been used for thousands of years to relax, rejuvenate and repair. With the exception of the ornate stone public baths and spas of antiquity most saunas have been constructed of wood. For many it was whatever wood species was available and could withstand the heat and humidity. Oak, cedar, spruce, teak and yew wood have been popular for many years.



Most if not all wood species will undergo the process of out-gassing when heated past a certain temperature. Out-gassing is generally defined as the emitting of gases over time and under certain environmental conditions. The application of heat is often a cause of outgassing, though petrochemicals will often outgas regardless of temperature changes. Many different materials will outgas including metals, rock, paints, stains, plastics and wood.

Yes, wood will outgas. The process of outgassing is particularly noticeable in cedars which are known for the aromatic scent of the wood. The outgassing may continue for many years depending on the species of wood and the ambient environmental conditions. Not all outgassing from wood is harmful since most of the vapor is water. Some wood species outgas more than others and many sauna manufacturers have begun to line their units with woods such as spruce as an alternative to traditional redwood cedar.

There are two basic types of saunas on the market today. The traditional and better-known steam type and models that utilize the dry heat of infrared. The steam type of sauna heats everything in the sauna room including the wood. Infrared models focus the heat on the body while the rest of sauna remains relatively cool. Advocates of infrared saunas make the claim that outgassing is greatly reduced since the wood is not heated though the process of outgassing continues whether or not the wood gets hot.

The wood used in constructing a sauna should be of a high grade and kiln dried. The process of kiln drying greatly lowers the moisture content of the wood and inhibits outgassing. Kiln dried wood is far less susceptible to rot and deterioration, more stable and not prone to cracking or warping when exposed to the heat of the sauna. The thermal insulation properties of the wood are enhanced if it is properly dried.

Wood used on the interior of the sauna should never be stained or preserved in any way since stains and wood preservatives outgas volatile hydrocarbons that can be extremely hazardous. Use water with a very mild soap to clean the inside of your sauna and never use harsh cleaners. Some chemical cleaners will penetrate the wood, eventually outgas and could result in adverse health consequences.

When making a purchase decision on your sauna always work with a reputable manufacturer and make sure the wood inside your new sauna is of a high grade and thoroughly dry.