Rocky Mountain Saunas uses only the very highest grades of Hemlock and Western Red Cedar in the fabrication of all our infrared sauna kits. Center cut, tongue and groove construction and Internationally Certified to be safe, non-toxic, non-outgassing. “Clear All Heart” is the actual lumber classification. It contains virtually no knots and is taken from the heart of the tree. This lumber has the highest amount of natural preservatives. We use a proprietary herbal formula to cure and kiln dry our woods. NO chemicals, pesticides or drying agents are ever used in the preparation of our woods. All sealants are organic, water based, non-toxic, non-outgassing. You can be sure your home sauna is as safe as can be. Whether you get a sauna using Hemlock or a Cedar sauna, at 8mm thickness, Rocky Mountain Saunas’ walls are almost twice as thick as the industry standard. Built to hold up under the wide temperature swings a far infrared sauna needs to endure.