The wood used to construct a far-infrared sauna cabin needs to be kiln-dried to about a 10% moisture content to prevent warping and cracking. This process takes 4-6 weeks and some manufacturers tend to ship out saunas that have not been afforded the necessary time to be properly cured

Many inexpensive infrared saunas use inferior grades of lumber in their product. Inferior quality woods not only looks poor, but they are also more prone to warp, buckle, ‘cup’, splinter, crack, split, and chips.
 

All sauna woods should be completely non-toxic and non-out-gassing. Panels with an excess of knots and cut horizontal to the grain of the wood are sure signs of poor grade wood. Knots can produce cracks and splits or sometimes fall out of the wall panel.
 

Low price saunas generally use thinner and marginally cured woods that are more likely to bow and warp with the continued exposure to the hot/cold temperatures of a sauna.
 

WHAT TO AVOID

Infrared Saunas made of the following types of wood are not a good choice:
 

• Aspen: Soft, light, and low in strength and stiffness. Non-toxic. Poor decay and shock resistance. Dents and scratches very easily. Too soft to prevent warping with constant heat exposure.
   

• Basswood: Also know as linden. Inexpensive, soft, light, low in tensile strength. Popular among hobbyists for model building and wood carving. Too soft for long term exposure to wide temperature fluctuation. Primarily used for fruit crates, picture frames, and wooden matches. not suitable for quality furniture. One of the softest woods in commercial use.
   

• Fir, White: Light, soft, moderately stiff. Low strength and shock resistance. Poor decay resistance. Some saunas that use fir produce a distinct odor.

• Western Pine: Moderately stiff, low strength, and shock resistance. Soft, light, and good stability in service. Not normally recommended for saunas. Subject to out-gassing, which can irritate eyes and nasal membranes. Knots are common.
   

• Sitka (Spruce): Moderately low in strength, but very high strength to weight ratio. Light and soft with low decay resistance. Non-out-gassing, but prone to excessive knots. Rough exterior. Some splitting, cracks, and splinters are common.
   

• Poplar: Most species are typically soft and porous with average ratings for strength, stiffness, decay resistance, and durability. Moderate heat retention. Not as stable as some woods under hot/cold conditions. Very easily bruised and dented. Contains high levels of tanic acid. Tends to have a fuzzy finish. Cheap and widely available.
   

• California Redwood: Generally straight-grained with a medium rough texture. Splinters are common. A light and softwood with moderate stiffness, very good decay resistance, and good stability in service. Heat retention is average. High cost limits widespread use. Durability is good.

WHAT TO LOOK FOR​

 

• Canadian/ Western Red Cedar: Renowned for its natural beauty and the outstanding physical properties that make it one of the world’s most unique species. Low shrinkage factor and superior to all other coniferous woods in its resistance to warping, twisting, and checking.
  
  With its low density and high proportion of air spaces, Canadian Cedar is the best thermal insulator among the woods commonly used for sauna construction. Excellent durability. Non-out-gassing when properly kiln-dried and treated to remove volatile oils. Best heat retention and durability for outdoor locations.
   

• Pacific Coast Hemlock: Very stable with little tendency to cup, check, or twist. Good cellular properties for expansion and contraction. Hemlock yields clean, straight edges and accurate contours. The combination of stability and smoothness has made Hemlock a favorite wood for the construction of saunas. An excellent choice if you have allergies, as it has very low resin and virtually no odor.

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