Sauna Insulation

In our opinion (and from many years of experience) insulation is one of the most important steps in a sauna.  Both indoor and outdoor saunas require insulation.  The type of insulation used can range from blown, fiberglass, rockwool or foam-cores.  Regardless the insulation used, just having insulation increases efficiency of your heat source, it betters the performance of the sauna, and it also protects the outside from the heat generated such as indoors.  Indoor saunas are not as concerned about the temperature affecting the interior performance, but certainly the heat loss spilling into the family room might make the rest of the house affected by the heat coming off the sauna when it is use.  

The insulation is always coupled by the foil.  Typically mounted inside the framing, to protect the framing, just behind the interior cladding.  The foil acts as a barrier to radiate the heat back into the sauna, but also the humidity is protected from escaping the interior.  It is usually plastic, believe it or not.  A woven reflective plastic (sometimes perforated) is key as it allows it to breath.  This is the reason why strapping is not necessary, the type of foil used is designed to breath and allow for some airflow to prevent mold and growth from the humidity.