Insulation of the sauna room is important, with the ceiling being the most critical location to insulate well. Regular fiber-glass insulation plus an aluminum foil vapor barrier should be used.

What kind of insulation do you use in a sauna?

Fiberglass is an excellent insulation material, with R-values ranging from R-2.9 to R-3.8 per inch. Mineral wool has an R-value ranging from R-2.8 to R-3.5. Polyurethane foam insulation tends to have approximately R-3.6 rating per inch of thickness. Polystyrene has the highest R-value of approx.

Can a sauna be installed outdoors?

An outdoor sauna will require more attention to the details of the structure itself, making sure it is up to local building codes, safe, and able to withstand local elements including heat, snow, wind, etc. In some areas you may want to construct an awning or covering to help protect the structure from weather damage.