Hekla saunas are built with Thermowood which is 100% natural. The heat treatment process is chemical-free and the improved performance is achieved simply by the controlled application of heat and steam. Our wood material is certified Nordic Spruce which is sourced from Northern European forests and grown with sustainable practices. Thermally modified Nordic Spruce is aesthetically pleasing wood material that is significantly more durable and stable than conventional timber. Roof shingles are also provided on the roof to protect the sauna and increase insulation.