Nuoska integrated sauna heater by Tulikivi at Asuntomessut 2013.
The right ventilation is crucial for the relaxing enjoyment of the sauna. The fresh air must enter to the sauna from the wall over the stove and leave from the bottom of the room. This is how you may keep your feet warm. Warm air stays only above the hot stones in the stove so build your sauna so that you may keep your feet above that level.
Im all about building your own sauna, but for people that arent interested in that the Castor Sauna Box is a pretty neat option. From their site: "This traditional wood-burning sauna is built into a shipping container. The Sauna Box is comp..