Sauna with Chimney
Until the beginning of the 20th century the smoke sauna was the only kind of sauna there was. In spite of the nice aroma and smooth löyly it has disadvantages: its heating takes time, cleaning the platform from soot each time is a chore and smoke saunas easily catch fire during heating.
About a hundred years ago another type of stove began to supersede the traditional one: the stones were covered with a conical metal top that was attached to a chimney to lead the smoke away. The top part had a door that could be used to control the temperature in the sauna by keeping it closed or open. The door was necessary per se to allow throwing water to the stones.
Where a smoke sauna would be heated for 3-4 hours and then let "settle" for another hour or two before bathing could begin, the new stove would require only a couple of hours´ heating and could be used almost immediately after the fire had completely died out. At that point the chimney would be closed with a metal plate to cut off the air flow through the stones into the sky.
This new type of stove spread rapidly, and in the 1950s about half of the saunas in Finland were of the new type. In eastern and northern parts of the country the smoke sauna persisted longer. In many places the old smoke sauna was left as it was and a new sauna with the chimney type stove was built next to it. Since the heating and maintenance of the latter one was much easier the smoke saunas were left unused. Without use and care they rotted and were torn down.
Another factor in favor of the chimney type stove was the industrialization and urbanization of the country. In the countryside every house had a sauna but in the city people had to use public saunas. Their stoves had chimneys (for obvious reasons) and people got used to this kind of sauna. In the 1920s and 1930s upper and middle class families living in towns started to build summer cottages in the country, usually on a lake or the sea, and like any Finnish settlers, they first built saunas. Practically all of them were of the new type, and usually an extra room was added to them to be used for living until a bigger summer house was built.