Development of the Sauna Building
The old smoke saunas have but one room with the stove and the platform. In them water was used sparingly and the body was cleaned through sweating and using the vihta or vasta (birch whisk). Soap did not exist until the 19th century. Rinsing and cooling was done in a lake or river or by pouring water over the body or in winter by rolling in the snow. If hot water was used it was heated in a wooden container by immersing hot stones in it.
Bathers came to the sauna lightly clad, and clothes were left hanging in pegs outside the sauna. After the sauna clean clothes were put on, but it was practical to leave the sauna lightly dressed to allow for proper cooling off, and to add more clothing later if needed.
With the development of hygienic standards and the availability of soap, washing the body in the sauna became more important than before. A container for hot water was added to the side of the stove or as a separately heated cauldron, and washing was done inside the sauna. In the summer it did not matter but in winter it was rather unthinkable to wash outside in the cold.
In public saunas in towns the hot rooms and washing rooms were separated, and with the chimney type sauna this style slowly spread into private saunas, too. After all, washing is more pleasant in a cooler room.
The sauna building developed in other respects, too. Starting in the 1920s many saunas had a porch and a separate dressing room. In the case of summer cottage saunas, other rooms, such as a kitchen and a bedroom, were often added if no other building was available for living.
The walls and the ceiling in any Finnish sauna are always wood, either logs or boards or wood paneling. The floor in the old smoke saunas was mostly plain earth, possibly covered with slats where bathers would step. The next phase was a floor built of boards, and ultimately floors are laid with tiles on concrete.