The science behind saunas

Enjoying a hot bath in a wood-clad sauna is perhaps a very Finnish past time. This lakeside sauna is no different from others, but has a story behind it.

One 1951 winter, a sauna was pulled in with a Citroën 15CV over the frozen lake.

Decades later, it fell into disrepair and was dismantled.

A new one was rebuilt on the same site, a modern, stylish villa made of oiled hardwood, white sailcloth, welded sheet steel, and black and white film-faced plywood.

The architects ALA designed the steam room the way they would a concert hall, with acoustic principles in mind.

The only enclosed space in this sauna is the steam room, spanning 7.5 m2. Here, eight people can relax comfortably while enjoying the heat, or löyly in Finnish.

The sauna works because the room has exactly the right height for the selected stove. Ventilation is optimised – the right kind of heat circulation is crucial. The heat capacity and reflection properties, moisture absorption and deterioration through age are different for different surface materials and have to be taken into account.

This one has a fairly large wood heated stove with 400kg of stones. The lower level of the “laude” (the sauna-bench) is at the same level as the top of the stove, to ensure that the heat circulates even on the level of the toes of a bather sitting on the upper “laude”. The upper “laude” is 1,100mm below the ceiling to fit a seated tall man. The floor is open to ensure that fresh air flows between the planks.

Three of the walls are black-tinted wood veneer. The materials were chosen for their heat and moisture absorption properties. The ceiling, floor and back wall are clad with the same hardwood as the terrace and its ceiling.

Although both the material palette and architecture of the sauna are contemporary, the bather who steps in will feel like he is stepping back in time.


Images: ALA Architects