The sauna has been designed to a set of strict parameters in terms of function and construction, the most important of these being moisture control.
The building, which is founded on columns, stands at the brow of a hill so that surface water from around the building drains away to open ground to the northeast. Two basic rules have been applied in the design and construction of the roof: a) the whole of the underside must be visible so that any leaks can be spotted immediately, and b) the waterproof layer must be protected from ultra-violet radiation and from mechanical wear and tear.
The various functions are housed in separate elements at the terrace level with the large roof and the shelter to the cladding on the rear wall acting as a rain cape or canopy. Thus, it has been possible to focus on functional requirements in the design of the spaces and it has not been necessary to consider the effect of rainwater on doors, windows and exterior panels.
The shower room is built of stone materials that work well with water. In the sauna, the most important thing is the enjoyment of the heat and the steam so that it is constructed of wooden materials that balance out the moisture: pine, alder and plywood, plus wood-fibre board and wood-fibre insulation.
The Finnish building regulations call for a layer of aluminium foil to be installed in saunas – fortunately not in this particular building. The untreated wooden surfaces and natural ventilation ensure that the indoor air is of the best possible quality.