Unique concrete building with hidden joints

The Art Sauna is located in Mänttä-Vilppula, Central Finland. It is part of the Serlachius Museums, which offer rich art experiences and tell the history of the Finnish paper industry. The Art Sauna combines the joy of art, design, and architecture with traditional Finnish sauna culture.

Precast concrete was used in the structure as well as the façade of the sculptural sauna building. The colored concrete surface is polished for a shiny finish, highlighting both aggregate and color. Attention is drawn to the continuous vertical grooves and the round steam room.

The sauna and museum buildings are found in a culture-historically significant landscape on the lake shore. The lower part of the slope, where the sauna is located, belongs to the so-called ‘stone world’, distinguished from the ‘wood world’ further up the hill. The structure is built partially inside the hill, and its round shape and green roof blend it into the landscape without covering the lake view from the hilltop.

The sauna was designed by architects Héctor Mendoza, Mara Partida, and Boris Bežan, while Pekka Pakkanen from Planetary Architecture took care of the execution planning in cooperation with Anna Kontuniemi. The same team also designed the Gösta Pavilion further up the hill.

“We decided to use precast concrete because the goal was a high-quality, finished whole with an uninterrupted pattern. We’ve used two different depths in the groove pattern, and the pattern repeats every 19 centimeters, making the joints of the panels invisible,” reveals Pakkanen.

More than 200 precast concrete elements were used for the building with sizes varying from the meter-long roof slabs to the curved, eight-meter panels in the steam room. The inventive groove pattern was made by hand at Betoniluoma Oy using plywood and plastic fillets. The special solutions were first tested on sample elements.

“To succeed, seamless cooperation between the design and implementation teams was required. The details of the elements as well as the concrete recipe were refined over and over,” Pakkanen notes about the level of finishing.

A shade slightly darker than medium gray has been used on the façades. The aggregate is white-grey limestone from the Kalanti in Southwest Finland mixed with black and green pigment.

The sauna building has no visible eaves, footings, or joints, although it consists of numerous curved precast panels that are connected in parallel, on top of each other, and to other structures. Finland’s climate added to the challenges, as weather conditions vary from severe frost to snow, rain, and heat waves during summer.

“Even though the structure looks uniform on the outside, we had to solve challenges with the structural design, ventilation, and how to lead moisture in the right direction. Discreetly connecting the materials and structures required a top performance of both designers and builders,” Pakkanen says while thanking everyone who has been involved in the process.

The precast roof elements function as eaves, and a common ventilation system was made beneath the panel grooves. The system takes care of the ventilation of both the roof and façades. Moisture insulation, sealing, and sheeting were installed in between the concrete elements without blocking the ventilation gap.

The lamps are also embedded in the façades, leaving only the light visible, hiding joints and connections. Quality was indeed a priority for both the client and the architects.

“I personally find it important that the customer orders and expects quality. The cooperation between the different parties was very successful. The level of finishing and the result look exactly as they should, like one seamless piece,” notes Pakkanen.