Realizing cutting-edge architecture – The Lonna Island sauna


In 2016, Hirsityö Heikkilä carried out the largest and most demanding building project in their history by delivering an almost 200 square meter sauna log frame to the governing body of Suomenlinna. The public sauna built on Suomenlinna’s Lonna Island is a tangible example of the sauna boom in our nation’s capital due to which several new public saunas have been built in Helsinki. The head designer of the new sauna was nationally and internationally award-winning OOPEAA member, architect Anssi Lassila. The sauna building he designed has two separate sauna rooms, both of which accommodate around 20 people. The washrooms are located downstairs, whereas the upstairs is reserved for the sauna with large windows opening up to a gorgeous sea view. Both saunas have large one time heated wood stoves.

Puu kaatuu


Large sauna with a log frame
Hirsityö Heikkilä had to prove their know-how in log construction as early as in the bidding stage. The bid had to include information and pictures of log frames built in the same manner using the same construction material and the quality of hewing was inspected. The concrete work started with obtaining suitable wood. An apt stand marked for cutting was found in Kuorevesi, Jämsä, where 166 cubic metres of Central Finnish high-quality wood was acquired. The diameter of the largest tree bases was 70 centimetres. Then the building process continued in Karstula where the bark was first peeled off and the trees were square sawed with the company’s own sawmill. After sawing, the log blanks were taken to the Honkarakenne wood dryer for a month. Lonna saunan veistohirttä asennetaan paikalleen Lonnassa

Carving the frame itself began by building foundations that were used during the construction stage. It was quite an operation since the measurements of the log frame base were 20 meters times 8,5 meters. The carving began in the end of March 2016 and was finished by the end of May. After that, over 220 square meters of the building’s wall area was hewed with an axe. Next, the logs of the frame were marked and dismantled into log stacks for transportation. The frame was transported to Sompasaari, Helsinki from where it was ferried to Lonna Island on the last week of June. On Lonna Island, erecting the frame and sawing openings and inlays were completed in a couple of weeks. Thus, Hirsityö Heikkilä’s part in the construction project, that began in January 2016 with logging, was completed. However, the construction work of the sauna was continued until late in the autumn. First bathers got to enjoy the sauna in the May of 2017.Lonna sauanan miesten puoli

Lonnan sauan naistenpuoli