Location: Pudasjärvi, Finland
The city of Pudasjärvi grew tired of indoor air problems affecting the city's facilities and invested into log building. In a decade, the world's largest log school and a dozen other large public log buildings have been constructed. The town of over 8,000 residents has become a trendsetter for log building.
In 2009, the town of Pudasjärvi faced a typical Finnish problem: schools and kindergartens had indoor air problems. Half of the schoolchildren and teachers suffered from symptoms of poor indoor air, and schools had been moved to temporary premises. The people of Pudasjärvi wondered if things could be done differently so that the cycle would end. The town had an idea to start experimenting with building public spaces. The tradition of log building already existed in the area as Kontio, the largest log manufacturer in the world, is located in the city.
The town had not previously tried log in public buildings. As a first kind of a "laboratory test", the town built two town office buildings out of log in the city centre in 2009-2012. One building has Metsähallitus, a state-owned enterprise responsible for the management of the woods, and the other has a hotel as well as smaller offices. It was possible to test the suitability of log construction in public construction in these two buildings. At the same time, more accurate measurements of the ecology, energy consumption and indoor climate of the buildings were obtained.
-The experiences were really promising. The employees of Metsähallitus were delighted with the cozy log building. The indoor air and acoustics were found to be pleasant. Because the experiences with the first buildings were good, the town decided to use log building in other projects as well, says Aila Ryhänen, the project manager of Pudasjärvi log town.
In 2013, Pudasjärvi then built a daycare centre for a hundred children, the largest log daycare center in the world. Log rental properties by Pudasjärvi Ltd. were also constructed. The town noticed that log is well suited for both low-budget residential housing as well as construction of larger facilities.
World’s largest log school
The town of 8,000 citizens took an even more daring step by building the world's largest log school in 2014. A log building of this magnitude had never been built in Finland or anywhere else in the world. The end result was the Log Campus, which saw over 800 pupils move in to study in the shelter of its wooden walls in 2016. The premises are over 10,000 square meters and have students from little preschoolers up to senior high-school pupils.
-These log buildings were a brave project and one that Pudasjärvi would most likely not have ventured into it if we had not already had the experience of building larger log buildings. Nonetheless, during the design and construction phase of the school, a lot of new construction solutions had to be explored and developed, as the campus combined large glass surfaces and robust log walls in a completely new way, says Aila Ryhänen.
The construction of the school was carried out as a new kind of life-cycle model. The city acquired the school building by a so-called lease agreement where the builder constructed the log school, but also maintains it for the next 25 years.
- Pudasjärvi got a new, cool school. On the other hand, with the agreement we were able to ensure that the school was well built and will be taken care of in the future as well, as it is in the developer's interest to maintain the school. When the contract expires after 25 years, the city may, if it wishes, redeem the school for half of the cost of the construction, says Pudasjärvi City project manager Aila Ryhänen.
In order to keep the costs under control, the project accepted bids from various log suppliers and construction companies. Finally, the trio of Lemminkäinen, Kontio and architecture firm Lukkaroinen were selected to undertake the project.
Good acoustics and indoor air condition
When Pudasjärvi did a survey for schoolchildren and teachers after being moved into Hirsikampus in 2016, the results were very different compared to before moving to the building: indoor air problems no longer existed.
- Based on previous experience, Pudasjärvi was aware that log buildings have a good indoor climate, but the positive results still came as a surprise. The wood has antibacterial properties and no toxic compounds evaporate from the wooden walls. Log also naturally compensates for the heat and moisture fluctuations between the outside and the indoor air, which makes the indoor air pleasant. Our daily experiences confirmed these research results. People in the log school are feeling great.
The log structures also had other unpredictable, positive effects.
-Yes, we knew that log buildings have good acoustics, but we still did not realize how enormous the effect of log structures would be for the sound in the school. In short, the acoustics in the Log Campus are great. There is much less school-like noise.
The only drawback that Pudasjärvi has experienced in the decade-long log project has been finding moisture in the concrete slabs of the first log office building.
- This was not due to log construction, as the concrete slab had not dried sufficiently during the construction phase before surface materials were installed. Therefore, it is good to remember that in all construction – whether the building material is log or something else - good results can only be obtained if every construction phase is done with care, reminds Ryhänen.
Finland’s log capital
The log building in the Finnish town of Pudasjärvi has attracted great interest both in Finland and abroad. The project has brought visitors to the city from all over Northern Ostrobothnia and Lapland and many local government officials have wanted to come and see what it is like to study in the log school.
- We have already had more than 9000 visitors from Finland and abroad. The reception has been curious and enthusiastic, says Aila Ryhänen. In addition to the visitors, the project has brought a lot of positive publicity to the small town of 8,100 inhabitants, as log building in Pudasjärvi has received a great deal of publicity in the media. It has given the whole community new enthusiasm and a sense of accomplishment. Pudasjärvi plans to continue with log building in the future. In 2015, the city made a formal decision that log will be used as the primary material for public buildings in the future. At the opening of the Log Campus, the town even proclaimed itself as the Log Capital of the world.
After building the Log Campus, the town has built Hirsikartano service home, which has been constructed from logs. In addition, there are plans to build a large center for well-being that will include a healthcare center and cultural facilities, such as a library and an auditorium. At the Iso-Syöte skiing center, a multifunctional sports and exercise hall is under construction.
If decision-makers were suspicious about log building in the early days, they have changed their opinions over the years, at latest when they went to visit the new, comfortable log premises. Now people in Pudasjärvi are quite unanimous that log construction will continue, says Aila Ryhänen.
Although Pudasjärvi can now boast of having many of the world's largest log buildings, the city considers the citizens’ access to healthy and purposeful facilities the most important achievement of all. At the same time, the small town has, with its own, non-mainstream decision-making, launched a new era in log building and it has not gone unnoticed. For example, the Finnish Association of Architects at SAFA awarded the city the SAFA prize in 2017.
-In ten years, the idea of what can be built out of log has changed radically. The Pudasjärvi projects have brought more credibility to large-scale log construction and have shown that log is suitable for modern architecture and public buildings. Many other municipalities are now launching their own log projects and we are extremely happy about it, says Aila Ryhänen.