In autumn 2021, Finland’s first two log high-rises built with a small carbon footprint were completed in Pudasjärvi.
Read the article in Finnish: Hirsihovi
Located in the centre of Pudasjärvi, Hirsihovi is a complex of two apartment buildings built with logs. Initial plans called for three structures, but the designs were whittled down to two larger buildings instead. This way, the buildings line the street without feeling cramped and enhance the Pudasjärvi cityscape.
Log is visible in the facades and in the bright apartments, and the hybrid buildings also make clever use of concrete elements. The understated design language of modern log construction is a good fit for the urban environment. For example, Hirsihovi has none of the overlapping corner joints associated with traditional log houses. Residents also praise how quiet the building’s rental apartments are, and they are indeed in high demand.
The buildings have a total of 53 apartments, ranging from 35.5 m² to just over 80 m² in size. The apartments were intentionally designed to be relatively small. This makes them a good option for the elderly moving from the suburbs to the city centre. Of the rental apartments, 15 are designated as Keva apartments for the disabled. To meet accessibility requirements, the turning radiuses in the corridors and common areas are larger than usual. The commercial spaces are at street level, and there are three residential floors. The total heated gross area of the two buildings is 3,712 m².
Hirsihovi is one of Finland’s first multi-storey log buildings, so the entire project team had plenty of brand new challenges on its hands. Their new solution, for example, was to bind the concrete intermediate floors to the log exterior walls to meet the fire safety and sound insulation requirements.
Log and concrete structures were both valued in Hirsihovi for their individual strengths. According to the developer, wooden intermediate floors run the risk of water damage and poor sound insulation. In addition, ease of maintenance factors into a building’s carbon footprint, which further favoured using concrete hollow slab floors instead. The wet rooms and the walls between neighbouring apartments are also concrete. Log shows its strengths in the exterior walls.
In addition to the exterior walls and facade, the partitioning walls inside apartments are made of non-settling log. By contrast, the walls between neighbouring apartments have been built from concrete as they are load-bearing and form fire-compartments. The logs have nice level corners on both sides. Log ends and joint details are hidden under corner mouldings. The project used a total of 9.5 kilometres of Kontiotuutti’s 275 mm x 275 mm non-settling beams, and the walls store a total of 670 tons of carbon dioxide.
Wood use in the otherwise concrete-framed building added no special fire-technical requirements. The fire class is P1, which meant that no sprinkler system was necessary. Each apartment and stairwell form their own fire compartments. Flame retardant paint was used on the facades at ground floor level and on the walls with balconies as the balconies serve as the building’s emergency exits.
Feedback from residents on soundproofing has been good. Impartial measurements also gave the sound insulation good marks, and disabled residents who are particularly sensitive to sound have praised the comfortable silence of their homes.
Construction kicked off in May 2020 with the concrete frame and the roof. The logs were installed in autumn 2020, and construction was complete a year later.
Pudasjärvi residents are pleased with how Hirsihovi has improved the cityscape and promoted the region in general. Hirsihovi’s inhabitants have also enjoyed their homes, particularly the visible logs of the facade and partitioning walls. The apartments have been a hit with residents, and the queues for new availabilities are long.
Jaakko Kallio-Koski is an architect with a wide range of experience in different fields of architecture, mainly focused on housing design and urban planning in the recent years. He is currently working as a design director at Sweco Architects. He is mainly working as a principal designer in projects, current works including several housing projects of different sizes as well as large scale urban city block development projects. Kallio-Koski has received rewards in several architectural competitions.
Anu Kortet Is an architect who is currently working with various housing projects from smaller scale retirement homes to larger scale urban housing city blocks. Her focus is on functional and timeless design that is in harmony with surrounding environment.
Project in brief
- Location | Pudasjärvi
- Purpose | Residential building
- Constructor/Client | Pudasjärven Vuokratalot Oy
- Valmistumisvuosi | 2021
- Total area | 3 700 m2
- Volume | 12 760 m3
- Investointikustannukset | 9 500 000€
- Architectural Design | Linja Arkkitehdit Oy (now part of Sweco Architects), Jaakko Kallio-Koski, Anu Kortet
- Structural design | Sweco, Tuomas Jaakkola
- Pääurakoitsija | Rakennusliike Lapti Oy
- Wood component supplier | Kontiotuote Oy
- Photographs | Juha Nyman, Pudasjärven kaupunki
- Text | Puuinfo (source: RIA 3/2021)