HomeArchitectureNorway is home to the world’s tallest timber tower
September 15, 2019

Norway is home to the world’s tallest timber tower

Mjøstårnet represents a genuine milestone in its use of timber for construction and cladding
Image credit: Voll Arkitekter

Upon its completion in March 2019, Mjøstårnet in Norway was officially verified as the world’s tallest timber tower by the Council on Tall Buildings and Urban Habitat (CTBUH). Designed by Voll Arkitekter, it took the title of world’s tallest timber building from the 53-metre-high Brock Commons Tallwood House in Vancouver, which has a hybrid wood and concrete structure and Treet in Bergen, Norway, which is 49 meters high.

Mjøstårnet is located in Brumunddal, a small city with 10,000 residents, about an hour and a half drive north of Oslo. Standing alone on the riverbank of Brumunda, Mjøstårnet has a majestic appearance, overlooking Lake Mjøsa, the largest lake in Norway. The name ‘Mjøstårnet’ is Norwegian and means ‘The tower of Lake Mjøsa’. Mjøstårnet is to be a symbol of the ‘green shift’, and proof that tall buildings can be built using local resources, local suppliers and sustainable wooden materials.

With its distinct architectural appearance, Mjøstårnet is a landmark, both in the way it stands tall at 85.4 meters in amongst the landscape, but also in its revolutionary use of timber in the construction and cladding. A modern mixed-use tower, with facilities that the residents, locals and visitors can exploit, the tower has already attracted a lot of attention both in Norway and abroad. Voll Arkitekter has been responsible for the regulation of the site, the design of the tower and the storey layout, as well as the design and layout of the public bath connected to the tower.

The tower consists of 18 storeys with different programs. With a footprint of only 17m in width and 37.5m in length, each floor is about 640 square meters. The total program for the tower is about 10,500 square meters with an additional 4,900 square meters for the public bath. The ground floor is public space with a lobby, reception and restaurant. In addition, there is an adjoining public bath on the ground floor with two 25-meter length pools. The second storey is reserved for rentable meeting rooms and technical facilities. The next five storeys are dedicated to office space.
Image credit: Voll Arkitekter

Mjøstårnet has 72 hotel rooms, 18 on each floor from the 8th storey to the 11th. In total, there are 33 apartments in the project, ranging from 50 to 180 square meters, with 6 apartments on each floor on the 12th to 16th floor, and 2 apartments on the 17th floor together with an event room that can be used for weddings, celebrations and larger conferences. On the top floor is a penthouse apartment and a public viewing terrace.

The design concept for Mjøstårnet was inspired by the Paris Agreement to combat climate change and began as an idea to reduce carbon dioxide emissions while sustainably sourcing construction materials locally. Wood was chosen as the structural material due to recent advancements in the field of mass timber – particularly following the increased availability of large glue-laminated timber and cross-laminated timber (CLT) structural elements. Notably, wood is also the world’s only truly renewable building material, as it sequesters carbon throughout its lifecycle.

All key structural components of Mjøstårnet are composed of engineered timber, utilizing glue-laminated timber for beams and columns and cross- laminated timber for the core walls containing the building’s elevator and stairway shafts. The glue-laminated columns were fabricated with pre-drilled holes and assembled onsite into vertical trusses of up to five floors in height, providing stability to horizontal and vertical forces.

Floor slabs for levels 11 and below are also crafted from timber beams, topped with laminated veneer lumber and a thin 50-millimeter layer of concrete for acoustical and vibrational performance, while levels 12 and above have floor slabs fully composed of concrete to increase weight and achieve the desired dynamic behavior in periods of strong winds.
Image credit: Voll Arkitekter

The main load bearing consists of large-scale glulam trusses along the façades as well as internal columns and beams. The trusses handle the global forces in horizontal and vertical direction and give the building its necessary stiffness. CLT walls are used for secondary load bearing of three elevators and two staircases. Large prefabricated façade elements are attached to the outside of the timber structures and make up the envelope of the building. These sandwich type elements come with incombustible insulation and external panels already fixed.

Moelven Limitre, the project’s structural engineer, supplied glulam columns, beams and diagonals, CLT elevator shafts, stairs, and floor slabs. The company was also responsible for the direct installation of the wooden structures in the building. In addition, every wooden part in the facade construction had to be fireproof. As such, a fire safe pine product from Woodify was chosen for the cladding. As Brumunddal is in an area of Norway with a major forestry and wood processing industry, the materials were primarily sourced locally.

Mjøstårnet was built four storeys at a time in five construction stages. An internal scaffolding and a large crane was used to hoist the pre-fabricated sections and floor slabs into place. Mjøstårnet has a base width of 16 meters but Moelven Limitre believe that it would have been possible to build taller if this was increased. The width traditionally determines the height of a timber building: greater width means the building sways less. A wider building would make it unproblematic to build higher than 100 meters, and even perhaps 150 meters or more.

Its height may not be all that impressive compared to the average non-timber skyscraper, but Mjøstårnet represents a genuine milestone in sustainable construction. Different materials will be used side by side for many years to come, and Mjøstårnet is by no means the ultimate blueprint of a tall timber building. However, the most important aspect of this building is to show that it is possible to build large, complex timber buildings, and in that fashion, inspire others to do the same.

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