Sweden’s Tallest Timber Building Is a Towering Feat of Sustainable Architecture

Airtight and quick to assemble, Sweden’s carbon-sequestering Kajstaden tower is a beacon for green building.
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An hour outside of Stockholm, C.F. Møller Architects has crafted the tallest timber tower in Sweden. Inaugurated last February, the record-breaking Kajstaden Tall Timber Building serves not only as a landmark for the newly founded Kajstaden district of Västerås, but also as a powerful symbol of the many benefits—sustainable, structural, and otherwise—of high-rise timber structures.

The Kajstaden Tall Timber Building has nine floors with an elevated ground floor and a double-height top floor. C.F. Møller Architects designed the building in collaboration with Martinsons, Bjerking and Consto AB, for client Slättö Förvaltning.

The Kajstaden Tall Timber Building has nine floors with an elevated ground floor and a double-height top floor. C.F. Møller Architects designed the building in collaboration with Martinsons, Bjerking and Consto AB, for client Slättö Förvaltning.

"The building in Kajstaden constitutes a new chapter in the history of construction, as it is currently Sweden’s tallest solid-timber building," says Ola Jonsson, associate partner at C.F. Møller Architects. "Through research projects and our other timber projects we have focused on innovation and contributed towards developing ways of realizing high-rise buildings made of timber. Industrial timber technology also provides architects with better tools for designing beautiful houses that boast a high degree of detail."

Located in the central residential neighborhood of Kajstaden near the water, the building is the ideal height for CLT construction, which ranges between three and 11 stories. Buildings taller than 11 stories require greater weight—such as concrete cores—for stabilization.

Located in the central residential neighborhood of Kajstaden near the water, the building is the ideal height for CLT construction, which ranges between three and 11 stories. Buildings taller than 11 stories require greater weight—such as concrete cores—for stabilization.

The architectural potential of building with wood has been greatly expanded thanks to cross-laminated timber. The prefabricated solid timber panels are engineered for high levels of resistance against fire and moisture, which are common problems associated with old wooden buildings.

With over 100,000 square meters of solid timber projects in the works, C.F. Møller Architects is showing through example how solid wood is a climate-conscious alternative to concrete. Designed for extreme strength, cross-laminated timber also retains wood’s flexible and lightweight advantages that translate to faster installation times and fewer deliveries to the construction site.

Each floor of the building took four craftsmen an average of three days to put together. There are four apartments on each floor.

Each floor of the building took four craftsmen an average of three days to put together. There are four apartments on each floor.

The use of locally sourced CLT allowed for a significantly reduced construction time, which offset the cost of using a newer material.

The use of locally sourced CLT allowed for a significantly reduced construction time, which offset the cost of using a newer material.

Keeping the building’s life cycle in mind, the architects specified mechanical joints and screws so that the structure can be taken apart later, and the materials can be reused.

Keeping the building’s life cycle in mind, the architects specified mechanical joints and screws so that the structure can be taken apart later, and the materials can be reused.

"Wood technology facilitates a value-adding lifecycle perspective in all stages of construction, and is crucial to the goal of a bio-based circular economy," says Rob Marsh, sustainability manager at C.F. Møller Architects. "The total carbon dioxide savings from the use of solid wood instead of concrete are estimated at 550 tons of CO2 over the building’s life."

The building has an estimated 120-year lifespan, with a carbon footprint calculated to be 44% less than its concrete equivalent.

The building has an estimated 120-year lifespan, with a carbon footprint calculated to be 44% less than its concrete equivalent.

The benefits of solid-timber construction extend beyond the environment and cost savings—the high-precision technology involved in CNC-milled solid timber with glulam elements also results in airtight and energy-efficient envelopes without the need for extraneous materials. 

Positioned to take in beautiful views of Lake Mälaren, the high rise sits at the entrance of the recently redeveloped Kajstaden residential neighborhood in the old postindustrial harbor in the Öster Mälarstrand area of Västerås.

Positioned to take in beautiful views of Lake Mälaren, the high rise sits at the entrance of the recently redeveloped Kajstaden residential neighborhood in the old postindustrial harbor in the Öster Mälarstrand area of Västerås.

All parts of the building, from the walls and beams to the balconies and elevator shafts, are made of locally sourced cross-laminated timber.

All parts of the building, from the walls and beams to the balconies and elevator shafts, are made of locally sourced cross-laminated timber.

The architects also note research suggesting that wood-framed buildings contribute to human health and well-being thanks to improved air quality and acoustic qualities.

Three-meter-tall CLT panels were selected to reduce the need for cutting on-site and to maximize ceiling height on all floors.

Three-meter-tall CLT panels were selected to reduce the need for cutting on-site and to maximize ceiling height on all floors.

The building is located within walking distance to green space and the marina, which features an electric boat sharing system. The community also has bicycle storage and charging stations for electric vehicles.

The building is located within walking distance to green space and the marina, which features an electric boat sharing system. The community also has bicycle storage and charging stations for electric vehicles.

"We’re currently experiencing a greater focus on building with timber than ever before, but whilst blocks of flats are currently being built in timber in the Nordic countries and worldwide, when it comes to tall buildings, timber is far from the natural choice within the construction industry," says Peter Fynholm, vice director of the Nordic Network for Tall Wood Buildings, an organization that includes C.F. Møller Architects.

"It’s annoying, as there’s untapped potential in the use of a renewable resource in an industry that affects the climate as much as the construction industry does. It’s therefore crucial that we learn from our experiences, e.g. what we’ve learned from Kajstaden in Västerås." 

Sedum green roofs top the apartment building and help manage stormwater runoff.

Sedum green roofs top the apartment building and help manage stormwater runoff.

Kajstaden Tall Timber Building

Kajstaden Tall Timber Building

Kajstaden Tall Timber Building CLT construction diagram

Kajstaden Tall Timber Building CLT construction diagram

Kajstaden Tall Timber Building sustainability diagram

Kajstaden Tall Timber Building sustainability diagram

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