Sundbyberg is a rapidly growing municipality next to Stockholm. Folkhem, a developer that previously worked with smaller developments, were offered one of the best locations on a brownfield area next to lake Mälaren. The combination of possibilities of a view over the water and supreme communications next by, opened for a slightly more exclusive touch. We designed the plan with five lamella buildings and introduced the idea to employ wood wherever possible.
Folkhem restrained from building all the lamellas, and focused their limited resources on two houses that took advantage of their large experience of smaller wooden homes. A manufacturer, Martinssons, that produces wooden element for prefab houses, developed a system that convinced everybody that it was possible to create a tall building with prefabricated wooden elements.
The elements from Martinssons arrived to the site cladded with shingles of Canadian cedar. They were mounted under a temporary roof, which made the entire construction site dry and comfortable. As the elements of cross-laminated massive wood are very light compared to concrete, the attic had to be fixed to the foundation with bolts. Shingles were chosen because their natural variation in color. The façade (and the roof of building B) will turn gray. As we know that this process not will be even over the entire building, shingles will handle this variation naturally and without any demands for maintenance.
The multiple demands for new solutions made the buildings more costly than a conventional concrete structure. As the experience grew, the costs were reduced. The first house was circa 25 percent more costly, but the second only circa ten percent. It is not unlikely that the compressed construction time on site could reduce the cost even further.
The wooden structure did not meet any major risk calculations in terms of fire. However, the wooden façade is a potential source of transportation of a fire from one story to another. This risk was met by equipping all apartments with sprinklers. Structurally, the wooden structure did not face any problems, not even as elevator shafts. The risk of vertically transmitted noise was eliminated by a second ceiling supported by the wall.
The buildings have gained a wide recognition, and been awarded for their forward-looking, yet traditional and well proved, technology. The architecture has a parallel character; contemporary in its combination of wood, glass and balconies, but also conventional in its almost iconic “house” shape with references to a widely spread type in Swedish post-war architecture. A low carbon footprint is an important factor for the trade, the customers and for the society at large. Strandparken have proved its possibilities and we are now testing the technology in even taller buildings.
It started in the 1990s with Arne Olson, a young man with a passion for ecology. We met one night by complete coincidence in Copenhagen. It turned into a deep dive through all that was known at the time about green building, with the big construction firm picking up the tab. Sure, wood framing ought to be the future even for multi-family housing.
Arne later came to Folkhem to be the CEO after Sven-Harry. We won an urban planning competition in Sundbyberg in 2007, and got to design four apartment buildings for Folkhem. The first is called B and has just now been occupied in the summer of 2013.
It’s nine stories high with a load-bearing frame of solid wood from Martinsson’s, and the outside is entirely clad in cedar shingles. It looks like a wooden house.
A wood-framed building weighs only a third of what it would if it had been made of steel and concrete. It’s so light that it has to be tied down to the foundation with 23-mm metal rods that reach all the way to the eighth floor.
It ended up costing 15% more than it would have with conventional construction (the next one is only going to be 10% more, and on the one after that we’ve got it!). We’re doing four buildings, one after the other….
This is the kind of building that elected officials should demand when they call for cost-efficient prefabricated homes. It’s warm and dry inside, with the aroma of wood, sheltered from precipitation during construction under a protective roof with an integrated crane. A beloved archetype, a winning Monopoly house.