The beech wood dowels are kiln-dried and incorporated during the manufacture of the elements, and swell up to the building humidity (approx. 15% ± 3%), so that they adjust to the pressure on the soffits of the holes. No separate component to ensure airtightness is necessary.
(the spacing scheme is 30 cm lengthways and 24 cm at right angles, whereby the rows of dowels are offset in a lengthways direction, 15 cm from one another). The mechanical join within the board stack elements works using friction between the beech wood dowels and the perforations in the cross-laminated timber elements.
The outer walls are made of solid timber with cross-laminated timber elements. The board layers of these elements were fixed and mechanically joined to beech wood dowels using a specific system (DeepGreen/Holz100). The dowels are placed at right angles to the board layers, at frequent intervals
High quality materials such as solid timber boards can also be re-integrated during conversion work. Empty ducts and flexible connection options (Homeway) also ensure maximum flexibility for building services in case of renovation or conversion.
Due to the permeable structure with highly insulating building components, these problems are virtually eliminated. The façade construction was examined in a durability simulation so as to ensure that living costs remain as low as possible. Optimal construction, fire safety, humidity control, and a weather-proof structure go hand-in-hand.
In the same way, due to the dry, mortarless construction method used, whole levels can be divided up into their components and re-used without any further processing required.
In general, the materials were selected for their potential durability. The manufacturer provides a 50-year warranty on condensation and mould growth.
All of the load-bearing outer walls and ceiling elements are simply screwed together and can be disassembled without waste. All of the elements can be separated from each other at a factory using a CNC joinery machine. In theory, the individual board layers and squared timbers can then be used again in new elements.
The emphasis of the design is on clarity of form and clear contrasts, even in terms of the materials used. A purist approach was deliberately chosen in order to ward off cosy associations with traditional timber construction. This very approach resulted in exciting contrasts between organic building materials and the systematic use of forms.
The monolithic reinforced concrete core was simply given a wooden floor in the foyer and deliberately sparse lighting. On walking into the building one therefore encounters an open space that is flooded with light and has sweeping wooden surfaces.
The façade was made of larch wood, edged with timber moulding, in order to emphasise the use of a single material for the outer wall structure. Dark grey metal soffits complement the deep-set windows, enhancing the punctuated appearance of the façade. The surface of the cut-away area is covered in plaster in order to make it distinct from the timber.
There is further contrast inside the building: the structural system enables different layouts to be configured on each floor. Despite the building’s outwardly uniform appearance, there is diversity inside.
This ambiguity is carried through to the division of the façades. In order to ease the defined structure of the balconies, square windows were positioned in the façade, seemingly at random. Their dimensions and heights do, however, follow the functional requirements. This results in deep windows that allow the people inside to see out even when seated.
Many contrasting design elements were implemented in order to break up the strict look of the basic geometric shape. Clear geometry is important to the building’s appearance from a distance, while from close up we see a detailed, horizontal alignment with the organic structure of the wood grain.
In order to ensure clear orientation, the entrance has been cut into the northern side of the building as a negative form. This allows the building’s cube shape to appear closed. Deliberately mounted on a visible base, the main body of the building is on a level surface. The surfaces of the outdoor facilities are completely flat in order to display the cube from all sides to the same extent.
This is emphasised by the way in which their undersides are clad in the same material as the façade. Inside the building, at the very centre, is the concrete lift and staircase core. This forms a clear contrast with the timber outer shell and the interior spaces within the apartments.
As part of the IBA Hamburg, the “WOODCUBE” was intended take on a clear structural form and act as a prototype. This gave rise to the distinct cube shape, which ensured a high recall value. The building’s cubature is enhanced by irregularly spaced, freely overhanging balconies. These are designed in such a way as to give the impression that they swing out of the basic shape.
Possibility of Conversion
Due to the large floor spans, almost every type of room layout can be achieved within the building. Every floor features different types of apartments. As there are no load-bearing walls, room structures can be changed at any time. Some of the apartments are also set up in such a way that, if required, they can be made completely accessible without major alteration work.
Above the basement, which is a waterproof concrete tank, almost all of the load-bearing construction components are made of timber elements, with the exception of the staircase core. The basement contains space for storing bicycles and technical and supply rooms, along with a laundry room and storage spaces for the apartments.
Large windows that run the width of the balcony and smaller square, or rectangular windows that seem to be arranged without reference to one another, break up the façade. The vertical openings for the building services installations are in ducts on the eastern and western outer walls. The bathrooms and kitchens are arranged around these ducts. Overall, the cubic form of the building makes it very compact.
The apartments on the west side of the second and third floors were joined together vertically to form a maisonette. The fourth floor, however, is designed as a closed unit. Each apartment has at least one balcony on a corner of the building and oriented east, south, or west. The roof, which is covered with a photovoltaic unit, is not accessible.
The outer wall of the entrance side is indented by half an axis, so that on this side the entrance to the central opening is located inside the cube itself.
The building is accessed from the north. From the ground to the third floor, there are two apartments on each level.
The building has a basement floor with a pillar foundation, topped by five full storeys on a square layout, with an edge length of 15.10 metres. The cube is divided into three horizontal axes, whereby the dimensions of the centrally oriented staircase with its lift shaft define the dimensions of the respective central axes. The staircase core is also square.
Due to its carbon balance in construction and operation, the “WOODCUBE” demonstrates the potential, within the climate-neutral building sector, of solid wood construction and energy supply using renewable forms of energy.
A sophisticated building services concept with central building control and smart metering supports the consistently low energy consumption.
Compared with conventional buildings, approximately 8,500 tonnes of carbon were saved during the construction phase alone.
The “WOODCUBE” project is the first time that a apartment complex has been built that does not emit any greenhouse gases over its life cycle, and is almost completely biologically recyclable. All of the construction materials were therefore checked for their carbon potential and biological compatibility in building.