The large-scale development measuring 7000 square metres is located adjacent to the listed Jewish cemetery of Adass Jisroel. This location alone makes "Quartier Wir" in the north-east of the city a very special project in the capital. In its brief, the developer UTB Projektmanagement GmbH insisted that the brownfield site was not just to offer homes for 250 people, but was to contribute to the vibrant social and communal life of Berlin.
Following an architectural competition, the contract was awarded to Deimel Oelschläger Architekten who proposed a complex consisting of four and five-storey timber-frame buildings, as this method of construction offers great flexibility as regards different forms of housing and living together. One third of the 113 housing units are to be sold to owner-occupiers, while the rest will be allocated to the cooperative housing organisation BeGeno16, who will put about half of them up for rent in the private market while the other half is reserved for subsidised housing. BeGeno16 will also select the tenants to ensure a true mix or generations and forms of living within the complex. There will be traditional housing units for families, studios for singles and communal rooms, as well as living clusters for migrants, students and people suffering from dementia. At ground floor level, the buildings include commercial units serving the wider community, such as a crèche, a coffee shop, a restaurant with training kitchen and a newsagents. The indoor pool will however only be open to people living in "Quartier Wir".
Flexibility thanks to timber skeleton construction
Given the ambitious objectives of the development, the architects opted for a construction that meets high sustainability standards. The building shell conforming to the KfW-40 standard is positioned so that it fits perfectly into the existing building stock, linking the new quarter seamlessly to the public and private outdoor areas that make Berlin Weissensee such a popular area. In addition, the supporting structure and all enclosure walls are made in timber – a renewable construction material and CO2 sink with exceptional structural strength properties. The supporting structure consists of a skeleton made from glulam posts and beams. The floors are also in glulam, while the external walls consist of complete prefabricated timber-frame elements with windows and cellulose insulation. After installation, these elements are clad in plasterboard at the inside while the outside is rendered. One of the main advantages of a skeleton construction with stud walls separating rooms and housing units is its flexibility as regards floorspace design. With this method, it is possible to construct housing units with completely different layouts one on top of the other.
Standardised construction element dimensions with high-strength BauBuche posts and beams
From a construction point of view, the five apartment blocks are virtually identical. Above a concrete basement, we have several storeys with housing units, linked by a stairwell core at the centre that provides additional stiffening. Around this core is the timber skeleton construction. It consists of two outer and two centre post rows along the entire length of the building. The outer posts along the façade are positioned 2.80 m from each other, which is half the distance between the posts along the axis extending from the stairwell walls. Combined with the relatively low vertical loads along the façade, these small spans enabled the designers to opt for slim posts and beams made in spruce glulam of strength classes GL24h–32h.
In order to cater for greater flexibility in floorspace design, the two rows of posts at the centre are spaced wider (which means greater loading widths and higher vertical loads). With spruce posts, this construction would have required rather large elements, which would not have fitted in well with the rest of the exposed structure, and would have obstructed the construction of the demand-controlled ventilation system. That is why the designers chose BauBuche of strength class GL70 for most of the posts and beams in this area. In contrast to the floors, which are of the same construction throughout the building and made from 24 cm spruce glulam elements resting on beams that are narrower at the top than at the bottom, the cross-sections of the BauBuche posts and beams vary, depending on the actual strength requirements.
Combination of spruce and BauBuche
Similar to the supporting structure, all connecting elements and fasteners are standardised and can thus be used for both spruce and BauBuche elements. Thanks to this clever decision, elements in spruce and BauBuche can be combined as required for best design and load strength. For fixture to the staircase walls, the beams are slit and secured with bar dowels to sword-shaped elements that are welded to concrete-embedded steel plates. Steel plates flush-mounted to the post tops and bases, and vertical bar dowels inserted into pre-drilled holes in the beams transfer the vertical forces from post to post. As all the fastening devices are concealed, the rooms are characterised by beautiful timber surfaces without any obstructing other features.
Social and structural sustainability
From the outside, it is not obvious that the blocks of "Quartier Wir" are timber constructions, as the exterior walls are rendered. When entering the buildings, this changes instantly, as the interior is characterised by the natural warmth and haptics of parquet flooring, timber windows, and the wooden supporting structure. Throughout the buildings, timber in many shapes and guises is the predominant material. In the large apartments and cluster homes, free-standing posts and exposed beams reveal the idea of maximum flexibility that is at the heart of the development. The skeleton construction method facilitates not only future changes to floor plans as housing needs change, but would also allow for conversion of the housing units to offices, which is however highly unlikely. In addition, it will make it easy to recycle materials when the building has reached the end of its service life. Given the sustainable design of "Quartier Wir", this will however not happen any time soon.
-Text by Roland Pawlitschko-