Residential house in wood hybrid construction
rundzwei architects have closed a narrow gap in Berlin-Moabit with a residential building in wood-hybrid construction. Facing the street, the "iceberg" with its light aluminium façade appears urban and cool. The south-facing courtyard side with external access offers maximum openness, lots of light and generous balconies. The low-energy house was built largely from recyclable materials and makes optimal use of the small plot: Thus, 11 low barrier rental flats were created on only 100 m² of floor space.
Maximizing space through creativity
Both the different façades and the planning interventions to maximise space shape the appearance of the residential building: on the street side, a curved bay window enlarges the flats. On the courtyard side, Marc Dufour-Feronce and Andreas Reeg have moved the stair core and the lift outwards, into the courtyard. This allowed the architects to generate the maximum possible usable space on the relatively small plot. This pragmatic approach to the largest building volume feasible under building law is consistently developed architecturally in the floor plans and façades.
From the ground floor to the 4th floor, the unusual geometry allows comfortable floor plans for nine 2-room rental flats, each with approx. 55 m² of usable space. The loft-like cooking, dining and living areas connect the north and south façades. Cross-ventilation and views in both directions are thus possible. All flats have bathrooms directly adjoining the bedroom and a utility room.
On the fifth and sixth floors are two maisonette rental flats, each with 96 m² of floor space. Here, the cooking, dining and living area facing the courtyard has a double room height. All flats are accessible without steps via the lift. Inside, too, all residential units (except for the maisonettes) are completely free of thresholds for the elderly.
Flush outer skin versus open framework structure
The symmetrical and strictly gridded street façade is covered with an almost flush outer skin of corrugated aluminium sheet. It extends as a natural, flowing form over the recessed entrance area on the ground floor and the bay window above it, which curves elegantly out of the façade. All windows facing the street can be closed with folding shutters. The aluminium sheet on their outer sides is perforated so that daylight falls through the windows even when they are closed and the view outside is still possible.
To the south, "The Iceberg" shows a completely different face: an open scaffolding structure supports and encloses the stair core and lift pushed into the courtyard, as well as the elongated balconies in front of all the flats. Floor-to-ceiling windows allow the sun to penetrate far into the rooms in winter, while in summer the continuous balcony surfaces protect against too much solar radiation without impairing the view of the bright inner courtyard with its old trees. In the attic, the extensive green roof provides a cooling effect during the hot months of the year.
Accelerated construction process thanks to prefabricated timber elements
The "Iceberg" is realised as a timber frame construction with load-bearing solid timber ceilings, façade elements in timber panel construction, sand-lime brick and reinforced concrete walls as well as steel and timber supports. Prefabricated timber elements were used as far as possible to speed up the construction process and keep the finishing work to a minimum. Due to the static structures of the walls and roofs, the building achieves the German low-energy standard (KfW 55).
The moisture-absorbing wood and lime plaster surfaces of the construction and interior wall cladding are open-pored and thus contribute to the natural air conditioning of the room air. This reduces possible later structural damage due to insufficient manual ventilation by the tenants. A district heating system supplies the underfloor heating of the residential units. Air is exchanged automatically and quietly in the bathrooms and kitchens and through humidity-controlled night vents in the windows. This eliminates the need for a complex ventilation system with heat recovery.
Local materials - simple, functional, recyclable
Marc Dufour-Feronce and Andreas Reeg of rundzwei give great importance to simple, locally produced and at the same time functional materials: instead of glass, the balcony parapets and stairways were secured with simple stainless steel nets, the elevator was covered with expanded metal and painted a bright golden yellow.
Instead of elaborate floor coverings, the Berlin architects opted for polished concrete in all apartments. The timber ceiling structure was left exposed allowing the natural beauty of white oiled spruce to come through and create softness to the living spaces. The courtyards’ floor-to-ceiling timber-aluminium windows are perfectly matched with wooden "seat windows" on the street side.
Except for screed and plastered surfaces, all building materials are simply mechanically fixed to facilitate later recycling. Ideally, environmental friendliness and economy are combined on the north façade with the corrugated white aluminium: the inexpensive material contains a percentage of recycled content and can be 100% recycled.
Marc Dufour-Feronce and Andreas Reeg attach great importance to simple materials that are as locally produced as possible and at the same time functional: instead of glass, the balcony balustrades and staircases were secured with simple stainless steel nets, the lift was fitted with expanded metal cladding and painted bright golden yellow.
Instead of elaborate floor coverings, the Berlin architects opted for exposed screed floors in all flats. The planners also left the wooden ceilings made of spruce uncovered, only oiled white. Perfectly matched to the floor-to-ceiling wood-aluminium windows on the courtyard side and the wooden "seat windows" on the street side.
Except for screed and plaster surfaces, all building materials in the residential building are only mechanically fixed to facilitate later recycling. Ideally, environmental friendliness and economic efficiency can be combined as optimally as in the case of the corrugated aluminium sheeting of the white north façade: it is cost-effective, has a high recycling content and can be 100 % recycled.
Project team rundzwei:
Luca Di Carlo, Marc Dufour-Feronce, Johann Göhler, Miriam Lopez, Andreas Reeg, Mathias Rühl
Structural engineering: ifb frohloff staffa kühl ecker, Beratende Ingenieure PartG mbB
Energy consultant: Enegieberater Land Brandenburg ELB, Brandenburg
Site survey: Andreas Zill, Berlin
Mechanical engineering: ITV GmbH (Ingenieur Team Versorgungstechnik GmbH)
Electrical engineering: Planungsbüro Oliver Kautz GmbH
Site supervision: ZRS Architekten und Ingenieure GmbH
Contractors
Wood facade and windows: Zimmerei Sieveke GmbH
Wood and concrete construction: Caerus Construction GmbH
Steel works: Uckermetall GmbH
Roof: Fa. Hanebutt Zörner Berlin GmbH
Elevator: SMW Aufzugsysteme GmbH, Berlin
Dry walling: BTB Systembau GmbH, Berlin
Screed: Thiemer Werner Fußbodenservice GmbH, Berlin
Painter: Wolfgang Lüttgens GmbH, Berlin
Heating and mechanical works: Dörr GmbH Lübben
Electrician: Manfred Küchenmeister Antennen- und Elektroanlagen, Berlin
