Somewhere between the daily madness of real estate sharks, major investors, and gentrification, a popular alternative model has developed in Berlin over the past decades – the building group (Baugruppe). The D2 building group, consisting of fifteen families, was fortunate enough to secure one of the last vacant plots in a central location in Neukölln. The design task for IFUB* was to create a building that is well-integrated into the city, ecological, yet modern and friendly, with lots of greenery and shared spaces in the courtyard and on the rooftop.
Building groups are a very popular form of creating new housing in Berlin. Multiple parties come together, pool their interests and finances, and jointly build one or more houses. The beauty of building groups? Future owners are involved from the very beginning and can influence the concept and design.
The vacant lot at Donaustraße 2 had not been fully developed when it was sold to the group of young families after a workshop and garage rental business shut down. The design task was complex: the narrow, elongated plot had only a small buildable area toward the street in the north, but a long inner courtyard area that also needed to be utilized. Given the high land price and Berlin’s tight housing market, making full use of the site was essential.
The legally required closing of the block’s perimeter was located at the southern end of the long Pannierstraße at a small T-junction. In response, the front building was designed with a prominent corner, visually referencing the street-facing gables of the neighboring buildings and moderating the different eave heights to either side. The building fits harmoniously into the urban context, supported by the punctuated facade and a recessed ground floor. This base houses two commercial units to activate the neighborhood, with colorful glazed brick slips referencing 1970s Neukölln facades and visually linking to the rear building.
The front building also features large south-facing balconies at the rear, already hinting at a key design feature: all residential floors in the front building are designed to function either as one large or two smaller apartments. This adaptability is central to the concept of durable and long-lasting buildings. Therefore, the apartments can easily be divided or combined later.
The rear garden building was built against an existing fire wall and staggered in height to maintain required setbacks. The south- and east-facing setbacks were designed as terraces, offering maximum outdoor living quality.
A view from the front building toward the garden building shows: even fire-resistant walls don’t have to be dull! The open fire escape staircase at the gable end of the garden building had to be surrounded by non-combustible materials. This clever move eliminated the need for dedicated fire truck access zones, allowing the courtyard to be used entirely as a garden. Bikes and bins are stored in the semi-basement, keeping the courtyard free and green. The colorful, non-combustible brick slips visually grow from the base of the front building across the entire garden facade toward the sky.
Due to building code restrictions, the floor plans in the garden building are more heterogeneous than in the front house. A diverse apartment mix, ranging from compact 1.5-room units to spacious six-room maisonettes, accommodates the diverse needs of the residents. A special feature: ground floor units have private gardens instead of balconies.
Another key element is the use of different facade materials. The front facade is clad in larch wood, which—with its large panels and flush joints—reflects the planar quality of neighboring plaster facades while signaling the unusual wooden sandwich construction. This is combined with white-stained wooden windows and zinc sheet metal detailing.
The glazed brick slips were manufactured locally in the Berlin region. As a unifying design feature, they appear on the base of the front house and the stairwell and base of the garden house in a cheerful, colorful pattern.
The fire stairwell had to have not only a non-combustible interior enclosure but also a fully non-combustible exterior facade. Therefore, untreated, 100% recyclable aluminum corrugated sheets were chosen. While the stairwell has a metal shell, the rest of the building features wooden balconies, windows, and walls, creating a harmonious material dialogue between front and rear buildings. Colorful fabric awnings complete the image.
The windows in both buildings have a distinctive cross pattern and are installed 45 cm above the floor, creating potential seating niches.
The gardens alongside the garden building are directly assigned to the adjacent apartments. The central courtyard between the front and rear buildings is reserved for the community and includes a flexible common room. The private garden plots are purposefully separated only by plants, not fences—and all vegetation throughout the outdoor spaces bears edible fruits. Every available surface, both vertical and horizontal, has been greened, though the full effect will only emerge in the coming years.
To strengthen the sense of community, both buildings have shared rooftop terraces for all residents, offering great views. From the front building’s rooftop, one can look straight down Pannierstraße to Görlitzer Park.
The flexible layout options came with an ecological cost. Due to the demanding soundproofing requirements for shifting apartment boundaries, a full timber structure would have been too complex and expensive. A hybrid structure was therefore chosen: load-bearing concrete construction with timber facades. This is visible in the central corridor, where exposed concrete ensures the necessary durability in this high-traffic area. Elevator doors carry the colors of the facade tiles into the building, adding splashes of color on every floor.
For convenience, the central passageway of the front building has automatic doors. The gently sloping drive leads past colorful mailboxes to the bicycle and stroller parking in the semi-basement of the garden building. Thanks to Berlin’s parking regulations, a car garage was not required—and wasn’t desired either. This saved CO₂ and costs, and only made the green courtyard possible.
The building systems rely on an exhaust air heat pump that uses the heat from indoor air to heat domestic hot water. Fresh air is provided through wall-mounted air inlets. Heating is supplied by district heating, and photovoltaic panels on the roof support the heat pump’s operation.
The apartment interiors could be co-designed by the residents. For ceilings, they could choose between raw concrete or plaster. Flooring, tiles, and sanitary fittings were also individually selected.
