Holzhaus

context

urban nest is the first, highly prefabricated five levels timber house ever built in Berlin.

architecture

The building footprint is 14.5m x 13m and is constructed in energy-efficient timber construction. It features a KfW-Effizienzhaus-55.
The staircase and the foundation slabs are the result of semi-prefabricated concrete elements, while timber technology construction is used in the main building.
The use of wood enables a high degree of prefabrication and thus precise assembly on site.
All timber construction work is carried out in accordance with construction planning, production planning for prefabrication or assembly planning and statics.
The building process consists of six stages:
1 building of pre-fabricated element _04-06.2017 digging and concrete foundation building _04-06.2017
3 concrete staircase assembly _ 08. 2017
4 timber elements assembly _ 09.2017
5 electrical and mechanical installation _ 10.17-04.17
6 interior finishes _ 01-05-18
timber elements were prefabricated in Bressanone, Italy in 44 working days and were later assembled on site in berlin in 21 working days (from August 29 to September 26, 2017) by 2 specialized LIGNOALP workers helped by 2 berlin-based local carpenter.

section

The new house consists of five levels, two units per level: a studio + a 2 bedroom unit that can be easily combined into one unit or divided into 3 smaller unit/studio. The roof profile replicates the existing condition of neighboring buildings.

structure

The roof of the building is built by a series of rafters slightly inclined (approximately 8°) towards the backyard. Towards the road the roof is divided into three parts. In the central part there is a large vertical glass façade, which is directly connected to the roof surface. To the left and right there are steep roof surfaces, which consist of horizontally stretched rafters. 

The ceilings in the living areas consist of HBV ceilings: a composite of wood boards and reinforced concrete to maximize the strengths of each individual building material. The lower layer is composed of 100mm high board stack elements –vertical separate boards glued together – the top layer of a 140mm thick concrete layer.  The lower layer absorbs the tension forces, the concrete layer bears compressive forces. To guarantee the power of transmission between both layers, notches were milled in the board stack elements on the upper surface. Due to the concrete pouring operation, which is carried out in a second step, after the montage of the lower level, the concrete interferes in these  notches and thus all forces can be transmitted between both layers.

Roof and ceilings are stretched in the same direction parallel to the road, so that a consistent load transmission is guaranteed over all five floors. The loads are transmitted to the lateral walls made of wood construction (laminated veneer lumber) adjacent to the neighbouring buildings and two additional bearing walls. The two additional bearing walls are approximately located to the left and right of the large central glass facade. In these walls a few steel girders are to be found. These girders are stretched over the complete housing depth and lie on respectively two or four supports.

The structure of supports at the same locations in the floor plan throughout the building allows a clean and consistent energy flow. At the connecting point between the steel girders at the exterior wood wall supports are integrated in the prefabricated wall-elements. In the interior area steel hollow sections are applied as supports, which allow an extremely slim cross section (S355, QRW 120/10). These supports can also be integrated in an apartment partition wall depending on the floor plan design. 

On the ground floor these supports are directly transmitted to the base reinforced concrete plate. A circulating concrete band of approximately 40cm serves as bearing base for the exterior wall.

The balconies on the back side of the building consist of simple timber beam construction, In each of these balcony, threaded rod girders are glued in. These threaded rods are supported by the exterior wall construction, they interfere in the overlay of the HBV ceilings and thus facilitate the cantilever or a support-free balcony construction.

LocationBerlin, Germany
Use: Residential
Client:Private client
Status:Completed
Design Team:

conrad-bercah, Erich Gruber, Michael Sedlmayer, Grupa 4