Katrin Gräf, Gerd Priebe
05/2014 – 01/2018
First, the former coach house had to be dried, gutted and made safe. Inside the existing walls, the architect placed a completely separate, free-standing timber construction made from 50 m³ BauBuche and extending over a floor space of 1375 m². This timber construction is divided into three sections, each consisting of a single-layer timber shell with seven floors measuring 170 m² each. The old stone shell protects the timber structure against the elements. The use of renewable timber for the interior of the building reflects the spirit of preservation and conservation in a broader context. The timber structure consists of 680 mm x 40-20 mm x 7 m BauBuche boards machined by Tischlerei Heinke. The former coach house with its coachman lodgings, stables and hey stock now serves as a modern mixed-use premises providing living and office spaces. It has also become an object lesson for modern design and sustainable building. As if to demonstrate that we should not be held back by deference to the past, the timber construction has been designed to extend above the roof of the former coach house, adding an extra 55 m² of floor space. With this step, Gerd Priebe also wanted to optimise his security of investment, as, in his view, economic viability must always be part of meaningful restoration.
All walls, floors, ceilings, internal doors and panelling are made in BauBuche. Only the external doors and the window frames are constructed in solid spruce. A 30 cm thick beech base was installed on the new reinforced concrete floor slab and levelled with the help of laser to serve as the construction base. It carries the BauBuche elements attached to each other with galvanised steel shell screws. The BauBuche posts and beams form the supporting structure for the shell consisting of BauBuche boards measuring only 40 mm in thickness, which are installed without any further insulation. The cavities between the elements house the technical building installations. Thanks to the protecting stone shell, the internal timber construction has only thin walls, providing more useful space. The precision prefabrication of the elements on CNC milling machines at the two carpentry shops prevented wastage of material and ensured that the aesthetics of the interior is extremely pleasing. The architecture of the revived coach house is unique in so many ways. Although the floorplan of the existing structure did not lend itself to a minimalist room concept, the designer achieved stunning simplicity through a harmonious sequence of narrow and wide spaces and changing lighting.
To match the sustainable construction materials, the building is heated with carbon fleece heating elements integrated into every second ceiling section and powered by electricity from sustainable sources. The system comes with large special foils that reflect the long-wave radiation heat from the carbon fleece elements into the room. This solution is much more cost-effective and sustainable than a conventional pipe-based heat distribution system with a pellet burner or heat pump. The building technology also includes a CO2-controlled, centralised ventilation system with integrated heat recovery. The elegant and efficient timber construction can also withstand the elements without the extra protection of the existing sandstone shell. Following the cradle-to-cradle principle of construction, around 85 percent of the material used in the restored coach house can be re-used or recycled. With this project, Gerd Priebe wanted once more to provide concrete answers to the challenges ahead: „In building construction, there is an urgent need for effective and integrated solutions that allow us to build in a sustainable manner for future generations,” says Gerd Priebe. He hopes that projects such as his coach house will lead the way.
– Text by Marc Wilhelm Lennartz –
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