The building comprises a low structure for the administration, utility services and recreation rooms and an adjacent production plant with approx. 1,150 m² of floor space. The filigree load-bearing structure of trusses and columns and the runway for the overhead crane are all made entirely of BauBuche. The ground-floor offices, recreational rooms and the adjacent production facility are all fronted by large glass façades divided by columns with approximately five-metre spacing. The interior office and production workplaces are only separated by sound-absorbing glass. The uninterrupted glass front of the façade is designed to emphasise the idea of equality and inclusion within the workplace and to improve overall team performance.
Above the transparent ground floor zone, the façade is clad with slate, the region’s traditional building material. The individual façade sections are tilted vertically at a range of different angles. The angle changes the way the sunlight hits the building envelope and the play of light and shadow intensifies the relief. This gives the façade its “craggy” appearance which, together with the anthracite-coloured material, alludes to the nearby Thuringian Slate Mountains. The narrow triangles created by the inclinations are offset with steel plates in the corporate colour green – a nod to the company motto, “elobau goes green”.
BauBuche load-bearing structure
The roof of the building is supported by roof trusses made of BauBuche. This type of construction is a so-called brace truss with additional support. The elements of the truss are subjected solely to tensile and compressive stress, so the high tensile and compressive strength of BauBuche make it ideal for construction with low-profile trusses and comparatively slender components. This provides an attractive, streamlined look with sufficient headroom for the installation of tall machinery and shelving. The top chords of the trusses are flush with the hall ceiling. The roof trusses are designed with a planned camber of 36 mm in order to reduce deformations.
Plan extract: merz kley partner ZT GmbH
Truss spacing
5 m
Columns
BauBuche GL70, 300 x 280 mm
Crane runway
BauBuche GL70, 180 x 360 mm
Roof trusses
Span
25 m
System height
1800 mm
Top chords
BauBuche GL70, 180 x 280 mm
Bottom chords
BauBuche GL70, 160 x 280 mm
Diagonals
BauBuche GL70, 160 x 280 mm
Vertical members
BauBuche GL70, 100 x 280 mm
Material comparison – BauBuche GL70 with GL glulam
BauBuche GL70
BSH GL24
Top chords
180 mm x 280 mm x 25 m
240 mm x 360 mm x 25 m
Bottom chords
160 mm x 280 mm x 25 m
260 mm x 360 mm x 25 m
Diagonals
160 mm x 280 mm x 28,8 m
180 mm x 360 mm x 28,8 m
Vertical members
100 mm x 280 mm x 7,2 m
100 mm x 360 mm x 7,2 m
Material consumption per truss
3,87 m³
6,63 m³
Material saving
ca. 42%
Material costs per m³ *)
700,00 €/m³
450,00 €/m³
Material costs per truss
2709,00 EUR
2981,00 EUR
Material cost savings
ca. 10%
*) To calculate material costs, we have applied mixed prices (ex-works, without transport costs or trade margin) for a range of qualities.
The high strength values of BauBuche enabled material savings of 42% for this project, while the slender BauBuche components not only lent the building a more elegant look, but also made it possible to reduce material costs by 10%.
Truss junctions / connectors
The junctions and chord joints of the roof trusses were secured with dowels and slotted metal plate connections, with the steel parts completely embedded in the timber. This not only creates aesthetically pleasing junctions, but also considerably increases fire protection, as external steel parts lose their strength very rapidly in the event of a fire. Normally, the holes are drilled separately through the timber and the steel, which requires millimetre accuracy to ensure that timber and steel are subsequently a proper fit.
However, in this project, the problem was neatly side-stepped by using self-tapping dowels (manufacturer: SFS intec AG).
The multiple-shear steel-timber joints are created with extremely high fitting precision using a WS connector and a setting tool, The dowels are driven through both the timber components and the embedded 5-mm thick steel in a single process. We used dowels with a diameter of 7 mm.
Stiffening of the building / wind bracing
The stiffening of the building is achieved using wind bracing, which is likewise made of BauBuche GL70 beams. BauBuche GL70 beams are also used for the crane runway.
Plan extract: merz kley partner ZT GmbH
Energy supply
The new facility is a zero-energy building with the heat of the machinery being used for space heating. The CO2-neutral production is supported by photovoltaic systems on the roof and nearby open spaces, while cooling requirements are covered by a geothermal collector system.
Project images
"I would definitely recommend BauBuche, it is a beautiful material that enables construction with a streamlined, elegant look. I shall be recommending it to clients and planners for the next suitable project."
Bernhard Tritschler, Managing Director, Holzbau Amann GmbH
So how did things go with the BauBuche project and what was your experience of joining BauBuche?
The timber-framed factory in Probstzella was our first project using the new material BauBuche. Both the material and the design of the junctions using SFS dowel/slotted plate connectors were specified by the structural engineers. While it took us a bit of time to get used to the BauBuche, our experience was extremely positive and we found it very good to work with.
We have two joinery machines, a Lignamatic and a Krüsimatic, and we had no problems at all trimming the BauBuche. It didn’t take our experienced machine operator long to work out the right settings. Because the BauBuche is highly dense, we had to considerably reduce the feed. And, of course, you have to use sharp carbide tools. We also had to make allowances for the high density in other areas. To prevent splintering, we initially rough-cut the beams larger than required on our joinery machine, and then cut them accurately in a second step using a fine saw blade, also on the joinery machine, of course.
How did you get on with the self-tapping dowels from SFS?
This project was also the first time the SFS dowels were used with BauBuche. At first, we had problems with the setting tools because they did not have a powerful enough motor for the hard BauBuche. But we had great support from SFS Intec, who immediately provided us with more powerful setting tools, although we had to reduce the speed due to the material’s high density (SFS Intec recommendation for BauBuche: 1600 – 2000 rpm). We counterbored the drill holes for the self-tapping dowels on the joinery machine, as we would not have otherwise been able to completely countersink the dowels.
BauBuche is very sensitive to moisture. How did you deal with this?
That’s true. Moisture sensitivity is the central issue when assembling BauBuche. And we had to take particular care with this project because all the components are exposed. We applied the waterproofing agent Induline IL-170 from Remmers to all the beams, and also treated the end grain areas with the special waterproofer Induline SW-910. In addition to the application of these protective agents, we planned the assembly precisely to ensure that the building site was as dry as possible. We assembled three trusses every day (if the weather was dry) and immediately followed that with the roof elements. In the evening everything was covered with tarpaulins and we made sure that the final truss was completely covered at the side with an extra long tarp overhang. We followed that up the next day with an emergency roof waterproofing – to ensure that the roof was completely waterproof. Our diligence paid off because we had no problems whatsoever during assembly and no water marks on any of the BauBuche components.
