Hybrid construction specialist chose sustainable wood elements made from Kerto® LVL

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  • Offsite construction, Kerto LVL, Hybrid construction

The German hybrid construction specialist, Brüninghoff, has built a concrete element plant. Metsä Wood’s Kerto LVL L-panels and Kerto LVL T-studs have been used for the prefabricated non-load-bearing wall elements. Due to the high level of prefabrication, assembly times were optimised. A building shell was implemented quickly while meeting strict standards of sustainability.

On a plot of around 31,000 square metres in Heiden, Germany, a modern concrete element plant has been built for the Brüninghoff Group. It has a production area of around 17,000 square metres and in the future, it will offer space for several stationary and carousel production systems. The plant significantly expands the production capacity of the company. The manufacturing process has a sustainable focus: On one hand, resource saving concrete (R-concrete) with recycled aggregate is brought into serial production, and on the other hand, production is consistently low in emissions. Sustainability was considered as early as the planning and construction phase of the plant. The plant has been built using prefabricated elements. That is why they decided to make the exterior non-load-bearing wall elements using high-quality Kerto LVL. The elements are attached to a load-bearing concrete frame consisting of a hybrid structure.  

“The Brüninghoff Group makes prefabricated wooden elements with a particular focus on products with a very high proportion of wood products, such as laminated veneer lumber. To this end, we carefully select partners that fit our sustainability strategy and who are also reliable and dependable. Possible capacity also plays a role, of course. In this context, we chose wall elements made of Kerto LVL from Metsä Wood for our element plant,” explains André Leipold, Technical Director of Brüninghoff Holz GmbH & Co.KG.

Standard dimensions for prefabrication

Kerto LVL products are particularly suitable for prefabrication. This is because the standard product range includes beams, posts, and panels with widths of up to 2.5 metres and lengths of 23 metres, in various thicknesses. Processing and further use of Kerto LVL products are as simple as possible and require only common processing equipment and tools. Kerto LVL is also extremely material-efficient; it is needed less in volume compared to other wood materials and its strength-to-weight ratio is excellent.

“We were also impressed by the technical properties of the laminated veneer lumber. They lay the foundation for further development of our wooden-frame construction elements, so we can make the most of the potential that this construction method offers. Ultimately, we want to continue to drive innovation in this area,” says Leipold.

Tall wall element construction made of Kerto LVL

The building has 239 wall elements with a total area of around 5,000 square metres. For the elements a total of 242 cubic metres of Kerto LVL was used, of which 128 m3 were Kerto LVL L-panels and 114 m3 Kerto LVL T-studs. The 25-millimetre-thick panel is combined with a structure made from 45 millimetre-thick and 180-millimetre-high Kerto LVL T-studs. These have a separation of 625 millimetres. The resulting intermediate spaces are insulated using a total of 780 cubic metres of blow-in insulation. In this way, the walls achieve a heat transition coefficient of 0.25 W/m2K. The exterior is a 16 millimetre-thick DWD panel.  

“According to calculations using the Metsä Wood Carbon Storage Calculator, just the Kerto LVL laminated veneer lumber used in the concrete element factory stores carbon a total of 165.8 tonnes of CO2eq. This means that in comparison to other construction materials, wood is highly sustainable,” explains Leipold.  

Kerto LVL products for Brüninghoff

Elements offer fast installation onsite

Exterior wall elements were produced at the Brüninghoff timber plant in Heiden and had a very short journey to the construction site. This short distance was a very important logistical factor, as the building used elements of the entire hall height. The elements were fastened to a concrete frame using an average of 30 screws. The Kerto LVL L-panel used in the element itself is 25 millimetres-thick and varnished white at the mill.

The natural wood structure remains visible as the panel covers the complete height of the element and therefore, does not have to be broken up into pieces. There are no visual disruptive breaks, otherwise, these would have to be laboriously sealed to ensure they were airtight. Only the vertical unions required Trelleborg seals to this end. This means it is possible to achieve an attractive surface quickly with the panels. The exterior DWD panel has a substructure for façade cladding. Trapezoidal profiles in dark grey were used and screwed into place in the recessed bead at the construction site.

Interior side of Kerto LVL wall element

A focus on sustainability

“The Brüninghoff Group is pushing for a structural change through the  factory towards construction that supports circular economy. This is because the construction sector is responsible for consuming many resources. For one thing, wood makes a significant contribution to reducing the use of fossil and finite raw materials. It is also a question of optimising construction methods involving concrete, developing low-emission concepts, and backing recycling solutions”, explains Frank Steffens, Managing Director of Brüninghoff.

The concrete element factory does not just gear production towards sustainability but also develops a consistently sustainable construction concept. This is reflected in the wall element material used. Furthermore, ease of dismantling the building was also considered. In this context, the building has already received pre-certification according to the ecological, economic, and social criteria of the German Society for Sustainable Construction (DGNB).