Double site visit at CARL hybrid timber high-rise project

As an innovative and sustainable hybrid timber construction project, the CARL high-rise building that ZÜBLIN is currently constructing for Baugenossenschaft Arlinger in Pforzheim is attracting considerable public interest. In the second week of December, the project received two site visits and hosted a large information event.
As the person responsible for the state of Baden-Württemberg’s timber construction campaign, Peter Hauk, the State Minister of Agriculture, Rural Affairs and Consumer Protection, visited the construction site on Friday, 9 December 2022, to find out more about the hybrid timber project. With the campaign, the state government wants to promote climate-friendly construction with wood.

Two days earlier, at the invitation of the proHolzBW initiative, a group of industry stakeholders met with the project’s creators for an informational event and a tour of the construction site. As a hub between the forestry and timber networks, proHolzBW is committed to promoting the use of wood in the state of Baden-Württemberg. The event gave architects, structural engineers, skilled trade workers and building owners a chance to learn how wood can be used today to build high-rise structures.

With its 14 storeys and a height of 45 m, the CARL hybrid timber high-rise will be one of the tallest wood buildings in Germany. As general contractor in charge of the project, ZÜBLIN Subdivision Karlsruhe plans to finish the timber construction highlight on a turnkey basis by the end of 2023. A team of experts from ZÜBLIN Timber is in charge of the extensive timber construction work currently underway.
The timber and façade modules are prefabricated industrial style at the ZÜBLIN Timber plant in Aichach. This principle simplifies and speeds up construction logistics. The prefabrication requires precise planning, however, as ZÜBLIN Timber expert Stefan Mederle, Project Manager Acquisition, and architect Peter W. Schmidt pointed out at the event. Ad hoc changes at the construction site are virtually impossible or cause significant additional work. The procedure for the building’s legal acceptance is also anything but routine. As Stefan Mederle notes, “In some places we are moving into areas that have not yet been adequately addressed by construction law.” That’s the way it is with innovative projects. Everyone involved is gaining experience that no one before has ever had. Simply because timber construction in these dimensions has never been done before.

A particularly unique feature of the CARL hybrid timber project is that the façade will also be made of wood. In order to make this possible, the building needs to be constructed in such a way that it complies with the strict fire safety regulations: each storey has a concrete ledge protruding all around it to prevent a fire from spreading. Architect Peter W. Schmidt adds: “But we also want to create good floor plans, not just an attractive wooden façade.” Except for the last two floors, each floor is divided into three flats of equal size. Timber construction is not an ecological end in itself here; it is about good architecture and modern, comfortable living.

This was echoed by Carsten von Zepelin, chairman of the board of Baugenossenschaft Arlinger: “The amount of wood used in this project allows us to save more than 2,000 t of CO₂ compared to the classic construction method. That is truly remarkable. This is only one of the defining features of CARL, however. It is our general goal to provide valuable living space while also complying with our urban development responsibility.”