Extension in Bolzano, Italy

Office and residential development, Bolzano

In the historic centre of Bolzano, an existing building was extended by three additional storeys for office and residential use, subject to challenging inner-city constraints. Narrow streets, dense development and severely restricted access posed significant challenges for the design, planning, construction process and logistics right from the start.

Project information

Volume used: 350 m³ CLTPLUS, 50 m³ BSH

Completion: 2024

Use: Office/residential development

Project partners

Architecture: R E ARCH RossatoElenaArchitetto

Carpentry: Südtirol Haus

Steel and timber in structural harmony

The basic structural framework of the existing three-storey building is based on a steel structure that transfers the loads. The additional storey was constructed using timber framing on top of this. The combination of steel and timber enabled an efficient load-bearing structure while keeping the extension’s dead weight to a minimum.

The irregular geometry of the existing building presented a particular design challenge. To ensure a precise fit, both the building itself and the adjacent structures were digitally surveyed. This allowed all deviations to be accurately recorded and directly incorporated into the design and manufacture of the timber components.

Prefabrication as a factor in quality and efficiency

Large-format CLTPLUS elements were used for the load-bearing and space-defining elements of the extension. A key factor in the choice of this building material was, in particular, the possibility of a high degree of prefabrication. Despite the complex existing conditions, all elements were manufactured to project-specific requirements and with millimetre precision. This enabled on-site assembly to be carried out much more efficiently and to a high quality standard.

Precise logistics: the key to success

In addition to the structural requirements, the inner-city location in particular posed a logistical challenge. The confined space and restricted access required a precisely coordinated construction schedule. Thanks to a clearly defined sequence of deliveries and assembly as part of our LRO, the prefabricated components could be delivered just-in-time and assembled immediately. This avoided the need for temporary storage on site and ensured a smooth, uninterrupted assembly process, even under the demanding conditions of the city centre.

Timber construction as a means of urban infill

This project demonstrates the potential of modern timber construction within the existing urban fabric. Combining an existing steel supporting structure with a multi-storey timber extension enables cost-effective, resource-efficient and architecturally high-quality solutions, even under challenging urban planning conditions.

Rendering video of the interior space in the newly constructed extension (Arch. Rossato)