Felsenburg House

Jul 23

Written by Omar Dahabra

Location: Biel/Bienne, Switzerland
Year: 2024
Architects: Sara Gelibter Architecte
Photography by: Cyril Käppeli

Felsenburg House is a project by Sara Gelibter Architecte involving the renovation and vertical extension of an existing building for an artist couple. The clients purchased the property in 2020. During the initial site visit, several critical issues emerged, which later proved pivotal in the development of the project. Only after the purchase did the owners discover that the roof was structurally unsound. What had initially been conceived as a minor interior refurbishment evolved into a complex renovation, including the addition of an entirely new floor.

The core idea of the project centres on the intersection of factors like the existing building, budget constraints, and the client’s desire to experiment with low environmental impact solutions. The building’s origins lie in the local wine industry, dating back to when Biel was still a rural village. The first nucleus was essentially a simple shed, later converted into a building serving the metal galvanising industry. Although precise data is lacking, the railway line was likely constructed during this phase: the trapezoidal shape of the extension appears to have been dictated by the presence of the tracks.
.
Originally, the building stood in a context free of railways; in the 1920s and 1930s, and then, with the arrival of the train, was expanded laterally and vertically. Subsequently, a separate volume was added, used for industrial production for about fifty years, until its transformation into a youth hostel in 1968. From that point onward, the building underwent a series of fragmented and inconsistent interventions that progressively compromised its structure: it was subdivided into small rooms, and the rhythm of the windows was altered, and in the 1980s, it suffered severe damage when it was converted into family housing. At that time, the ceiling height was raised to 2.40 metres to make the top floor habitable, and the tension rods that ensured the structural integrity of the spans were cut. The structural damage to the roof went unnoticed for over forty years, which is why the clients were unaware of it when purchasing the property.

From these critical issues emerged an opportunity to develop a radically different project. An analysis of the current regulatory framework identified the possibility of adding a floor to the building, a feature that shaped the intervention. The need to reconstruct the now precarious roof provided the chance not simply to replicate the existing form, but to imagine a completely new solution: a sort of ‘house on top of a house’, increasing the total volume and floor area and allowing for the addition of two new rooms to accommodate the clients’ activities. This transformation, clearly visible in the architectural profile of the building, gave the project a distinctive character, making it a true recognisable landmark within the village.
.
The construction method adopted, however, was dictated by practical logic: using prefabricated wood allowed the new structure to be assembled in a single day thanks to the combined use of a helicopter and on-site carpentry work. Regarding the exterior, design choices were strongly influenced by the need to protect the building from train noise. Fibre cement, made from recycled cement and wood fibres, was used because of its high sound inertia, low specific weight, and ease of installation. In addition to the use of insulating materials, the treatment of openings was also crucial: all existing windows on the railway side were closed, while the building fully opened on the other side towards the Alps.

A unique aspect of this project was the relationship established with the owners, who were open to unconventional solutions and actively participated in the design process, proposing ideas and carrying out a significant portion of the work. They took full responsibility for the ground floor, completing the flooring, painting, drywall, plasterwork, and furniture. The clients’ family has always maintained a strong connection to the construction world: the husband’s father worked in set design and lighting, while the wife’s brother is an electrician; both contributed to various aspects of the project. For the additional floor, every effort was made to reuse materials whenever possible: for example, elements from the existing kitchen were salvaged and integrated into the new living space.
.
A temporary protective structure was necessary during the roof opening, and all materials used for this structure were later reused for internal insulation. Wooden, instead of metal structures, were chosen to support the drywall. The recovered wood was also used to build an external pergola and make furniture. Finally, the inside stairs were salvaged from a theatre dismantled by the husband’s father, which coincidentally matched the building’s floor-to-floor height, creating a symbolic detail. Other prefabricated elements were transported and installed on the day of the helicopter lift. Text description by the architects.

Source: www.saragelibter.ch
Area: 280 m²

HouseSwitzerland

Haus Baden bei Wien

Rooms Without a Use