How can a historic residential building be thoughtfully evolved without losing its soul?
This question marked the beginning of a special project: a classic craftsman house from 1925 was to be complemented by a two-storey timber extension. Architect and client Susanne Büchi (Kollektiv Zebra) consciously decided against a radical break in favour of respectful "adaptive reuse." Her goal was not only to preserve the established spatial structure and original materials but to translate them into a contemporary form.

"The transition between the existing building and the extension was a central part of the design. I was interested in how different spatial qualities can arise within a small footprint and how they can be connected through visual axes."

While the existing structure and characteristic strip flooring were largely preserved, a new kitchen, bathrooms, and technical updates provide a contemporary update to the building. The timber extension sets a deliberate accent: the compartmentalisedcompartmentalized old building contrasts with a generous, light-filled space.

Space shaped by values

Behind this spatial composition lie deep ecological considerations. It was about the sustainable handling of the building fabric, the use of natural materials, and - consequently - the creation of a healthy indoor climate.

"For me, design and sustainability are inseparably linked. The careful handling of what is already there and working with natural materials were integral parts of the concept from the very beginning."

The Rematter floor slab: where construction becomes atmosphere

This commitment to material honesty finds its architectural climax on the raised ground floor of the extension. The simple, rectangular room gains its special quality significantly through the ceiling construction. Here, the Rematter floor slab functions not just as a structural element, but as a space-forming element that structures and orients the room without confining it.
By executing the floor as a beam ceiling with earth infill, rather than a conventional solid timber ceiling, the designers maximized the clear room height. This creates a generosity that stands in exciting contrast to the lower-ceilinged rooms of the existing structure.

"The extension feels significantly higher and more open than the existing rooms. It is precisely this contrast that makes the transition between old and new physically tangible."

The symbiosis of the timber structure and earth brings a structural clarity that directly affects well-being. Earth not only regulates humidity but also radiates visual tranquillitytranquility.

"Earth brings a sense of permanence to the construction. The indoor climate is noticeably pleasant - even for visitors who cannot identify the material by name."

From vision to precise implementation

For this atmospheric effect to succeed, close cooperation during the planning stage was crucial. The basic structure of the ceiling was defined architecturally at an early stage and then dimensioned together with Rematter. This early involvement created a high degree of certainty -both in the structural execution and the design finesse.
The choice of the timber quality and the nuances of the earth mixtures made the ceiling an integral part of the colourcolor and material concept. Thus, the system became much more than a component: it became the face of the room.

"The ceiling is not a neutral element, but part of the architectural language. Depending on the choice of material, it can significantly control the mood of the room."

The on-site execution was handled by a local carpenter, supported by the industrial precision of the prefabricated floor slab by Rematter.

Material as an impulse generator

The fact that visible materials also have a social component is evident during every visit to the house. The Rematter ceiling draws the eye and regularly becomes a topic of conversation, as the application of earth in this form is new to many.

"Many see this type of ceiling construction for the first time and ask curiously about the benefits of earth."

This interest shows that unconventional solutions promote dialogue about the way we want to build today.

Conclusion: quality through interplay

In the end, it is the interplay of opposites that defines the quality of this project. The high, modern room with its visible timber construction and Rematter floor slabs harmonizes with the lower-ceilinged rooms and the green panellingpaneling of the old building.

"It is precisely these contrasts that create an atmosphere that is inviting, calm, and simultaneously full of tension. I love spending time here and for me, that is the most beautiful proof of successful architecture."