Colmi

Densification of a backyard in Basel: an urban ensemble of apartments, small shops, town houses, studios and pavilion living in a communal courtyard.

Project: Direct commission, 2020 - ongoing
Location: Basel, Switzerland
Client: Private
Team: Shadi Rahbaran, Ursula Hürzeler, Simon Würgler(PL), Natacha Batista
Photography: Weisswert, Basel (Completion), Rahbaran Hürzeler Architekten (Construction Site)

Close to Burgfelderplatz, a dense urban ensemble of housing, small shops and studios is being created in a typical Basel backyard. The new living and working spaces are arranged along the existing courtyard walls and are realised both as conversions of existing structures and as complementary new buildings. The spatial and social centre of the project is the communal courtyard, which is equally accessible to all tenants and serves as a gathering place.  


The property at Colmarerstrasse in Basel is a perimeter block development typical of the district, with a corresponding courtyard and ancillary buildings that extend deep into the plot. 

The densely built-up plot has been shaped throughout the years by a constant increase of built volume. The area includes parts of buildings that were built at the end of the 19th century such as an overheight natural cellar for wine storage and a stable at the rear wall of the property. A front and rear building, a barn and other small extensions and additions for commercial use were constructed over the years, resulting in an almost completely overbuilt backyard space overgrown with creepers and climbing plants.  

The existing buildings were marked by a lack of maintenance, some were in decay or had already collapsed. Due to the poor conditions of the buildings, new replacements had to be planned for both the block perimeter building and the courtyard. However, the characteristic natural cellar and the horse stable were integrated into the further planning and new use. The existing, thoroughly idyllic courtyard world also served as inspiration for the design of the new buildings; this resulted in the idea of placing small-scale residential buildings along the firewalls in order to maintain the connection to the communal green courtyard. Small commercial spaces will still be present on site. There will be a store facing the street, an office space in the former wine warehouse and a residential studio space in the former horse stable.

The concept and idea of having diverse types of housing and small commercial units is for the creation of attractive living and working spaces that flourish and revolve around a communal courtyard in the middle of the city of Basel.

Filigree concrete structure meets prefabricated timber construction
The front building is designed as a slender concrete structure made of slabs and columns. Like stacked tables - and held by a stiffening core - the new structure stands between the side firewalls made of natural stone. The suspended façade facing the street is made of timber elements clad with a thin layer of metal panels and the inner façade facing the courtyard is clad with timber elements. The load-bearing elements are only a few columns, this saves material and at the same time increases the floor plan’s flexibility. Lightweight partition walls can be removed or added as required. The floor plan is thus designed either as one continuous figure or as four separate rooms.

Two residential studios are being built in the rear courtyard: the former horse stable is being converted into a two-storey open studio and in the middle of the courtyard there is a pavilion, made out of timber, which is suitable for both living and working. 

Three terraced houses in prefabricated timber construction are being built above the former wine cellar. Two concrete slabs separate the units from each other and serve as a support for the new timber structure and the existing firewall at the back, which is around 12 meters high. In the section, the cellars of the terraced houses interlock with the newly developed studio space in the existing cellar. 

The choice of mixed construction techniques such as exposed concrete and timber construction offers many advantages. Due to its specific properties, the material can react optimally and situationally to the various demanding situations and at the same time, the mixture of exposed concrete and timber structure gives the interior spaces an interesting architectural character.