Transformation of a Townhouse in Zollikon
Hermann Fietz’ small houses
Around 1929 the building cooparative „Allmend“ built 27 double and row houses with the architect Hermann Fietz in Zollikon. In the sense of the upcoming swiss small houses movement, they developed three-storey, scarce but functionally and very affordable homes. A house costing a maximum of 35'000.- swiss francs, depending on the size and the amount of land. They trusted in a simple yet specific structure. Thin cement stone masonry walls bear the timber structure (14x8cm). The wooden floors are directly nailed to the structure. The ceiling as well as the exterior walls were clad with 2cm thick slag plate. In this way, a good moisture content and at the same time a marginal thermal insulation could be achieved. The combination of almost membrane-like (6 to 8cm) thin inner walls and the very narrowly dimensioned windows, led to a paper-like spatial feeling.
We were fortunate to be able to deal with one of very few houses, which in the course of time was only changed slighty and very gently. The spatial structure as well as the surfaces were in the original state – which was quite a surprise given the age and the simple construction of the building. Only the attic (originally a not developed screed) was completely rebuilt in 1998 and supplemented with two large dormer windows. As part of the same modification one of the rooms in the first floor was transofrmed from bedroom to bathroom without changing size or proportion. As pleasing as the almost original state was, so challenging was the condition of the inner surfaces. The maintenance was mostly neglected for decades and most of all the slag plates proved to b e hardly sanitizable. In an intense research and a long lasting discussion with the owner we could achieve a strategy, which partly protects the existing and tries to strenghten the original ideals of the building where we have to replaces surfaces. The absolute simplicity in how things were made is really soothing from todays point of view. There are almost no layers and only very few different materials. This could be achieved in 1929 with a very intelligent approach in construction: using only materials that could fulfill multiple purposes at the same time. The project consists of a trilogy of interventions. From the radical changes in the groundfloor to the gentle restoration of the first floor to a modest yet effective coplementation of the attic. The three are held together by the same poetic directness of the transformation.
Ground floor – sculpture and collage
Joining the rooms of the ground floor to create a new openness, presents some technical but above all some formal challenges. The house was structured with walls, which, in their absolute thinness, seem to just bear the existing loads. A jump in room size and scale is fundamentally alien here and brings the risk to undermine the spatial calmness and self-evidentness of the given spaces. To handle this situation we were looking for a strategy that can both, add the new and protect the togetherness and the relaxed juxtaposition of the spatial elements. An expressive concrete sculpture standing in the middle of the groundfloor and expanding to different extents in different directions. It might surprise at firt glance by its sheer mass and geometrical complexity, but it supports the wooden ceiling, carries the loads of the upper storey, creates a fireplace and storage for firewood, zones the space in functionally and atmospherically different areas and characterizes the space with it’s materiality. With it’s mass it, above all, adds centre and weight to the house. The proportions and expressive shape are both, structural element but also sculpture. This shifts the perception of the new openness from a structural effort to a familiar side by side of elements. In order to cast the new concrete structure in a tiny house, the formwork and the pouring of the concrete had to be minutely planned. On the ground floor, besides the extensive formwork, there was only a very small passage for accessibility and the important vibration of concrete. On the upper storey, existing floors had to be temporarily opened so that the concrete could be evenly distributed in all the arms and parts of the sculpture. A rather tough mixture of white cement and broken, local limestone was sandblasted directly after the stripping , in order to reveal the typical air inclusions and to give the material more depth. It perfectly blends in the interplay of existing unsealed surfaces and materials and links to the open-pored haptic qualities of the 1929 house. The velvety and rather rough conrete body, the new oiled cement spatula floor and the uncoated lime-cement plaster meet the right tone for a self-assured but calm interpretation of the space. The existing wooden floor was cut up rather inconspiciously and reassembled in it’s geometry to a new whole. Parts of the waste were reused to restore the had-to-be-destroyed area under the concrete framework in front of the chimney. Thus, the floor is today a simplified, carpet-like element between entrance, concrete sculpture and garden facade. On the garden facade is the only externally visible intervention of the conversion. The parapet height of the living room window has been carefully adjusted. The old window sill was removed from the wall and walled at a lower height again. The relief of the side gowns were reproduced using simple wooden framework and concrete casting again.
First floor – renewal and materiality
The existing chamber structure remains intact on the first floor. Accordingly, the slag panels on the ceiling were carefully refreshed and preserves. The floors were uncovered and grinded and oiled. The new lime-cement plaster surfaces fit in with their lively and open-pored texture between the existing woodwork of doors, window frames and ceiling edge strips. The high quality of surfaces compared to todays regular synthetic materials of system-suppliers, are a real pleasure. Thus, the subtleties of light and the depth and haptics of all used materials, old and new, makes us perceive the ordinary as a quality for everyday life.
Top floor – the caravan
We added two new, 85cm deep room layers on the short sides of the storey. They regulate the overall proportions and make the appearence of the space much more calm. As in a caravan, the walls become roomy and functional. The first layer includes the steep staircase as well as a spacious warderobe and a hat compartement. Opposite, the wall contains a shower with a toilet and a lavabo as well as the new distribution of all technical installations. On the street side, a deep sideboard pushes the edge of the room further towards the gable. So the lowest walkable area of the room measures 1.50m and makes it possible to properly furniture a bed. The existing paneling, the window frames, the chimney and all new surfaces are painted in a silky white tone. This, in combination with the lively fir floor, leads to a certain calmess for the small room with many angles and edges and emphasizes the view into the properties beautiful garden.