SCL Straw-bale House
This detached house in Vicenza (Italy) is the first in town designed using straw-bales as building technique.
The project reveals an idea of architecture rooted in archetypes. Two elements, a roof and a wall, define the domestic space.
Clients in the first place asked for a conventional wooden house.
Since the house is the domain of its inhabitants, we tried together to understand what their needs were and what the priorities with an holistic approach to sustainability, design process and construction.
CLIMATE, CONTEXT, GENIUS LOCI
Design process is fundamentally rooted on the analysis of climate and the contexts. Information on ground temperature during the year; wind’s main direction and strength; sun shading over the seasons and presence of water (rain and aquifer) affects the design mindset.
Context (both at the urban scale and the neighbour) and site layout were studied in order to control external factors. Here where’re close to the city centre of Vicenza. The plot was empty, sunny and disposable. All around the place buildings have two floor maximum.
Palladio’s Rotonda is world-wide known as a definitive example of what genius loci means. Like the Rotonda is an urban residence out of town so we imagined the project. We kept in mind as icon reference the plan of the villa oriented to north as it is in facts.
TYPOLOGY, VALUES, IDEA
In a massive sea of detached houses the single object loses its attention. Plus the obsolescence of buildings and technologies around us is for us the spur to try to step aside when we go for a new design.
The main goals that the clients wanted to achieve were: privacy of their home (since the street is quite busy and there’s a parking beside the plot); specific functions related to their habits such as a big porch and a playroom; the economy in a broad sense, of architectural moves, materials, money. Main architectural value was the archetype as trend-proof horizon.
The archetype for home is shelter. You can make a shelter with a fence, a wall, a canopy; but you still can’t get a house. Starting from the house icon we tried to rotate the roof. This single move adds three more elements: a patio and two porches.
PLAN, VENTILATION, SUN SHADING, SECTION
We designed a compact ground floor on the golden section since we wanted a figure as much stable as possible. Living room faces south and looks to a patio. Rooms are in the northern part. An attic floor hosts a playroom and a guest room.
Airflow design and the good transpiration of a straw-bale wall with lime render help to avoid tools and technology. We checked natural ventilation between buildings. The perimeter wall contributes to slow down winds coming from south-west. A downwind comfort zone is on the east side of the plot.
During summer solstice the big east-west oriented roof shades over the main outdoor living areas and windows. In winter time the sun enters the rooms and lights the patio. In order to control the accuracy of design solutions we also check how much light radiation enters the house in winter solstice. Wide openings facing south let the sun fulfil the living even in december.
We asked to digital model how light’s projections in the two extreme positions of the sun over the house are. We verified the building’s behaviour with a particular attention to section. A water basin lies underneath a gravel floor supported by a steel structure. It contributes to water supply for gardening and to temper micro-climate of the patio.
BUILDING SITE, STRUCTURE, STRAW-BALES WALL
The basin and the foundations are made in reinforced concrete. Ground floor insulation is a layer of recycled crushed foam-glass on a geotextile membrane laid directly on subsoil to avoid rising damp.
Wooden structure is made for both the perimeter wall and the roof. This was our first straw-bales building so details were carefully designed with attention to junctions. We rely on literature, visits to other buildings under construction and previous experience of the constructor.
In this building we tried to reduce constructive solution to the very few that the project needed. As a single architectural entity the perimeter wall is entirely made with straw-bales. We would like to get the continuity of the perimeter and prove the versatility of the material if carefully protected. The main wooden structure is filled up with straw-bales to maximise the level of insulation. A 30mm lime render finished with silicate paint is both internal and external, it lets the whole wall transpires. The straw wall has also an high level of fire resistance, the same thickness of a C.A. wall stands less.
DETAILS, SUPERIMPOSITION, PATIO
The roof is designed like a folded sheet of paper; a metal sheet covers the roof. Wooden baseplate is filled with crushed foam-glass insulation on edge. Cross supports are made with dyneema cables.
The pitched roof is superimposed on the mass of the white wall. We strived to get a big shadow effect with glasses and black wooden panels under the cantilever porches. A narrow window lets winter light shine through the patio.
With building completion we got the feeling that it echoes some Chinese traditional garden wall. The patio is a stone garden above the basin. That hosts a non-stop natural light show.
Interiors are in direct visual and physical contact with the patio and the garden. Living room is a double high space. It connects the patio with the attic as a single and unique volume. The superimposition effect its clear also from inside.