Residence in Schlins
On a steep, south-facing slope in the town of Schlins in Vorarlberg – Austria’s westernmost province – stands a house and atelier belonging to Martin Rauch, a pioneer in loam construction. The loam excavated on site was used as building material, from the foundations to the roof, and for exterior walls as well as for fitting out. Loam’s versatility is astonishing: while still moist, it was utilized for the rammed-earth walls, floor assemblies and the kitchen stove. It was fired to attain a water-resistant covering for the terrace and roof, as well as ornamental ceramic tiles. The stair steps are of compacted loam reinforced with steel wire. Even the weathering of the exterior surface in the years to come has been carefully gauged.
Building with rammed earth
Thanks to the makeup of the loam available locally, almost all of the material excavated from the site could be used without additives; it only required sieving. Aided by modern formwork technology and optimal material composition, loam can be highly compacted, thereby increasing the walls’ load-bearing capacity. The earth is placed in the formwork in 12-cm-high layers and compacted with pneumatic rammers to about 8 cm (see also: DETAIL 6/2003). The surfaces are untreated. A 45-mm-thick exterior wall with two layers of 5-cm-thick reed mats and loam plaster provides sufficient thermal protection; the heating is also integrated in these walls. In loam construction, moisture protection has the highest priority. In this project, the cellar is also constructed of rammed earth and sealed with a bituminous layer. The untreated facade will undergo planned erosion: due to the optimal grain size distribution of the rammed earth and loam’s physical properties, water does not penetrate beyond the material’s surface. Fired mud bricks, also from the material excavated on site, are incorporated in the rammed-earth wall as horizontal bands. They halt the force of flowing rainwater and provide articulation for the facade. The architect testifes to the excellent indoor climate – the result of the balanced humidity and the massive building envelope.