Alpine loft In the course of our work we found a wooden barn, decaying and useless, but whose demolition would have left an open, unfillable void in a decisive position in the village fabric. The structure had lost its function of sheltering cattle, as well as storing and drying hay. Instead it revealed the spatial qualities of an ancient building typology open for other uses. The envelope was built with spaces between the wooden logs to allow the natural ventilation of the hay inside. The barn carried the promise of a large sheltered space, like a rural alpine loft, following the Germanic origin of the word, Luft in German, Lucht in Dutch. The space extended, in our memories as well as through the gaps between the wooden logs, far beyond the village, to the opposite mountain slopes, high up to the alps’ pastures, to the hay fields carefully cut and combed year by year.
The split levels of the hay platforms were spatially intertwined. They offered an unexpected moment of freedom, like the empty stage of a theatre waiting for the next piece. What should the barn become? Could this interwoven spatial play and the platforms be carried over beyond the barn’s transformation? This question became our focus and program. The function wouldn’t be that of a home or holiday house, but a space for dwelling. It would serve neither as an office nor an atelier, but a retreat for calm concentrated work. We consciously and repeatedly avoided the question of the barn’s purpose in order to keep its functional openness and transparency intact.
Typology and structure Log houses have their own typologies and construction rules. The barn in Mathon corresponds to the standard type of a hay barn combined with a stable, as Walser carpenters in the canton of Graubünden have constructed them throughout the centuries. Log houses, like woven wicker baskets, are rigid structures that can be moved and punctually supported. Single elements can be replaced. Like nomad building types these structures can be taken apart and rebuilt somewhere else.
Our barn had not only lost its use but also stood on a widened road and was impeding the larger hay carts. It had to be moved back by half a meter. After the back wall was moved, the structure braced, it was then to be mounted on a few solid steel rolls with strategically positioned foundations. Then the rest of the building was excavated. Balanced on the rolls, the whole building was then mobilised by means of cables pulling it, with leveling done in mid-air. Only once the final position was reached were the new foundations built and ground-sills replaced, fixing the whole structure in place.
How can a massive wooden structure, kept open to let the wind go through, create an insulating as well as load bearing wall? We found the answer in clay, a material found all over the world with rural associations and compatible with wood. The problem was how to stabilise the log structure vertically while making the wall airtight through the seasons. The biggest deformations due to changing snow loads and the possible twisting of the free-spanning trunks were countered by inserting larch wedges vertically under the rafters and the roof beams, which would structurally activate the trunks together.
On the outer side we inserted clay and straw mortar between the logs and pressed them to close and fit the logs forming compact solid bodies. Battens with a trapezoidal section are fixed to the logs to make the bond between wood and mortar. The mortar immobilises the structure further and provides the regulating function of water protection. As it is drier than the wood, it can inhale and exhale humidity. In an extreme scenario it would play the role of a fuse; with to much water the clay would soften and eventually fall out, meaning that it could be newly mixed and inserted.
The plastic quality of clay and straw mortar makes the connections airtight although open to vapour diffusion; joints of uneven logs, cracks, fissures, twists and large-scale gaps. In today’s construction it would be equivalent to a huge silicon joint. Therefore the carpenter doesn’t need to try and make impossible adjustments to the distorted structure but can keep the right angles.
The applied clay and straw technique is called bauge in French. Straw has the role of reinforcing. Adding unwashed sand reduces the shrinking of the drying mortar. Cow manure makes it more malleable and, as we experienced, leads to more vivid surfaces. Unskilled labour inserted most of the mortar between logs, into window cavities and around log connections. In the course of a few days the open barn became a ‘house’. Patience during the curing process was essential, the shrinking clay and straw mortar were compressed further every two days. In that process new surface qualities arose, recalling the expression of handcrafted walls in Japanese temples.
