August eco-construction of our ‘Almond house’ and earthworks

This month we focused on the cob house building and less to the other activities in the garden. We designed the house, found and moved materials, and started building the foundations of our first almond shape cob room. Meanwhile the wild boars visits became more frequent as weather is getting cooler and the first rains started.

– Cob House Design –

Materials  and Technique:  Our aim is to build with materials that we can find on the site or common local materials. This house must be easy to reproduce, the space to reuse, and the materials to retrieve in case we need to destroy it. The roof must also function as rainwater collector. The cob building  seem to be an appropriate technique for this site as clay cover all the site and is our most abundant resource for building. Construction wood is less available in such climate, but we can find recently many dead trees in the nearby pine forest. Straw is a very common product in the region. Additionally, the cob walls are adequate to regulate the high summer temperatures and windy cold winters.

Siting: For the location of the house, we compared several alternatives, that allow to not touch the trees. We tried to figure out how the orientation relative to the sun can help moderate the heat of the summer months and the cold of the windy winter. We selected criteria to consider before choosing: orientation, wind, rainwater draining, trees proximity, feeling… We were surprised how our views differ for each place and we decided to chose the place where both of us feel ok, and with the idea that later we can still build in another place.

Shape, Size and Extension: The shape of the house didn’t take us a lot of energy as we have chosen to do a round shape, more organic and stable for cob houses. The space of the construction is limited by trees and we only needed a small room, about 15m². We also imagined a second room as a future extension. The trees all around helped us find the contour of the room: we kept a small distance from the trunk and canopy, and we traced the contour that looks like an almond, the most abundant tree on the site. The ‘almond house’ has a lot of similarities with almonds: it is small, it won’t have water inside, it will be well drained and we hope it will be beautiful!

Functions and Interior Design: This room will function as a place to rest, to chill out and also as a storage place for materials. We aimed to have a quite separated sleeping and living place. Also we wanted to look toward the windows and avoid looking toward the bed when entering the room or when sitting on the small living place. Finally as we know that this design was quickly done, we wanted it to be simple and tranformable to future needs. So we decided not to make built in benches and furniture immediately.

– Cob construction –

Drainage: To drain the walls from rainwater, we choose to make a rubble trenchWe made a trench of about 50cm deep and 50cm large all along the cob walls. Our sub-soil is sandy with stones so we compacted very well with a tree trunk and water.
We ajusted the ground level so that the water can flow easily. We placed a thin layer of gravel and then compacted again. We had to choose between industrial materials like semi-flexible irrigation pipes, pvc, geotextile or more natural traditional potery tubes, stones and straw. Finally we used 100% local ecological materials. We installed our draining channel, a traditional clay gutter, that we bought directly from the potery ovens. We covered with gravel and compacted again. The draining channel drive the water entering in the foundations of the house, and release it at daylight, 5 m from the walls downhill, through an exit drain. Finding and choosing materials took us a lot of time, and we also tried to gather our own gravel stones from the surroundings, but we ended up ordering a truck of gravel. Most of local stones were a friable sandstone and even though it was too slow to collect other type of small rocks, we learned a lot about them.

Exit drain: potery tubes covered with small stones, net fabric, straw and decorative stones

Stone wall: Now, we are building our foundation stone wall with stones from an old ruin on the site. We are only at the first layer and the stone puzzle takes more time than we thought it would take. We are doing two parallel walls that we fill in between with smaller stones. The first layer won’t have any form of cement and needs to be completely stabilized with stones associations. We now feel that the room is bigger than it could be.

– Earthworks –

To complement the drainage rubble trench, in order to keep the ‘Almond room‘ dry even during the more heavy rainfall, we modified the surrounding ground profile. We made a surface draining berm parallel to the house walls.
We also made a swale uphill of the house. This swale role is to protect the house from extreme rainfall and water the surrounding vegetation, so we won’t put clay on the bottom this channel. It will not retain water as the first swale we built, but it will infiltrate in the underground levels and it will overflow towards the first swale.

– Harvest –

This month we harvested a lot of prickly pears (Opuntia cactus fruits) and few figs. These dangerous but tasty fruits are very healthy and can be transformed to a jam or syrup. We made nice liquid jams from two different varieties of opuntia cactus red and yellow fruits combing them with other fruits. Next step is to taste the salad of young pads (nopales)!


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