Rammed Earth House - ZEST architecture

YEAR

2023

LOCATION

Spain

ARCHITECT

ZEST Architecture

SIZE

300 m2

In a remote olive grove with gorgeous mountain views, we created Rammed Earth House. This poetic off-the-grid house has a low carbon footprint and a reduced palette of materials: rammed earth, wood and steel. While the house adapts to the movements of the sun, the views and the Summer breezes in plan, the relationship between inside and outside defines everything else.

We designed a long horizontal volume with two separate wings (living and sleeping), connected by double height space housing entrance and study. The design stands out through careful detailing inside and outside and has a zen-like effect on the inhabitants.

To bring the landscape into the building, we used earth recycled from the excavation of the foundations and the swimming pool. We crafted this into a unique rammed earth wall that runs throughout the house. Because it creates thermal mass, the wall helps mitigate the strong temperature differences in the harsh Spanish climate.

The striking roof slopes in various directions and has wide eaves wrapped in stainless steel, protecting the inside from the sunlight and the rammed earth wall from the rain. But their wide overhang also creates an intermediary space between inside and outside, reminding of the Japanese engawa.

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The rammed earth wall forms an element that invites touch, and that changes throughout the day depending on the light. It anchors the house to the landscape and creates a unique tactile architecture. This villa is a prime example of green architecture full of bespoke detailing. For example all windows and doors are custom made to slide into the walls. As a result they allow maximum views of the landscape. All of these are paired with shutters that slide or fold away.

While the large eaves were designed to the mm to keep out the sun in the hot months, they still allow it to passively heat the house in other seasons. The result is an intermediary space between inside and outside that invites contemplation of the surrounding landscape. With its warm choice of materials, and the use of earth and stones from the site itself, this house fits entirely in the landscape, in spite of its modernity.

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A local team built the rammed earth wall over the course of a Summer. While mixing the excavated earth with sand, aggregate and lime, they also sorted it the earth into layers of different colours. After that they poured it into the formwork and rammed it to compression layer by layer. The rest of the load bearing construction is made from wood, prefabricated off site to the highest standards.

Manufacturing off site allowed for better quality control for this very remote project. It also guaranteed high insulation values and better airtightness. The house complies with Passivhaus standards, and has a ventilation system with heat recovery. Additionally a radiant floor provides heating and cooling, while a solar array on the roof of the garage provides electricity.

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Technical Data

Name: Rammed Earth House

Location: Spain

Client: Private

Budget: Undisclosed

Surface area: 300 m²

Project design: 2019-2021

Construction: Completed 2023

Architects: Co Govers, Maria Matamala, Anna Vidal, Bianca Schaub (ZEST Architecture)

Graphic documentation: ZEST Architecture

Pictures: Pol Viladoms (unless otherwise stated)

Details

In an area where most pristine rural land cannot be built upon, our clients stumbled upon an olive grove. Although the municipality allowed them to build a new house of 300 m2, it had to have a sloping tiled roof. They asked us to build them a house for year-round enjoyment of the landscape. Other than that, we had carte blanche (apart from the budget) to build a sustainable house. In this area the climate is harsh, with hot Summers and very cold Winters. Although the landscape is beautiful, it’s very remote; there is no city within 100 miles. Therefore we had to find a way to control the execution without having to be on site every week.

Concept

Because we detected a summer breeze in one location on the plot, we located the house there and oriented it so as to allow summer shading and winter passive heating. Apart from this, the views determined everything because we felt we had to create a house with a strong relationship with the stunning landscape. As a result, the house develops almost entirely over one floor with living and sleeping functions divided over two wings. Although the wings run in different directions, they meet in the middle around a volume housing the entrance and the study.

Rammed earth wall

Running through the house from one extreme to the other is a rammed earth wall, which we created with earth excavated for the pool and foundations. Rammed earth is actually an ancient technique used in Spain in the past, although it has entirely disappeared. With this wall we anchor the house to the landscape, allowing us to fully experience the landscape inside as well as outside. Apart from offering a visual experience (the wall changes throughout the day, depending on the light) this element also invites touching. As a result this house has a unique tactile architecture.

The rammed earth wall gives thermal mass to the house. This means you experience less peaks in temperature when it’s hot, while the load bearing construction is entirely made from wood. Because we prefabricated this construction off site, we had more quality control and could add high insulation and airtightness. On top of this, we designed the large windows to slide into the walls to allow uninterrupted views. These all have wooden shutters that either fold or slide.

The roof shape

To meet the roof regulations, we stretched the understanding of “sloping” to its limit by designing a sculptural roof that has just the minimum slope. The roof of each wing meets around the entrance volume, which serves as a kind of hinge. While the roof’s wide eaves wrapped in stainless steel provide protection from the sunlight, they also cover and protect the rammed earth wall. Because the eaves are paired with wooden decking and run around the perimeter of the house, we create an intermediate space between inside and outside. The Japanese “engawa” inspired this element, typically a space that is neither inside nor outside and which invites us to contemplate the landscape.

Passive House standards

We built the house to Passive House standards. It has underfloor heating and cooling as well as ventilation with heat recovery. Because the house had to be entirely off the grid, power comes from a large solar array on top of a separate garage building, some 100 meters away.