Catalan architecture: 10 buildings built with soil

BarcelonaEarth is an ancient building material that has been used all over the world. For several years, it has been gaining increasing importance in architectural firms due to all the advantages it offers. "Actually, we've always built with earth, but we abandoned it after the industrial revolution," explains Manuel Bouzas, architect and curator of the Spanish pavilion at the upcoming Venice Architecture Biennale along with his partner Roi Salgueiro. "Perhaps ten years ago it would have surprised us quite a bit, but today it doesn't, and that's because we're getting used to it. The wood"Wood, for example, is already quite established. Today, any public building or housing competition, basically, is all made of wood. It's become popular. Which also requires thinking about what comes next," says Bouzas. Thus, he predicts that other materials will also become much more common. "Other materials, such as stone and earth, may not be as popular, but they are starting to become so. And the growth potential in the coming years is extremely high. Among other reasons, because it's an omnipresent material," he adds.

Tova housing prototype in Barcelona (2022)

Institute of Advanced Architecture of Catalonia (IAAC) and 3D WASP (World's Advanced Saving Project)

This is the first 3D-printed building in Spain. One of its potential applications is to build temporary housing and settlements in humanitarian emergency situations. The clay used is local and mixed with additives and enzymes to give it sufficient elasticity. A waterproofing layer was then applied. The foundation is made of geopolymer and the roof is made of wood. Construction took seven weeks and left no residue. Tova received one of the most important awards of the New European Bauhaus, which is included in the Museu del Disseny's new long-term exhibition, Matter matters"Building is no longer synonymous with extracting and depleting, but with reactivating and connecting, turning cities and territories into repositories of discursive materialities for regeneration," says architect Olga Subirós, curator of the exhibition and member of the scientific committee of the Spanish pavilion at the Venice Architecture Biennale.

Raw Rooms (earth houses): 43 protected homes in Ibiza (2018-2022)

Peris + Toral Architects, with blocks by Fetdeterra

This is the pioneering compacted earth building in Ibiza, promoted by the Balearic Housing Institute (IBAVI). In the earth houses, Marta Peris and José Manuel Toral have continued the same idea as their wooden blocks, in which the homes are designed as a matrix of multipurpose rooms with the kitchen at the center, making the latter a more inclusive space. In this other case, compacted earth is included in the project to ensure the comfort of the inhabitants because there is no machinery that generates emissions. The earth blocks help control the high relative humidity of the site and also have good thermal inertia. Compacted earth controls humidity twice as well as wood.

Renovation of a farmhouse in Girona (2022)

Bosch Capdeferro, with wall and floor coverings from Terram

Terram is another prominent example of soil construction in Catalonia. Its origins date back to a master's degree in "sustainable earth construction" from the University of Girona, which Macari de Torres of Fetdeterra also completed. Terram specializes in flooring, cladding, and furniture. Among its most ambitious projects are the exterior and interior cladding and the 215 m2 floor.² of a farmhouse renovated by the Bosch Capdeferro studio, all made with local earth. Earth is a common material in traditional architecture, but now a "more technical vision" is needed to break new ground, as technical architect Carlos Sedeño, founder of Terram, says. "We don't seek to standardize the material, although we know that doing so gives confidence to architects and clients and complies with regulations," explains Sedeño. Therefore, his work is always personalized: "Our goal involves giving value to the earth, seeking the limits in the material and design, through texture, shape, and color, with the aim of achieving a unique and unrepeatable work."

Rehabilitation of Camping Els Alfacs in Alcanar (2017-2023)

Bajet Giramé and Julià Associate Architects (JAAS), with blogs from Fetdeterra

This work is not the result of a single project but rather a "set of architectural strategies and infrastructural interventions" that have taken shape over the years during the autumn and winter months. The use of the land takes the form of exterior rammed earth pavilions and responds to the designers' desire to connect the complex with the landscape through materials, including water-eroded concrete and wood. Furthermore, the compacted earth provides very adequate thermal comfort in facilities used in summer. This work won the 2024 FAD award in the city and landscape category. ex aequo with the square and the tourist office of the Portuguese city of Piódão, by architects João Branco and Paula del Río.

Neutral House. Esgueva Valley (Valladolid) (2020-2024)

Noro Estudio, with blogs from Fetdeterra

Architects Sergio Alonso and Ariadna Gutiérrez, with studios in Valladolid and Barcelona, ​​define this work as "a house that combines the tradition of the site and the modernity of our times." One of its distinctive features is that the rooms are arranged around six courtyards. "The house presents a clear and forceful idea: a volume enclosed on the outside, but which within hides a whole vegetal and transparent world, which must be discovered little by little," say the architects. The walls are made of compacted earth blocks to create a direct relationship with the surroundings, while the roof is made of a concrete slab. "An introverted house open to the valley landscape, to the sunset, and to the changing colors of the countryside," say Alonso and Gutiérrez.

Ca na Pau. Binissalem (Mallorca) (2024)

Munarq

The most commonly used materials in Mallorca were stone and sandstone, but in areas where there was none, they built with whatever they had, with the earth from the site. Architect Pau Ramis had seen many houses made of earth and decided to build the Ca na Pau house in Binissalem using the ballast technique; that is, a mixture of clay, with large stones, smaller stones, and gravel, mixed again with mortar or lime cement for greater strength. But this technique fell into obscurity about sixty years ago, so the Munarq studio learned it from people who had seen them work, and from the Moroccan builders who built Ca na Pau, who know how to work with these materials. In the case of this house, which will be part of the Spanish pavilion at the upcoming Venice Architecture Biennale, the process of extracting the earth, the traditional process for making a cistern, is also special. "Since they didn't excavate to build the house in the past, the cistern was made and they had another material right there," says Pau Munar.

Ivars d'Urgell City Council (2019-2024)

Made of earth

For architect Maite Sainz de Maza, this project, the result of the renovation and expansion of the town's old school, is like a manifesto, because for the first time the government has addressed the restoration of earthen built heritage. One of the challenges of such a project is finding materials absolutely compatible with traditional earth construction; furthermore, the construction can be costly and time-consuming and must be carried out by specialized teams. To address this challenge, Sainz de Maza and Macari de Torres developed another block, this time with controlled erosion. That is, the surface of the block is washed until coarse aggregates appear. Prior to this building, another emblematic project of the firm is the rehabilitation of a space at the Sorigué Foundation to exhibit Bill Viola's video. Ocean without a shore, where they made a flat roof of compacted earth for the first time.

38 homes in Palma (2020-2025)

Vivas Arquitectos, with blocks by Fetdeterra

The homes are distributed in one block of thirty and another smaller one of eight. The structure and façade are made of compacted soil, and the floors are made of wood. Spatially, the Ibavi jury highlighted the order of the layout and the "natural" way the architects resolved the corner. Unlike the Raw Houses, in this case the blogs are local. "The Raw Houses were a pilot test, and since we saw that it worked, in the next competition we committed to manufacturing the blocks with soil from the island and also making them on the island," says Sainz de la Maza. For this reason, he created a new manufacturing facility in Mallorca, after convincing the managers of a concrete block company to make it with compacted soil. "Our idea is to establish ourselves in the locations to avoid travel and carbon dioxide emissions," he emphasizes.

A100 office blog in Barcelona, ​​​​under construction

BatlleiRoig (BIR), with Hechicero blocks on the interior facades, on the terraces and in the interior lobby

The complex consists of two buildings. One is lower and lighter, made of metal and glass, which serves as the entrance to the complex and acts as a thermal regulator. The second building has eight floors and houses the compacted earth blocks, specifically in the façade cladding. "We use compacted earth because it responds to our desire to minimize the carbon dioxide footprint and incorporate innovative solutions with environmental, technical, and aesthetic value," says architect Albert Gil Margalef, the studio's CEO and one of the partners. "Furthermore, it offers excellent thermal performance, promotes energy savings, and increases interior comfort for users," he emphasizes.

La Regadora housing cooperative in the Sant Andreu barracks (Barcelona), under construction

Arqbag, with blocks from Fetdeterra

Initially, the architects had conceived this block as two separate buildings: one made of soil, wrapped in a wood-framed structure. But in an effort to make earth construction affordable and popular, they discovered they could be even more efficient by joining the two together. Thus, they constructed the building with load-bearing walls of compacted soil and wood inside the dwellings, because they wanted the compacted earth to automatically control air humidity and thermal inertia. In contrast, the exterior is made of simple sheet metal to protect it from the elements. "It's key that everyone can live in good living conditions, and we believe we have a shared responsibility for this to happen, to bring earth construction up to date technically and for it to reintegrate into buildings," says architect and Arqbag member Jordi Mitjans. "We're building at a rate of about 1,250 euros per square meter, which is very affordable. Today, these social housing units are priced at about 1,400-1,500 euros per square meter," he says.