---
title: "The construction site starts in the field"
locale: "en"
url: "https://irz.fr/en/articles/architectes-producteurs-materiaux-en"
markdown_url: "https://irz.fr/en/articles/architectes-producteurs-materiaux-en.md"
category: "craft"
tags: ["architecture", "bio-based materials", "hemp", "raw earth", "craft", "construction", "supply chain"]
published_at: "2026-08-26T10:45:00.000Z"
author: "Arthur Lacoste"
translation: "https://irz.fr/fr/articles/architectes-producteurs-materiaux-fr.md"
---

# The construction site starts in the field

Some architecture practices stopped picking materials from a swatch book: they grow the hemp, press the excavated earth and formulate their own mixes. What that actually changes in how things get made.

In Edegem, on the edge of Antwerp, a regional house built for nature education carries arches made of roughly 19,000 compressed earth blocks. The building rounds off a former fort turned public park, and its material was never ordered from a supplier: the blocks were produced during a three-week open workshop, then 312 square metres of hemp-lime insulation followed on the envelope over the next two weeks. More than 150 people took part in producing those materials and building with them[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers)[5](https://www.archdaily.com/896828/regional-house-edeghem-bc-architects).

The project's architect, Brussels practice BC architects, did not pick this matter off a swatch book. They organized its manufacture: where to find it, how to process it, who trains the hands that put it in place[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers).

That shift is what deserves attention, well beyond architecture. A profession defined for a century around the act of **choosing** materials is taking back, on a few projects, the older gesture of **producing** them. Three European practices tell the story from different angles, and what they discover along the way: producing a material is not something you improvise between two drawings.

## The swatch and the field

For a long time, practising architecture meant specifying. The studio draws, writes prescriptions, and the material shows up on site with its datasheet, produced by somebody else somewhere upstream. The profession's tools frame that choice: specification databases, catalogues, samples. UK software such as NBS exists to describe every element of a building in normalized language.

Material Cultures, the London non-profit led by Paloma Gormley, Summer Islam and George Massoud, started by turning that emblematic object inside out: the materials library. Theirs fits less in a room than in supermarket crates kept permanently in circulation, one set per live project. Summer Islam calls them "live specification sets": when a client or consultant comes round, the samples come out and get handled while the writing happens[3](https://architecturetoday.co.uk/materials-library-material-cultures/).

> Illustration: Strock block of clay-rich earth and chopped straw produced by HG Matthews for internal loadbearing walls. An air-dried earth-and-straw block rated for loadbearing internal walls up to three storeys: a standard product, but from a very different chain than fired brick. Credit: [Agnese Sanvito · via Architecture Today](https://architecturetoday.co.uk/materials-library-material-cultures/).

But the library is only the visible part. The real work sits upstream, where nobody in the profession usually goes. "We try to untangle the whole ecosystem around a material and the political economy that feeds it," explains George Massoud. Where resources come from, who processes them, how they reach construction[3](https://architecturetoday.co.uk/materials-library-material-cultures/).

That sentence describes the job change precisely. Specifying means trusting a chain you never see. Producing means seeing all of it.

The persuasion work isn't trivial either. Summer Islam notes that clients now come to them because they know the kind of work the practice does; it's more often the other consultants — a cost consultant, say — who need convincing about alternative materials[3](https://architecturetoday.co.uk/materials-library-material-cultures/). Massoud adds the method: avoid siloed conversations, keep reframing material choices for different audiences, otherwise you keep having the same conversation with the same converted people[3](https://architecturetoday.co.uk/materials-library-material-cultures/).

## Twenty acres of wall

The sharpest demonstration fits inside a 100-square-metre country house with three bedrooms. In 2019, at Margent Farm — a Cambridgeshire experimental farm developing bio-plastics from hemp and flax — Practice Architecture and Material Cultures completed Flat House, designed from the start as a prototype of prefabricated hemp construction meant to scale up to larger housing[2](https://www.archdaily.com/931730/flat-house-practice-architecture-plus-material-cultures).

The scheme: prefab cassettes filled with hemp grown on 20 acres of the farm itself, about eight hectares. The panels were raised into place in two days[2](https://www.archdaily.com/931730/flat-house-practice-architecture-plus-material-cultures). Between those two dates lies an entire chain the two-day erection never shows: harvesting, separating fibre from hurd, formulating the infill, designing a cassette that accepts this material, testing, starting over.

The team went as far as the cladding. The hemp-fibre panel developed with Margent Farm binds 60–70% cellulose with a sugar-based resin made from agricultural waste — corn cob, oat hulls, bagasse. Corrugated, it wraps the house facade, its first real-world use[3](https://architecturetoday.co.uk/materials-library-material-cultures/).

> Illustration: Entrance of Flat House with corrugated hemp cladding and timber joinery. The corrugated hemp cladding was developed with Margent Farm for this project, before it existed as a product. Credit: [Oskar Proctor · via ArchDaily](https://www.archdaily.com/931730/flat-house-practice-architecture-plus-material-cultures).

Hemp didn't enter their vocabulary as dogma. A friend of Paloma Gormley who farms hemp suggested the plant as a good insulator. First real use: a self-build project in Greenwich where site constraints ruled out any scaffolding — put up a timber frame, insulate from inside. "Hempcrete answered so many problems," she recalls: thermally efficient monolithic walls able to protect the frame from fire, installed by people with no construction experience[3](https://architecturetoday.co.uk/materials-library-material-cultures/).

> **From field to cassette**
> - of hemp grown on the farm to fill the cassettes: 20 acres
> - to raise the prefab panels onto the house: 2 days
> - cellulose content in the cladding panel developed with Margent Farm: 60–70%
> Flat House, Cambridgeshire, 2019 — sources: ArchDaily, Architecture Today

What Flat House really shows is a new interface between agriculture and construction. The prefab panel is the object that lets a field become a wall without the field leaving farming time or the house leaving construction time.

## Excavated earth

In Brussels, BC architects took the logic one step further and created a dedicated structure. BC materials turns streams usually treated as waste into building matter: soil excavated from sites, agricultural by-products, demolition debris. Five activities chain together: developing materials and advising partners, making bespoke mixes, designing and prefabricating constructive systems, training contractors and craftspeople, and producing a brand of standard materials sold as Léém[4](https://bcmaterials.org/en/concept). Their services page splits it into consultancy and development, workshop and training, design and prefab[4](https://bcmaterials.org/en/concept).

Their own sales pitch, stated openly: low embodied carbon because the materials need no fossil fuels or energy-intensive processing; circularity that keeps them reversible and endlessly reusable at end of life; indoor comfort from unfired natural materials free of VOCs that regulate humidity[4](https://bcmaterials.org/en/concept). Commercial claims before any independent audit — and at least they spell out what the product has to prove.

One line from their concept page says a lot about transmission: materials stay heavy and their cultures stay local, but "our knowledge travels lightly"[4](https://bcmaterials.org/en/concept). The recipe crosses borders even when the earth doesn't.

> Illustration: Compressed earth block arches inside the Regional House in Edegem. Edegem's structural arches are compressed earth blocks from local clay; hemp-lime takes care of facade and roof insulation. Credit: [Thomas Noceto · via ArchDaily](https://www.archdaily.com/896828/regional-house-edeghem-bc-architects).

Edegem remains their most readable public demonstration: local clay becomes structure, hemp-lime becomes thermal envelope, and everything was produced in the open in front of a learning audience[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers)[5](https://www.archdaily.com/896828/regional-house-edeghem-bc-architects).

The most interesting detail sits elsewhere: in the credits of a project that isn't theirs. For the Lot 8 Design and Research Laboratory in Brussels, designed with Assemble and Atelier LUMA, BC materials appears in the credits as manufacturer[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers)[6](https://www.archdaily.com/1027190/lot-8-design-and-research-laboratory-bc-architects-and-studies-plus-assemble). Expertise born inside an architecture practice became a supplier role for other teams. That is exactly what becoming a producer means: existing as a link in somebody else's chain.

> Illustration: Lot 8 Design and Research Laboratory in Brussels, facade and outdoor space. At Lot 8, BC materials is credited as manufacturer of a project designed with Assemble and Atelier LUMA: material expertise becomes a standalone role. Credit: [Joana Luz · via ArchDaily](https://www.archdaily.com/1027190/lot-8-design-and-research-laboratory-bc-architects-and-studies-plus-assemble).

## A concrete vocabulary

Third model, almost the inverse. Studio Ossidiana grows nothing and presses no bricks. Its playground is concrete itself: swap the ingredients, shift the proportions, hand back some of the expressiveness an industry drained out of the stuff. The studio describes this research as creating a new material vocabulary — pigments, stones, sand and cement combined in different ratios[7](https://www.studio-ossidiana.com/materials-1).

Petrified Carpets is the best-known series: mineral "carpets" whose colours, textures and surface finishes shift with each formulation. The research goes further with Cast Soils, a collection borrowed from horticulture and farming: salt lick blocks for animals, hemp and charcoal storing CO2 and improving soil, expanded clay for drainage, lime in small quantities as binder, and spices replacing mineral pigments for colour. Mixtures conceived as forms of soil themselves — soils that could be farmed, transformed, cultivated, the studio says[7](https://www.studio-ossidiana.com/materials-1).

And for Art Pavilion M in Almere, the studio developed Surf and Turf terrazzo incorporating local shells and aggregates drawn from surrounding horticulture[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers)[8](https://www.archdaily.com/984744/three-floating-rooms-art-pavilion-studio-ossidiana).

> Illustration: Textured mineral surface from Studio Ossidiana's Petrified Carpets series. Petrified Carpets: each mineral carpet is a different formulation of pigments, stones, sand and cement. Credit: [Studio Ossidiana](https://www.studio-ossidiana.com/materials-1).

> Illustration: Surf and Turf terrazzo floor at Art Pavilion M in Almere. Art Pavilion M's Surf and Turf terrazzo embeds shells and aggregates from Almere's local horticulture. Credit: [Riccardo de Vecchi · via ArchDaily](https://www.archdaily.com/984744/three-floating-rooms-art-pavilion-studio-ossidiana).

At Ossidiana, material production works like a language: every project adds words. Actual manufacturing stays with specialist producers[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers), but the formulation decision — what goes into the mix and why — remains inside the studio.

## Three ways upstream

These practices are not doing the same thing, which is precisely what makes the movement readable.

> **Three ways to become a producer**
> - Territory: waste streams in, standard products out.: BC materials
> - Vertical integration, from grown field to raised panel.: Material Cultures
> - Formulate the mix, delegate the manufacturing.: Studio Ossidiana
> - Owning upstream stages that used to precede design.: The common move
> Sources: bcmaterials.org, materialcultures.org, studio-ossidiana.com, ArchDaily

BC industrializes a territory: regional waste streams in, standard products out, artisan training as a commercial activity[4](https://bcmaterials.org/en/concept). Material Cultures integrates vertically, field to panel, and adds policy and supply-chain research on top[3](https://architecturetoday.co.uk/materials-library-material-cultures/)[15](https://www.architectural-review.com/essays/letters-from-the-editor/ar-july-august-2026-industry). Ossidiana keeps hold of the language and delegates fabrication[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers).

What they share: they take on stages that normally unfold before a design project even exists. Sourcing the resource, developing the mixture, testing components, organizing fabrication[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers). In the profession's vocabulary, they walk upriver.

## Counting hands

Back to Edegem, because numbers there say something manifestos forget. 19,000 blocks in three weeks works out at roughly 900 blocks a day, with more than 150 participants[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers). Then 312 square metres of hemp-lime envelope over two more weeks[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers).

ArchDaily frames the jump well: going from sample to building raises questions of scale, consistency, fabrication and assembly. A material's dimensions ripple through structure, enclosure, finishes and construction sequence; producing it demands equipment, time, and people who know how[1](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers). None of that appears on a product datasheet.

> Illustration: Regional House Edeghem under construction, blocks and timber frame being placed. Producing Edegem's 19,000 blocks took three weeks of open workshop, plus two more weeks for the hemp-lime envelope. Credit: [Thomas Noceto · via ArchDaily](https://www.archdaily.com/896828/regional-house-edeghem-bc-architects).

Producing your own material means accepting this arithmetic. A wall ordered from a supplier arrives with working hours already paid somewhere, invisible. A wall manufactured by the project exposes all those hours — and still has to guarantee that the thousandth block matches the first.

That consistency across reproduction is the technical heart of the subject. Inventing a mix is lab work; reproducing it thousands of times through many different hands is transmission work. It's why training at BC materials isn't a nice extra but an activity listed alongside manufacturing[4](https://bcmaterials.org/en/concept), and why their workshops run year-round — Earth Discovery Days, two-day rammed-earth courses[4](https://bcmaterials.org/en/concept). At Material Cultures too, skill doesn't stay inside the agency: the practice spends part of its capacity building skills in communities and organisations[13](https://materialcultures.org/about/), while its research arm maps the land-use impact of bio-based materials and the health effects of building practices — feeding the next argument with data rather than intuition[13](https://materialcultures.org/about/).

Any maker knows this loop already: whoever makes their own clay body, recycled filament or inks learns that a recipe only counts if it survives a change of hands. These architects are rediscovering that law at building scale.

Material Cultures organizes itself around the same principle. The practice splits into architecture and design, learning and communities, research and policy — three arms for one belief that how we build shapes the world we live in[13](https://materialcultures.org/about/). Production knowledge isn't a department there. It's the spine.

## Science, still young

Now let's not claim more than the science supports. Hemp-lime is often sold as a "carbon negative" material, and the research literature urges caution on exactly that point.

A life cycle assessment published in late 2024 puts industrial hemp's footprint at about −1.72 kgCO₂e per kilo, but concludes that a hemp-lime mix only reaches carbon negativity at roughly 20% hemp by weight, and only if the lime's reabsorption of CO₂ is counted[9](https://www.sciencedirect.com/science/article/pii/S2666165924002539). In other words: the verdict depends on dosage and accounting method, not on the slogan.

Available figures put storage in the range of 110 to 180 kg of CO₂ per cubic metre of hempcrete depending on the study, counting lime-production emissions more or less carefully — and those emissions are very real[10](https://www.frontiersin.org/journals/sustainability/articles/10.3389/frsus.2024.1508940/full). The material stores carbon; processing emits some; the balance depends on the mix. Less catchy than a label, considerably more honest.

Same caution on perception. Every straw project raises rodents and fire questions, Summer Islam observes, blaming a fairy tale: "That fairy tale has a lot to answer for!" Three Little Pigs did more damage to straw than any fire ever did. Densely packed straw in prefab systems leaves no cavity and performs well in fire, she argues — but the straw cladding system dipped in clay that her practice is developing to reduce fire risk is, precisely, still being tested[3](https://architecturetoday.co.uk/materials-library-material-cultures/). The operative word: still.

Homegrown, the 2023 exhibition staged with London's Building Centre, previewed this hybrid of old craft and industrial logic: a prefabricated thatch panel sized to a thatcher's square — the trade's unit, a hundred square feet or about nine square metres — made by a master thatcher from a rye-wheat hybrid, with a lifespan of 30 to 70 years[11](https://www.ribaj.com/culture/homegrown-building-a-post-carbon-future-with-thatch-and-bio-based-materials). Around it sat a small library of grown products derived from mycelium, hemp, cob, waste clay, glass and timber, chosen to show that you can specify for performance *and* provenance at once[11](https://www.ribaj.com/culture/homegrown-building-a-post-carbon-future-with-thatch-and-bio-based-materials). A millennia-old material, put into cassettes, tested, dated. Neither nostalgia nor gimmick: product development with a craftsperson at the centre.

## Software doesn't follow

Here is the most useful contradiction in the whole file. Studios can now produce their own materials; the institutional infrastructure can't always name them.

When Material Cultures researched potential UK bio-based supply chains, the picture was "slightly depressing", in Summer Islam's words: literacy gaps at every stage of the chain. Specification software like NBS doesn't include some of these materials. Standards don't acknowledge them in places. Building Regulations don't legislate in their favour[3](https://architecturetoday.co.uk/materials-library-material-cultures/).

> Illustration: Close-up of a hempcrete wall showing the texture of the mix. Hemp-lime: a material whose performance depends on dosage, and whose regulatory recognition lags well behind practice. Credit: [Jnzl's via ArchDaily · CC BY 2.0](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers).

The British context gives the stakes their measure: construction generates about 60% of the country's waste, and 80% of timber products are imported[11](https://www.ribaj.com/culture/homegrown-building-a-post-carbon-future-with-thatch-and-bio-based-materials). Growing constructive matter locally is no designer whim — but the administrative machine meant to receive these products was calibrated for a century of industrial supply.

There's a neat irony here, spotted at Homegrown: the Building Centre itself began life ninety years ago as the Architectural Association's materials bureau[12](https://www.buildingcentre.co.uk/whats_on/exhibitions/homegrown). The institution that helped steer the profession towards the catalogue is now hosting a show about getting back out of it.

## What makers already knew

Step outside architecture. What plays out here speaks to anyone who builds something with their hands.

Produce your own material and you inherit its variance. The filament batch that snaps, clay that shrinks differently with humidity, ink that shifts tone between batches: buying standard delegates that problem, making confronts it. The three practices above chose confrontation, and their answer is identical everywhere: turn intuition into recipe, recipe into transmissible protocol, protocol into training[4](https://bcmaterials.org/en/concept).

That's the second life of craft inside a technological profession. Not a return to the past — Massoud and colleagues spend as much time on life cycle analysis and political economy as on mixes[3](https://architecturetoday.co.uk/materials-library-material-cultures/). But it recognizes that drawing an object and knowing where its matter comes from are no longer two jobs separated by an opaque supply chain.

In March 2026, the Royal Architectural Institute of Canada's international prize recognized Material Cultures, praising its "collective working model" and research-driven material innovation[14](https://raic.org/news/raic-recognizes-exceptional-firms-through-its-2026-annual-awards/). Months later came Tipping Point East: a 20,000-square-metre industrial site in London's Royal Docks shared with Yes Make and Resolve Collective for material reuse, low-carbon construction and training[15](https://www.architectural-review.com/essays/letters-from-the-editor/ar-july-august-2026-industry). From materials library to whole industrial district, the trajectory is coherent.

## Manufacturer, in the credits

One detail in this story stays with me. On Lot 8's project page, among the architects and photographers, one line credits BC materials as manufacturer[6](https://www.archdaily.com/1027190/lot-8-design-and-research-laboratory-bc-architects-and-studies-plus-assemble).

That word almost vanished from architecture credits once design and production split. It's coming back, carried by people who didn't ask for it out of nostalgia: they run LCAs, fire tests, dosage trials and training workshops. They simply found that the material they wanted didn't exist yet, and the only way to specify it was to make it exist first.

Next time a swatch book promises the perfect shade, remember Edegem: a wall can start in a field, or in a shovel of excavated earth. Somebody still has to harvest, sieve and press — and teach everyone else to do the same.

## References

1. [ArchDaily, From Selecting to Making: When Architects Become Material Producers, August 25 2026](https://www.archdaily.com/1183813/from-selecting-to-making-when-architects-become-material-producers)
2. [ArchDaily, Flat House / Practice Architecture + Material Cultures, January 13 2020](https://www.archdaily.com/931730/flat-house-practice-architecture-plus-material-cultures)
3. [Architecture Today, Materials library: Material Cultures, interview with Paloma Gormley, Summer Islam, George Massoud, December 2023](https://architecturetoday.co.uk/materials-library-material-cultures/)
4. [BC materials, Concept](https://bcmaterials.org/en/concept)
5. [ArchDaily, Regional House Edeghem / BC architects, June 25 2018](https://www.archdaily.com/896828/regional-house-edeghem-bc-architects)
6. [ArchDaily, Lot 8 Design and Research Laboratory / BC architects & studies + Assemble](https://www.archdaily.com/1027190/lot-8-design-and-research-laboratory-bc-architects-and-studies-plus-assemble)
7. [Studio Ossidiana, A New Material Vocabulary](https://www.studio-ossidiana.com/materials-1)
8. [ArchDaily, Three Floating Rooms — Art Pavilion M / Studio Ossidiana, 2022](https://www.archdaily.com/984744/three-floating-rooms-art-pavilion-studio-ossidiana)
9. [Examining the global warming potential of hempcrete mix designs, ScienceDirect, December 2024](https://www.sciencedirect.com/science/article/pii/S2666165924002539)
10. [Memari et al., In-situ measurement of residential buildings with hempcrete walls, Frontiers in Sustainability](https://www.frontiersin.org/journals/sustainability/articles/10.3389/frsus.2024.1508940/full)
11. [RIBA Journal, Pamela Buxton, Homegrown show makes a compelling case for post-carbon construction, January 26 2023](https://www.ribaj.com/culture/homegrown-building-a-post-carbon-future-with-thatch-and-bio-based-materials)
12. [The Building Centre, Homegrown: Building a Post-carbon Future, January 20 – April 15 2023](https://www.buildingcentre.co.uk/whats_on/exhibitions/homegrown)
13. [Material Cultures, About us / Learning & Communities](https://materialcultures.org/about/)
14. [RAIC, Recognizes exceptional firms through its 2026 annual awards](https://raic.org/news/raic-recognizes-exceptional-firms-through-its-2026-annual-awards/)
15. [The Architectural Review, Industry, July–August 2026](https://www.architectural-review.com/essays/letters-from-the-editor/ar-july-august-2026-industry)