--- title: "At six blocks a minute, earth is no longer the bottleneck" locale: "en" url: "https://irz.fr/en/articles/ose-ceb-bottleneck-en" markdown_url: "https://irz.fr/en/articles/ose-ceb-bottleneck-en.md" category: "craft" tags: ["compressed earth", "Open Source Ecology", "construction", "open hardware", "CEB", "housing"] published_at: "2026-08-26T09:05:00.000Z" author: "Hugo Marchal" translation: "https://irz.fr/fr/articles/ose-ceb-bottleneck-fr.md" --- # At six blocks a minute, earth is no longer the bottleneck OSE's open-source press can make six earth blocks a minute. At that rate, the hard part moves away from compression and into soil, handling, laying and water protection. From a distance, a compressed earth block looks elemental: soil, a mould, pressure, then a wall. Open Source Ecology's press tells a much more industrial story. OSE documents an automated hydraulic machine that can produce **six 4 × 6 × 12 inch blocks per minute** with the appropriate hydraulic flow.[2](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) In 2021 the organization announced a return to compressed earth blocks for its Seed Eco-Home while US lumber prices were soaring.[1](https://www.opensourceecology.org/back-to-compressed-earth-blocks/) The instinct is obvious: replace purchased material with soil from the site and push wall cost down. At six blocks per minute, the press finishes its own job fast enough to expose everything around it. ## The press is too fast OSE's documentation quickly breaks the image of a small press fed by two people with shovels. Its production notes are much more revealing. To sustain six blocks per minute, the organization estimates roughly **two cubic yards of soil per hour** must reach the machine through a loader, while three people collect and stack finished blocks on pallets.[2](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) Without a mechanical loader, OSE estimates that around thirty people with shovels and buckets would be needed merely to keep up with the press's demand for soil.[2](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) Compression is automated far enough that the bottleneck moves before and after the machine. > 6 BLOCKS/MIN > **The press is only one station** > - uniform soil, screened and continuously available: Upstream > - automated hydraulic compression: Press > - ejection, handling and pallets: Downstream > - laying, alignment, openings and protection: Wall > Speed up one manufacturing station and the stations that cannot keep up become obvious. That shift makes the project interesting. The earth remains local; **production becomes a logistics system**. ## 5,400 blocks OSE's wall workflow arrives at roughly **5,400 compressed earth blocks** for the Seed Eco-Home.[3](https://wiki.opensourceecology.org/wiki/Bricks_in_a_Wall) The count uses 27 wall sections at around 200 blocks each. At the nominal six-block-per-minute rate, pressing 5,400 units would represent fifteen hours of continuous machine cycles in theory. That is a production bound, not a build time: it ignores soil preparation, interruptions, quality checks, transport and laying. The distinction matters more than it first appears. At hundreds of blocks an hour, **the price of one block no longer describes wall economics**. They depend on how many people are needed around the press, how far soil, machine, pallets and wall are from one another, then how quickly the stacks can become a building envelope. OSE acknowledges the problem in its own build notes. After several rapid CEB builds, the team records that string levelling does not work well in an “extreme build” scenario and looks for faster laying methods.[3](https://wiki.opensourceecology.org/wiki/Bricks_in_a_Wall) A faster press does not give the wall faster hands. ## Soil is a feedstock “Use dirt from the site” looks almost free on paper. It is also where the idea of a universal material starts to crack. OSE states that block-height consistency depends on soil uniformity, with its dimensional tolerance assuming a consistent mixture.[2](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) Mechanical performance likewise depends on particle distribution, clay content, moisture, compaction pressure and, where used, stabilizer dosage.[4](https://www.sciencedirect.com/science/article/pii/S2352710225006242) An open, reproducible machine still does not make soil interchangeable. The material still needs sampling, screening, sometimes pulverizing, moisture adjustment and a recipe stable enough for thousands of blocks. > **Local material still has to become repeatable** > Four-step chain from raw soil to wall: preparation, compression, handling and protection > - LOCAL does not mean UNIFORM > - SOIL screen + mix > - PRESS shape + density > - HANDLE without damage > - WALL protect it > - The press standardizes shape. The build still has to standardize material and exposure. > Repeatability comes from soil preparation and control as much as from the compression machine. The pattern is familiar from digital fabrication: making a machine reproducible does not automatically make its feedstock predictable. ## Water decides Another shortcut is treating earth as a wall material that needs no supporting system. The 2025 review by Gharbage, Benmahiddine and Sebaibi notes that water exposure, whether rain or capillary rise, can weaken compressed earth blocks. Typical responses involve building geometry and material treatment: suitable foundations, overhangs, coatings or stabilization.[4](https://www.sciencedirect.com/science/article/pii/S2352710225006242) Stabilization then changes the environmental balance the material was meant to improve. Cement can raise strength and water resistance, but it also brings a higher-impact industrial material back into the mix. A 2026 study on ecological mix design for stabilized earth blocks frames the problem exactly this way: **mechanical performance, water resistance and carbon impact** have to be balanced, and different hydraulic binders shift that trade-off differently.[5](https://www.sciencedirect.com/science/article/pii/S0959652626006220) The most “natural” block is not automatically the one that survives a given climate. The most durable block is not automatically the one that preserves the best carbon advantage. ## An open machine OSE's more distinctive move sits elsewhere. The press is not only a way to make blocks: OSE publishes the mechanics, controller and substantial manufacturing documentation. The v17.08 specification records dimensions, hydraulic requirements, throughput and control logic.[2](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) That openness enables something buying finished masonry cannot: **move material production close to the build and modify the production tool itself**. It also requires real capital. In 2021 OSE advertised a fully automated press around $10,000, or roughly half that in materials for a self-build, without the hydraulic power source.[1](https://www.opensourceecology.org/back-to-compressed-earth-blocks/) OSE's specifications put the machine around 1,700 pounds and require a suitable tractor or hydraulic power unit.[2](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) Local material therefore does not mean light infrastructure. > OPEN HARDWARE > **Local material moves capital into the tool** > - capital sits with manufacturer, material travels: Bought masonry > - capital sits in press, hydraulics and preparation: On-site CEB > - soil can come from the site: Gain > - the production chain comes with it: New constraint > Open hardware does not remove infrastructure. It lets builders regain control over it. That is less romantic than “building with dirt.” For a builder, it is more useful. ## What the press reveals OSE's project is most useful when compressed earth blocks are read without nostalgia. The material can be local. The press can be open. Throughput can be high. None of those facts cancels soil preparation, labour, laying quality, water detailing or stabilization trade-offs. Instead, **a very good machine exposes those constraints**. When the press is slow, the whole build waits for blocks. When it produces six every minute, it forces attention onto everything before and after the machine. That may be the most useful lesson for a maker: speeding up one operation does not necessarily simplify a process. It simply reveals the next place where the process resists. ## References 1. [Marcin Jakubowski, Back to Compressed Earth Blocks, Open Source Ecology, May 8, 2021](https://www.opensourceecology.org/back-to-compressed-earth-blocks/) 2. [Open Source Ecology, CEB Press Intro — specifications and production flow](https://wiki.opensourceecology.org/wiki/CEB_Press_Intro) 3. [Open Source Ecology, Bricks in a Wall — Seed Eco-Home workflow and block count](https://wiki.opensourceecology.org/wiki/Bricks_in_a_Wall) 4. [Imane Gharbage, Ferhat Benmahiddine, Nassim Sebaibi, Mechanical, thermal and hydric properties of compressed earth blocks: A review, Journal of Building Engineering, 2025](https://www.sciencedirect.com/science/article/pii/S2352710225006242) 5. [Mathieu Audren et al., Strategy for ecological mix-design of stabilised compressed earth blocks, Journal of Cleaner Production, 2026](https://www.sciencedirect.com/science/article/pii/S0959652626006220)