Why Earthen Construction Is Illegible
The 74% Problem
Earthen construction doesn’t have a performance problem. It has a legibility problem.
A recent literature review by Afaha, Oguike, and Akah surveyed the global landscape of earthen building standards and found that 74% of existing codes address only a single technique. Say adobe alone, or compressed earth blocks alone, or rammed earth alone. Only 27% cover stabilized systems, where cement or lime is added to improve durability. The soil science underlying all these methods is shared. The regulatory infrastructure pretends otherwise.
This isn’t news to anyone who has actually built with earth. But seeing it quantified clarifies something practitioners feel but rarely articulate: the barrier isn’t the material. The barrier is that institutions haven’t figured out how to see the material.
The fragmentation in practice
Consider what a practitioner encounters when crossing jurisdictions. ASTM E2392, the most comprehensive American standard for earthen wall design, derives its engineering logic from concrete masonry — the hollow block construction that dominates conventional building. It thinks in terms of laboratory testing, structural calculations, engineered design. The SADC standard in Southern Africa works from the other direction entirely. Hands-on field methods where you roll a soil sample between your palms or drop it from a set height to judge moisture content and clay behaviour. Germany’s DIN 18945–18948 series, New Zealand’s NZS 4297–4299, Peru’s NTE E.080, each code defines soil classification differently, specifies different testing protocols, permits different stress values, handles seismic design with different assumptions.
None of them are wrong. All of them are incomplete.
The New Mexico Building Code was the first jurisdiction to formally approve compressed earth blocks, mandating structural testing every 5,000 blocks and a minimum compressive strength of 300 psi, roughly the pressure of a loaded pickup truck distributed across a single block face. That was a genuine advance. But it remains a provision specific to compressed earth blocks. If your project involves rammed earth walls with compressed block infill — not uncommon — you’re stitching together guidance from codes that weren’t designed to talk to each other.
Where the real damage shows
The review cites McGregor et al. (2014), who tested 48 rammed earth and compressed earth block specimens using standard durability methods: spraying water at a wall sample to simulate driven rain, dripping water onto a surface to measure absorption, soaking specimens and then testing their strength. The same material batches, tested across different laboratories, produced results varying by more than 40%. That isn’t material inconsistency. That’s measurement inconsistency. You cannot reliably specify what you cannot reliably measure, and you cannot codify what you cannot specify.
Soudani et al. (2016) found something equally troubling from the opposite direction. Engineers increasingly use software to predict how walls will handle heat and moisture over time — essential for energy performance ratings and building approvals. But when researchers compared these software predictions against actual measurements from instrumented rammed earth walls monitored over twelve months, the models underestimated the wall’s ability to absorb and release moisture by up to 18 percentage points. The software was calibrated for manufactured materials — concrete, brick, insulation — that behave predictably within narrow parameters. Earth behaves predictably too, but by its own logic, which nobody has bothered to codify properly into the tools that engineers and regulators rely on.
This is the circle. The models don’t account for earthen materials because the data doesn’t exist in the format the models require. The data doesn’t exist because no standard mandates its collection. No standard mandates it because the models haven’t demonstrated it matters. Meanwhile, builders in Fujian maintained 160-year-old rammed earth walls with soot-lime coatings, and builders across the Sahel have kept earthen structures standing for centuries through maintenance practices that no code acknowledges.
The institutional gap
The paper’s most important argument is developmental. In sub-Saharan Africa, South Asia, and Latin America — where roughly a third of the world’s population already lives in earthen structures — the absence of nationally recognized codes means governments cannot regulate or improve what is already being built. This isn’t a question of introducing a new technology. It’s a question of making an existing technology visible to the institutions that govern construction.
Cement-stabilized earth can match concrete in compressive strength. That finding, confirmed across multiple studies, should have settled the structural adequacy debate. It hasn’t, because structural adequacy isn’t the real question. The real question is institutional legibility. Whether the material fits the categories that codes, insurers, lenders, and building officials use to make decisions.
What this means for practitioners
The paper recommends a harmonized international framework covering all principal earthen systems within a single coherent structure. That’s the right long-term direction. In the near term, the practical position is defensive: know your jurisdiction’s applicable standard, understand what it covers and what it doesn’t, document your own testing rigorously, and be prepared to educate the officials you work with—expect resistance and deal with it.
If you’re working in a jurisdiction with no earthen building code, which describes most of India, for instance — ASTM E2392 and the SADC standard are the most comprehensive reference points, though they serve fundamentally different contexts. ASTM for engineered design backed by laboratory data. SADC for field-practical assessment rooted in hands-on testing. Neither alone is sufficient.
The 74% figure is worth remembering. Not because it’s surprising, but because it makes visible what we already know: earthen construction’s problem isn’t that the material is inadequate. It’s that the institutions responsible for seeing it have chosen to look through a keyhole.¹
¹ Afaha, A.U., Oguike, M.C., & Akah, U.E. (2026). Technical Considerations for Earthen Construction: A Comprehensive Study of Standards, Practices and Performance Criteria. Gaspro International Journal of Eminent Scholars, 13(2), 76–90. ISSN: 2630-7200.
