Compressed earth block

Environmental Impact Rating

Harvesting — Negligible to Low

Site soils will have negligible impacts. Regionally sourced soil will have minimal impacts from the machinery used for excavation and handling.

If hydraulic binders are used, they are mechanically extracted from quarries and can have low to high impacts on habitat and ground and surface water contamination and flow.

Manufacturing — Negligible to Low

Human-powered presses will have negligible impacts. Hydraulic presses will have impacts from the fossil fuel use of the machinery.

Hydraulic binders like lime and portland cement are fired at extremely high temperatures and have high impacts including fossil fuel use, air and water pollution and greenhouse gas emissions.

Transportation — Negligible to High 

Sample building uses 52,833 kg of rammed earth:

49.7 MJ per km by 35 ton truck

Many CEB manufacturers bring equipment to a site and use native soil, resulting in negligible impacts. Blocks are a heavy and high-volume material and accrue impacts proportional to distance traveled. CEB tends to be used regionally, with little long distance shipping.

Installation — Negligible

Waste: Low

Biodegradable/Compostable — Unmodified soil ingredients, block offcuts, natural insulation materials.

Landfill — Cement bags, manufactured insulation offcuts.

Chart of Embodied energy & carbon

Energy Efficiency: Low to moderate

An earth block wall has a lot of thermal mass and can easily be an airtight wall system, but it has no inherent insulation value (see Thermal Mass vs. Insulation sidebar). The overall energy efficiency of a CEB wall system will be dependent on the insulation strategy. Insulation can be placed on either the interior or exterior of the wall or a double wythe system can have insulation in the center of the wall.

Insulation on either side of the wall will force a builder to create a finished surface over the insulation, which adds cost and complexity to the wall system and isolates all of the available thermal mass on one side or the other. Core insulation is more effective and leaves the blocks exposed as the finish on both sides. Unlike rammed earth walls, core insulation can be added after the walls are built, leaving many more options for the builder, including loose-fill insulation types poured between the wythes.

Material costs: Low to moderate

The basic soil mixture for blocks may be found on site or close to the building site for no or little cost. Pre-manufactured blocks can range widely in price depending on the economies of scale, with costs ranging from $1-4 per block regionally.

Labour Input: moderate to High

There are two distinct labor phases in CEB construction. Making the blocks requires excavation, movement, mixing and compressing of soil. The more mechanization in this process, the less labor required. It is also possible to purchase ready-made blocks from a supplier in some regions, which eliminates this portion of the labor from the on-site inputs of the builder. For builders who don’t want to learn about soil mixes and block making but wish to use rammed earth material, CEBs make rammed earth available as a product.

Laying up CEBs requires the same labor input as any masonry unit construction.

Skill level required for homeowners: moderate

The operation of a low-tech, manual earth block press can be learned quickly. Experimentation and research can help a novice arrive at an appropriate soil mixture.

Purpose-made block pressing machines are expensive and complicated, and this type of production is usually left to professional producers.

The laying of CEBs requires the same skill sets required for any masonry unit construction. A newcomer can learn to lay blocks, and many avenues for such training exist and would be recommended prior to tackling an entire wall system. Working with clay mortar is more forgiving than with hydraulic mortars, as working times are greatly extended.

Sourcing & availability: Easy to Difficult

Soils suitable for making earth blocks are widely available, as are the ingredients needed to amend less ideal soils.

A manual block press can be built using very basic and widely available materials. Hydraulic block presses are made by only a few companies and will need to be imported to most regions.

CEB producers are common in some regions and much less so in others. Blocks are not likely to be sold at conventional building supply stores, even in areas where they are commercially produced. Research will need to be done to locate suppliers.

Durability: moderate to High

Though compressed earth blocks do not have quite the same long history as rammed earth walls, the basic material is the same and will have very similar properties. CEBs are susceptible to degradation from wetting and freeze-thaw cycles. Blocks with stabilizers may be less vulnerable. Permeable paints and coatings can improve water resistance, as can plasters and other protective siding options. Adequate roof overhangs and proper site drainage can limit the amount of exposure to precipitation, helping durability.

Earth blocks are quite easy to repair, as new earth mix can be plastered over weathered blocks to restore appearance.

Code compliance

Commercially produced CEBs have consistent strength properties that suit codification. In some regions, CEBs are an accepted solution, and where this is not the case there are a wide range of test documents that can simplify alternative compliance applications. Because masonry unit construction is familiar and code-recognized in all jurisdictions, building officials are likely to understand the principles of the system and therefore be receptive to its use. A structural engineer’s approval may be required to validate test results and apply them to a particular design.

Indoor air quality: moderate to high

Uncontaminated earth is generally agreed to have no inherently dangerous elements and is consistent with the aims of high indoor air quality.

Soil contamination, from natural sources like radon or synthetic sources like petrochemicals, is possible, and it is wise to inspect and/or test soils before using them to build a house.

Resources for further research

Galer, Titane, Hubert Guillaud, Thierry Joffroy, Claire Norton, and Oscar Salaza. Compressed Earth Blocks: A Publication of Deutsches Zentrum Für Entwicklungstechnologien — GATE, a Division of the Deutsche Gesellschaft Für Technische Zusammenarbeit (GTZ) GmbH in Coordination with the Building Advisory Service and Information Network — BASIN. Braunschweig, Germany: Vieweg, 1995. Print.

Rael, Ronald. Earth Architecture. New York: Princeton Architectural Press, 2009. Print.

Morton, Tom. Earth Masonry: Design and Construction Guidelines. Bracknell, UK: IHS BRE, 2008. Print.

Jaquin, Paul, and Charles Augarde. Earth Building: History, Science and Conservation. Bracknell, UK: IHS BRE, 2012. Print.

Keefe, Laurence. Earth Building: Methods and Materials, Repair and Conservation. London: Taylor & Francis, 2005. Print.

Future development

CEB construction lends itself well to more widespread acceptance and use. The building process and appearance of bricks and concrete blocks is familiar, and the switch to a raw earth version takes less adaptation than other alternatives. Block presses are well-developed machines with a proven history and lend themselves to mass production of blocks. Most regions have a large enough pool of masons capable of building CEB walls to meet growing demand. Codification of CEB construction is made simpler by the manufacturing process, which can eliminate many of the variables that make other natural building systems hard to regulate.