Building with compressed-earth blocks makes sense, and not just because most of the construction materials are right under our feet. Earthen walls regulate temperatures, dampen sound, repel mold and, with the right build, they can resist earthquakes, fires and other disasters. [For more on earthen construction, please see our Q&A with Jim Hallock.]
We had heard that earthen blocks have another advantage, too, that building with them is simple. With the right blocks, building a wall can be like stacking huge Legos. To find out if that’s really the case, we turned to the earthen construction expert Adam De Jong. Adam co-founded Dwell Earth, an earthen construction firm that works with both non-profits and businesses to create functional and beautiful buildings around the world.
Dwell Earth trains organizations and communities in block making, offers design guidance and then leads them through the construction process. The company helped the machinery manufacturer Vermeer design a block press that churns out easy-to-stack interlocking bricks. With these bricks, even novice builders can erect tough, straight walls with only a little training.
There is a village near Ciudad Barrios in the mountains of eastern El Salvador where a Dwell Earth crew taught families to build their own homes. It was a sweat-equity program in which the residents worked alongside Dwell Earth’s consultants. Using pictures of key stages of the process, Adam guided us through the construction of the walls up to the roof. We’ll run a how-to guide on roof construction in a later installment.
This is how to build a two-room home from compressed-earth blocks. See an animation of this build on YouTube, and you can open the sequential plan by clicking on the image above (coming soon). For up-to-date videos and animated construction guides, please see Dwell Earth’s YouTube channel. And follow the company on Facebook for updates on its projects worldwide.
Start by testing the soil to determine attributes such as clay content. In this build, the soil had a lot of clay, so the builders mixed in some sand. Then add six to 10 percent Portland cement to weather proof the block before pressing (top left). Community members follow a pictorial guide (upper right), and we have provided a version of that in the link through the image at the top of this page. And the bricks cured for one week while wrapped in plastic and banana leaves to preserve their moisture (bottom).
Dig a foundation trench. This is an earthquake-prone area, so the foundation is deeper, at about three feet (one meter). It is filled with a layer of volcanic ash as a footer, with rock bound with concrete on top of that. Rebar set vertically in the foundation ties into the horizontal eight-inch beam shown on top. The guide strings help ensure that it is level.
A concrete layer locks in the rebar beam, which is now covered and not visible, and the vertical rebar pictured.
Tie in corners, windows, doors and inner walls.
In low-seismic areas, dry-stacking the blocks without mortar is possible, but on this build in El Salvador, the rows of blocks sandwich a slurry made of the same dirt, sand and cement mixture of which the blocks are made. Every fifth row is mortared with cement.
Novice block layers can quickly learn to build straight, level walls.
Here you can see a gray line of cement between two rows of blocks.
The arrow above points to a J bolt embedded between two rows of blocks. It will anchor the door frame.
Electrical outlets can be cut out of the blocks as shown. The three pictures of sand-colored blocks are from another build, shown here as an illustration.
Here you can see the walls of the covered porch and the two doorways into the home. The walls are nearly finished.
Here is the home nearly finished with a laminate roof and a partial coat of paint.
For an idea of how fancy you can get with earthen construction, here is the Blessman Ministries Lodge of Dreams in Limpopo, South Africa, designed and built by Dwell Earth. Photo by Jacob Sharp.
tags: compressed-earth, Compressed-Earth-Block-Home, How to...